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CENTRE OF COMPETENCE PAPER AND BOARD

Overview of the reject streams applications

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Table of content Internal applications ...........................................................................................................................3

I. Energy recovery ......................................................................................................................3

1. Secondary fuels – pellets/fluff .................................................................................................3

2. Oil distillation out of plastics....................................................................................................4

3. Gasification .............................................................................................................................4

4. Fluidized bed combustion ........................................................................................................6

5. Paper sludge to Ethanol ...........................................................................................................8

6. Reject treatment project .........................................................................................................9

7. Anaerobic digestion into biogas ............................................................................................. 10

8. Torrefaction .......................................................................................................................... 11

II. Reuse of paper rejects in paper and board production .......................................................... 12

1. Recyclable fibres – application in own plant/ other mills .................................................... 12

External applications ......................................................................................................................... 12

III. Constructions ........................................................................................................................... 12

1. Softboard ............................................................................................................................. 12

2. Hybrid MDF ....................................................................................................................... 14

3. Cement bonded sludge board ............................................................................................ 15

4. Roads – sand/heavy materials ........................................................................................... 16

5. CDEM ................................................................................................................................ 16

6. Absorbent, composting, animal bedding ........................................................................... 17

7. Metals ............................................................................................................................... 17

References: ............................................................................................................................... 19

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Internal applications

I. Energy recovery Materials for energy recovery must meet certain requirements concerning the calorific

value. The following streams are suitable:

- mixture of fibres and plastics, laminated paper and board, wet strengths,

- plastics [1]

1. Secondary fuels – pellets/fluff Secondary fuel pellets technology creates hard, easily shippable pellets from waste streams that can fuel

industrial processes with the energy-equivalence of coal. They can even be used to fuel their own production

process.

A fully developed system can produce hard, consistent fuel pellets from cellulose and plastic waste, and

significantly reduce the costs associated with waste-handling.

Depending on the composition (cellulose - paper and up to 60% plastic), one ton of pellets can have an energy

content as the equivalent energy of coal. The high carbon - content pellets burn efficiently and could fire part of

their own production process, thus further reducing costs of production. They can be added to a plant’s coal feed.

The process can be applied for handling of the waste stream from paper industry. Markets for the pellets have

included power plants and cement furnaces. Pellets can be dosed into coal-fired plants of any type, as they are

energy-equivalent to coal.[1]

Figure 1 Secondary fuel production scheme

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2. Oil distillation out of plastics

The idea is towards recycling of plastic waste materials and other rubbers and plastics fractions. It is chance to

become the manufacturer of the synthetic paraffin out of waste streams arising during recovered paper

processing. This technology is an good option for coarse rejects or the ragger rejects with plastic wires.

Figure 2 Oil out of plastic installation

The idea of producing oil out of rejects has lots of advantages, except the environmental ones there are also

economical benefits:

- estimated cost of installation that produces 500 litres of paraffin per hour is 1,5 million

euro;

- less costs of waste disposal with mill have to pay for getting rid of rejects

(50-100 euro/ton);

- the final product in the form of oil can be sold to a refinery (0,3 euro - price of one

litre of that product in Poland where that kind of installation works);

- service staff of two people on shift is necessary, all staff necessary is five people.[1]

3. Gasification

Gasification is a process that converts carbonaceous materials, such as coal, petroleum, petroleum coke or

biomass, into carbon monoxide and hydrogen.

Four types of gasifier are currently available for commercial use: counter-current

fixed bed, co-current fixed bed, fluid bed and entrained flow.

1. The counter-current fixed bed ("up draft") gasifier consists of a fixed bed of carbonaceous fuel (e.g.

coal or biomass) through which the "gasification agent" (steam, oxygen and/or air) flows in counter-

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current configuration. The ash is either removed dry or as a slag. The slagging gasifiers require a higher

ratio of steam and oxygen to carbon in order to reach temperatures higher than the ash fusion

temperature. The nature of the gasifier means that the fuel must have high mechanical strength and must

be non-caking so that it will form a permeable bed, although recent developments have reduced these

estrictions to some extent. The throughput for this type of gasifier is relatively low.

Thermal efficiency is high as the gas exit temperatures are relatively low. However, this means that tar

and methane production is significant at typical operation temperatures, so product gas must be

extensively cleaned before use or recycled to the reactor.

2. The co-current fixed bed ("down draft") gasifier is similar to the counter-current type, but the

gasification agent gas flows in co-current configuration with the fuel (downwards, hence the name

"down draft gasifier"). Heat needs to be added to the upper part of the bed, either by combusting small

amounts of the fuel or from external heat sources. The produced gas leaves the gasifier at a high

temperature, and most of this heat is often transferred to the gasification agent added in the top of the

bed, resulting in an energy bed of char in this configuration, tar levels are much lower than the counter-

current type.

3. In the fluid bed gasifier, the fuel is fluidized in oxygen (or air) and steam. The ash is removed dry or as

heavy agglomerates that defluidize. The temperatures are relatively low in dry ash gasifiers, so the fuel

must be highly reactive; low-grade coals are particularly suitable. The agglomerating gasifiers have

slightly higher temperatures, and are suitable for higher rank coals. Fuel throughput is higher than for

the fixed bed, but not as high as for the entrained flow gasifier. The conversion efficiency is rather low,

so recycle o subsequent combustion of solids is necessary to increase conversion. Fluidized bed

gasifiers are most useful for fuels that form highly corrosive ash that would damage the walls of

slagging gasifiers. Biomasses generally contain high levels of such ashes.

4. In the entrained flow gasifier a dry pulverized solid, an atomized liquid fuel or a fuel slurry is gasified

with oxygen (much less frequent: air) in co-current flow. The gasification reactions take place in a

dense cloud of very fine particles. Most coals are suitable for this type of gasifier because of the high

operating temperatures and because the coal particles are well separated from one another.

The high temperatures and pressures also mean that a higher throughput can be achieved, however

thermal efficiency is somewhat lower as the gas must be cooled before it can be cleaned with existing

technology. The high temperatures also mean that tar and methane are not present in the product gas;

however the oxygen requirement is higher than for the other types of gasifiers. All entrained flow

gasifiers remove the major part of the ash as a slag as the operating temperature is well above the ash

fusion temperature. A smaller fraction of the ash is produced either as a very fine dry fly ash or as a

black colored fly ash slurry. Some fuels, in particular certain types of biomasses, can form slag that is

corrosive for ceramic inner walls that serve to protect the gasifier outer wall. However some entrained

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bed type of gasifiers do not possess a ceramic inner wall but have an inner water or steam cooled wall

covered with partially solidified slag.

These types of gasifiers do not suffer from corrosive slags. Some fuels have ashes with very high ash

fusion temperatures. In this case mostly limestone is mixed with the fuel prior to gasification. Addition

of a little limestone will usually suffice for the lowering the fusion temperatures. The fuel particles must

be much smaller than for other types of gasifiers. This means the fuel must be pulverised, which

requires somewhat more energy than for the other types of gasifiers. By far the most energy

consumption related to entrained bed gasification is not the milling of the fuel but the production of

oxygen used for the gasification.

Process

In reactors, the waste materials are converted under precisely defined process conditions into synthesis gas. This

gas is then processed in the following parts of the plant (gas and steam turbine power station, methanol plant)

into steam, electricity and methanol. Pressurized solid-bed gasification is used for processing solid waste.

The waste is mixed with coal and enters the reactor through an airlock system.

The reactors operate at a pressure of 25 bars, using steam and oxygen as gasification agents. Gasification is

carried out at a temperature of 800 – 1300 °C. The remaining solid residues, in the form of slag, comply with the

requirements of the waste dump class 1 of the German garbage disposal laws.[1]

4. Fluidized bed combustion

In recovered paper processing mills fluidized and circulating fluidized bed combustion for solid waste and

sludge is in common use. FBC combines high efficiency combustion of low-grade fuels with reduced emissions

of sulphur and nitrogen oxides (SOx and NOx).

The fuel is fired in a bed of inert solids such as silica, sand or ash fluidized by air. The air is blown from

below into the combustion area using a perforated bottom. The air serves as the medium for combustion. At

velocities of 1-2,5 m/s, it fluidizes the inert solid layers. The fuel is added above the fluidized bed. Due to its

high heat capacity and dynamic fluid characteristics, the inert bed material provides heat transfer and

temperature averaging. The fuel is therefore quickly ignited as it is fed. Doe to intensive mixing of fuel and

combustion air in the fluidized area, very favorable material and heat exchange conditions occur. For this reason,

good combustion results even with fuels of low quality.

The combustion temperatures of fluidized bed combustion systems are 800°C – 900°C. The combustion gases

emitted from the fluidized bed flow into the free space above which an after-burning zone is created by the

addition of secondary air. In this zone, the exhaust gases react at temperatures of 800°C – 950°C. Retention

times of 2–4 seconds guarantee complete combustion. The after-burn chamber can be separate outside the

fluidized bed combustion chamber and optionally has an after-burner.

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Depending on the dimension of the fluidized bed and the level of the operating pressure, the following

techniques are possible:

- stationary fluidized bed

- circulating fluidized Bed

Stationary fluidized bed The stationary fluidized bed has a slightly expanded fluidized bad and a defined bed surface. Fluidizing speed

and solid grain size are matched to a tolerable loss of small amounts of particles from the fluidized bed. The heat

generation related to the perforated bottom is 1-2MW/m2. A stationary fluidized bed. A stationary fluidized bed

has primary use in industrial facilities with heat outputs less than 50MW. For furnaces with greater output

capacities unfavorable combustion conditions exist due to the increased fluidized beddimensions and resulting

mixing problems.

Figure 3 Stationary fluidized bed[2]

Circulating fluidized Bed Circulating fluidized bed incinerator is the latest sludge incinerator. Since the temperature in combustion

chamber is uniform, it can burn together with sludge, screenings, or other refuse easily. Moreover, gas flow

velocity is high and a diameter of furnace serves as half as compared with the Bubbling fluidized bed incinerator.

Better result for the quality of combustion and emission reduction than with stationary fluidized bed, are possible

with this kind of fluidized beds. These plants operate with higher gas speeds up to 8m/s and considerably smaller

grain sizes of the bed material. The high gas speed produces a strongly expanded fluidized bed and removes a

large share of the solids from the furnace.

Depending on the heat requirement, a direct return or a return via fluidized bed heat exchangers is possible. The

continuous return of the finely grained solid material guarantees almost complete combustion and keeps the

fluidized bed in the furnace in balance. Using multiple stepped air feed to the furnace provides very low nitrogen

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oxides emission below 100mg/m3. The high air and solid throughput permits average thermal cross-sectional

loads up to 12MW/m2. A heat output of 500MW is the ceiling limit.[1]

Figure 4 Circulating fluidized bed

The described above installation have definitely some significant advantages. They can cause reduction of

costs of electricity while maintaining good standards of the processes in paper mill, reduction of solid waste

emission and minimization of greenhouse gases emission through the use of advanced technologies, reduction of

premium, and high value industrial fossil feedstock for the production of electricity.

However high costs of installations fluidized bed combustion plants are serious disadvantage and they are

rather offered only for large scale plant units and are not suitable installations for smaller mills with lower

emission of waste. Another disadvantage is that due to the mechanical specification and requirements of the fuel,

preprocessing of the material can be necessary such as extraction of the metals and grinding.[1]

Table 1 Heating content, ash content and moisture content of solid fuels

5. Paper sludge to Ethanol

Domestic production and use of ethanol for fuel can decrease dependence on foreign oil, reduce trade deficits,

create jobs in rural areas, reduce air pollution, and reduce global climate change carbon dioxide buildup.

Ethanol, unlike gasoline, is an oxygenated fuel that contains 35% oxygen, which reduces particulate and NOx

emissions from combustion. Ethanol can be made synthetically from petroleum or by microbial conversion of

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SORTING DRUM REJECTSORTER

FERRO/NON FERRO REMOVAL

SHREDDER

MIXING/STORING CHEST

DRUM SORTERREJECT

STOCK PREPARATION LINE

ACCEPT

ACCEPT

REJECT

REJE

CT

REJE

CT

biomass materials through fermentation. In 1995, about 93% of the ethanol in the world was produced by the

fermentation method and about 7% by the synthetic method.

The fermentation method generally uses three steps: the formation of a solution of fermentable sugars, the

fermentation of these sugars to ethanol, and the separation and purification of the ethanol, usually by distillation.

Figure 5 Cellulosic Ethanol from paper sludge production scheme [3]

6. Reject treatment project The overall assumptions of the project direct towards the non-paper and non-recyclables that arise from

recovered paper processing within the paper industry. The dedicated reject treater is planned to be designed and

further on installed at the sides of the paper mills that produce brown packaging grades paper and board out of

100% recovered paper as raw material. The installation’s objective is reduction of the losses of recyclable fibres

as the first stage of treatment.

From the reject treatment and optimal application at the location of a paper mill, there are several benefits that

can be named. There are as well environmental as economical. First of all there is great contribution to

sustainable development as the efficiency of use of secondary raw materials is to be improved. Secondly, there is

a significant reduction of emission of solid waste, when they are reused/recycled. Finally there are economical

savings for the paper mills and those are among others a function of:

a). waste disposal costs of coarse rejects

b). savings on the fibre raw material purchase

c). extra fuels from bio-diesel unit of reject treater

Figure 6 Concept of the Reject Treater installation

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Figure 7 Reject treater pilot plant

The results from the pilot scale installation has showed that the quality of the recyclable fibres was proofed to be

on the similar level that the fibres used for paper production.

The rest of the treated coarse rejects that is not accepted in the reject treater – rejected plastics fraction could be

applied for other purposes – i.e. energy recovery via bio-diesel production. This option has been tested

simultaneously with the reject treater installation’s performance investigation. And proved to be success. In this

terms, the 100% of coarse rejects could be reused/recycled/re-energized at the location of paper mill. [4]

7. Anaerobic digestion into biogas

Anaerobic digestion is a series of processes in which microorganisms break down biodegradable material in

the absence of oxygen. It is widely used to treat wastewater sludges and organic waste because it provides

volume and mass reduction of the input material.[1] As part of an integrated waste management system, anaerobic

digestion reduces the emission of landfill gas into the atmosphere. Anaerobic digestion is a renewable energy

source because the process produces a methane and carbon dioxide rich biogas suitable for energy production

helping replace fossil fuels. Also, the nutrient-rich solids left after digestion can be used as fertiliser.

There are three principal products of anaerobic digestion: biogas, digestate and water.

Biogas is the ultimate waste product of the bacteria feeding off the input biodegradable feedstock, and is

mostly methane and carbon dioxide, with a small amount hydrogen and trace hydrogen sulfide. (As-produced,

biogas also contains water vapor, with the fractional water vapor volume a function of biogas temperature. Most

of the biogas is produced during the middle of the digestion, after the bacterial population has grown, and tapers

off as the putrescible material is exhausted. The gas is normally stored on top of the digester in an inflatable gas

bubble or extracted and stored next to the facility in a gas holder.

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The methane in biogas can be burned to produce both heat and electricity, usually with a reciprocating engine or

microturbine often in a cogeneration arrangement where the electricity and waste heat generated are used to

warm the digesters or to heat buildings. Excess electricity can be sold to suppliers or put into the local grid.

Electricity produced by anaerobic digesters is considered to be renewable energy and may attract subsidies.

Biogas does not contribute to increasing atmospheric carbon dioxide concentrations because the gas is not

released directly into the atmosphere and the carbon dioxide comes from an organic source with a short carbon

cycle.[5]

Figure 8 Biogas holder

8. Torrefaction Torrefaction is a mild heat treatment at 250-300°C that efficiently turns solid biomass into a brittle,

easy to pulverise material (“bio-coal”) that can be treated as coal.

Furthermore, torrefied biomass can be pelletised very easily to obtain a dense and easy to transport

biomass fuel. The hydrophobic nature of torrefied material further simplifies logistics. Pulverized

torrefied biomass can be fed like coal, thus enabling a smooth transition from coal to biomass.

Torrefaction is a new technology to upgrade biomass for combustion and gasification applications. The

product properties of torrefied biomass (TOP pellets) are superior over the biomass it is produced

from. Still, the required technology that will make its introduction in biomass-to-energy chains

economically justified is not yet mature. [6]

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II. Reuse of paper rejects in paper and board production

1. Recyclable fibres – application in own plant/ other mills One of the biggest streams of rejects, generated by paper industry, is coarse rejects stream, especially in paper

mills which occur only mechanical cleaning of pulp (without deinking stage). Characteristic of coarse reject has

been made and it has shown that in that stream of rejects significant amount of recyclable fibers can be found.

Those fibers can be re-use again to paper production, thus improve efficiency of recovered paper use in paper

mills and savings.

The application for the recyclable fibres is paper and board production. They can be used at the location, in the

processes of the paper mill that produces the rejects. As the quality of the fibers is equal/better than the quality of

the main fibrous fraction used for pulp production. In other cases, the fibrous fraction can be used externally by

other neighbor paper mill producing lower quality pulp.[1]

Figure 9 Coarse rejects

External applications

III. Constructions

1. Softboard The main area of application of the softboard is non-load bearing uses such as thermal/acoustic insulation, a

ceiling tile and in-fill product for timber frame construction.

Table 2 Softboard specification

Raw materials: 80% sludge - 10% MDF fibre Adhesive: 10 % Phenolic formaldehyde resin Surface lamination: Conventional wall paper or insulation waived aluminium foil Board thickness: 10-45mm Type of process of manufacture: Continuous

Significant capital investment is required for the setting up of a softboard line with an in house refining

capability. The most energy demanding production stages are the refining and the drying.

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Board pressing can be done efficiently on a continuous basis. Energy savings can be achieved with the utilization

of bio-fuels such as wood waste. The installation of bioenergy generators may be proved a significant cost

saving investment

Figure 10 Process flow diagram for Softboard

Advantages One of the main advantages of the softboard is that it is made with 80% waste material. The disposal of paper

waste residues (sludge) is a significant waste disposal operation for the paper industry which is associated with

high costs. If route for re-use can be established that could demonstrate that regular amounts of sludge could be

utilised from a mill, the material may be supplied at negligible cost. The cost of the raw material on that basis

should be negligible and probably will only reflect to transport costs.

The softboard in general has a good feel is very lightweight and has good resistance against wetting. The high

inorganic content (35-40%) of the sludge should enhance the fire retardancy and the decay resistance against

basidiomycetes and mould fungi.

A conventional type softboard is made utilising refined wood fibre and adhesives. The softboard that was

manufactured in this project contains 80% paper mill waste of which 40-60% are inorganic compounds. It is

hypothised that the high inorganic content of sludge softboard will enhance its fire retardancy properties and in a

fire test in a straight comparison with a conventional softboard should show superior performance. However,

further work is needed to evaluate the later assumption.

Disadvantages The biggest disadvantage of the softboard is its low bending strength. As a result the product is brittle and not

flexible. Consequently the softboard would require careful handling during installation. The surface

characteristics may cause difficulties during the surface lamination stage. However, the surface characteristics

are improved through lamination, which also helps improve some of the mechanical properties. The non-

laminated product has a strong smell that of “dry sludge”. This smell is reduced when a laminate is applied on

the surface.[7]

Figure 11 Softboard

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2. Hybrid MDF General purpose (Upholstery furniture, wall sheathing, floor covering, packaging, etc.) or laminated furniture

components.

Table 3 Hybrid MDF specification

Raw materials: 45% sludge and 40-45 % MDF fibre (40+35+15 =100%) Adhesive: 10-15 % (based on the dry weight of the mix) Phenolic formaldehyde resin or Melamine Urea formaldehyde resin Surface lamination/modification: as MDF Board thickness: 10-25mm Type of process of manufacture: Continuous

Figure 12 Process flow diagram for Hybrid MDF

The hybrid MDF product presented promising results in terms of bending strength and can be used in several

applications in dry conditions where high internal bond strength is not required. Improving the internal bond

strength would create opportunities for the product for other applications (i.e. furniture, doors etc.). The internal

bond result 0.5 N/mm2 was very close to the standard MDF requirement (IB= 0.55 N/mm2).

Advantages This product has good mechanical properties such as stiffness and combined with promising decay and fire

resistance properties could be targeted towards high-added product value markets.

In general the product has normal density and it is not heavy in comparison to standard MDF. The surface

quality is acceptable. The product has good machinability i.e. router produced a good quality profile.

The high inorganic content in the sludge could hide some special characteristics, which are required from the

product for new finishing technologies. Finally it could substitute virgin wood in conventional MDF production

with significant cost savings. However, further work is needed to exploit this potential.

Disadvantages This product needs some further optimization. The high fines content produces a mat with very high compaction

capacity, which is difficult to hot press. High resin contents were used in order to achieve good internal bond

strengths, but add to the production cost. The fines also contribute to the pre-curing process on the surface

increasing any sanding tolerances, and making sanding more difficult.[7]

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3. Cement bonded sludge board The cement bonded sludge board presented excellent test results with comparable or even better properties than

the standard requirement and therefore presents real potential for further development.

Figure 13 Cement bonded sludge board

Table 4 Cement board specification

Raw materials: 30% sludge- 70 % Cement Adhesive: Not required Surface lamination/modification: As a normal cement bonded particleboard Board thickness: 10-25mm Type of process of manufacture: Continuous

Figure 14 Process flow diagram for cement bonded sludge board

Advantages Key advantages of this product are strength, fire resistance and dimensional stability. These characteristics

combined with decay resistance performance make this product a candidate for exterior applications in addition

to interior applications.

Disadvantages High density products and the slow production times may raise concerns for manufacturers. There is not a big

established market for cement bonded particleboard in Europe and although it has competitive properties it is

difficult to compete against lower density products such as Orientated Strand Board (OSB) which have

dominated the construction market.[7]

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4. Roads – sand/heavy materials The sand like matter materials as well as heavy particles that origin from paper and board recycling can be

applied in construction. They can be used as substitute of worse quality sands as bottom layers of minor roads

construction etc. The above mentioned materials could to a large extent be used in road construction. It could be

primarily used as fill in embankments and as granular subbase of course.

Similar practices have taken place in Denmark. This is the result of development during the last 20 years. The

use of heavy fractions as subbase in light and medium trafficked roads, paths and parking areas has proved to be

successful. In 1993, a more heavily trafficked test load was constructed. Layers of 20 cm bottom of those

materials from various plants was used as subbase and compared to the standard material which is virgin,

relatively uniform sand. After 3 years of medium to heavy traffic, the test road shows no signs of rutting or

progressive damage or other signs of rapid deterioration of the road construction. However, a period of 3 years

has been estimated to be too short to recommend general use of the heavy waste fractions in heavily trafficked

roads.[1]

5. CDEM

CDEM method of waste recycling is based on an innovative sludges-to-energy technology that achieves the cost-

efficient disposal of deinking sludge without the harmful environmental effects of traditional methods such as

landfill.

CDEM converts the input – deinking sludge, consisting of: - in-organics (kaolin and calcium carbonate), - organics (cellulose, additives, latex), - water by means of an exothermic reaction at 800oC into: - meta-kaolin, - calcium carbonate, - calcium oxide, - heat, - CO2, - vapour.[1]

Figure 15 CDEM technological scheme

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6. Absorbent, composting, animal bedding

Absorbent production is one of the possibilities of the paper waste utilizing. Kadant GranTek Inc. produces

KadantGran-sorb industrial absorbent which is made from fibrous paper sludge waste and used for spill cleanup,

liquid stabilization, bioremediation, site remediation, among other industrial absorbent uses. This

environmentally responsible product absorbs oils, solvents, lubricants, coolants, water, and most non-aggressive

liquids on contact. (2)

Figure16 Industrial absorbent from paper sludge.

Paper mill sludge can also be used as a bulking agent or carbon source for composting, animal bedding, or raw

material in the manufacture of absorbents. May also be used as alternative cover at a sanitary landfill when

mixed with soil in a 50/50 volume. [8]

7. Metals Metals sources of waste metals consist primarily of residential and commercially generated items such as steel

and aluminum cans, small appliances and other miscellaneous items (metal furnishings, fasteners and fittings).

Most sources of scrap metals are not considered part of the municipal solid waste stream, as they have

traditionally been recovered for recycling due to their high value and are unlikely to end up in landfill. Steel

made from recycled scrap uses only one-quarter of the energy it takes to make it from its primary resource, iron

ore.

Aluminum can be recycled at savings of up to 95 per cent of the energy used to manufacture it from aluminum

ore. Close to 75 per cent of ferrous scrap (steel) and 45 per cent of non ferrous scrap (aluminum, brass, copper)

are recovered for recycling.[1]

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1. Composting The goal in a composting system is to provide a healthy environment and nutrition for the rapid decomposers,

the bacteria.

Paper sludge were traditionally landfilled or burned. Over the years, the use of paper sludge on soils has

increased, as well as the concerns about their environmental effects. Therefore, the chemical characterization of

paper sludge and their young (immature) compost needed to be investigated, and over 150 inorganic and organic

chemicals were analyzed in de-inking paper sludge (DPS). In general, nitrogen, phosphorus and potassium

contents were low but variable in raw DPS and its young compost. The contents of arsenic, boron, cadmium,

cobalt, chromium, manganese, mercury, molybdenum, nickel, lead, selenium, and zinc were also low and

showed low variability.

However, the copper contents were above the Canadian compost regulation for unrestricted use and required a

follow-up.[1]

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References: 1. Ecotarget, “D 2.3.6 - Feasibility of implementation of pilot plant for reuse of solid rejects on the side of

a paper mill” 2. www.aee-vonroll.us/downloads/fluidbedtech.pdf 3. http://www.agwest.sk.ca/publications/infosource/inf_may98.php 4. Ecotarget, “TD2.3.8 - Design of reject treater. Pilot plant installation – design and performance” 5. www.wikipedia.com 6. Published at 14th European Biomass Conference & Exhibition, “Torrefaction for biomass upgrading”,

Paris, France, 17-21 October 2005 7. WRAP Project code: PAP009-011, „Research into using recycled waste paper residues in construction

products” 8. www.kadant.com