appendix 4: analysis of collated studies and updated

Appendix 4: Analysis of collated studies and updated estimates of national municipal waste composition

The combined datasets were analysed in conjunction with operational data (from WasteDataFlow) to produce updated estimates of municipal waste composition in the UK. Due to the large amounts of data collated that met the strict qualifying criteria for kerbside studies in England, the national municipal waste compositional estimates are the most robust to have been produced to date and are therefore likely to be of key interest to stakeholders.

This Appendix is structured as follows:

• Appendix 4.1: Updated national municipal waste composition estimates: introduction - approach to component categories at the primary level; analysis of variation in kerbside and HWRC waste composition;

• Appendix 4.2: Updated national composition estimates: methodology overview -methodologies and issues relating to producing compositional estimates for England

• Appendix 4.3: Composition of municipal waste streams in England - including separate compositional estimates for various municipal waste streams (i.e. kerbside, HWRC, etc);

• Appendix 4.4: Overall municipal waste composition estimates for England – including an assessment of statistical robustness and an estimate of the biodegradable content of municipal waste in England;

• Appendix 4.5: Comparison with previous municipal waste composition estimates for England and Devolved Administrations.

Many of the issues addressed in this Appendix inform the gap analysis in Appendix 6.

4.1 Updated national municipal waste composition estimates: introduction

Compositional data from all collated district-level studies were converted into a consistent set of primary compositional categories, in order to perform further analysis across the combined datasets (see Appendix 4.1.1 below). Using the primary category summaries for each qualifying study, the variability of composition was explored for the kerbside residual and recyclable waste streams. The data was then used to shed further light on issues of coverage and variability of composition, as a back-check on the approach taken in Appendix 3. The need to adjust for biases in coverage through weighting the results was then considered (see Appendix 4.1.2).

4.1.1 Component categorisation: primary categories Component categorisation has posed several challenges for this project, due to the different categorisation methods used across the various selected studies in line with the differing local information needs and practices of waste analysis contractors. In view of this, a relatively simplified primary category list, described in Table 4.1, has been applied for the purpose of producing national municipal waste composition estimates. Table 4.1 also notes the assumed content of biodegradable municipal waste (BMW) for each of the primary categories, in line with guidance provided by the Environment Agency.

Defra WR0119: A Review of Municipal Waste Component Analyses – APPENDIX 4 1

Table 4.1: Primary category list applied for producing national compositional estimates

CATEGORY ASSUMED BMW CONTENT

Food waste 100%

Garden waste 100%

Other organic (includes pet bedding & excrement, unidentified putrescibles) 100%

Paper 100%

Card 100%

Glass 0%

Metals 0%

Plastics 0%

Textiles (includes clothing, shoes, bed linen / duvets / pillows, handbags, soft toys) 50%

Wood 100%

Waste Electrical & Electronic Equipment (WEEE) 0%

Hazardous (excluding WEEE) 0%

Sanitary (including nappies) 50%

Furniture (likely to include a mixture of combustible and non-combustible components) 50%

Mattresses (likely to include a mixture of combustible and non-combustible components) 50%

Miscellaneous combustible (includes carpets & underlay, rubber, unclassified combustibles) 50%

Miscellaneous non-combustible (includes rubble, ash, ceramics, DIY/renovation wastes, unclassified non-combustibles) 0%

Soil (primarily soil from gardens which has been separately identified in audits of HWRC wastes) 0%

Other wastes (typically a mixture of combustible & non-combustible components; includes bric-a-brac & other re-usable items, floor tiles, composite packaging; in rare cases, some datasets also include a small element of unsorted bagged residual waste)

50%

Fines (typically <10mm or <20mm) 50%

Note: Assumed BMW content figures provided by the Environment Agency

The ‘other wastes’ category includes materials which cannot be readily classified in terms of either being combustible or non-combustible; in general, materials in this category are likely to constitute a mixture of combustible and non-combustible elements. The category list has been designed so as to minimise the types of materials that will be classified as ‘other wastes’.

Whilst most categories are, in theory, applicable across all municipal waste streams, the categories for ‘furniture’, ‘mattresses’ and ‘soil’ are more specifically related to HWRCs (and to bulky waste collections), due to the nature of wastes that are often deposited at HWRCs and the


relatively detailed categorisation associated with many of the collated studies which audited wastes taken to these sites.

Due to different approaches to categorisation employed across the compositional studies included in our analysis, there is likely to be some ‘leakage’ between categories. For example, some studies have included a separate category for ‘sanitary waste’, whilst others have not and in the latter cases it is likely that any sanitary wastes found during these audits will have been included in the miscellaneous combustibles category. Furthermore, material specific categories for recycling in WasteDataFlow (WDF) are sometimes insufficiently detailed. For example, WDF includes a ‘mixed paper and card’ category for several municipal recycling streams. In these instances, reference data has been used to split out WDF tonnages in terms of the primary category list; in this example, splitting out ‘paper’ and ‘card’ separately.

Whilst it is beyond the scope of this study to analyse municipal waste components according to a more detailed categorisation system than that shown in Table 4.1, a case study analysing plastics at a more detailed level is presented in Appendix 2. This demonstrates the scope for drilling down further into the combined datasets to address a range of policy and operational questions, whilst also highlighting some of the issues around reconciling different category lists at this level of detail. This more detailed exercise would permit a number of policy-relevant sub-sets of the data to be compiled, for example:

• the fraction of waste that is packaging;

• proportion of waste that is part of the group of materials commonly targeted for recycling;

• the split between food preparation waste / peelings and cooked food waste and what proportion is likely to be home compostable.

4.1.2 Analysis of variation in kerbside compositional datasets A more detailed discussion of some of this issues explored here is presented in Appendix 10.

In presenting a picture of the coverage of the collated district-level studies a number of different approaches can be taken to local authority classification. So far this report has used 2007 ‘Index of Multiple Deprivation’ scores and Government Office Region to portray the coverage of collated datasets. What cannot be known in advance is how good a choice these dimensions are as a means of grouping districts in ways that are most relevant to variations in waste composition. This question is important to the issue of grossing-up the collated studies to produce national estimates. A successful classification might be used to weight the collated data in order to correct for any significant biases in coverage of the collated datasets.

With the data from 120 authorities on kerbside residual waste combined with WasteDataFlow estimates of materials source-separated at kerbside for recycling and composting, it is possible to explore the effectiveness of different methods of classifying districts in terms of waste composition. One way of doing this is to perform an analysis of variance (ANOVA). This involves comparing the variation in compositional estimates within and between the different elements of the classifications. An effective way of classifying districts in terms of their compositional datasets will be one in which the variation within groups is significantly less than variation between groups. The test that is used to compute whether or not these differences are statistically significant is called the F-test (equivalent to the ‘t’-test, commonly used to compared differences between means relating to two independent samples). The F-value compares the variance between categories to that within categories. Categories that differ a lot from one another produce higher F-values and this implies that the classification highlights important differences between authorities for that particular component of the waste stream.

A classification that produces large and statistically significant F-values across a range of primary categories is likely to contain factors that are highly associated with the materials arising as waste. For instance, a simple three part classification of area types that shows significant variation in garden waste across groups might be labelled ‘urban districts’, ‘suburban districts’ and ‘rural districts’. An F-test can show how significant that variation in garden waste is, and therefore say that garden waste (kg/household/week) is highly associated with this area classification. Further analysis might reveal some of the underlying causes: such as significant differences between groups in mean garden size, housing type, population age and affluence etc.


Classifications that have been applied to local authorities when comparing waste parameters fall into four main types: regional classifications, local authority area typologies, socio-economic classifications and waste policy related (methods of kerbside waste containment, garden waste policies, collection system characteristics etc.). In order to explore the ability of different classifications to group the results of the collated kerbside datasets and potentially provide a basis for weighting the data, a simple set of classifications was chosen to represent the different ways of grouping local authorities:

1. Government Office Region ( as used in Appendix 3) 2. 2007 Index of Multiple-Deprivation (quartiles, based on IMD scores as used in Appendix

3) 3. ONS local authority area classification (modified Super Group level) 4. Classification of local authority collection systems (developed for WRAP kerbside cost

benchmarking project 2008)1. Each classification was devised so as to contain a reasonable number of districts with selected waste analyses within each cell (Table 4.2), with the exception of ‘Government Office Region’, which was left unmodified, with no regions being combined to form larger groups.

Table 4.2: Classifications of English Districts used to explore variability in kerbside primary categories

Government Office Region

Districts with no selected waste analyses

Districts with selected waste analyses

Total

E Midlands 30 10 40

Eastern 23 25 48

London 22 11 33

North East 15 8 23

North West 33 10 43

S East 44 23 67

S West 26 19 45

W Midlands 25 9 34

Yorkshire/Humber 16 5 21

Total 234 120 354

Index of Multiple Deprivation 2007

districts with no selected waste analyses

districts with selected waste analyses

Total

lowest quartile of multiple deprivation 52 37 89

2nd quartile 65 20 85

3rd quartile 61 26 87

highest quartile of multiple deprivation 56 37 93

Total 234 120 354 1 Kerbside Recycling: Indicative Costs and Performance, WRAP June 2008


Table 4.2 (continued): Classifications of English Districts used to explore variability in kerbside primary categories

Collection System Characteristics Districts with no selected waste analyses


Total

Co-mingled AWC RCV 42 26 68

Co-mingled weekly RCV 50 23 73

Kerbside sort AWC RCV 40 19 59

Kerbside sort weekly RCV 58 38 96

Other/ unclassified 44 14 58

Total 234 120 354

Area Classification Districts with no selected waste analyses


Total

London & periphery 24 11 35

Mining ex-industrial 36 18 54

Other urban 24 16 40

Prospering smaller towns 82 29 111

Prosperous non-London 35 33 68

Rural & coastal 33 13 46

Total 234 120 354 Figures 4.1 to 4.4 compare kerbside compositions (residual waste primary categories derived from waste analysis, kerbside recycling/composting derived from WDF, methods described in more detail in Appendix 4.2.1) across the four classifications. Although these charts show that there are differences across each method of grouping the 120 districts, it is difficult to discern overall patterns, although a few basic findings emerge:

• Regional differences in the quantities of primary categories collected at kerbside appear to be quite pronounced across the 120 authorities. However, there is uncertainty associated with the low number of districts with selected waste analyses representing North East, West Midlands and Yorkshire/Humber. The East Midlands and Eastern region appear to collect significantly more garden waste at the kerbside than elsewhere (2.78 versus 1.69 kg/hhld/week, t=4.2, 99.9% CI) and London and the South East collect more food waste at kerbside (4.50 versus 3.91 kg/hhld/week, t=3.9, 99.9% CI).

• More affluent districts have more waste collected at the kerbside than less affluent

districts, but within this, there are significant differences in composition. Less garden waste and more metals and textiles are associated with districts in the highest quartile of


IMD scores (all differences significant at 99.9%). The compositional studies from the quartile with the highest IMD scores (most deprived) have an average set-out of 0.61 kg/household/week of metals (likely to be mostly beverage/food cans) compared with a mean of 0.49 from districts in the lowest quartile. Quantities of food waste set out per household do not vary significantly across the IMD dimension (either in terms of per capita or per household). However, it is likely that the type of food waste does vary, with poorer households spending less on fresh food (Defra, Family Expenditure Survey): a pattern also supported by the significantly higher quantities of metal cans associated with these households. The type of food waste could be explored further by the development of secondary categories for food waste, as most of the 120 studies differentiated cooked food from food preparation waste and vegetable peelings.

• ONS area types: the data suggest that ‘rural/coastal’ districts did not collect the most

garden waste at the kerbside and that ‘prospering smaller towns’ collected significantly more. Although ‘rural/coastal’ districts have larger average garden sizes than other area types, variation in garden waste at HWRC and home composting might account for the difference. ‘Other urban’ districts with compositional data had significantly less food waste than all other area types (3.4 kg/hhld/week compared with 4.2, significant at 99% level).

The compositional estimates presented in Figures 4.1 to 4.4 refer to total kerbside arisings (residual plus recycling).


Figure 4.1: Primary kerbside compositional categories (kg/household/week) by Government Office Region

Figure 4.2: Primary kerbside compositional categories (kg/household/week) by 2007 Index of Multiple-Deprivation, grouped by quartile


Figure 4.3: Primary kerbside compositional categories (kg/household/week) by ONS area classification

Figure 4.4: Primary kerbside compositional categories (kg/household/week) by classification of local authority collection system


Some primary categories show considerably less variation across the four classifications than others. Plastics and paper both have the lowest coefficients of variation of all the primary categories (with a ratio of standard deviation to mean of 15.9% and 16.5%); whereas garden waste has the highest coefficient of variation (60%). Although the influence of collection policy on kerbside composition is evident for some materials (particularly the lower quantities of glass collected by co-mingled collections, Figure 4.4), the data suggest that for paper and plastics the quantities arising do not vary much by socio-economic gradient or regionally. However, as was discussed with food waste, the variability might be found at the secondary category level; (see Appendix 2 for secondary level case study of plastics). On the basis of the above analysis, all four classifications appear to have some merit in grouping the compositional datasets in meaningful ways. A more formal approach is provided by analysis of variance (ANOVA) tests performed on the data and summarised in the matrix in Table 4.3. All of the classifications produce significant F-values, notably:

• Government Office Region: significant F-values across all primary categories except card, glass and miscellaneous combustible. For metals and textiles, higher mean quantities per household for waste analyses in 10 districts in the North West were largely responsible for the association between these materials and region.

• IMD quartiles: significant F-values for garden waste (2.81, 95% significance level), metals (F=6.77, 99% significance level), textiles (F=5.50, 99% significance level). The latter two were again related to results from analyses in the North West region. For all other primary categories, no significant associations were found between IMD quartiles and kg/ household.

• Collection system characteristics: associations were found with glass and garden waste (fewer co-mingled systems take glass compared with kerbside-sorted, less glass captured by kerbside systems means more glass is generally taken to bring sites). The association between garden waste and system characteristics is partly due to the nature of many alternate week collections that take garden waste in the alternate week to refuse collection.

• Area classification: significant associations were found between area type and food waste, glass, metals and sanitary.

Table 4.3: ANOVA: classifications used to explore variability in primary kerbside compositional categories (residual + kerbside recycling / composting)

Classification food waste

garden waste

paper card glass metals plastics textiles sanitary misc. comb.

misc. non comb

Government Office Region 3.71 3.69 2.23

5.23 2.91 3.85 3.37

3.08

Index of Multiple Deprivation 2007

2.81

6.77

5.50

Collection System Characteristics

2.46 5.85 3.82 3.19 8.09

Area Classification 4.60 2.81

2.57 3.51

4.42 2.62

All F-values significant at the 0.05 level or higher


The complexity of the pattern of associations shown in the ANOVA results is partly explained by the correlations between different groups of primary categories. Many are significantly inter-correlated (Table 4.4); for instance, paper kg/household is positively correlated (r = 0.2 to 0.4, 99% significance level) with the main dry recyclables (except glass) and garden waste quantities are negatively correlated (r = -0.2, 95% significance level) with food waste, card, miscellaneous categories, sanitary (mainly nappies) and textiles. On the whole, the packaging categories are all positively correlated with one another, with the exception of glass, which, unlike plastics and metals, is significantly associated with collection system type (due to the co-mingled collection issue already mentioned, hence the high F-value in Table 4.3).

In an attempt to explain variations in compositional data further, a regression model was constructed to examine the extent to which the high degree of variation in garden waste could be explained by regional, waste management and area type variables. The results show that the model was able to explain about a third of the variation in kerbside collected garden waste (R2 adjusted value 33%) based on four variables: population density, local garden waste policy (kerbside collected garden waste charged or not), method of residual waste containment at the kerbside and whether the district was located in Eastern / East Midlands region or elsewhere. This modelling attempt did not include any variables to capture variation relating to quantities of garden waste taken to HWRCs or home composting activity.

A variable was tested for the number of phases associated with each compositional analysis study, but did not produce a significant improvement in the model. However, as a first attempt, the model does demonstrate that by using a combination of variables that included household, regional and waste policy variables, it was possible to make some sense of district level variations in waste composition. Although the selection of explanatory variables for other compositional categories is likely to differ (for instance, a preliminary model for metals used IMD scores and housing type variables), it is reassuring that it is possible to explain some of the significant sources of non-random variation in the kerbside compositional data.


Table 4.4: Correlation matrix for primary kerbside compositional categories

Correlations

food waste

garden waste

paper card glass metals plastics textiles sanitary misc comb

misc non

comb food waste

Pearson Correlation 1 -0.222* -0.131 -0.021 0.268** 0.039 -0.085 0.089 0.140 0.139 0.190*

Sig. (2-tailed) 0.015 0.154 0.817 0.003 0.674 0.355 0.336 0.129 0.130 0.038

garden waste

Pearson Correlation 1 0.063 -0.184* -0.003 -0.119 0.001 -0.181* -0.225* -0.184* -0.225*

Sig. (2-tailed) 0.497 0.044 0.971 0.196 0.992 0.048 0.013 0.044 0.013

paper Pearson

Correlation 1 0.261** -0.114 0.303** 0.391** 0.100 0.072 -0.013 0.091

Sig. (2-tailed) 0.004 0.214 0.001 0.000 0.280 0.435 0.890 0.323

card Pearson

Correlation 1 0.093 0.383** 0.318** 0.247** 0.167 0.213* 0.099

Sig. (2-tailed) 0.312 0.000 0.000 0.007 0.069 0.020 0.280

glass Pearson

Correlation 1 0.166 -0.007 0.061 -0.001 -0.197* 0.047

Sig. (2-tailed) 0.071 0.937 0.511 0.990 0.031 0.609

metals Pearson

Correlation 1 0.439** 0.498** 0.057 0.174 0.284**

Sig. (2-tailed) 0.000 0.000 0.533 0.058 0.002

plastics Pearson

Correlation 1 0.317** 0.290** 0.013 0.111

Sig. (2-tailed) 0.000 0.001 0.889 0.225

textiles Pearson

Correlation 1 0.118 0.200* 0.359**

Sig. (2-tailed) 0.198 0.028 0.000

sanitary Pearson

Correlation 1 0.231* 0.160

Sig. (2-tailed) 0.011 0.081

misc comb

Pearson Correlation 1 0.271**

Sig. (2-tailed) 0.003

misc non comb

Pearson Correlation

1

Sig. (2-tailed)

N 120 120 120 120 120 120 120 120 120 120 120

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).


Figure 4.5: Kerbside compositional profiles for unweighted and weighted data, comparing four different district classifications used as basis for weighting factors

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

unweighted regionally weighted collection system weighted IMD score weighted area type weighted

In terms of grouping kerbside compositional data for the purposes of adjusting biases in coverage, it is difficult to choose a single classification that works equally well for all primary categories, based on the evidence in Table 4.3. There is a chance that making an adjustment to the grossing-up procedure by weighting the data by one dimension might work better for some materials than others. For example, primary categories that are more exclusively discarded into kerbside systems (for example, food waste, plastics and sanitary) could be subject to a different set of biases in waste analysis coverage compared with materials that are less-exclusive to kerbside (e.g. garden waste, glass and card).

In order to assess the options, four different sets of weighting factors were derived from the classifications and were applied to the compositional estimates from the 120 collated kerbside studies. For each classification, the weighting factors, based on household numbers, were used to adjust for the proportion of households found in each group across all districts with qualifying compositional data against the proportion of total households in England found in each group. After the weighting factors were applied to the estimated kerbside tonnages associated with each primary category, an alternative national compositional profile was generated for each classification. The results in Figure 4.5 compare weighted % kerbside composition with the unweighted data.

Overall the weighted kerbside composition did not vary much from the unweighted estimates, with the main differences associated with garden, food, other organic and ‘miscellaneous’ categories. For example, the results weighted by region produced a lower proportion of garden waste compared with the unweighted results (largely as a result of down-weighting Eastern Region and South West, see Figure 3.7), but this was offset by an increase in ‘other waste’. The net effect was a 0.6% reduction in total BMW compared with unweighted estimates. The primary categories that produced the largest proportionate changes in the weighted data (ie the difference


compared with unweighted results in proportion to the overall share of total kerbside waste) were associated with the three miscellaneous categories:

• ‘other organic’, which, amongst other things, contains unidentified putrescible wastes (2.5% of total weight in unweighted data, on average 2.1% weighted);

• ‘miscellaneous non-combustible’ (1.4% unweighted, on average 1.6% weighted); and

• ‘other wastes’, mainly containing miscellaneous wastes that are a mix of combustible and non-combustible (2.0% unweighted, 2.3% weighted).

In view of the difficulties associated with standardising the primary categories, some of the differences between weighted and unweighted data relating to these three miscellaneous categories might relate to an association between different contractors and sorting procedures with the different classifications.

Results of the comparative weighting exercise suggest that weighting the data would have limited benefit in improving national estimates because:

• the variations generated by each weighting system are likely to be well within the confidence intervals associated with the unweighted data (an issue discussed in Appendix 4.2.2);

• the weighted data cannot be used to examine variability and confidence intervals in the same way as unweighted data,

• there is no clear choice as to which system to adopt.

4.2 Updated national composition estimates: methodology overview

The majority of data collated during this project relates to local authorities in England. Therefore the exercise of producing updated national estimates of municipal waste composition has primarily focussed on compositional estimates for England, as detailed in Appendix 4.3. Nonetheless separate estimates for the Devolved Administrations have been produced, primarily drawing on previous work, as detailed in Appendix 4.4. With this in mind, it should be noted that the issues discussed below regarding producing national compositional estimates relate primarily to England, though some of these issues are also applicable to the Devolved Administrations.

Compositional estimates for residual waste streams (or for recycling streams where WDF provides insufficient detail) have been derived through analysis of relevant datasets collated during this project. The extent and coverage of these datasets is detailed in Appendix 3. Good coverage has been achieved for kerbside and HWRC waste streams. However there are many local authorities for which data are not available (or for which collated datasets do not meet the selection criteria). To take the example of kerbside residual waste, this project has collated compositional datasets meeting the selection criteria for 120 local authorities. This represents 34% of the 354 local authorities that collect household residual waste from the kerbside in England. Datasets (meeting the selection criteria) on kerbside residual waste composition are not available for the remaining 66% of the relevant local authorities in England.

For other municipal waste streams, more limited data from compositional studies are available; for example, for bulky waste collections, municipally collected commercial waste, schools waste etc. It is nevertheless suggested that overall composition for these waste streams should be inferred from the available data. This is considered a suitable approach, since these streams account for a small proportion of overall municipal waste, and errors arising from assuming overall composition from a limited number of studies will be minimised in the context of overall municipal waste compositional estimates. Above all, ‘some data is better than none’: (i) even a misleading study of a ‘minor’ municipal waste stream is a better basis than assuming composition on a spurious basis (i.e. composition of the ‘minor’ stream assumed to be the same as overall municipal waste composition); (ii) this project has demonstrated that outputs are evidence based wherever possible, even if the evidence base will be very narrow for some of the ‘minor’ municipal waste streams.


4.2.1 WasteDataFlow and compositional estimates Updated national municipal waste compositional estimates have been produced broadly according to the methodology applied by Julian Parfitt in previous recent work. This approach is illustrated in Figure 4.6 below. In essence, this methodology involves integrating WasteDataFlow (WDF) operational data for the relevant authority (using WDF where available) and the relevant period with supporting compositional data, in particular, kerbside residual data and – where available, HWRC residual data.

This approach uses operational tonnage data wherever possible and controls for the very highly (and increasingly) significant effects on residual waste composition due to continually improving municipal recycling performance. The significance of recycling in kerbside and HWRC streams is illustrated by the fact that in England during 2006/07, recycling accounted 25% of kerbside tonnages reported to WDF, whilst for HWRCs recycling account for 50% of WDF reported tonnages.

WDF tonnages from 2006/07 have been used to produce updated compositional estimates for England, since this is the period with the best overall fit with the compositional datasets meeting the selection criteria (Appendix 3). Furthermore it has been assumed that municipal waste constitutes those waste streams that are reported in WDF, though with the exclusion of separately collected rubble.

An overview of England municipal waste tonnages reported in WDF for 2006/07 is provided in Table 4.5, which illustrates the proportion of each waste stream in relation to overall municipal waste arisings. Furthermore Table 4.5 distinguishes between those waste streams for which material specific recycling tonnages have been reported (left-hand column with percentages) and the remaining waste streams which constitute either residual waste or recycling tonnages with no material specific tonnages reported (right-hand column with percentages).

Figure 4.6: Outline methodology for calculation of UK municipal waste compositional estimates


Table 4.5: Summary of municipal waste streams reported in WDF for England 2006/07

ENGLAND 2006/07 Tonnes Material specific tonnages reported

No material specific tonnages reported

Kerbside household residual 14,050,000 48.21%Kerbside household recycling 4,656,625 15.98%HWRC household residual 2,576,000 8.84%HWRC non-household residual 270,006 0.93%HWRC recycling, excluding rubble 2,556,704 8.77%Other household residual 1,173,000 4.02%Household recycling, bring sites 665,856 2.28%Household recycling, street recycling bins 19,165 0.07%Other household recycling 77,649 0.27%Non-household residual (excluding HWRC) 2,137,994 7.34%Non-household recycling 961,000 3.30%TOTAL 29,144,000 27.10% 72.90%

As Table 4.5 shows, 27% of England’s municipal waste during 2006/07 is reported in WDF in terms of material specific tonnages. For several waste streams and material types, the level of detail provided by WDF has been insufficient and it has been necessary to estimate the breakdown of particular materials, often through reference to datasets collated by this project; these issues are discussed in Appendix 4.3.

Nonetheless, WDF is a highly valuable resource in estimating national municipal waste composition, providing operational recycling tonnages for over a quarter of the England’s municipal waste. Moreover WDF provides essential detail for assessing the composition of separate elements of national municipal waste. As noted above, recycling tonnages reported through WDF account for around 25% of kerbside collected material and 50% of materials disposed at HWRC. Calculating the overall composition of kerbside and HWRC streams must therefore be based upon combining data on recycling (from WDF tonnages) with assessments of the composition of, respectively, kerbside and HWRC residual waste.

4.2.1.1 Grossing up methods for national estimates The method for grossing up compositional estimates for municipal waste streams presented here is broadly in line with the method applied by Julian Parfitt in previous reviews. This applies in particular to the two most significant streams in municipal waste, namely kerbside and HWRC. As discussed above, this method essentially consists of combining residual waste estimates (derived from authorities for which residual waste audit data is available) with WDF recycling tonnages.

Under this method, the tonnage of the various components (Food waste, Garden waste, etc) in residual waste is estimated for each authority for which waste audit data (meeting the project’s selection criteria) is available. In the case of kerbside residual waste in England, data is available for 120 local authorities. The total estimated tonnage for each component has then been calculated (ie the total Food waste in kerbside residual across the 120 authorities, total Garden waste, etc).

These tonnages have then been grossed up by applying a conversion factor to each of the components in residual waste. In the case of kerbside residual in England, the 120 authorities accounted for 5,291,737 tonnes of residual waste, in comparison to the 14,050,000 tonnes of kerbside residual waste collected across all England authorities during 2006/07. The conversion factor applied to each component was therefore 14,050,000 / 5,291,737 = 2.66. For example, amongst the 120 authorities with residual waste audit data, Food waste consisted of an estimated 1,678,738 tonnes; so the total food waste in all kerbside residual waste in England was estimated as 1,678,738 x 2.66 = 4,457,189 tonnes.


This grossing up method provides some degree of control for varying populations across different local authorities, since more populous authorities contribute larger tonnages to the estimates for each waste component2.

The tonnages of residual waste thus estimated for each component have then been added to recycling tonnages for each component, derived from WDF tonnages for 2006/07. For example, our analysis of WDF tonnages suggests that 51,096 tonnes of food waste was collected by England authorities during 2006/07. Therefore the total food waste in all kerbside (residual + recycling) has been estimated as 4,457,189 tonnes (as per the calculation above) plus 51,096 tonnes, ie 4,508,285 tonnes. It should be borne in mind that there is some uncertainty in allocating certain WDF recycling categories to the primary categories used in this project; the case of kerbside recycling is discussed in Appendix 4.3.1.2, whilst a general discussion of the uncertainties around WDF recycling tonnages is presented in Appendix 4.4.2.

However this project has also been required to produce confidence intervals for the various components in municipal waste. The estimated tonnages for different components in residual waste described above do not represent a statistical distribution from which confidence intervals can be derived. One of the key problems is variation in recycling performance, with different materials being targeted with varying degrees of efficiency across the range of authorities included in the analysis. Therefore it is necessary to consider the overall compositional profile (residual + recycling) for kerbside and HWRC streams. In the case of kerbside, overall compositional profiles were produced for the 120 authorities for which residual waste audit data was available, and arisings of each component were expressed in terms of kg/hh/year, residual + recycling. Using kg/hh/year provides a mean of producing a statistical distribution, with each authority ‘equally weighted’. Confidence intervals were then derived for each component (Food waste, Garden waste, etc) and expressed in terms of kg/hh/year. Further comments on calculating confidence intervals are provided in Appendix 4.2.2 below and Appendix 4.4.1.

In relation to other municipal waste streams (ie aside from kerbside and HWRC streams), a simpler approach was required, due to the relative dearth of waste composition data. For residual waste streams (bulky waste collections, street cleansing, etc), mean values and confidence intervals were calculated from all the collated studies and were applied consistently across the relevant WDF residual waste tonnages for all England authorities. For recycling streams, WDF recycling tonnages were applied in order to estimate the national composition of these streams. However, as with kerbside and HWRC recycling, uncertainties arose regarding the allocation of some WDF recycling tonnages to the primary categories used in this project.

4.2.2 Assessing statistical confidence for compositional estimates In producing updated national estimates of municipal waste composition, we have attempted to assess the statistical robustness of these estimates through:

(i) interpretation of the outcomes of the analysis of district-level variation in kerbside datasets that explored different weighting scenarios (see Appendix 4.1.2);

(ii) calculating 95% confidence intervals for different components of the municipal waste stream.

In relation to the calculation of confidence intervals, it should be noted that this issue is complicated by the process of combining WDF tonnages (which theoretically do not have any statistical variation, since these are annual operational tonnages) with waste audit datasets (for which statistical variation certainly does apply). We can express this issue in crude terms by referring to Table 4.5, which shows that for England, WDF material specific tonnages relate to 27% of municipal waste. Therefore it is reasonable to assume that confidence intervals do not apply to this portion of municipal waste. For the remaining 73% England’s of municipal waste, confidence intervals can be calculated. However once overall compositional estimates are produced, the confidence intervals for this portion of municipal waste will be ‘diluted’ through, for example, combining estimates for kerbside residual waste composition with operational recycling tonnages from WDF.

2 Further discussion regarding the sizes of authorities included in the kerbside residual analysis for this project is presented in Appendix 10.


Additionally, for some of the material specific recycling categories in WDF, there is uncertainty about the breakdown of these tonnages in terms of the primary categories (Table 4.1) being used in this study. For example, WDF includes a co-mingled recycling category for several waste streams. Reference data has been used to estimate the breakdown of these categories (for instance, how much paper, card, plastics, glass, metals, etc there are in WDF co-mingled recycling tonnages). Where this process has been carried out this has introduced additional uncertainty to compositional estimates.

Issues relating to statistical confidence and categorisation of WDF recycling tonnages are detailed in Appendix 4.3 as appropriate. Refer also to Appendix 4.4 for an overview of these issues in relation to overall municipal waste composition estimates for England.


4.3 Composition of municipal waste streams in England In this Appendix we present our analyses of compositional estimates for various municipal waste streams in England. The foundation for these compositional estimates has been WDF tonnages for England during 2006/07. Therefore our analyses have been structured in the same terms in which WDF tonnages have been reported, as follows:

• Appendix 4.3.1: kerbside (household collected, residual and recycling);

• Appendix 4.3.2: HWRC (household and non-household, residual and recycling);

• Appendix 4.3.3: other household (other residual, bring sites recycling, street bins recycling, other recycling);

• Appendix 4.3.4: non-household (residual and recycling, though excluding HWRC residual and rubble recycling).

For each of these municipal waste streams we summarise the source data, outline the methodologies used to arrive at national compositional estimates, identify issues relating to data confidence and statistical robustness, and report summary results. Overall estimates of municipal waste composition for England are presented in Appendix 4.4.

It is worth bearing in mind the relative magnitude of the above mentioned municipal waste streams. The relative tonnages of different municipal waste streams in England during 2006/07 are summarised in Table 4.6, which shows that the most significant waste streams are kerbside and HWRC, which together account for 83% of England’s municipal waste. Other significant waste streams are ‘Other household residual’ (street sweepings, litter and bulky waste collections), which accounts for 4% of municipal waste; and non-household residual (mainly commercial waste collections), which accounts for nearly 7% of municipal waste. Figure 4.7 also illustrates the annual tonnages for different municipal waste streams in England in 2006/07.

Table 4.6: Tonnages for main municipal waste streams, England 2006/07

Municipal waste stream Tonnes % of all municipal waste

Kerbside household residual 14,050,000 48.2%Kerbside household recycling 4,656,625 16.0%Subtotal Kerbside 18,706,625 64.2%HWRC household residual 2,576,000 8.8%HWRC non-household residual 270,006 0.9%HWRC recycling, excluding rubble 2,556,704 8.8%Subtotal HWRC 5,402,709 18.5%Other household residual 1,173,000 4.0%Household recycling, bring sites 665,856 2.3%Household recycling, street recycling bins 19,165 0.1%Other household recycling 77,649 0.3%Subtotal other household 1,935,671 6.6%Non-household residual, excluding HWRC 2,137,994 7.3%Non-household recycling 961,000 3.3%Subtotal non-household excluding HWRC 3,098,994 10.6%TOTAL 29,144,000 100.0%


Figure 4.7: WDF reported tonnages for main municipal waste streams, England 2006/07

0

2,000,000

4,000,000

6,000,000

8,000,000

10,000,000

12,000,000

14,000,000

16,000,000

18,000,000

20,000,000

Kerbside:residual &recycling

HWRC:residual &recycling

Bulky wastecollections:

disposal(estimate)

Streetcleansing &

litter(estimate)

Bring sitesrecycling

Otherhouseholdrecycling

Non-household:residual &

recycling (exclHWRC)

Tonn

es, 2

006/

07

Residual Recycling

Note: tonnages for bulky waste collections and street cleansing litter are based on an estimated breakdown of WDF’s ‘Other household residual’ tonnages; see Appendix 4.3.3.


4.3.1 Kerbside composition estimates for England Kerbside collected household waste and recycling accounts for 64.2% of England’s municipal waste, according to WDF tonnages reported during 2006/07.

4.3.1.1 Kerbside residual waste The majority of kerbside collected household waste is residual waste, accounting for 75% of kerbside collected waste. Kerbside residual waste audits for 120 England local authorities met the selection criteria and have been included in this analysis. If it assumed that these local authorities are representative of all the 354 England local authorities that collect ‘dustbin’ waste, then the composition of kerbside residual waste in England can be estimated by taking a simple average of compositional data across all the datasets. Compositional estimates for English kerbside residual waste, calculated on this basis, are detailed in Table 4.7 and illustrated in Figure 4.8. Table 4.7 expresses the composition of kerbside residual waste in terms of tonnes during 2006/07, kilogrammes per household per year and percentage arisings.

Table 4.7: Compositional estimates for kerbside residual waste in England

Category Tonnes: England, 2006/07

Kilogrammes per household per year

Arising in kerbside residual, %

Food waste 4,457,189 207.1 31.72%Garden waste 873,263 40.6 6.22%Other organic 379,210 17.6 2.70%Paper 1,806,920 84.0 12.86%Card 730,808 34.0 5.20%Glass 685,442 31.9 4.88%Metals 477,251 22.2 3.40%Plastics 1,900,250 88.3 13.52%Textiles 517,351 24.0 3.68%Wood 152,929 7.1 1.09%WEEE 165,971 7.7 1.18%Hazardous 70,509 3.3 0.50%Sanitary 662,259 30.8 4.71%Furniture 1,034 0.0 0.01%Mattresses 0 0.0 0.00%Misc combustible 198,750 9.2 1.41%Misc non-combustible 289,643 13.5 2.06%Soil 0 0.0 0.00%Other wastes 393,763 18.3 2.80%Fines 287,459 13.4 2.05%TOTAL 14,050,000 653.0 100.00%


Figure 4.8: Compositional estimates for kerbside residual waste in England

Food waste31.7%

Garden waste6.2%

Other organic2.7%

Paper12.9%

Card5.2%

Glass4.9%

Metals3.4%

Plastics13.5%

Fines2.0%

Other wastes2.8%

Misc non-combustible2.1%Misc combustible

1.4%

Hazardous0.5%

Sanitary4.7%

WEEE1.2%

Wood1.1%

Textiles3.7%


4.3.1.2 Kerbside recycling According to WDF tonnages for England in 2006/07, recycling accounts for about 25% of all kerbside collected wastes. WDF reports kerbside recycling tonnages in a reasonable level of detail and the categories included in WDF for kerbside recycling are listed in Table 4.8 (left-hand column). The relative magnitude of each WDF component, in terms of proportion of all kerbside recycling tonnage collected is also shown in Table 4.8.

Table 4.8: WDF kerbside recycling categories in relation to this study’s primary categories

WDF recycling category Proportion of kerbside recycling

Primary category for producing national estimates

Aluminium cans 0.04% MetalsAluminium foil 0.00% MetalsAutomotive batteries 0.01% HazardousBooks 0.00% PaperBrown glass 0.23% GlassCard 0.64% CardClear glass 0.96% GlassCo mingled materials 26.08% VariousFluorescent tubes 0.00% WEEEFridges & Freezers 0.43% WEEEFurniture 0.06% FurnitureGreen glass 1.31% GlassGreen waste only 29.58% Garden wasteMineral Oil 0.00% HazardousMixed cans 1.16% MetalsMixed glass 6.81% GlassMixed paper & card 6.52% VariousOther compostable waste 8.09% VariousOther electrical goods 0.02% WEEEOther materials 0.28% Other wastesOther Scrap metal 0.19% MetalsOther White Goods 0.12% WEEEPaint 0.00% HazardousPaper 16.33% PaperPlastics 0.53% PlasticsPost consumer, non automotive batteries 0.01% HazardousSteel cans 0.15% MetalsTextiles & footwear 0.39% TextilesVegetable Oil 0.00% Food wasteWood 0.09% Wood

Table 4.8 also shows how the various WDF recycling categories match up with the primary categories being used for this study. Several of the WDF categories include more than one of the primary categories, as indicated in the yellow cells in Table 4.8. These WDF categories account for a significant proportion of kerbside recycling tonnages. The methodologies for producing recycling tonnage estimates for these categories in terms of the primary categories are detailed below.


Co-mingled materials

Of the 354 England local authorities reporting kerbside recycling tonnages to WDF in 2006/07, 184 stated a tonnage figure for the WDF category co-mingled materials3. Through cross-checking these authorities against a kerbside recycling collection classification system developed for WRAP, it was found that 116 local authorities provide co-mingled dry recycling collections to residents. The remaining authorities employ a variety of systems (kerbside sort, one or two stream, etc), but have not stated separate tonnages for the different materials collected.

In any event, tonnages for co-mingled materials clearly represent a variety of materials, most likely to be dry recyclables. A breakdown of co-mingled materials into various primary categories (Table 4.1) was estimated for each local authority. The dry recycling materials targeted by each local authority were determined through analysing data from the WRAP collection systems classifications4.

The proportion of different types of materials was determined through analysis of kerbside dry recycling audit data collated during this project, and meeting the selection criteria. A distinction was made between co-mingled and other dry recycling systems. The average proportional breakdowns of dry recyclables derived from the kerbside dry recycling audits are presented in Table 4.9.

Table 4.9: Assumed proportional breakdown of dry recyclables in WDF ‘Co-mingled materials’ kerbside recycling tonnages

Collection system type Paper Card Glass Metals Plastics Textiles

Comingled collection systems 64.4% 14.2% 3.6% 5.4% 11.4% 1.0%

Other kerbside dry recycling systems 57.6% 7.2% 26.2% 4.8% 3.5% 0.6%

The method of apportionment of WDF Co-mingled materials tonnages is illustrated in the following simple example. A local authority has reported that it collected 10,000 tonnes of Co-mingled materials during 2006/07. The WRAP collection system classification system indicates that the authority provides a kerbside sort dry recycling collection system to its residents, targeting paper and glass. Applying the assumptions in Table 4.9, the amount of paper collected would be estimated as:

(57.6% / (57.6% + 26.2%)) x 10,000 tonnes = 6,874 tonnes.

Likewise, the amount of glass collected would be estimated as:

(26.2% / (57.6% + 26.2%)) x 10,000 tonnes = 3,126 tonnes.

Mixed paper & card

The WDF Mixed paper & card has been split out into separate estimates for paper and card, on the basis of the average arisings of, respectively, paper and card found in the kerbside residual waste audits5 (meeting the selection criteria; see Appendix 3). This was found to be 72.6% paper and 27.4% card.

3 Of these 184 local authorities, 58 are members of the group of 120 local authorities for which kerbside residual waste compositional data (meeting the selection criteria) are available. 4 It was assumed that all local authorities targeted, at the least, paper, metal (i.e. cans) and textiles, apart from single stream collections, which were assumed to only collect paper. Additionally the WRAP collection system classifications identified whether each targeted card, plastics and/or glass. On this basis, an individualised collection profile was developed for each of the 184 local authorities stating Co-mingled materials tonnages in WDF. 5 An average figure was not derived from kerbside dry recycling audits, since the relative arisings of paper and card would be distorted by the degree to which different local authorities target, respectively, paper and card for recycling.


Other compostable waste

It was assumed that local authorities stating tonnages in WDF’s Other compostable waste category provide residents with a mixed garden waste collection, which also targets materials such as food waste and/or cardboard. An average breakdown of Other compostable waste was derived from the kerbside organics composting audits (meeting the selection criteria) which, due to the compositional breakdown indicated by the audits, were almost certainly referring to mixed garden waste collections. Kerbside organics composting audits for 16 local authorities met these criteria and the average composition of mixed organics found in these audits is shown in Table 4.10.

Table 4.10: Assumed proportional breakdown of mixed organics in WDF ‘Other compostable waste’ kerbside recycling tonnages

Food waste

Garden waste

Other organic Paper Card

13.6% 70.5% 3.2% 5.3% 7.4%

On the basis of the above assumptions, the estimated composition of kerbside recycling in England in 2006/07 is detailed in Table 4.11 and illustrated as a pie chart in Figure 4.4.

Table 4.11: Compositional estimates for kerbside recycling in England

Category Tonnes: KilogrEngland, 2006/07

ammes per household per year

Arising in kerbside recycling, %

Food waste 51,096 2.4 1.10%Garden waste 1,643,108 76.4 35.29%Other organic 12,118 0.6 0.26%Paper 1,828,437 85.0 39.27%Card 282,335 13.1 6.06%Glass 479,439 22.3 10.30%Metals 140,493 6.5 3.02%Plastics 142,494 6.6 3.06%Textiles 29,923 1.4 0.64%Wood 4,163 0.2 0.09%WEEE 26,564 1.2 0.57%Hazardous 773 0.0 0.02%Sanitary 0 0.0 0.00%Furniture 2,779 0.1 0.06%Mattresses 0 0.0 0.00%Misc combustible 0 0.0 0.00%Misc non-combustible 0 0.0 0.00%Soil 0 0.0 0.00%Other wastes 12,905 0.6 0.28%Fines 0 0.0 0.00%TOTAL 4,656,625 216.4 100.00%



Figure 4.9: Compositional estimates for kerbside recycling in England

Garden waste35.3%

Other organic0.3%

Paper39.3%

Card6.1%

Glass10.3%

Food waste1.1%

Plastics3.1%Metals

3.0%

Textiles0.6%

Wood0.1%

WEEE0.6%

Other wastes0.3%

4.3.1.3 All kerbside collected household waste Whilst kerbside recycling compositional estimates are available for all 354 England local authorities that reported kerbside recycling tonnages in WDF, kerbside residual compositional estimates are only available for the 120 local authorities for which kerbside residual waste audit data (meeting the selection criteria, see Appendix 3) are available. The overall composition of kerbside collected waste can be estimated for these authorities by combining estimated kerbside residual waste tonnages with the relevant kerbside recycling tonnages for each authority.

If it is assumed that these local authorities are representative of all the 354 England local authorities that collect ‘dustbin’ waste, and kerbside recycling, then the composition of all kerbside waste in England can be estimated by taking a simple average of compositional data across all 120 local authorities for which residual waste composition estimates are available. 95% confidence intervals can likewise be calculated for different components of kerbside waste, if we assume that the 120 datasets are representative of England as a whole. However these confidence intervals apply only to residual waste, and the inclusion of recyclables effectively ‘dilutes’ the confidence intervals. Compositional estimates for all kerbside waste in England, calculated on this basis, are detailed in Table 4.12 and illustrated in Figure 4.4.

Figure 4.5 illustrates the relative tonnages of different types of materials found in, respectively, kerbside residual waste and recycling. These tonnages relate to England in 2006/07, applying the compositional estimates shown in Table 4.12.

Table 4.12: Compositional estimates for all kerbside waste in England

Arisings per household, England 2006/07

95% confidence interval

95% confidence interval: LOWER BOUND

95% confidence interval: UPPER BOUND

Food waste 4,508,285 209.5 7.3 202.2 216.8Garden waste 2,516,371 116.9 12.3 104.6 129.3Other organic 391,327 18.2 2.0 16.1 20.2Paper 3,635,357 169.0 5.0 163.9 174.0Card 1,013,142 47.1 2.4 44.7 49.5Glass 1,164,881 54.1 3.5 50.7 57.6Metals 617,743 28.7 1.1 27.6 29.8Plastics 2,042,743 94.9 2.8 92.2 97.7Textiles 547,274 25.4 1.3 24.2 26.7Wood 157,092 7.3 1.1 6.2 8.4WEEE 192,535 8.9 1.0 8.0 9.9Hazardous 71,281 3.3 0.4 2.9 3.7Sanitary 662,259 30.8 2.4 28.3 33.2Furniture 3,813 0.2 0.2 0.0 0.4Mattresses 0 0.0 0.0 0.0 0.0Misc combustible 198,750 9.2 2.0 7.2 11.3Misc non-combustible 289,643 13.5 2.6 10.8 16.1Soil 0 0.0 0.0 0.0 0.0Other wastes 406,668 18.9 4.3 14.6 23.2Fines 287,459 13.4 1.6 11.8 15.0TOTAL 18,706,625 869.4 na na na

Kilogrammes per household per yearCategory Tonnes: England, 2006/07


Figure 4.10: Compositional estimates for all kerbside waste in England, kg/hh/yr in 2006/07

0 50 100 150 200 250

Fines

Other wastes

Soil

Misc non-combustible

Misc combustible

Mattresses

Furniture

Sanitary

Hazardous

WEEE

Wood

Textiles

Plastics

Metals

Glass

Card

Paper

Other organic

Garden waste

Food waste

Kg/hh/yr, England 2006/07

Note: The red “error bars” indicate 95% confidence intervals.


Figure 4.11: Estimated tonnage arisings of materials in kerbside waste, England 2006/07

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

8,000,000

9,000,000

10,000,000

11,000,000

12,000,000

13,000,000

14,000,000

15,000,000

Kerbside residual Kerbside recycling

Estim

ated

tonn

es, 2

006/

07

FinesOther wastesSoilMisc non-combustible

Misc combustibleMattressesFurnitureSanitaryHazardousWEEEWood

TextilesPlasticsMetalsGlassCardPaper

Other organicGarden wasteFood waste


4.3.2 HWRC composition estimates for England Waste and recycling material collected at HWRCs accounts for 18.5% of England’s municipal waste, according to WDF tonnages reported during 2006/07. Tonnage arisings of HWRC wastes reported in WDF for England in 2006/07 are summarised in Table 4.13. A total of 135 English local authorities reported HWRC tonnages in WDF during 2006/07; this includes several Waste Collection Authorities in London who have reported HWRC tonnages separately from their respective Waste Disposal Authorities. In these instances the Waste Disposal Authorities6 had also stated HWRC residual waste tonnages, though these did not tally with the aggregate HWRC residual waste tonnages stated by their respective Waste Collection Authorities. It was thus apparent that HWRC residual was, to a greater or lesser extent, being double counted in these London authorities. Using reference data from a HWRC best practice study carried out on behalf of the Greater London Authority by Resource Futures earlier this year7, it was determined that the HWRC residual waste tonnages stated by the Waste Collection Authorities were likely to be more reliable and therefore the HWRC residual waste tonnages stated by the relevant Waste Disposal Authorities have been excluded from the analysis presented here.

Table 4.13: Summary of HWRC tonnages reported in WDF for England, 2006/07

ENGLAND HWRCs 2006/07 Tonnes % of all HWRC wastes, excluding rubble

HWRC household residual 2,576,000 47.7%HWRC non-household residual 270,006 5.0%Subtotal HWRC residual 2,846,006 52.7%HWRC recycling, including rubble 3,074,528 56.9%Rubble separated for recycling 517,824 naSubtotal HWRC recycling, excluding rubble 2,556,704 47.3%TOTAL, excluding rubble 5,402,709 100.0%

As Table 4.13 shows, somewhat over half a million tonnes of rubble was separated at England HWRCs for recycling during 2006/07. However this material has been excluded from our analysis since this material is not regarded as municipal waste, in particular on the basis of guidance from the Environment Agency regarding the determination of the quantity of biodegradable materials in municipal wastes. Even with the exclusion of rubble, a highly significant proportion of wastes deposited at HWRCs are recycled, accounting for 49.8% of HWRC tonnage throughputs.

Having excluded separated rubble from the analysis, 50.2% of HWRC wastes constituted residual waste. A proportion of this tonnage is from non-household sources (slightly over 270,000 tonnes). HWRC residual waste from household and non-household sources has been aggregated for the purposes of this analysis, although none of the HWRC residual waste audit datasets collated by this study related specifically to HWRC non-household residual wastes. Therefore it has been assumed that the composition of HWRC non-household residual waste is the same as HWRC residual waste, though this is by no means certain.

Relatively high HWRC non-household residual waste tonnages have been reported by several authorities in London. This may well be due to many London HWRCs being located adjacent to transfer stations; and these tonnages may refer to commercial wastes accepted over weighbridges at these transfer stations, rather that at HWRCs.

Additionally, it should be noted that this study has attempted to separately categorise soil collected at HWRCs. Many of the collated HWRC compositional studies included a separate category for soil, referring to soil from gardens. However other studies did not separately identify garden soil and this material is likely to have been included either in a garden waste category, or DIY or miscellaneous non-combustibles category. Even those studies that did separately categorise garden soil may not have accounted for all of this material, since soil is often difficult to

6 East London Waste Authority, North London Waste Authority and West London Waste Authority 7 Resource Futures on behalf of the Greater London Authority, London Reuse and Recycling Centre Best Practice Guidance, 2008.


separate from other garden wastes (from shrub roots, etc). Furthermore, very few of the collated studies separately identified other types of soil, from building or DIY work and where such material was found in the audits, it is likely that these types have been included in the miscellaneous combustibles category used in this study. Therefore there is considerable uncertainty regarding the arisings of soil at HWRCs, and in other municipal waste streams.

4.3.2.1 HWRC residual waste HWRC residual waste audits for 34 English local authorities met the selection criteria8 and have been included in this analysis. If it assumed that these local authorities are representative of all the 135 England local authorities that report HWRC tonnages to WDF, then the composition of HWRC residual waste in England can be estimated by taking a simple average of compositional data across all the datasets. Compositional estimates for England HWRC residual waste, calculated on this basis, are detailed in Table 4.14 and illustrated in Figure 4.6.

Table 4.14: Compositional estimates for HWRC residual waste in England



Arising in HWRC residual, %

Food waste 100,797 4.7 3.54%Garden waste 149,447 6.9 5.25%Other organic 27,296 1.3 0.96%Paper 137,243 6.4 4.82%Card 77,045 3.6 2.71%Glass 70,137 3.3 2.46%Metals 63,585 3.0 2.23%Plastics 297,768 13.8 10.46%Textiles 128,091 6.0 4.50%Wood 430,193 20.0 15.12%WEEE 69,321 3.2 2.44%Hazardous 43,548 2.0 1.53%Sanitary 7,532 0.4 0.26%Furniture 236,962 11.0 8.33%Mattresses 68,120 3.2 2.39%Misc combustible 390,075 18.1 13.71%Misc non-combustible 425,245 19.8 14.94%Soil 51,998 2.4 1.83%Other wastes 49,024 2.3 1.72%Fines 22,579 1.0 0.79%TOTAL 2,846,006 132.3 100.00%

8 refer to Appendix 3.4, Table 3.12.


Figure 4.12: Compositional estimates for HWRC residual waste in England

Metals2.2%

Plastics10.5%

Textiles4.5%

Wood15.1%

Hazardous1.5%

Furniture8.3%

Mattresses2.4%

Misc combustible13.7%

Misc non-combustible14.9%

Garden waste5.3%

Food waste3.5%

Other organic1.0%

Glass2.5%

Card2.7%

Paper4.8%

WEEE2.4%

Soil1.8%

Fines0.8%

Other wastes1.7%

Sanitary0.3%


4.3.2.2 HWRC recycling According to WDF tonnages for England in 2006/07, recycling accounts for about 50% of all HWRC collected wastes9. WDF reports HWRC recycling tonnages by separate materials, (though in less detail in comparison to kerbside recycling). The categories included in WDF for HWRC recycling are listed in Table 4.15 (left-hand column). The relative magnitude of each WDF component, in terms of proportion of all HWRC recycling tonnage collected is also shown in Table 4.15, along with the allocation of WDF categories to the primary categories used in this study (see Appendix 4.1.1). Rubble accounts for about 17% of HWRC recycled materials, though it has been excluded from the analysis presented here; (see Appendix 4.2.1).

Table 4.15: WDF HWRC recycling categories in relation to this study’s primary categories

WDF recycling category Proportion of HWRC recycling


Cans 0.35% MetalsCo mingled 0.09% VariousCompost 44.24% Garden wasteGlass 2.36% GlassOther 20.98% VariousPaper & Card 8.70% VariousPlastics 0.40% PlasticsScrap & White goods 21.85% VariousTextiles 1.02% Textiles

It has been assumed that the WDF Compost category refers exclusively to garden waste. A review of HWRC tonnage data held by Resource Futures indicates that HWRCs rarely, if ever, accept food waste for composting.

Due to the limited level of detail in WDF HWRC recycling categories, nearly half of the WDF categories refer to more than one of the primary categories being used in this study, as indicated by the yellow cells in Table 4.15. These WDF categories collectively account for over half of HWRC recycling tonnages. The methodologies for producing recycling tonnage estimates for these categories in terms of the primary categories are detailed below.

Co-mingled

No reference data is available on the compositional breakdown of co-mingled recycling accepted at HWRCs. In the absence of such data, it has been assumed that the composition of HWRC Co-mingled recycling is the same as the average composition of kerbside co-mingled wastes. This waste stream is relatively insignificant, accounting for only 0.09% of HWRC recycling tonnages.

Other

WDF’s Other recycling category is problematic, since it could in principle refer to any type of material recycled at HWRCs. Additionally, Other recycling accounts for around 21% of HWRC recycled tonnage. The breakdown composition of this category was estimated through analysing detailed recycling tonnage data from over 130 HWRCs10 and excluding those materials thought to be likely to be reported in the remaining WDF categories shown in Table 4.15 above. The estimated average breakdown of the WDF’s HWRC Other recycling category in terms of this study’s primary categories is summarised in Table 4.16.

Whilst the best data available has been applied to address this issue, estimating the breakdown of a category which is as broad as Other recycling is not satisfactory. This problem could be

9 Including HWRC non-household residual waste, but excluding rubble recycled at HWRCs; see introduction to Appendix 4.2.2. 10 90 high recycling HWRCs, from a review of HWRC composition typologies carried out by Resource Futures on behalf of Defra LASU in 2004; and 41 HWRCs in London, from a best practice HWRC study carried out by Resource Futures on behalf of the Greater London Authority in 2008.


surmounted by requesting local authorities to provide a breakdown WDF of Other recycling tonnages by various subcategories, when reporting to WDF.

Table 4.16: Assumed proportional breakdown of materials in WDF ‘Other’ HWRC recycling tonnages

Wood WEEE Hazardous Furniture Misc combustible

Other wastes

68.5% 9.8% 5.6% 4.2% 0.3% 11.6%

Paper and card

The average breakdown of the WDF Paper and card category was estimated through analysing 4 HWRC datasets collated during this project which sampled waste inputs11. Across these 4 studies, the average breakdown of paper and card delivered to HWRCs was found to be almost exactly 50% paper and 50% card.

Scrap & white goods

A similar approach was used to estimate the breakdown of Scrap & white goods, with 5 of the collated HWRC input datasets having sufficient detail to be included in the analysis. Across these 5 studies, the average breakdown of Scrap & white goods was found to be 68% scrap metal and 32% white goods.

On the basis of the above assumptions, the estimated composition of HWRC recycling in England in 2006/07 is detailed in Table 4.17 and illustrated as a pie chart in Figure 4.7.

Table 4.17: Compositional estimates for HWRC recycling in England



Arising in HWRC recycling, %

Food waste 298 0.0 0.01%Garden waste 1,131,248 52.6 44.25%Other organic 1 0.0 0.00%Paper 112,687 5.2 4.41%Card 111,578 5.2 4.36%Glass 60,428 2.8 2.36%Metals 388,834 18.1 15.21%Plastics 10,536 0.5 0.41%Textiles 26,141 1.2 1.02%Wood 367,367 17.1 14.37%WEEE 231,466 10.8 9.05%Hazardous 29,832 1.4 1.17%Sanitary 4 0.0 0.00%Furniture 22,509 1.0 0.88%Mattresses 0 0.0 0.00%Misc combustible 1,322 0.1 0.05%Misc non-combustible 2 0.0 0.00%Soil 0 0.0 0.00%Other wastes 62,447 2.9 2.44%Fines 4 0.0 0.00%TOTAL 2,556,704 118.8 100.00%

11 Typically these studies sampled all wastes being delivered by members of the public, before these wastes were deposited in the various residual and recycling containers at the site.



Figure 4.13: Compositional estimates for HWRC recycling in England

Garden waste44.2%

Paper4.4%

Card4.4%

Glass2.4%

Metals15.2%

Wood14.4%

WEEE9.1%

Textiles1.0%

Hazardous1.2%

Furniture0.9%

Other wastes2.4%

Plastics0.4%

4.3.2.3 All HWRC wastes Whilst HWRC recycling compositional estimates are available for all 135 England local authorities that reported HWRC recycling tonnages in WDF, HWRC residual compositional estimates are only available for the 34 local authorities for which HWRC residual waste audit data (meeting the selection criteria, see Appendix 3) are available. The overall composition of HWRC collected waste can be estimated for these authorities by combining estimated HWRC residual waste tonnages with the relevant HWRC recycling tonnages for each authority.

If it is assumed that these local authorities are representative of all the 135 England local authorities that collect HWRC wastes, then the composition of all HWRC waste in England can be estimated by taking a simple average of compositional data across all 34 local authorities for which residual waste composition estimates are available. 95% confidence intervals can likewise be calculated for different components of HWRC waste, if we assume that the 34 datasets are representative of England as a whole. However these confidence intervals apply only to residual waste, and the inclusion of recyclables effectively ‘dilutes’ the confidence intervals. This effect is highly significant for HWRCs, since HWRC recycling accounts for 47% of all HWRC tonnages (excluding recycled rubble). Compositional estimates for all HWRC waste in England, calculated on this basis, are detailed in Table 4.18 and illustrated in Figure 4.14.

Figure 4.15 illustrates the relative tonnages of different types of materials found in, respectively, kerbside residual waste and recycling. These tonnages relate to England in 2006/07, applying the compositional estimates shown in Table 4.18.

Table 4.18: Compositional estimates for all HWRC waste in England

Arisings per household, England 2006/07

95% confidence interval



Food waste 101,094 4.7 1.0 3.7 5.7Garden waste 1,280,695 59.5 12.7 46.8 72.2Other organic 27,296 1.3 0.5 0.8 1.8Paper 249,930 11.6 1.8 9.8 13.4Card 188,623 8.8 1.4 7.4 10.1Glass 130,565 6.1 1.1 4.9 7.2Metals 452,419 21.0 3.0 18.0 24.1Plastics 308,304 14.3 2.1 12.2 16.4Textiles 154,232 7.2 0.9 6.2 8.1Wood 797,561 37.1 5.3 31.8 42.3WEEE 300,787 14.0 1.9 12.1 15.8Hazardous 73,380 3.4 0.6 2.8 4.0Sanitary 7,536 0.4 0.2 0.2 0.5Furniture 259,471 12.1 3.2 8.9 15.2Mattresses 68,120 3.2 1.1 2.1 4.3Misc combustible 391,397 18.2 2.7 15.5 20.9Misc non-combustible 425,247 19.8 3.9 15.8 23.7Soil 51,998 2.4 1.2 1.2 3.6Other wastes 111,471 5.2 2.0 3.2 7.1Fines 22,583 1.0 0.6 0.4 1.7TOTAL 5,402,709 251.1 na na na



Note: excludes rubble separated for recycling


Figure 4.14: Compositional estimates for all HWRC waste in England, kg/hh/yr in 2006/07

0 10 20 30 40 50 60 70 80

Fines

Other wastes

Soil


Misc combustible

Mattresses

Furniture

Sanitary

Hazardous

WEEE

Wood

Textiles

Plastics

Metals

Glass

Card

Paper

Other organic

Garden waste

Food waste

Kg/hh/yr, England 2006/07

Notes: (1) The red “error bars” indicate 95% confidence intervals; (2) includes non-household residual waste collected at HWRCs, but excludes rubble separated for recycling.


Figure 4.15: Estimated tonnage arisings of materials in HWRC waste, England 2006/07

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

HWRC residual HWRC recycling

Estim

ated

tonn

es, 2

006/

07

FinesOther wastesSoilMisc non-combustible

Misc combustibleMattressesFurnitureSanitaryHazardousWEEEWood

TextilesPlasticsMetalsGlassCardPaper

Other organicGarden wasteFood waste



4.3.3 Other household wastes composition estimates for England Other household wastes account for 6.6% of WDF tonnages reported in England during 2006/07. Residual waste accounts for around 61% of these materials. Several of the waste composition studies collated during this project include analyses of operational tonnages for this waste stream, relating to a total of 24 districts. The average breakdown of residual tonnages in other household wastes for these local authorities was found to be:

• 23% bulky waste collections (materials sent for disposal);

• 77% street cleansing, sweepings and litter.

The proportion of bulky waste collections in other household residual wastes varied considerably between different districts. However, in the absence of other data, the average figure of 23% bulky waste collections in household residual wastes has been applied across all England local authorities for the purposes of the analysis presented here.

The remaining waste streams in WDF’s ‘other household wastes’ tonnages all relate to recycled materials:

• bring sites;

• street bin recycling;

• ‘other household recycling’.

The latter category, ‘other household recycling’, is likely in many instances to refer to recycling from bulky waste collections (though it could also include recycling from community skips).

Applying these assumptions results in the following estimated breakdown of WDF’s ‘other household waste’ tonnages for England.

Table 4.19: Estimated breakdown of WDF ‘other household wastes’ tonnages, England 2006/07

ENGLAND Other household wastes 2006/07

Tonnes % of all other household wastes

Street cleansing, sweepings & litter 903,210 46.7%Bulky waste collections: disposal 269,790 13.9%Subtotal other household residual 1,173,000 60.6%Household recycling, bring sites 665,856 34.4%Household recycling, street recycling bins 19,165 1.0%Bulky waste collections: recycling 77,649 4.0%Subtotal other household recycling 762,671 39.4%TOTAL other household 1,935,671 100.0%

4.3.3.1 Other household wastes: residual Residual waste accounts for 61% of all WDF ‘Other household waste’ tonnages for England during 2006/07.

Street cleansing, sweepings and litter

This project collated 21 datasets relating to the composition of street cleansing, sweepings and litter (including street litter bins and beach/caravan park litter wastes). Some of these studies audited all these types of wastes, whereas other studies only audited one element (ie wastes from litter bins). Overall, there was insufficient data consistency and coverage to warrant statistical sub-analysis of the variability in composition. However there is no data available to estimate the relative tonnages of these types of wastes and therefore the average composition of all the 21 collated studies has been used for this analysis, as detailed in Table 4.20. This shows


that the 95% confidence intervals for some waste types are relatively high, reflecting the paucity of data, and possibly also the degree of variability in the composition of this waste stream.

Table 4.20: Compositional estimates for street cleansing, sweepings and litter in England


95% confidence interval, tonnes

95% confidence interval: LOWER BOUND, tonnes

95% confidence interval: UPPER BOUND, tonnes

Food waste 109,924 31,313 78,611 141,237Garden waste 78,458 51,934 26,524 130,392Other organic 63,696 38,350 25,346 102,046Paper 117,015 31,316 85,699 148,331Card 45,568 11,945 33,623 57,513Glass 61,856 19,159 42,697 81,016Metals 38,783 14,048 24,736 52,831Plastics 147,485 38,337 109,148 185,822Textiles 12,710 6,922 5,788 19,632Wood 4,264 2,543 1,722 6,807WEEE 1,701 1,871 0 3,572Hazardous 1,225 1,510 0 2,735Sanitary 8,181 5,851 2,330 14,031Furniture 0 0 0 0Mattresses 0 0 0 0Misc combustible 5,609 4,100 1,508 9,709Misc non-combustible 16,947 14,525 2,422 31,472Soil 0 0 0 0Other wastes 69,689 32,930 36,759 102,619Fines 120,099 83,639 36,460 203,738TOTAL 903,210 na na na

Bulky waste collections

A total of 17 compositional studies of bulky waste collections (destined for disposal) were collated. There is considerable variation in the compositional estimates arrived at in these studies, not least due to local authorities having widely varying policies regarding bulky waste collections and a mix of other local factors that are likely to influence (for example: whether or not bulky waste collections are charged for, proximity and access of a neighbourhood to HWRCs and kerbside containment capacity). The average composition of all the 17 collated studies has been used for this analysis, as detailed in Table 4.21, which includes 95% confidence intervals.


Table 4.21: Compositional estimates for bulky waste collections disposal in England





Food waste 183 253 0 436Garden waste 6,128 6,133 0 12,260Other organic 88 122 0 210Paper 630 998 0 1,628Card 511 792 0 1,302Glass 501 719 0 1,220Metals 1,748 1,549 199 3,297Plastics 2,535 3,494 0 6,029Textiles 1,274 1,539 0 2,813Wood 11,123 9,791 1,332 20,914WEEE 97,474 29,173 68,301 126,647Hazardous 264 217 47 482Sanitary 27 38 0 66Furniture 98,199 18,727 79,472 116,926Mattresses 4,042 4,600 0 8,642Misc combustible 20,059 19,358 700 39,417Misc non-combustible 2,631 3,012 0 5,643Soil 0 0 0 0Other wastes 21,691 12,915 8,776 34,606Fines 682 925 0 1,607TOTAL 269,790 na na na

All residual wastes in other household waste

Applying the assumption that bulky waste collections constitute 23% of WDF’s ‘other household waste’ residual tonnages (see introduction to Appendix 4.3.3), combining compositional estimates for bulky waste collections and street cleansing, sweepings & litter results in overall compositional estimates for this waste stream, as presented in Table 4.22 below. The 95% confidence intervals for, respectively, bulky waste collections and street cleansing etc have been grossed up in tonnage terms for each category of material, to enable calculating confidence intervals for ‘other household waste’ residual. Table 4.22 applies tonnages from WDF for England in 2006/07. The estimated composition of ‘other household waste’ (residual) is also illustrated in Figure 4.16.


Table 4.22: Composition estimates for ‘other household waste’ (residual) in England





Food waste 110,107 31,566 78,540 141,673Garden waste 84,586 58,067 26,519 142,653Other organic 63,784 38,473 25,311 102,256Paper 117,645 32,314 85,331 149,958Card 46,079 12,736 33,342 58,815Glass 62,357 19,879 42,479 82,236Metals 40,531 15,596 24,935 56,128Plastics 150,020 41,831 108,188 191,851Textiles 13,984 8,461 5,523 22,445Wood 15,388 12,334 3,054 27,722WEEE 99,174 31,044 68,130 130,219Hazardous 1,489 1,727 0 3,217Sanitary 8,208 5,889 2,319 14,097Furniture 98,199 18,727 79,472 116,926Mattresses 4,042 4,600 0 8,642Misc combustible 25,668 23,459 2,209 49,126Misc non-combustible 19,578 17,537 2,041 37,115Soil 0 0 0 0Other wastes 91,380 45,845 45,535 137,225Fines 120,781 84,564 36,217 205,345TOTAL 1,173,000 na na na


Figure 4.16: Composition estimates for ‘other household waste’ (residual) in England

Food waste9.4%

Garden waste7.2%

Other organic5.4%

Paper10.0%

Card3.9%

Glass5.3%

Metals3.5%Plastics

12.8%Textiles1.2%

Wood1.3%

WEEE8.5%

Sanitary0.7%

Furniture8.4%

Mattresses0.3%



Other wastes7.8%

Fines10.3%


4.3.3.2 Other household wastes: recycling The majority of ‘other household waste’ recycling consists of recycling from bring sites. A small tonnage of recyclable material is collected from street recycling bins and the remainder of ‘other household waste’ recycling has been assumed to consist of recycling from bulky waste collections. For the tonnage breakdown of these different types of recycling, refer to Table 4.19.

Bring sites recycling

According to WDF tonnages for England in 2006/07, bring sites recycling accounts for about 26% of all ‘other household wastes’ (see Table 4.19). WDF reports bring sites recycling tonnages by separate materials and the categories included in WDF for bring recycling are listed in Table 4.23 (left-hand column). The relative magnitude of each WDF component, in terms of proportion of all bring sites recycling tonnage collected is also shown in Table 4.23, along with the allocation of WDF categories to the primary categories used in this study (see Appendix 4.1.1).

Table 4.23: WDF bring sites recycling categories in relation to this study’s primary categories

WDF recycling category Proportion of bring sites recycling


Cans 1.39% MetalsCo mingled 1.12% VariousCompost 2.23% VariousGlass 52.14% GlassOther 0.72% VariousPaper & Card 33.17% VariousPlastics 2.19% PlasticsScrap & White goods 0.44% VariousTextiles 6.60% Textiles

Due to the limited level of detail in WDF bring sites recycling categories, over half of the WDF categories refer to more than one of the primary categories being used in this study, as indicated by the yellow cells in Table 4.23. With the exception of WDF’s Paper & Card category, these categories account for a relatively small proportion of bring sites recycling tonnages.

No reference data is available on the compositional breakdown for these waste types collected at bring sites12. In the absence of such data, the same assumptions applied as for kerbside or HWRC recycling in terms of the compositional breakdown of these categories, as follows:

• Co-mingled, Compost, Paper & Card: same assumptions as for kerbside recycling (see Appendix 4.3.1.2);

• Other, Scrap & White goods: same assumptions as for HWRC recycling (see Appendix 4.3.2.2).

On the basis of the above assumptions, the estimated composition of bring sites recycling in England in 2006/07 is detailed in Table 4.24 and illustrated as a pie chart in Figure 4.17.

12 One of the collated studies analysed bring site recycling data. However it was considered that it would be highly misleading to apply assumptions for bring site composition derived from a single study.


Table 4.24: Compositional estimates for bring sites recycling in England



Arising in bring site recycling, %

Food waste 2,071 0.1 0.31%Garden waste 10,607 0.5 1.59%Other organic 480 0.0 0.07%Paper 165,693 7.7 24.88%Card 62,647 2.9 9.41%Glass 347,443 16.1 52.18%Metals 11,604 0.5 1.74%Plastics 15,394 0.7 2.31%Textiles 44,003 2.0 6.61%Wood 3,315 0.2 0.50%WEEE 1,415 0.1 0.21%Hazardous 271 0.0 0.04%Sanitary 13 0.0 0.00%Furniture 202 0.0 0.03%Mattresses 0 0.0 0.00%Misc combustible 24 0.0 0.00%Misc non-combustible 6 0.0 0.00%Soil 0 0.0 0.00%Other wastes 654 0.0 0.10%Fines 14 0.0 0.00%TOTAL 665,856 30.9 100.00%

Figure 4.17: Compositional estimates for bring sites recycling in England

Paper24.9%

Card9.4%

Glass52.2%

Metals1.7%

Plastics2.3%

Food waste0.3%

Garden waste1.6%

Wood0.5%

Textiles6.6%

WEEE0.2%


Street bins recycling

Street bins recycling accounts for only a very small portion of overall municipal waste arisings, 0.07% of municipal waste tonnages reported in WDF for England in 2006/07.

WDF reports street bins recycling tonnages by separate materials and the categories included in WDF for bring recycling are listed in Table 4.25 (left-hand column). The relative magnitude of each WDF component, in terms of proportion of all street bins recycling tonnage collected is also shown in Table 4.25, along with the allocation of WDF categories to the primary categories used in this study (see Appendix 4.1.1).

Table 4.25: WDF street bins recycling categories in relation to this study’s primary categories

WDF recycling category Proportion of street bins recycling


Aluminium Cans 0.01% MetalsCo mingled 96.69% VariousGlass 1.75% GlassMixed Cans 0.06% MetalsPaper & Card 1.44% VariousPlastics 0.02% PlasticsSteel Cans 0.03% Metals

The compositional breakdown of WDF ‘co-mingled’ and ‘paper and card’ categories has been estimated from average compositional data from only three audits of street bins recycling collated by this study. The coverage is particularly limited in view of the range of locality types and strong seasonal factors that are likely to influence composition. Co-mingled materials account for the vast majority of WDF reported tonnages for street bins recycling and the estimated breakdown of these materials in terms of the primary categories employed in this study are detailed in Table 4.26.

Table 4.26: Assumed proportional breakdown of materials in WDF ‘Co-mingled’ street bins recycling tonnages

Paper Card Glass Metals Plastics

31.4% 8.9% 43.5% 5.1% 11.1%

The proportional breakdown of materials in WDF’s Paper & Card category is estimated to be 78% paper and 22% card.

On the basis of the above assumptions, the estimated composition of street bins recycling in England in 2006/07 is detailed in Table 4.27 and illustrated as a pie chart in Figure 4.18.

Table 4.27: Compositional estimates for street bins recycling in England


Arising in street bin recycling, %

Paper 6,041 31.52%Card 1,708 8.91%Glass 8,394 43.80%Metals 955 4.99%Plastics 2,067 10.79%TOTAL 19,165 100.00%


Figure 4.18: Compositional estimates for street bins recycling in England

Plastics10.8%

Metals5.0%

Glass43.8%

Card8.9%

Paper31.5%

4.3.3.3 ‘Other means’ household recycling WDF includes a waste stream described as ‘Other means’ household recycling. These materials account for 0.27% of overall municipal waste arisings in England. The breakdown of these tonnages by waste stream, according to WDF tonnages for England in 2006/07 is summarised below.

Table 4.28: WDF ‘Other means’ household recycling tonnages by waste stream

Waste stream Tonnes % of "Other means" household recycling

Parks & grounds 41,428 53.4%Community skips 852 1.1%Other waste capture 35,369 45.6%Total "Other means" household recycling 77,649 100.0%

Parks & grounds recycling has been assumed to be only garden waste. The remainder of ‘Other means’ household recycling has been assumed to be recycling from bulky waste collections; due to lack of reference data, recycling from community skips has been included in these tonnages. The estimated compositional breakdown of bulky waste collections recycling has been derived from 17 bulky waste collection residual waste audits. The materials considered to be most likely to be targeted for recycling have been extracted from these datasets to arrive at a compositional estimate for bulky waste collections recycling, as summarised in Table 4.29, along with associated tonnages for England during 2006/07.



Table 4.29: Estimated composition for bulky waste collections recycling


Mean composition

Garden waste 1,008 2.78%Paper 104 0.29%Card 84 0.23%Glass 82 0.23%Metals 288 0.79%Plastics 417 1.15%Textiles 210 0.58%Wood 1,830 5.05%WEEE 16,039 44.28%Furniture 16,159 44.61%TOTAL 36,221 100.00%

4.3.3.4 All other household wastes combined The estimated overall composition of WDF’s ‘other household wastes’, residual plus recycling, is detailed in Table 4.30 – with 95% confidence intervals – and illustrated in Figure 4.19.

Table 4.30: Estimated composition of WDF ‘Other household wastes’ (residual plus recycling) for England





Food waste 112,178 31,566 80,611 143,744Garden waste 137,629 58,067 79,563 195,696Other organic 64,263 38,473 25,790 102,736Paper 289,483 32,314 257,169 321,797Card 110,517 12,736 97,781 123,254Glass 418,276 19,879 398,397 438,155Metals 53,379 15,596 37,783 68,975Plastics 167,898 41,831 126,067 209,729Textiles 58,197 8,461 49,736 66,658Wood 20,533 12,334 8,199 32,866WEEE 116,629 31,044 85,585 147,674Hazardous 1,760 1,727 32 3,487Sanitary 8,221 5,889 2,332 14,110Furniture 114,560 18,727 95,833 133,287Mattresses 4,042 4,600 0 8,642Misc combustible 25,692 23,459 2,233 49,150Misc non-combustible 19,585 17,537 2,048 37,122Soil 0 0 0 0Other wastes 92,034 45,845 46,189 137,879Fines 120,795 84,564 36,231 205,359TOTAL 1,935,671 na na na


Figure 4.19: Estimated composition of WDF ‘Other household wastes’ (residual plus recycling) for England

0 100,000 200,000 300,000 400,000 500,000

Fines

Other wastes

Soil


Misc combustible

Mattresses

Furniture

Sanitary

Hazardous

WEEE

Wood

Textiles

Plastics

Metals

Glass

Card

Paper

Other organic

Garden waste

Food waste

Tonnes, England 2006/07


Figure 4.20 illustrates the relative tonnages of different types of materials found in the various waste streams that are reported as ‘Other household wastes’ in WDF. These tonnages relate to WDF reported data for England in 2006/07.

Figure 4.20: Estimated tonnage arisings of materials in WDF ‘Other household wastes’, England 2006/07

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

1,000,000

Bul

ky w

aste

col

lect

ions

:di

spos

al

Stre

et c

lean

sing

,sw

eepi

ngs

& li

tter

Brin

g si

te re

cycl

ing

Stre

et re

cycl

ing

bins

Par

ks a

nd g

roun

ds

Bul

ky w

aste

col

lect

ions

:re

cycl

ing

Estim

ated

tonn

es, 2

006/

07

Fines

Other wastes

Soil


Misc combustible

Mattresses

Furniture

Sanitary

Hazardous

WEEE

Wood

Textiles

Plastics

Metals

Glass

Card

Paper

Other organic

Garden waste

Food waste


4.3.4 Non-household waste composition estimates for England Non-household waste accounts for 10.6% of WDF tonnages for England during 2006/07, amounting to 3,098,994 tonnes. However 803,888 tonnes of this consists of rubble recycling, which, for the purposes of this study, is excluded from our compositional estimates for municipal waste in England. Of the remaining material (2,295,106), the great majority of this material is residual waste (93%), with the remainder constituting non-household recycling.

4.3.4.1 Non-household residual waste Most of non-household residual waste is likely to relate to commercial waste collected by local authorities. Wastes from other sources, such as civic wastes (from council buildings and premises) and schools wastes may be included in non-household residual waste tonnages reported by some local authorities in WDF. However there is no reference data available to ascertain the proportion of non-household residual waste which derives from these other sources. The situation is complicated by the fact that many local authorities contract out the collection of civic or schools wastes and as a result some wastes thus collected may not be reported in WDF.

In view of this, the estimated composition of commercial residual waste collected by local authorities has been applied to non-household residual waste tonnages for WDF. A total of 25 studies of municipally collected commercial residual waste were collated during this project. The mean composition of commercial waste across these studies is presented in Table 4.31, along with 95% confidence intervals; and is illustrated in Figure 4.21.

A proportion of HWRC residual waste is reported in WDF as non-household waste. However since we have assumed that composition of HWRC non-household residual waste is similar to HWRC household residual waste, this proportion of non-household waste has been included in our analysis of HWRC waste composition; see Appendix 4.3.2.

Table 4.31: Estimated composition of municipally collected commercial waste in England





Food waste 334,702 33,009 301,693 367,712Garden waste 55,086 15,000 40,086 70,087Other organic 7,465 3,473 3,993 10,938Paper 452,241 46,022 406,219 498,264Card 387,801 68,281 319,521 456,082Glass 126,711 40,200 86,510 166,911Metals 86,158 20,562 65,596 106,720Plastics 307,045 28,496 278,550 335,541Textiles 43,113 7,439 35,674 50,552Wood 81,562 20,479 61,083 102,041WEEE 10,615 4,226 6,389 14,842Hazardous 2,975 2,237 737 5,212Sanitary 33,998 13,597 20,402 47,595Furniture 1,939 3,001 0 4,940Mattresses 0 0 0 0Misc combustible 55,827 16,183 39,645 72,010Misc non-combustible 64,361 23,487 40,875 87,848Soil 147 251 0 398Other wastes 47,957 42,303 5,654 90,261Fines 38,289 8,889 29,400 47,178TOTAL 2,137,994 na na na


Figure 4.21: Estimated composition of municipally collected commercial waste in England

Food waste15.7%

Garden waste2.6%

Paper21.2%

Card18.1%

Glass5.9%

Metals4.0%

Plastics14.4%

Textiles2.0%

Wood3.8%

WEEE0.5%

Sanitary1.6%



Other wastes2.2%

Fines1.8%

Although civic and schools wastes have been excluded from our analysis, compositional data from collated studies that relate to these waste streams are summarised in Table 4.32 below. Seven datasets were collated for civic residual wastes13 (council offices and premises, sometimes including canteens, libraries, etc); and 6 studies were collated for schools residual wastes, though one of these studies was carried out over 4 local authority areas14.

13 8 datasets were collated for civic wastes; however 2 datasets related to the same local authority and were therefore combined into one set of average compositional estimates, resulting in a total of 7 datasets for civic wastes. 14 The nature and scale of waste produced by schools in England, WastesWork on behalf of WRAP, 2008


Table 4.32: Estimated composition of residual civic and schools wastes in England

Category Mean composition: CIVIC

Mean composition: SCHOOLS

Food waste 19.36% 35.69%Garden waste 0.21% 1.73%Other organic 0.33% 0.03%Paper 41.19% 20.88%Card 13.30% 10.82%Glass 1.52% 1.29%Metals 3.58% 3.10%Plastics 12.03% 11.23%Textiles 0.26% 1.23%Wood 1.65% 1.78%WEEE 0.54% 0.22%Hazardous 0.23% 0.90%Sanitary 0.52% 0.53%Furniture 0.63% 2.08%Mattresses 0.00% 0.00%Misc combustible 0.21% 2.02%Misc non-combustible 0.28% 2.00%Soil 0.00% 0.15%Other wastes 3.82% 2.45%Fines 0.34% 1.85%

4.3.4.2 Non-household recycling With the exception of rubble recycling, WDF does not report material specific tonnages for non-household recycling. Rubble accounts for the great majority (84%) of non-household recycling. However, as discussed elsewhere, recycled rubble is excluded from this study’s compositional estimates for municipal waste in England.

In the absence of reference data, the composition profile of kerbside household dry recycling (excluding rubble) has been used in the absence of waste stream specific data. The estimated compositional breakdown of WDF kerbside co-mingled recycling tonnages (Table 4.9, Appendix 4.3.1.2) was applied, using estimates for ‘other kerbside dry recycling’ systems (i.e. not co-mingled dry recycling collections; and textiles were excluded from estimates, since it was thought unlikely that this would be a significant component in non-household recycling. The resulting estimated compositional profile for non-household recycling is summarised in Table 4.33 and illustrated in Figure 4.22.

Table 4.33: Estimated composition of non-household recycling in England


Mean composition

Paper 91,102 9.48%Card 11,414 1.19%Glass 41,366 4.30%Metals 7,636 0.79%Plastics 5,594 0.58%Subtotal, excl rubble 157,112 16.35%Rubble recycling 803,888 83.65%TOTAL 961,000 100.00%

Recycling excluding rubble



Figure 4.22: Estimated composition of non-household recycling (excluding rubble) in England, using a modified compositional profile from household dry recycling

Plastics3.6%Metals

4.9%

Glass26.3%

Card7.3%

Paper58.0%

4.3.4.3 All non-household waste Overall estimates of non-household waste (residual plus recycling) have been arrived at through applying the assumptions detailed above. Non-household wastes collected at HWRCs are excluded here, since they have already been included in our analysis of HWRC waste composition; (see Appendix 4.3.2).

The estimated overall composition of non-household waste, residual plus recycling, is detailed in Table 4.34 (including 95% confidence intervals) and illustrated in Figure 4.23. Figure 4.24 illustrates estimates of the relative tonnages of different types of materials found in non-household waste. These tonnages relate to WDF reported data for England in 2006/07.

Table 4.34: Estimated composition of all municipal non-household waste in England





Food waste 334,702 33,009 301,693 367,712Garden waste 55,086 15,000 40,086 70,087Other organic 7,465 3,473 3,993 10,938Paper 543,343 46,022 497,321 589,365Card 399,216 68,281 330,935 467,496Glass 168,077 40,200 127,876 208,277Metals 93,794 20,562 73,232 114,356Plastics 312,640 28,496 284,144 341,135Textiles 43,113 7,439 35,674 50,552Wood 81,562 20,479 61,083 102,041WEEE 10,615 4,226 6,389 14,842Hazardous 2,975 2,237 737 5,212Sanitary 33,998 13,597 20,402 47,595Furniture 1,939 3,001 0 4,940Mattresses 0 0 0 0Misc combustible 55,827 16,183 39,645 72,010Misc non-combustible 64,361 23,487 40,875 87,848Soil 147 251 0 398Other wastes 47,957 42,303 5,654 90,261Fines 38,289 8,889 29,400 47,178TOTAL 2,295,106 na na na


Figure 4.23: Estimated composition of all municipal non-household wastes in England

0 100,000 200,000 300,000 400,000 500,000 600,000 700,000

Fines

Other wastes

Soil


Misc combustible

Mattresses

Furniture

Sanitary

Hazardous

WEEE

Wood

Textiles

Plastics

Metals

Glass

Card

Paper

Other organic

Garden waste

Food waste

Tonnes, England 2006/07

Notes: (1) excludes non-household wastes collected at HWRCs; (2) excludes rubble recycling.


Figure 4.24: Estimated tonnage arisings of materials in municipal non-household waste, England 2006/07

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

Non-household residual Non-household recycling Rubble recycling

Estim

ated

tonn

es, 2

006/

07

Fines

Other wastes

Soil


Misc combustible

Mattresses

Furniture

Sanitary

Hazardous

WEEE

Wood

Textiles

Plastics

Metals

Glass

Card

Paper

Other organic

Garden waste

Food waste

Notes: (1) excludes non-household wastes collected at HWRCs – refer to Appendix 4.3.2; (2) rubble recycling tonnages included for illustrative purposes only – rubble recycling has been excluded from this study’s analysis of the composition of municipal waste in England.



4.4 Overall municipal waste composition estimates for England This Appendix presents estimates of the overall composition of municipal waste in England, on the basis of the data sources, methodologies and assumptions detailed elsewhere in this report. The estimated composition of each municipal waste stream (kerbside, HWRC, etc) has been considered in Appendix 4.3. Estimates for the comparative composition of main municipal waste streams are illustrated in Figure 4.25.

Figure 4.25: Estimated comparative composition of main municipal waste streams in England

Residual + recycling

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Kerbside HWRC, exclrubble

Otherhousehold

Non-household,excl HWRC &

rubble

Fines

Other wastes

Soil


Misc combustible

Mattresses

Furniture

Sanitary

Hazardous

WEEE

Wood

Textiles

Plastics

Metals

Glass

Card

Paper

Other organic

Garden waste

Food waste

Notes: (1) rubble recycling is excluded from these municipal waste composition estimates; see Appendix 4.2.1. (2) “HWRC” includes non-household waste collected at HWRCs (and “Non-household” excludes non-household wastes collected at HWRCs).

Estimated tonnage arisings of different types of material, by each of the main municipal waste streams, are illustrated in Figure 4.26.

Table 4.35 details the estimated composition of municipal waste in England in terms of tonnages, relating to WDF tonnages reported for England in 2006/07, and includes the resultant estimated composition of all municipal waste in terms of percentage arisings.

Figure 4.26: Estimated tonnage arisings of materials in the main municipal waste streams, England 2006/07

0

2,000,000

4,000,000

6,000,000

8,000,000

10,000,000

12,000,000

14,000,000

16,000,000

18,000,000

20,000,000

Kerbside HWRC Otherhousehold

Non-household

Estim

ated

tonn

es, 2

006/

07

Fines

Other wastes

Soil


Misc combustible

Mattresses

Furniture

Sanitary

Hazardous

WEEE

Wood

Textiles

Plastics

Metals

Glass

Card

Paper

Other organic

Garden waste

Food waste

Note: ‘Non-household’ excludes non-household wastes collected at HWRCs; excludes rubble separated for recycling.


Table 4.35: Estimated tonnage arisings of materials in municipal waste in England, 2006/07

ENGLAND 2006/07

Kerbside total

HWRC total excl rubble

excl rubble

Other hhold residual

Bring recycling

Street recycling bins

Other hhold recycling

Non-hhold residual

Non-hhold recycling

All municipal waste

Estimated composition, all municipal waste (%)

Food waste 4,508,285 101,094 110,107 2,071 0 0 334,702 0 5,056,259 17.84%Garden waste 2,516,371 1,280,695 84,586 10,607 0 42,436 55,086 0 3,989,782 14.08%Other organic 391,327 27,296 63,784 480 0 0 7,465 0 490,352 1.73%Paper 3,635,357 249,930 117,645 165,693 6,041 104 452,241 91,102 4,718,113 16.65%Card 1,013,142 188,623 46,079 62,647 1,708 84 387,801 11,414 1,711,499 6.04%Glass 1,164,881 130,565 62,357 347,443 8,394 82 126,711 41,366 1,881,799 6.64%Metals 617,743 452,419 40,531 11,604 955 288 86,158 7,636 1,217,335 4.30%Plastics 2,042,743 308,304 150,020 15,394 2,067 417 307,045 5,594 2,831,585 9.99%Textiles 547,274 154,232 13,984 44,003 0 210 43,113 0 802,816 2.83%Wood 157,092 797,561 15,388 3,315 0 1,830 81,562 0 1,056,748 3.73%WEEE 192,535 300,787 99,174 1,415 0 16,039 10,615 0 620,566 2.19%Hazardous 71,281 73,380 1,489 271 0 0 2,975 0 149,396 0.53%Sanitary 662,259 7,536 8,208 13 0 0 33,998 0 712,015 2.51%Furniture 3,813 259,471 98,199 202 0 16,159 1,939 0 379,783 1.34%Mattresses 0 68,120 4,042 0 0 0 0 0 72,162 0.25%Misc combustible 198,750 391,397 25,668 24 0 0 55,827 0 671,666 2.37%Misc non-combustible 289,643 425,247 19,578 6 0 0 64,361 0 798,836 2.82%Soil 0 51,998 0 0 0 0 147 0 52,144 0.18%Other wastes 406,668 111,471 91,380 654 0 0 47,957 0 658,130 2.32%Fines 287,459 22,583 120,781 14 0 0 38,289 0 469,127 1.66%TOTAL 18,706,625 5,402,709 1,173,000 665,856 19,165 77,649 2,137,994 157,112 28,340,112 100.00%



Municipal waste and recycling tonnage arisings in England during 2006/07 are illustrated in Figure 4.27, with tonnages shown for each type of material and the tonnage arising via each of the main municipal waste streams: kerbside, HWRC, other household waste and recycling, and non-household waste and recycling. The distribution of materials across the different outlets for municipal waste is particularly relevant to issues discussed in relation to the household kerbside data, where the arisings of certain primary categories in Appendix 4.1.2. The estimates in Figure 4.27 suggest that for a number of categories significant quantities arise outside of the kerbside household waste stream, mainly at HWRCs: garden waste, wood, furniture, glass, miscellaneous combustible and non-combustible and WEEE. The distribution is subject to change, particularly for garden waste, where the proportion collected at kerbside has increased in recent years as a result of the expansion of separate collection of garden waste at kerbside. Food, ‘other organic’ and sanitary are the three categories most exclusively collected at kerbside.

Figure 4.27: Municipal waste tonnage arisings by material type and disposal route, England 2006/07

0 1,000,000 2,000,000 3,000,000 4,000,000 5,000,000 6,000,000

Fines

Other wastes

Soil


Misc combustible

Mattresses

Furniture

Sanitary

Hazardous

WEEE

Wood

Textiles

Plastics

Metals

Glass

Card

Paper

Other organic

Garden waste

Food waste

Tonnes, 2006/07

Kerbside HWRC Other household Non-household




4.4.1 Statistical robustness of compositional estimates for England The statistical robustness of the compositional estimates presented here have been chiefly assessed through calculating 95% confidence intervals from the compositional datasets used to estimate the composition of various residual waste streams (kerbside residual, HWRC residual, etc). For recycling streams, tonnages reported in WDF for England in 2006/07 have been analysed to assess the composition of these streams. Since these are operational tonnages, assessments of statistical variability do not apply to the compositions of recycling streams derived from these operational recycling tonnages. However, as discussed in Appendix 4.3, some recycling tonnage categories are insufficiently detailed in relation to the primary category list being employed in this study. For example, WDF uses a ‘Mixed Paper & Card’ category for several municipal recycling streams and for the purpose of our study it has been necessary to estimate the breakdown of tonnages in this category in terms of paper and card, through use of reference data where possible. For further comments on these issues, refer to Appendix 6.

In this Appendix we summarise confidence intervals applying across all municipal residual streams for each type of material15. We also summarise the extent of uncertainties in material classification arising from some of the broadly defined categories in WDF.

Estimated tonnages for all municipal waste in England are detailed in Table 4.36, with confidence intervals (deriving from analyses of residual waste audit datasets) expressed in terms of tonnage; compositional estimates and 95% confidence intervals for each waste type are also expressed in terms of percentage of total arisings of municipal waste.

Table 4.36: Confidence intervals for compositional estimates for all municipal waste

Estimated total tonnes in municipal waste

95% confidence interval, +/-

Estimated composition




Food waste 5,056,259 244,230 17.84% 0.86% 16.98% 18.70%Garden waste 3,989,782 611,804 14.08% 2.16% 11.92% 16.24%Other organic 490,352 96,391 1.73% 0.34% 1.39% 2.07%Paper 4,718,113 225,071 16.65% 0.79% 15.85% 17.44%Card 1,711,499 162,571 6.04% 0.57% 5.47% 6.61%Glass 1,881,799 159,664 6.64% 0.56% 6.08% 7.20%Metals 1,217,335 125,653 4.30% 0.44% 3.85% 4.74%Plastics 2,831,585 175,355 9.99% 0.62% 9.37% 10.61%Textiles 802,816 63,683 2.83% 0.22% 2.61% 3.06%Wood 1,056,748 169,492 3.73% 0.60% 3.13% 4.33%WEEE 620,566 96,254 2.19% 0.34% 1.85% 2.53%Hazardous 149,396 26,287 0.53% 0.09% 0.43% 0.62%Sanitary 712,015 75,919 2.51% 0.27% 2.24% 2.78%Furniture 379,783 95,213 1.34% 0.34% 1.00% 1.68%Mattresses 72,162 28,173 0.25% 0.10% 0.16% 0.35%Misc combustible 671,666 140,393 2.37% 0.50% 1.87% 2.87%Misc non-combustible 798,836 182,318 2.82% 0.64% 2.18% 3.46%Soil 52,144 26,691 0.18% 0.09% 0.09% 0.28%Other wastes 658,130 223,591 2.32% 0.79% 1.53% 3.11%Fines 469,127 141,261 1.66% 0.50% 1.16% 2.15%TOTAL 28,340,112 na 100% na na na

ENGLAND 2006/07 ALL MUNICIPAL WASTE

TONNES PERCENTAGE ARISINGS

Recycling tonnages which are subject to uncertain classification are detailed in Table 4.37 below, which shows WDF recycling categories which have had to be allocated across more than one primary category. As Table 4.37 shows, over 3.7 million tonnes of recyclables is subject to uncertainty in terms of how it should be classified in respect of the primary categories being used in this study.

15 Confidence intervals for separate municipal residual streams are reported in Appendix 4.3.


Figure 4.28: Estimated composition of all municipal waste in England during 2006/07, with 95% confidence intervals

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

Food

was

te

Gar

den

was

te

Oth

er o

rgan

ic

Pap

er

Car

d

Gla

ss

Met

als

Pla

stic

s

Text

iles

Woo

d

WE

EE

Haz

ardo

us

San

itary

Furn

iture

Mat

tress

es

Mis

c co

mbu

stib

le

Mis

c no

n-co

mbu

stib

le

Soi

l

Oth

er w

aste

s

Fine

s

Tonn

es, E

ngla

nd 2

006/

07

Notes: (1) Green bars indicate assumed 100% BMW (biodegradable municipal waste) content; shaded green bars indicate assumed 50% BMW content; grey bars indicate assumed 0% BMW content; (2) excludes rubble separated for recycling.


Table 4.37: Recycling tonnages whose classification in terms of primary categories is uncertain due to broad WDF categories, England 2006/07

Other means

Non-hhold

Co

min

gled

m

ater

ials

Mix

ed p

aper

&

card

Oth

er c

ompo

stab

le

was

te

Co

min

gled

Oth

er

Pap

er &

Car

d

Scr

ap &

Whi

te

good

s

Co

min

gled

Com

post

Oth

er

Pap

er &

Car

d

Scr

ap &

Whi

te

good

s

Co

min

gled

Pap

er &

Car

d

Non

-mat

eria

l sp

ecifi

c re

cycl

ing

Non

-mat

eria

l sp

ecifi

c re

cycl

ing

Food waste 51,096 17 281 55 2,014 3 53,465Garden waste 265,569 44 142 10,466 42,436 318,656Other organic 12,118 1 2 478 12,598Paper 826,361 220,326 19,999 1,422 111,264 4,592 788 160,313 5,827 215 104 91,102 1,442,312Card 141,065 83,194 27,885 314 111,264 1,014 1,099 60,534 1,647 61 84 11,414 439,576Glass 46,094 78 253 8,058 82 41,366 95,932Metals 69,210 120 379,883 388 1,978 937 288 7,636 460,440Plastics 117,774 252 812 2,062 417 5,594 126,912Textiles 11,930 22 70 210 12,232Wood 3 367,364 10 3,305 1,830 372,512WEEE 3 52,694 178,769 10 474 931 16,039 248,920Hazardous 1 29,831 2 268 30,102Sanitary 4 13 17Furniture 22,509 202 16,159 38,870Mattresses 0Misc combustible 4 1,318 12 12 1,346Misc non-combustible 2 6 8Soil 0Other wastes 29 62,418 92 562 63,101Fines 4 14 18

1,212,434 303,520 376,667 2,320 536,415 222,528 558,652 7,489 14,844 4,826 220,847 2,909 18,531 275 77,649 157,112 3,717,018TOTAL


TOTALWDF categories

Prim

ary

cate

gorie

s us

ed in

this

stu

dy

Waste stream Kerbside recycling HWRC Bring recycling

4.4.2 Estimated biodegradable content in municipal waste in England The biodegradable content of municipal waste in England has been estimated through following guidance from the Environment Agency in relation to the assumed biodegradable content for different classifications of materials. Table 4.38 summarises estimated total municipal waste composition for England in 2006/07, with 95% confidence intervals, expressed in terms of tonnage arisings. The assumed BMW (biodegradable municipal waste) content for each category of material is applied to these tonnages to arrive at, respectively, estimated arisings of BMW in 2006/07 and confidence intervals, both expressed in terms of tonnages.

Table 4.38: Estimated tonnage arisings of BMW for England, 2006/07

Estimated total tonnes in municipal waste

95% confidence interval, +/- tonnes

Assumed BMW content

Estimated tonnes BMW in municipal waste

95% confidence interval, +/- tonnes

Food waste 5,056,259 244,230 100% 5,056,259 244,230Garden waste 3,989,782 611,804 100% 3,989,782 611,804Other organic 490,352 96,391 100% 490,352 96,391Paper 4,718,113 225,071 100% 4,718,113 225,071Card 1,711,499 162,571 100% 1,711,499 162,571Glass 1,881,799 159,664 0% 0 0Metals 1,217,335 125,653 0% 0 0Plastics 2,831,585 175,355 0% 0 0Textiles 802,816 63,683 50% 401,408 31,841Wood 1,056,748 169,492 100% 1,056,748 169,492WEEE 620,566 96,254 0% 0 0Hazardous 149,396 26,287 0% 0 0Sanitary 712,015 75,919 50% 356,007 37,959Furniture 379,783 95,213 50% 189,891 47,606Mattresses 72,162 28,173 50% 36,081 14,087Misc combustible 671,666 140,393 50% 335,833 70,196Misc non-combustible 798,836 182,318 0% 0 0Soil 52,144 26,691 0% 0 0Other wastes 658,130 223,591 50% 329,065 111,795Fines 469,127 141,261 50% 234,564 70,630TOTAL 28,340,112 na 18,905,601 1,893,676

ENGLAND 2006/07

ALL MUNICIPAL WASTE BMW IN MUNICIPAL WASTE

The estimated proportion of BMW in municipal waste in England is presented in Table 4.39, with confidence intervals, expressed in terms of tonnage arisings and overall percentage BMW in municipal waste.

Table 4.39: Estimated proportion of BMW in municipal waste, England 2006/07

ENGLAND 2006/07

Estimated tonnes total municipal waste

Estimated tonnes BMW in municipal waste

95% confidence interval lower bound

95% confidence interval upper bound

Tonnes 28,340,112 18,905,601 17,011,925 20,799,277

% in municipal waste na 66.71% 60.03% 73.39%



According to the compositional estimates presented here, the BMW content of municipal waste in England is estimated to be 66.71%, with a 95% confidence interval of +/- 6.68%, resulting in a lower bound of 60.03% and an upper bound of 73.39% at the 95% confidence level16.

The estimated BMW content in each of the main municipal waste streams (kerbside, HWRC, etc) is shown in Table 4.40, with 95% confidence intervals.

Table 4.40: Estimated proportion of BMW in main municipal waste streams, England 2006/07

Estimated tonnes BMW




Estimated BMW in municipal waste, %




Kerbside 18,706,625 13,274,686 777,487 12,497,200 14,052,173 70.96% 2.74% 68.22% 73.71%

HWRC 5,402,709 3,152,605 602,957 2,549,647 3,755,562 58.35% 2.13% 56.22% 60.48%

Other household 1,935,671 946,374 281,262 665,112 1,227,636 48.89% 0.99% 47.90% 49.88%

Non-household 2,295,106 1,531,937 231,970 1,299,967 1,763,906 66.75% 0.82% 65.93% 67.57%

TOTAL 28,340,112 18,905,601 1,893,676 17,011,925 20,799,277 66.71% 6.68% 60.03% 73.39%

ENGLAND 2006/07

Total tonnes in municipal waste

TONNAGE ARISINGS PERCENTAGE ARISINGS

However, uncertainties in the classification of some WDF recycling tonnages mean that a proportion of the tonnages of materials with biodegradable content may in fact actually be other materials with no biodegradable content. Conversely, it may also be the case that a proportion of tonnages with no biodegradable content may in fact consist of materials with biodegradable content. This issue is demonstrated in Table 4.41, which shows tonnages of recycling reported in WDF which are subject to uncertainty in terms of their breakdown composition in respect of the primary categories used in this study; (these are the same recycling tonnage figures that appear in Table 4.37 above).

For example, the first column of figures in Table 4.38 shows the estimated breakdown of tonnages for co-mingled materials in kerbside recycling. WDF has reported a total of 1,212,434 tonnes of this material for England in 2006/07 and in this study estimates have been made as to how this tonnage is apportioned across our primary categories; in this case Paper, Card, Glass, Metals, Plastics and Textiles. These categories consist of a mix of materials in terms of biodegradable content: Paper, Card - 100% biodegradable content; Metals, Plastics - 0% biodegradable content; Textiles - 50% biodegradable content. Therefore the uncertainty as to how to apportion WDF co-mingled recycling tonnages across these primary categories results in uncertainty regarding the overall content of biodegradable material in co-mingled recycling tonnages.

In the second column in Table 4.41, estimates have been made for the breakdown of the WDF Mixed Paper & Card category. However, since this tonnage has been apportioned only to the primary categories of Paper and Card, which both have 100% biodegradable content, there is no uncertainty regarding the overall biodegradable content for these tonnages – they are 100% biodegradable, regardless of how much paper or card is included in the WDF Mixed Paper & Card category.

The total WDF recycling tonnages subject to uncertainty in terms of biodegradable content amounts to 2,031,620 tonnes, of which 1,573,074 tonnes is assumed to consist of BMW. Therefore, of the 18,905,601 tonnes of BMW estimated to be in municipal waste in England in 2006/07 (Table 4.40 above), 1,573,074 tonnes (8.3%) of this material is subject to uncertainty regarding whether it is indeed biodegradable, due to the use of broad categories for some WDF recycling tonnages. This tonnage represents 5.6% of municipal waste arisings in England.

16 Variation in kerbside composition datasets only has a limited contribution to the magnitude of this confidence interval. Hypothetically, if confidence intervals for the kerbside element of England’s municipal waste were zero the resultant confidence interval for BMW content of municipal waste in England would be 66.71% +/- 3.94%, at the 95% confidence level.

Table 4.41: Recycling tonnages reported in WDF for which overall biodegradable content is uncertain

Notes: Green cells indicate estimated tonnages with biodegradable content. Pink cells indicated estimated tonnages with zero biodegradable content. Red borders indicate those tonnages which consist of a mix of materials in terms of biodegradable content, and which are therefore subject to uncertainty regarding their overall biodegradable content.

Other means

Non-hhold

Co

min

gled

m

ater

ials

Mix

ed p

aper

&

card

Oth

er c

ompo

stab

le

was

te

Co

min

gled

Oth

er

Pap

er &

Car

d

Scr

ap &

Whi

te

good

s

Co

min

gled

Com

post

Oth

er

Pap

er &

Car

d

Scr

ap &

Whi

te

good

s

Co

min

gled

Pap

er &

Car

d

Non

-mat

eria

l sp

ecifi

c re

cycl

ing

Non

-mat

eria

l sp

ecifi

c re

cycl

ing

Food waste 51,096 17 281 55 2,014 3Garden waste 265,569 44 142 10,466 42,436Other organic 12,118 1 2 478Paper 826,361 220,326 19,999 1,422 111,264 4,592 788 160,313 5,827 215 104 91,102Card 141,065 83,194 27,885 314 111,264 1,014 1,099 60,534 1,647 61 84 11,414Glass 46,094 78 253 8,058 82 41,366Metals 69,210 120 379,883 388 1,978 937 288 7,636Plastics 117,774 252 812 2,062 417 5,594Textiles 11,930 22 70 210Wood 3 367,364 10 3,305 1,830WEEE 3 52,694 178,769 10 474 931 16,039Hazardous 1 29,831 2 268Sanitary 4 13Furniture 22,509 202 16,159MattressesMisc combustible 4 1,318 12 12Misc non-combustible 2 6SoilOther wastes 29 62,418 92 562Fines 4 14


WDF categories

Prim

ary

cate

gorie

s us

ed in

this

stu

dy

Waste stream Kerbside recycling HWRC Bring recycling


4.5 Comparison with previous municipal waste composition estimates for England and Devolved Administrations

Meaningful comparisons between compositional estimates produced by the current work and those derived from other national datasets (elsewhere in the UK and previous estimates for England) are problematic because the various estimates differ significantly in terms of the following key parameters:

• local authority coverage • extent of coverage of different municipal waste streams • selection criteria used and how rigorous • assumptions made about the % BMW content of different fractions • the sorting categories used • the original objectives in carrying out the work • when the work was conducted.

Figures 4.29, 4.30 and 4.31 compare national estimates for England, Wales and Northern Ireland. Four previous studies have been compared alongside the municipal waste estimates for England from the current study. In order to provide consistency across the categories used, it has been necessary to re-work the original data to comply with the primary categories developed for the current study. A brief summary of each study is given below.

1. The 2002 study for the Prime Minister’s Strategy Unit: 27 out of 70 available datasets from English districts were selected. The kerbside data was derived from a profile of districts with IMD scores that broadly matched the national profile. However HWRC data were very limited and were based on site input surveys that did not differentiate residual from segregated materials: for this reason would not have qualified for inclusion in the current study. There was also a high degree of uncertainty associated with garden waste arisings at HWRCs, these were estimated to be about 40% of HWRC arisings (nearly twice the estimate from the current study). The study’s objective was to provide indicative compositional data for the model used in the Strategy Unit’s review ‘Waste Not Want Not’. There was no coverage of non-household municipal waste. The method of grossing up involved integration with 2000/01 municipal waste returns in a similar way to the current study.

2. Work carried out in 2007 for Defra’s LAWRRD model and for Waste Strategy 2007 again

focused on household arisings in England at kerbside and HWRCs. It included waste compositional studies carried out in 2004/05 and 2005/06, mainly funded through Defra’s Local Authority Support Unit (LASU), integrated with WasteDataFlow – the 2005/6 quarterly returns. The dataset is considered to be an improvement on the 2002 Strategy Unit study as there were significantly more waste analyses used (kerbside residual compositional data from 104 districts and kerbside dry recycling from 35 districts) and the WasteDataFlow returns provided a more detailed and accurate national tonnage dataset compared with the 2000/01 municipal waste management survey. However, the study did not include input on non-household municipal waste streams (e.g. trade wastes, litter, street sweepings etc). The composition of household residual waste was therefore applied to these waste streams for the purposes of gross-up estimates to total municipal arisings. For HWRC composition, an average split of the composition of separated recyclables from the NACAS dataset was applied to WasteDataFlow returns in cases where recycling tonnages were not material specific or did not contain the level of detail required for the sorting categories that needed to be compiled so as to match those developed for residual composition. A separate dataset from 9 Essex HWRC sites was used to estimate residual waste composition for HWRC sites and applied to the tonnages in WDF for each site. These estimates were based on a small sample from a single WDA and are not particularly representative compared with the data available to the current study.



In terms of the Devolved Administrations, two sets of national compositional estimates have been included in the comparison with English estimates: the 2003 Welsh Assembly Government study and the 2008 RPS study for the Northern Ireland DoE – Environment and Heritage Service.

3. The 2003 Welsh Assembly Government study comprises of specifically designed fieldwork that was undertaken between 2000 and 2003 to provide data on the composition of municipal waste in Wales, including all kerbside, HWRC and non-household streams. 9 of the 22 local authorities in Wales were sampled, selected to represent urban, rural and Welsh valley authority types. This study represents the most comprehensive integrated compositional analysis programme to date in the UK.

4. The Northern Ireland DoE Environment and Heritage Service 2008 and ARC 21 studies

provide two sets of linked kerbside compositional analysis work carried in two different seasons in 2007 (6 local authorities sampled across the three regional groupings) and samples from residual streams at 6 HWRCs sampled from across Northern Ireland. The waste analysis programme did not include non-household municipal wastes. The estimates contain an unusually high proportion of glass.

The most directly comparable datasets in terms of the extent of coverage of the different municipal waste streams are the current study and the 2003 Welsh Assembly Government study. However, the 2003 Welsh study includes construction and demolition waste arising at HWRCs as part of municipal waste. Figure 4.31 provides a version of the comparison with this element excluded from the ‘miscellaneous non-combustible’ category in the Welsh data. With this adjustment, there are still major differences, with the Welsh data having a much higher proportion of fines, other wastes and ‘miscellaneous combustibles’. Whether or not these differences are due to genuine differences in waste arisings, or to differences in waste classification or sorting methodology (particularly in relation to the fines fraction) is difficult to determine without more detailed analysis. The current study and the 2007 England study used similar methods of data collation, but the latter lacked any coverage of non-household streams and had weak coverage of HWRCs. These two studies overlap to only a limited degree (having 30% of the selected district kerbside studies in common), so it is somewhat reassuring that they appear so closely matched in compositional profiles. On the other hand, the Strategy Unit Study, based on a limited set of kerbside compositional analyses, appears to have a significantly higher proportion of garden waste compared with any other UK study.

Figure 4.29: Comparison of England municipal waste composition estimates for current study and previous reviews


Figure 4.30: Comparison between current study and previous UK reviews (version with HWRC rubble included in Welsh data)



Figure 4.31: Comparison between current study and previous UK reviews (version with HWRC rubble excluded in Welsh data)

Aside from the municipal waste compositional studies detailed above, little additional municipal waste composition data is available for the Devolved Administrations. The additional data collated by this project is summarised below:

• Scotland: 13 kerbside datasets, of which 2 meet the selection criteria (see Appendix 3.2); 2 communal residual datasets, neither of which meet the selection criteria; 2 HWRC residual datasets;

• Wales: 2 kerbside datasets, neither of which meet the selection criteria; 1 HWRC residual dataset; 1 sweet sweepings dataset;

• Northern Ireland: no data additional to the RPS review described in Appendix 4.5 above. Therefore there is clearly a requirement for more municipal waste compositional data in the Devolved Administrations, most particularly in Scotland, which has not been subject to a municipal compositional review in the same manner as Wales and Northern Ireland; see Appendix 6 for further comments. In order to compile more up-to-date UK compositional estimates it is important that the data used across the UK should be as contemporary and as consistent as possible.


appendix 4: analysis of collated studies and updated

Documents