Resources, Conservation and Recycling 87 (2014) 126136

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Resources, Conservation and Recycling

jo u r n al homep age: www.elsev ier .com/ locate / resconrec

Added-value from innovative value chains by estcycles

Oliver M unda Leibniz-Instit tanceGermanyb Humboldt-Un nomicc Humboldt-Un ics, Ph

a r t i c l

Article history:Received 2 JulReceived in revised form 20 March 2014Accepted 20 March 2014Available online 23 April 2014

Keywords:Added-valueNutrient cycleWastewater trPhosphorusPhosphorus reStruvite

as beof nutrients such as phosphorus (P). Global reserves of phosphate rocks are limited and are being increas-ingly depleted. At the same time, P is disposed of via various substance-streams in wastewater treatment.Establishing nutrient cycles may solve these problems and lead to innovative added-value chains with ahigher added-value. The objective of this paper is to assess the added-value of P-recovery from sewagesludge via struvite precipitation and its application as fertilizer in Berlin-Brandenburg (Germany). The

1. Introdu

The cyclof our planand magnestems due toand Likens, the disruptreduce exislimit huma

Particulacern about

CorrespoPotsdam-BornAllee 100, 144

E-mail add

http://dx.doi.o0921-3449/ eatment

covery

added-value from struvite precipitation was determined by performing a cost/benet analysis based ondata from standardized questionnaires and interviews with operators of wastewater treatment facili-ties. Surveys of 146 farmers were used to ascertain what crops were cultivated in the study area and togauge the willingness of farmers to substitute struvite for conventional mineral P-fertilizer. Benets fromusing struvite were found by calculating the fertilizer costs when struvite is substituted for conventionalmineral fertilizer. The results indicate that the precipitation of struvite and its use as fertilizer gener-ates added-value gains for wastewater treatment facilities (416,000 D ) and for crop producers (35,000D ). In wastewater treatment, struvite precipitation reduces operating costs and yields additional rev-enues through struvite sales. In crop production, fertilization costs are reduced by substituting struvitefor mineral P-, N- and Ca-fertilizers. The distribution of the added-value in the struvite value chain isdetermined by the marketing strategy of struvite. Farmers may obtain a higher share of added-value ifstruvite is marketed via direct sale.

2014 Elsevier B.V. All rights reserved.

ction

e of elements in the biosphere is a life-sustaining featureet. Some cycles, for example the phosphorus, calciumium cycles, continually sustain losses in biological sys-

erosion, and they ultimately land in the sea (Bormann1967: 424): Acceleration of losses or, more specically,ion of local cycling patterns by activities of man couldting pools, restrict productivity, and consequentlyn population.rly in the case of phosphorus (P), there is growing con-

the worldwide depletion of this life-sustaining nutrient

nding author at: Leibniz-Institute for Agricultural Engineeringim e.V., Technology Assessment and Substance Cycles, Max-Eyth-69 Potsdam, Germany. Tel.: +49 0 331 5699 919.ress: omaass@atb-potsdam.de (O. Maa).

(Cordell et al., 2009; Dry and Anderson, 2007; Van Vuuren et al.,2010). Substantial P inputs are required for optimum plant growthand adequate food and bre production (OECD/FAO, 2011). Thenutrient P is produced completely from non-renewable resources,essentially from phosphate rocks. The geographical distribution ofthese phosphate rocks is extremely uneven. Just ve countries, pri-marily Morocco, control about 91% of the global P reserves (USGS,2012). Therefore, all importing countries are dependent on and vul-nerable to shortages and price volatility. Today, about 90% of thephosphate rocks mined globally are processed into mineral fertil-izer for agricultural production (Brunner, 2010; Cordell, 2010).

Estimates on the global P reserves vary greatly and are veiledby data availability and uncertainty (Schrder et al., 2010). Somestudies state that phosphate rock reserves may be depleted within50100 years (Cordell, 2010; Schrder et al., 2010; Smit et al., 2009).Other studies indicate that total global reserves may last 300400years (Cooper et al., 2011; USGS, 2012), but single countries willhave depleted their reserves within 100 years (Cooper et al., 2011).

rg/10.1016/j.resconrec.2014.03.0122014 Elsevier B.V. All rights reserved.via struvite

aaa,b,, Philipp Grundmanna,c, Carlotta von Bockute for Agricultural Engineering Potsdam-Bornim e.V., Technology Assessment and Subs

iversitt zu Berlin, Department of Agricultural Economics, Division of Horticultural Ecoiversitt zu Berlin, Department of Agricultural Economics, Division of Resource Econom

e i n f o

y 2013

a b s t r a c t

The establishment of nutrient cycles hablishing nutrient

Polacha,c

Cycles, Max-Eyth-Allee 100, 14469 Potsdam,

s, Philippstrae 13, 10115 Berlin, Germanyilippstrae 13, 10115 Berlin, Germany

en widely proposed as a strategy for an efcient management

O. Maa et al. / Resources, Conservation and Recycling 87 (2014) 126136 127

Regardless of these estimates, it is evident that a deciency in P inagriculture would severely restrict the crop yields and food securityof the worlds increasing population (Cordell et al., 2009; Koninget al., 2008). Other concerns about P are related to environmentaland economic matters. P-pollution in the surface water can lead toproblems with eutrophication. P-mining, processing and marketingare highly resource and emission-intensive (Ekardt, 2011). Anotherproblem of P is soil contamination, due to its frequent combina-tion with heavy metals, which could enter the entire food chain.The quality and accessibility of the remaining phosphate rocksare decreasing while production costs are increasing (Cordell andWhite, 2011). The price of phosphate rocks is expected to increasein the long term (Cordell et al., 2009; Von Horn and Sartorius, 2009),having signicant consequences for farmers and food productionsystems (Cordell and White, 2011).

Simultaneously, P leaves the nutrient cycle due to the outowof P in diffeinstance, esmultiple str(Table 1).

Awareneery of P frcycle as ageral P-fertildependency

Presentlmainstreamoption to uare alreadyter treatmeused matteapplied promal treatmerate (Corde

One of timplementebiological pphosphate precipitatioment proceorthophosp(Uludag-Deoped to prmajority ofanaerobic dlarge-scale from digestOstara, 201While it is wcan cause ostruvite ha(Parsons et

Present focused on

Table 1P-recycling po

Substance-s

WastewaterWastewaterSewage sludSewage sludManure Animal by-p

* These pote

process (Gaterell et al., 2000; Jaffer et al., 2002; Shu et al., 2006;Ueno and Fujii, 2001; Von Mnch and Barr, 2001). Little attentionhas been paid to assessing the added-value of nutrient-cycling viastruvite precipitation and its use as an agricultural fertilizer.

This papstruvite preperspectivefeeding nutvative valuis tested indigested sein agriculturesearch qu

1. What tetewaencevite ft arblishas ag

is the cha

oret

eral leaded repectahn

2000ptiontowbstanentemet ma

valubusinvaluactitifectivps ofses (Breatee dife valrticu

valutributribued atieorris

theking

the whihain

and ed

undmect o. Thisrent streams of wastewater treatment. In Germany, fortimates indicate a high potential of recoverable P fromeams of wastewater treatment and animal production

ss of this potential has motivated research on the recov-om wastewater and its reinsertion into the nutrientricultural fertilizer. Since recycling of P replaces min-izer, it may also contribute to easing the problems of

on P imports and depletion of stocks.y, the recovery and reuse of P is still far from being a

practice (Cordell et al., 2011). However, besides these quality-assured sewage sludge on farmlands, there

a variety of techniques for recovering P at wastewa-nt plants. These techniques differ by the origin of ther (wastewater, sludge, sludge liquor, sludge ash), thecess (precipitation, wet chemical extraction, and ther-nt) (Satorius et al., 2011), and the potential P-recovery

ll et al., 2011).hese techniques is struvite precipitation, which can bed in wastewater treatment plants that use enhancedhosphorus removal. Struvite (magnesium ammoniumor MAP (MgNH4PO46H2O)) is formed by a basicn reaction in different stages of the wastewater treat-ss where magnesium (Mg2+), ammonium (NH4+) andhate (PO43) occur under weak alkaline conditionsmirer et al., 2005). Various techniques have been devel-ecipitate struvite on both full and pilot scales. The

these techniques use sludge liquors, generated fromigesters as inuent (Le Corre et al., 2009). Commercialstruvite production plants which precipitate struviteed sludge liquors are operating in the USA, Canada (see3; Britton et al., 2009) and Japan (Ueno and Fujii, 2001).ell known that the uncontrolled formation of struviteperational problems in wastewater treatment plants,s the potential to be used as fertilizer in agricultureal., 2001).studies on struvite production and use have mainly

the techno-economical aspects of the precipitation

tential of different substance-streams in Germany (UBA, 2012).

tream Estimated potential ofrecoverable P in t year1

(municipal) 54,000*

(industrial) 15,000ge (municipal) 50,000*

ge ash 66,000*

444,000roducts 20,000

ntials are not addable due to their competitive recycling paths.

wassequstru

2. Whaestause

3. Howvalu

2. The

Sevwhich a denthe res2005; Het al., assumthe ouand suimplemto the efcien

Thetional added-and prand efthe steprocesvalue cIt is thand ththat pa

Thethe disThe disquantibe idenand Mseen inrisk-taand toinputsvalue cchainsperformand Grthe effbutioner aims to complement the existing assessments ofcipitation and use in agriculture from an added-value-. We aim to test the hypothesis that innovations forrient cycles are conducive to the emergence of inno-e chains with a higher added-value. This hypothesis

the case of P-recovery via struvite precipitation fromwage sludge and the substitution of mineral fertilizerre. In particular, the study will address the followingestions:

chno-economic changes occur in the value chains ofter treatment and agricultural crop production as a con-

of the precipitation of struvite and the substitution ofor mineral P-fertilizer?e the monetary costs, benets and added-value froming a P nutrient cycle via struvite precipitation and itsricultural fertilizer?e added-value of struvite distributed along the struvitein?

ical concepts

studies have argued that innovations in value chains, to the completion of substances and energy cycles ingion, may contribute to increasing the added-value inive region (Baum, 2004; Bentzen et al., 1997; Fritsche,e, 2006; Hillring, 2002; Lindenthal et al., 2004; Marsden; Tischer et al., 2006). These studies are based on the

that the outow of resources from a region (especially of capital) is reduced when ows and cycles of energyces are completed within the region. Accordingly, the

ation of technical innovations for recycling P may leadrgence of innovative value chains that foster a morenagement of P.e chain perspective in this paper is driven by a func-ess view, evaluating costs, benets and ultimately thee as a basis for competitive comparisons. Researchersoners have used this approach to improve the efciencyeness of value chains by analyzing the added-value at

a value chain and redesigning the internal and externalrown, 2009). The added-value indicates the increase ofd by economic activities at every step of the value chain.

ference between the market value of a good or serviceue of the inputs required for producing and deliveringlar good or service (Haller, 1997).e chain analysis approach is further used to understandtion of costs, benets and revenues in the value chain.tion of the added-value among the participants can bend critical stages and transactions in the value chain cand (Kaplinsky and Morris, 2001). According to Kaplinsky

(2001: 42) the distributional outcome (. . .) is to be incomes arising to capital (for its entrepreneurship,and ownership of technology), labour (for its effort),owners of natural resources (for their command overch arise as gifts of nature) in each of the links in the. The distribution of the added-value along the valuethe return on the individual production factors can bemethodologically by means of decomposition (Kimmich

ann, 2008). Further, conclusions can be drawn aboutf governance structures and the determinants on distri-

aids in making policies that foster economic activity at

128 O. Maa et al. / Resources, Conservation and Recycling 87 (2014) 126136

certain steps of the value chain, e.g., with participants in deprivedareas.

Costs, benets and technical challenges inuence the efcientusage of nutrients in innovative value chains. In addition, institu-tional arranOstrom, 20tions, e.g., tspecic govresource tr1996). We scontributesthat the coocosts needeory forms ton the adde

3. Materia

3.1. Bounda

The prodinnovation crop produtreatment tion and ut(Wamanneral outputtreated wasThe treatedBuilt-up sewsewage gasheat. Struviture. After tsludge is deproductionThey includintroductiochain analy

The valugas is not althe sewagesteps of dewcipitation ocharacteristthe watersues can be sewage sluties of sewThe subseqincinerationdisposal of vite. The saenergy valueral P-fertilsucceedingthe value chchains, butand the add

3.2. Case st

The valuproductionFederal Staoperated b

Table 2Nutrient and heavy metal contents of struvite, superphosphate (SUP) and other P-fertilizers.

Component

ntshorusen (N)

(S) siumm (Ca

metaum (Cium (r (Cu)

(Ni)c (As)Pb) n)nese

obalder, 20

s a trlent tewalied iroug

leadf sluthe ntialenteratucedeinzmitatiory ane slues stam pms ce durm o

TM o derecipiced in a large-scale prototype of a struvite reaction vesselating the digested sludge and adding magnesium chloridef et al., 2009). Furthermore, a washer was installed for puri-

he struvite from organic matter. The investment costs of thislogy were 2.3 Mio Euros. Under the stable-system operatingions, an annual production of up to 900 t of struvite can bed.le 2 presents the pure nutrient and heavy metal contents ofuvite produced at the Wamannsdorf Treatment Plant. Theutrients are magnesium and phosphorus. Furthermore, thee contains amounts of nitrogen and calcium, as well as smallts of sulfur and potassium. The struvite from the Wamans-eatment Plant has an N:P:K-ratio of approximately 4:9:0.

heavy metal content of struvite varies, since it greatlyds on the ambient abundance pattern of these elements. Inn, the amount of enclosed heavy metals may vary, depend-

the precipitation technique used. The concentrations ofmetals in mineral P-fertilizers vary considerably (Adler,Camelo et al., 1997). Compared to conventional mineralgements affect resource management (Hagedorn, 2008;05). Whenever goods or services are transacted, fric-ransaction costs, play a major role. To reduce frictions,ernance structures and rules are needed to manage theansactions and interactions of the actors (Williamson,tate that not only does a linkage in several value chains

to managing resources more costefciently, but alsoperation of actors minimizes transaction costs and thed to run the system. Although the transaction costs the-he background of this study, the focus of this paper isd-value approach.

ls and methods

ries of the investigation

uction of struvite and its utilization as P-fertilizer is anthat links the value chains of wastewater treatment andction. Fig. 1 shows how the value chains of wastewaterand crop production are linked through the produc-ilization of struvite in the specic case of this studysdorf Treatment Plant). The gure indicates that sev-s result from the treatment of wastewater, includingtewater, sewage sludge and the precipitated struvite.

wastewater is discharged into the receiving water.age sludge is stabilized anaerobically and the obtained

is used in cogeneration units to produce electricity andte is precipitated from the digested watersludge mix-he precipitation and separation of struvite, the digestedhydrated and incinerated in power plants for energy

. The grey boxes in Fig. 1 show the focus of this study.e the steps in the value chain that are altered by then of struvite, and depict the boundaries of the valuesis.e chain step of the production of energy from sewagetered, since the precipitation of struvite takes place after

sludge has been digested. The subsequent added-valueatering and sludge disposal are affected, since the pre-

f struvite leads to an improvement of the dehydrationics of the sewage sludge. The percentage of water inludge mixture is reduced and higher dry substance val-achieved. Furthermore, struvite is extracted from thedge. These effects result in a reduction of the quanti-age sludge that have to be transported and disposed.uent steps in the value chain of sludge disposal (i.e., the

of digested sludge, the generation of energy and theashes) are not inuenced by the precipitation of stru-me applies to the downstream steps of the food ande chains, since the replacement of conventional min-izer with struvite has no further implications for the

links in the value chains. Therefore, the boundaries ofain analysis do not include these sections of the value

focus on the added-value from struvite precipitation,ed-value from struvite fertilization in agriculture.

udy

e chain analysis is based on a case study of struvite at the Wamannsdorf Treatment Plant, located in thete of Brandenburg, Germany. This treatment plant isy the Berlin Water Works (Berliner Wasserbetriebe)

NutriePhospNitrogKali (KSulfurMagneCalciu

HeavyCadmiChromCoppeNickelArseniLead (Zinc (ZManga

a (Theb (Adl

and haequivaof wasbe apped thwhichment o

In substaequipmthe opintrodogy (Hpreciprecovesewagcipitatupstreproblestruvitfers froPEARLliquorsThe pris induby aer(Stumpfying ttechnoconditrealize

Tabthe strmain nstruvitamoundorf Tr

Thedepenadditioing onheavy 2001; Unit Struvitea Superpho-sphatea

OtherP-fertilizersb

(P) g kg1 91.0 84.0) g kg1 42.7 3.0

g kg1 0.5 7.0g kg1 1.2 116.0

(Mg) g kg1 70.0 3.6) g kg1 8.4 212.0

lsd) mg kg1 0.3 15.5 9.0100.0Cr) mg kg1 11.0 65.9 90.01500.0

mg kg1 39.0 51.3 10.060.0mg kg1 2.0 36.0 5.070.0

mg kg1 2.4mg kg1 5.0 4.0 0.540.0mg kg1 100.0 312.0 50.0600.0

(Mn) mg kg1 210.0 21.0

et al., 2012)01)

eatment capacity of 230.000 m3 d1 with a population(p.e.) of 1,200,000. In 2011, an average of 197,000 m3 d1

ter was treated in this plant. Struvite precipitation cann the treatment process because the wastewater is puri-h an enhanced biological phosphorus removal systems to dissolution processes during the anaerobic treat-dge.past, the spontaneous formation of struvite caused

incrustations and blockage in the sludge treatment. In order to ensure for stable operations, and to reduceing costs, a controlled precipitation of struvite was

by a set of modications in the process and technol-ann and Engel, 2006). In 2010 an innovative struvite

n process (AirPrex) was implemented to optimize thed separation of P and other nutrients from the digesteddge. The AirPrex technique is innovative since it pre-ruvite from the digested watersludge mixture in anrocess of dewatering. This way, possible operationalan be avoided such as an uncontrolled formation ofing the mechanical sludge-dewatering. This process dif-ther full scale precipitation processes such as OSTARAr PHOSNIX, in which struvite is precipitated fromived from the dewatering of digested sewage sludge.tation reaction at the Wamannsdorf Treatment Plant

O. Maa et al. / Resources, Conservation and Recycling 87 (2014) 126136 129

sewagesludge

sludgedewatering

sewagegas

production

struviteprecipitation

digestedsewagesludge

energyproduction

ting

energyproduction

the sp

P-fertilizer,metals) pas2008; Rontethe contentphate (SUPat the Waheavy metaand manga(Theobald e

The strurequirementherefore beavailable P by Kern et (2003). Sincply, it is conet al., 20002009).

The strusold since brand namhave been cquantities osegment wexpansion oWater Woris sold diretraders whported by ththe case of

The marproduct, traIn 2011, on0.83 D kg1ments, the pdiffer from

1 Here and i

ribute thadorf.er, ths thrarea gricuor inties r

ta co

ecoe wavalud crohe ptreatedwastewater

waste-water

treatment

surfacewater flow

marke

wastewatercollection

struvite

Fig. 1. Map of value chains and boundaries of the investigation (grey boxes) in

some studies revealed that contaminants (e.g., heavys into the struvite in only small portions (Kern et al.,ltap et al., 2007; Ueno and Fujii, 2001). A comparison of

of heavy metals in mineral P-fertilizer, or superphos-), sold in Brandenburg reveals that struvite producedmannsdorf Treatment Plant has comparatively lowerl contents (Table 2). Only the loading rates of lead (Pb)nese (Mn) in the struvite are higher than those in SUPt al., 2012).vite from Wamannsdorf fully complies with thets of the German Fertilizer Ordinance (DMV) and can

distributed as fertilizer for agriculture. Its highly plant-content has been conrmed by pot experiments doneal. (2008), Rmer (2006), and Johnston and Richardse struvite guarantees a slow but steady nutrient sup-sidered to be a valuable slow-release fertilizer (Gaterell; Rahman et al., 2011; Yetilmezsoy and Sapci-Zengin,

of diststruvitmannsfertilizfarmerin the since aand poproper

3.3. Da

Thestruvitadded-vite anfrom tvite produced at the plant in Wamannsdorf has been2008 in the region of Berlin-Brandenburg under thee Berliner Panze. Various strategies and conceptsonsidered for marketing the struvite. Currently, smallf struvite are sold at local retail markets. This marketas chosen in order to advertise Berliner Panze. Anf this marketing channel is not planned by the Berlin

ks, due to high distribution costs. Most of the struvitectly from the treatment plant to farmers and fertilizero offer bids on large quantities. The struvite is trans-e traders themselves, or by the Berlin Water Works in

direct sales to farmers.ket price of struvite is derived from the price for thensportation costs, as well as the packaging logistics.

average, struvite was sold at a pure nutrient price ofP to 1.00 D kg1 P.1 Depending on the selling arrange-rice paid by the end customers (i.e., mostly farmers) canthe selling price of the Berlin Water Works. In the case

n the following the term P refers always to pure P.

costs and thand the redusing struvstruvite is stion, the ansubstitute s

Three opBerlin Watwastewaterinto the waThese internaires in oproductionobtain purccation as fecalculated b

The anavalue descrcalculated purchased ivite producsales and pprocess. Thincineration ashdisposal

struvitefertilizationtransport

cropproduction

renewablesproduction

foodconsumption

sludgedisposal

ecic case of the Wamannsdorf Treatment Plant.

ion via traders, farmers have to pay a higher price forn those who purchase it directly from the plant in Wa-

In order to establish struvite as a regional sustainablee Berlin Water Works aims to sell the struvite directly toough permanent contracts with local farmers. Farmersmay intend to use struvite as a slow-release fertilizer,ltural soils in Brandenburg are characteristically sandy

nutrients, with a limited P storage capacity. These soilequire a frequent and regular P-fertilization.

llection and data analysis

nomic assessment of establishing nutrient cycles vias based on the determination of the costs, benets ande along the value chains of wastewater treatment, stru-p production. The analysis of the added-value gained

recipitation of struvite included the estimation of the

e benets resulting from the revenues of struvite salesuction of the operating costs. The added-value fromite was found by calculating the fertilizer costs whenubstituted for conventional mineral fertilizer. In addi-alysis provided information on farmers willingness totruvite for conventional mineral P-fertilizer.en interviews were conducted with employees of the

er Works to obtain information on the value chain of treatment, the introduction of struvite precipitationstewater treatment process and the marketing strategy.views were complemented by standardized question-rder to determine the costs and benets of struvite. An open interview with a farmer was conducted tohase information on struvite by farmers and its appli-rtilizer. The added-value of the struvite production wasy conducting a cost/benet analysis.lysis followed the method for calculating the added-ibed by Haller (1997). According to this method, wethe net added-value by subtracting the total costs fornputs and depreciations from the total benets of stru-tion. The total benets include revenues from struviteossible cost reductions in the wastewater treatmente added-value can also be interpreted as the sum of

130 O. Maa et al. / Resources, Conservation and Recycling 87 (2014) 126136

Table 3Fertilizer needs of different crops and soil-quality categories in Brandenburg (with a soil-quality index scale from 7 (lowest) to 100 (highest)) (LELF, 2010).

Crop Soil-quality category (SQC) and fertilizer needs of N, P, K and Ca in kg ha1

SQC I SQC II SQC III SQC IV SQC V

K

Winter rye 73 Spring whea 71 Winter barle 71 Summer fee 55 Oats 70 Winter tritic 81 Grain maize 125 Winter rape 131 Summer rap 61 Sunowers 185 Linseed 26 Ware potato 168 Starch potat 196 Sugar beets 252 Grain peas 83 Grain lupine 70 Buckwheat Silage maize 125 Whole crop 108 Corn-cop-m 113 Liesch-cop-s 125 Forage crops 69 Lucerne dry 216 Lucerne sila 216 Extensive gr 32 Poplar 28

prots, taxpayments) ingly, the inbut as revenas part of tthe interestapplied pre

The marfrom a wrivey was coof the cropers to substinformationof croplandthe P-fertilthe agricultstruvite pro

The contmineral P-flating the efertilizer anvated in Brafrom LELF (tion metho

In practithey considfertilizer renutrient suaccount. Futilizers and

The calcof the nutrused in Bra

The reduparing the the costs oK- and Ca-fe

ries oal anplicang co. Thvite ously

(Cahe reow pvite onto a

secN P K Ca N P K Ca N P

125 30 101 320 112 27 90 280 90 21 t 166 34 107 320 139 29 90 280 111 23 y 140 31 104 320 120 26 89 280 96 21 d barley 109 24 86 320 92 20 73 280 70 15

114 27 113 320 92 22 92 280 70 17 ale 139 31 117 320 126 28 106 280 97 21

193 35 166 320 169 31 146 280 145 26 191 45 183 320 163 38 157 280 136 32 e 99 24 96 320 76 18 74 280 63 15

137 41 288 320 118 36 247 280 88 27 60 9 36 280 43 7

es 131 21 188 280 117 19 oes 148 24 213 280 137 22

253 41 308 320 230 38 280 280 207 34 21 116 320 18 100 280 15

s 15 83 280 13

162 30 158 320 149 28 145 280 128 24 silage 160 50 150 320 144 45 135 280 115 36 ix 156 27 143 320 143 25 131 280 123 21 ilage 162 30 158 320 149 28 145 280 128 24

120 29 238 320 80 23 188 280 80 12 green 15 29 257 320 15 27 243 280 15 24 ge 15 29 257 320 15 27 243 280 15 24 assland 8 42 8 39 6

14 42 14 42 10

payments and remuneration for capital (i.e., interestand labour (i.e., wage payments) (Haller, 1997). Accord-terest and wage payments are not regarded as inputs,ues for the capital providers and employees and thus,

he added-value of struvite production. The annuity of payments was calculated by assuming a funding of thecipitation technology by a municipal loan.ket potential for struvite was assessed using the resultstten survey of 146 farmers in Brandenburg. The sur-nducted in 2012 and collected data on the structures cultivated in 2011 and the willingness of the farm-itute struvite for conventional mineral P-fertilizer. The

on the cultivated crops was used to ascertain the share

categominimthe apapplyiculatedby struanalogcalciumfrom tto the lof strutaken i

In a

allocated to single crops in Brandenburg. Determiningizer needs of this crop distribution helped to identifyural area in Brandenburg that could be supplied withduced in Wamannsdorf.ribution to the added-value, by substituting struvite forertilizer in crop production, was determined by calcu-xpenditures per hectare (ha) for conventional minerald struvite. This was done for the 26 main crops culti-ndenburg. The fertilizer needs of each crop were taken2010), which gives an overview of agriculture produc-ds and costs in Brandenburg (Table 3).ce, farmers may apply lower quantities of fertilizers ifer that the P residuals from crop production and theserves in the soil are sufcient (LELF, 2010). Additionalpplies through organic fertilizers were not taken intorthermore, we assumed that conventional mineral fer-

struvite have the same effect on crop growth.ulation of the fertilizer costs was performed on the basisient prices paid for commercial fertilizers commonlyndenburg in 2010 (Table 4).ction of the fertilizer costs was determined by com-

costs of applying conventional mineral fertilizers andf applying struvite in combination with mineral N-,rtilizer. This was done for each crop and for all existing

reduction oing the ranfarms. The and includeital costs fof possible value in croarea that cdorf TreatmN containewas conduable.

We calcwhen spreastruvite maizer for techwe calculatfertilizer anof struvite worksteps Changes in in the costsreduces theFurthermorCa N P K Ca N P K Ca

220 69 16 55 160 45 11 36 100220 84 17 54 160 220 72 16 54 160 220 57 13 46 160 220 52 12 51 160 220 76 17 64 160 220 220 100 24 96 160 220 49 12 48 160 220 74 22 154 160 220 30 5 18 160 220 107 18 154 160 220 125 20 179 160 220 220 12 66 160 220 11 60 160 9 50 100

40 13 60 160 40 13 60 100220 101 19 99 160 176 33 172 100220 123 39 116 160 112 35 105 100220 97 17 89 160 168 29 155 100220 101 19 99 160 176 33 172 100220 7 55 160 40 100220 15 21 189 160 100220 15 21 189 160 100

5 23 4 18 6 18 6 18

f soil quality in Brandenburg in order to determine thed maximal value derived through reduced costs fromtion of struvite-fertilizer. In a rst step, the costs ofnventional mineral P-, N-, K- and Ca-fertilizer were cal-en, the conventional mineral P-fertilizer was replacedand the corresponding fertilizer costs were calculated. Since struvite contains amounts of nitrogen (N) and), the respective amounts of nutrients were deductedquired quantities of mineral N- and Ca-fertilizers. Dueotassium (K) content of struvite, the replacement effectn the requirements of the mineral K-fertilizer was notccount.ond step, the results were used for determining the

f the direct costs of crop production and for calculat-ge of possible cost reductions for each of the surveyeddirect costs of each crop were taken from (LELF, 2010)d the costs for fertilizer, seeds, pesticides and the cap-or the means of production. Furthermore, the rangecost reductions (i.e., struvites contribution to added-p production) was calculated based on the agriculturalan be supplied with struvite from the Wamanns-ent Plant. Since the plant availability of the nutrientd in the struvite is uncertain, a sensitivity analysiscted assuming that only 50% of the N is plant avail-

ulated the additional costs for labour and machinesding struvite in a separate workstep, since in some casesy not be spread in the same workstep as mineral fertil-nical reasons. In the case of applying mineral fertilizer,ed the costs for a single spreading of the N- and Ca-d a joint spreading of the P- and K-fertilizer. In the casefertilization, we calculated the costs for two separatefor spreading the struvite and the mineral K-fertilizer.the quantities of the applied fertilizers were considered

for labour and machines. The fertilization of struvite required quantities of mineral N- and Ca-fertilizer.e, higher quantities of struvite need to be spread, since

O. Maa et al. / Resources, Conservation and Recycling 87 (2014) 126136 131

Table 4Nutrient contents and prices of conventional mineral fertilizer in 2010 (LELF, 2010).

Fertilizer Nutrient Nutrient content Fertilizer price in Pure nutrient price in% Euro per 100 kg Euro kg1

Triple superphosphate P 20 22.00 1.10Calcium ammonium nitrate N 27 18.00 0.67Kali 60 K 50 30.00 0.60Calcium Ca 32 3.30 0.10

the P-content in struvite is lower than the P-content in the mineralP-fertilizer. These effects were taken into account when calculatingthe cost for spreading struvite.

4. Results

4.1. Substitution potential of struvite for mineral P-fertilizer inBrandenburg

The statistical analysis of the survey revealed the basic will-ingness of farmers to substitute struvite for mineral P-fertilizer,if the price of struvite does not exceed the price for conventionalmineral P-fertilizer. About 66% of the farmers questioned show awillingness to apply struvite. Of that number, 71% would applystruvite without any concern for food crop cultivation, and 70%would use struvite for energy crop cultivation (Daedlow, Maaand Theobald, unpublished survey results). Based on this informa-tion, we deduce that substituting struvite for conventional mineralP-fertilizer would be an option in Brandenburg.

In 2011/2012, 3760 t per year of pure P were sold as mineral fer-tilizer in Brandenburg (Federal Statistical Ofce Germany, 2012).The maximcipitation apure P. Thisment Plantto the agric

4.2. Effect owastewater

The impwater trea

416,000 D per year. This added-value was mainly generatedthrough the reduction of the operating costs. The reduction of theoperating costs was principally due to a decrease of occulatingagents required in the process. This improvement contributed to51% of the cost reduction. Another large reduction of operating costsresulted from the improvement of the dehydration characteristicsof sewage sludge. This improvement reduced the costs of sludgetransportation and disposal by higher dry substance values of thesewage sludge. It contributed to 39% of the total cost reductions.Further cost reductions were gained through the reduction of main-tenance work on the centrifuges (4%), the reduction of cleaningcosts (3%), and the prevention of incrustations in the sludge treat-ment equipment (2%). Due to a reduced mass ow of sewage sludge,resulting from struvite extraction, there was also a marginal reduc-tion of energy consumption by the centrifuges, which accounted for1% of the total cost reductions. Although struvite extraction fromthe sewage sludge reduced the cost of transportation, the effect ofstruvite extraction on the transportation costs was excluded herebecause it is only marginal and the extracted struvite had to betransported as well. Fig. 2 gives an overview of the annual operating

nd bent

cost appln ver theratint paroces

revecost he reum amount of P that can be recovered via struvite pre-t the Wamannsdorf Treatment Plant is 81 t per year of

implies that P recovered at the Wamannsdorf Treat- can replace about 2.2% of the mineral P-fertilizer soldultural sector in Brandenburg.

f struvite production on the added-value in the value chain

lementation of struvite precipitation in the waste-tment process generated an added-value of about

costs aTreatm

Thefor thereactiocosts fofor opeinteres(2%), p

Theto the cess. TFig. 2. Costs and benets of the struvite production in the Wamaenets of the struvite production in the WamannsdorfPlant in 2011.s of the struvite production included mainly the costsied magnesium chloride (37%), the depreciations of thessel and the magnesium chloride container (24%), the

anti-incrustation agents (13%) and the personnel costsg the precipitation vessel (13%). Further costs includedyments (capital costs) (5%), electricity (4%), cleanings water (1%), maintenance, repair and operations (1%).nues from struvite sales were relatively low comparedreductions attained in the wastewater treatment pro-venues accounted for only about 4% of the total benets.nnsdorf Treatment Plant in 2011.

132 O. Maa et al. / Resources, Conservation and Recycling 87 (2014) 126136

Table 5Commodity prices of different P-fertilizer in 2011 (World Bank, 2013; LELF, 2010).

P-fertilizer Fertilizer price in Euro t1 P nutrient content in % Pure P nutrient price in Euro kg1

DAP (world market) 452.00 20 2.26TSP (world market) 393.00 20 TSP in Brandenburg 220.00 20 Struvite in Brandenburg 9

Fig. 3. Reduct g pricscale from 7 (l

With thesetion costs cproductionof the opera

4.3. Impactproduction

The marhigher thansubstitutingthe costs oproduction

Dependifertilizer apbetween 1.of 1.00 D kgbetween 0.4

The savresulted frothe convenfrom the redanalysis shoP-fertilizatiquantities aby 716% a

Concernusing struviings (6976mineral N-ftion of P in about 222

2 Unless othstruvite was co

ts ofduct

adden 3.ps wationxtra surchlizer.ion of the fertilizer costs from the use of struvite sold at the average maximum sellinowest) to 100 (highest)).

revenues, only about 5% of the direct struvite produc-ould be covered. Therefore, the added-value from the

of struvite was mainly realized through the reductionting costs of wastewater treatment.

of struvite fertilization on the added-value from crop

ket prices for conventional mineral P-fertilizer were those for struvite in the studied case (Table 5). Hence,

amouncost re

Thebetwefor crofertilizof an efrom pP-ferti struvite for conventional mineral P-fertilizer reducedf fertilization and increased the added-value in crop.ng on the crop, the soil quality and the amount ofplied, the potential savings on fertilizer costs were

00 D ha1 and 21.00 D ha1, at a struvite selling price1 P (Fig. 3).2 The corresponding cost reductions are

and 5.9% of the total direct cost of crop production.ings on fertilizer costs through struvite applicationm directly substituting struvite at a lower price thantional mineral P-fertilizer. Additional savings resulteduced quantities of the required N- and Ca-fertilizer. Thewed that struvite fertilization could reduce the costs foron by 9%. Depending on the crop and soil quality, thend costs of mineral N- and Ca-fertilizer were reducednd 12%, respectively.ing the distribution of the overall cost reductions fromte, the analysis further revealed that the major cost sav-%) resulted from reducing the required amounts of theertilizer. The reduction of the costs due to the substitu-the struvite for P in the mineral fertilizer accounted for5% for most of the crops. The reduction of the required

erwise stated, the results refer to the case in which the application ofmpleted in the same workstep as the application of mineral fertilizer.

4.4. Total evalue chain

The subresulted in6000 D perping patterAccording tof cultivate58% for grarape, 8% foAssuming tstruvite woto 5000 ha yvalue chainto 35,000 Dchains of wduction in B

4.5. Distribapplication

The addoccurs in tvite markewastewater1.961.100.831.00

e (based on different soil-quality categories, with a soil-quality index

the mineral Ca-fertilizer accounted for 23% of the totalions.itional costs for a separate spreading of struvite were00 D ha1 and 5.00 D ha1. The analysis revealed thathich have relatively low P-needs, and do not need N-

(grain peas, grain lupines, grassland, poplar), the costpreading of struvite would exceed the benets resultingasing struvite at a lower price than conventional mineralffect on the added-value of struvite introduction ins in Brandenburg

stitution of struvite for conventional mineral fertilizer a reduction of the fertilization costs from 2500 D to

farm and year. This result applied to the specic crop-ns and outputs of the farms surveyed in Brandenburg.o the information obtained from the survey, the shared land allocated to the single crops in Brandenburg isin (i.e., winter rye and spring wheat), 19% for winterr grain maize, 6% for maize silage and 9% for others.his cropping pattern, the production of 900 t year1 ofuld be sufcient to meet the P-fertilizer needs of 2300 haear1. The associated increase of the added-value in the

of crop production would be approximately 33,000 D year1. The total added-value of struvite in the valueastewater treatment in Wamannsdorf and crop pro-randenburg would be 451,000 D year1.

ution of added-value from struvite production and

ed-value from struvite production and applicationhe value-added steps of wastewater treatment, stru-ting and crop production. The value-added step of

treatment accounted for the greatest part of the

O. Maa et al. / Resources, Conservation and Recycling 87 (2014) 126136 133

Table 6Distribution of added-value along the struvite value chain at different prices of struvite.

Value-added step Added-value year1 at purenutrient price of 830 D t1 P

Added-value year1 at purenutrient price of 1000 D t1 P

Change ofadded-value

Wastewater Crop produc Total added-

added-valudownstreamproduction,struvite andshare of thremain in thsales to locstruvite at However, pdirect salesthe distribufrom struvi

The addewith (a) lowvite appliedadded-valuvia fertilizethe same pr

Further of struvite. of struvite assuming dprice rangeplant in Wa

Table 6 sof struvite i830 D t1 P value step othe wastew

5. Discussi

5.1. Changecrop produc

Implemeculture leadand crop prthe treatmeof struvite a(i.e., only thcan be usecan generachain of crotuting struvthe value cvia struvitefor nutrienfarmers.

The precsignicantlyter treatme1015% of treatment pings showeinsufcientLarge amousewage slu

ain ier, s

treams wtechludgre. Te forainedviteuse dendorf.ge de, the

Brappliee (Milityicultts su

recycvite

Ca-f fullyis revstruvions tal ae for22,take . Thef 1.0

ions f crositivl N-tilizasing

as andr fur

plan tech

on tte fersametilizetion24,ndicing s treatment 410,000 D 416,000 Dtion 49,000 D 35,000 Dvalue 459,000 D 451,000 D

e. The distribution of the added-value generated in the steps of the value chain, including marketing and crop

depends on the marketing modalities and the price of conventional mineral P-fertilizer. In general, a highere added-value from struvite production and use wille local economy if the struvite is distributed via direct

al farmers. Direct sales allow farmers to purchase thea price below that of conventional mineral fertilizer.resently, struvite is hardly sold directly to farmers. Low

may indicate that transaction costs play a major role intion of struvite and the distribution of the added-valuete.d-value from struvite use in crop production increaseser prices for struvite and (b) higher amounts of stru-

as a substitute for conventional mineral fertilizers. Thee at the farmers level is less if the struvite is distributedr traders, because the traders sell the struvite at almostice as conventional mineral P-fertilizer.effects on distribution are caused by the sales priceTable 6 illustrates the effects of a 20% price increaseon the added-value in the steps of the value chain,irect sales to farmers. This variation corresponds to the

for struvite sold on site by the wastewater treatmentmannsdorf.hows that the added-value generated in the value chains reduced if the sales price for struvite is increased fromto 1000 D t1 P. The loss of added-value in the added-f crop production exceeds the gain of added-value inater treatment step by 8000 D .

on

s in the value chains of wastewater treatment andtion

nting struvite precipitation and its application in agri- to changes in the value chains of wastewater treatmentoduction. In the value chain of wastewater treatment,nt process is inuenced and extended by the productions an additional output. Some portion of the phosphatee dissolved phosphate) contained in the sewage sludged for producing a tradable product (struvite) whichte additional revenues for plant operators. The valuep production is altered by the opportunity of substi-ite for conventional mineral fertilizer. This linkage ofhains of wastewater treatment and crop production

leads to the emergence of an innovative value chaint recycling, including struvite producers, traders and

ipitation of struvite and its use as fertilizer can also change the present ow of nutrients in wastewa-nt and crop production. Meinel (2011) indicates thatthe phosphorus (P) contained in the inuent of thelant can be precipitated in the form of struvite. Our nd-

or remHowevtive forprobleOther from sin futustruvitbe obt

Struwhich in Branmannsthe lar(2012)level inwere amanurprobabthe agrnutriento the

StruK- andlow toanalysin the reductThe tostruvit20,000ent upuptakerange oreductcosts othe senmineravite ferwhen upattern(35%)need fofor the

Theimpactseparain the eral ferproduc13,000result ispreadd that the actual productivity of struvite precipitation is to reinsert larger quantities of P into the nutrient cycle.nts of the P contained in the treated wastewater anddge still get discharged into the receiving waters (4%)

5.2. Cost, b

The precmannsdorf 6000 D +2%14,000 D 29%

8000 D 2%

n the dewatered sewage sludge (81%) (Meinel, 2011).truvite precipitation may become particularly attrac-tment plants with biological P removal and operationalhich are caused by uncontrolled struvite formations.

niques with higher P-recovery rates (e.g., P-recoverye ashes) may be combined with struvite precipitationhis way, operational problems due to uncontrolledmations can be prevented and higher yields of P can.

precipitation is applicable only in treatment plantsbiological P removal. Currently, struvite is producedburg only in the wastewater treatment plant in Wa-

Hence, the struvite production is small compared tomand for P-fertilizer in Brandenburg. According to MILapplication of mineral P-fertilizer has stagnated at a lowndenburg in the last few years. In 2010, only 2 kg P ha1

d, on the average. In addition, 7 kg P ha1 was spread byIL, 2010). If this is taken into account, there is a higher

that struvite could contribute to meeting the P-needs ofural sector in Brandenburg. Since struvite also containsch as N, K and Ca, precipitating struvite may contributeling of these nutrients as well.

fertilization needs to be supplemented with other N-,ertilizers, since the nutrient contents of struvite are too

cover the plant nutrient requirements. The sensitivityealed that the accessibility of the nutrient N containedite for the plant has a signicant impact on the cost

and added-value from using struvite in crop production.dded-value gained in crop production by substituting

mineral fertilizer would be 13,000 D year1 less (i.e.,000 D year1 instead of 33,00035,000) if the N nutri-of the plants is only 50% of the previously assumed 100%

potential savings on fertilizer costs would be in the0 D ha1 and 13.00 D ha1, and the corresponding costwould be only between 0.4 and 4.1% of the total directp production. In the case of a plant uptake of 50% only,ity analysis revealed that the quantities and costs of

fertilizer could be reduced by only 38% through stru-tion. The cost reduction share from the single nutrients,

struvite instead of mineral fertilizers, showed the samebefore, but with a higher share for P (3751%) and Ca

a lower share for N (5661%). This result points out thether research to secure the accessibility of N in struvitets.nology for spreading the fertilizer has a signicant

he benet reaped from struvite use in crop production. Atilizer application is needed if struvite cannot be spread

workstep (for technical reasons) as conventional min-r. In this case, the added-value from struvite use in crop

would be approximately 20,000 D year1 lower (i.e.,000 D year1 instead of 33,00035,000 D year1). Thisates the relevance of providing technologies that enabletruvite and mineral fertilizer jointly in one workstep.enets and protability

ipitation vessel of the studied treatment plant in Wa-was not in continuous operation during the reference

134 O. Maa et al. / Resources, Conservation and Recycling 87 (2014) 126136

year 2011, due to building operations at the treatment plant, whichmeans that the capacity of struvite production was not fully reachedin this production year. We did not extrapolate the results for a full-capacity production scenario, since this would have jeopardized thequality of ooperators oprototype pthat they ara considera

The econand its reuscipitation pThe case anfrom struviHowever, stcosts of wathose of Sheconomicaland disposathe costs ofto the cost process. In is secured, dment. The rthat may be

The farmthe developto P from sform of trip3.21 D kg1ciated fertilet al., 2009value of strstruvite salP containedprice for strP-fertilizer,of availabilstruvite. Oustruvite andpensate forthe fertiliza

5.3. Distrib

Concernit is not equlargest sharof struvite (the added-vtuting struv

The resuafforded tovite. Empirseldom. Thetilizer tradeother minerprice as conegy pursuedmuch higheIn both casebetween cosome of thevite for convindicated thmore elastic

in the struvite production. The market players seem to know thatan increase in the sales price of struvite will result in added-valuelosses for the farmers and a decreased willingness to substitutestruvite for conventional mineral fertilizer.

resu suber, sers.

er mf stru

a denetwermersed thnal mhwhiion cttle t

clus

retuutescal inof nconoitatioater

supp for truvies a tcreas

of w addt cyblish

cal asrect i

of n locaia sttion stitu

impat cyled tld dildomres i

betow.

wled

authrlin cal mheirir cot of try ofur results, due to arbitrary assumptions. However, thef the treatment plant stated that the operation of therecipitation vessel is still in the beginning phase ande continuously gaining experience with it. Also, they seeble potential for optimizing the production of struvite.omic viability of P-recovery via struvite precipitatione as fertilizer depends on the protability of the pre-rocess and the market price of the struvite fertilizer.alysis of Wamannsdorf revealed that the revenueste sales cover only about 5% of the production costs.ruvite precipitation signicantly reduced the operationstewater treatment. These results are consistent withu et al. (2006), who described struvite precipitation asly benecial when savings for reduced sludge handlingl are taken into account. Our ndings demonstrate that

struvite precipitation need to be assessed in relationsavings achieved in the overall wastewater treatmentour study the economic viability of struvite productionue to the reduced operation costs for wastewater treat-evenues from struvite sales are an additional incentivecome more relevant with rising prices for P in the future.ers benet from using struvite will greatly depend onment of the price of P from mineral sources comparedtruvite. Between 2002 and 2012, the price of P in thele superphosphate (TSP) uctuated between 0.5 andP (World Bank, 2013). The price of phosphate and asso-izer is expected to increase over the long-term (Cordell; Von Horn and Sartorius, 2009). Thus, the economicuvite may increase by reaping higher revenues fromes. Currently, in mid-2013, the price of the nutrient

in TSP is about 1.21 D kg1 P (World Bank, 2013). Auvite, which is signicantly below the price of mineral

is needed to compensate farmers for the uncertaintyity as well as the additional handling and spreading ofr results show that the difference in the price between

mineral P-fertilizer in 2011 was large enough to com- the costs of extra handling and spreading and to reducetion costs for most crops.

ution of the added-value

ing the distribution of the added-value, we found thatal in each of the steps in the struvite value chain. Thee of the added-value was found in the production phase416,000 D , 92%), while a comparatively small share ofalue (35,000 D , 8%) was reaped by the farmers substi-ite for conventional mineral fertilizer.lts highlight that the share of the total added-value

the farmers is related to the sales strategy for stru-ical evidence suggests that direct sales to farmers are

Berlin Water Works also sold struvite to specialist fer-rs. It is assumed that traders mixed the struvite withal P-fertilizers and sold it to farmers at around the sameventional mineral P-fertilizer. Another marketing strat-

by traders is to sell struvite as premium fertilizer at ar price than that for conventional mineral P-fertilizers.s, the traders would seek to siphon off the price-marginnventional mineral P-fertilizers and struvite, and retain

added-value that accrues from the substitution of stru-entional mineral P-fertilizer in agriculture. The analysisat the added-value generated in crop production was

towards price changes in struvite than the added-value

Theers toHowevby farmfertiliztities othat isand bebe a pothe farprovidventioa wortoperatonly li

6. Con

ThecontribTechniration local eprecipwastewtion, itwell astime, sprovidand dechainshighernutrien

Estatechnithat dichainslishingcycle vinnovathat inerablenutriencycles was sostill sestructuerationcosts l

Ackno

Thethe Betechnithank tfor theas parMinistlts of the survey reveal a basic willingness of farm-stitute struvite for conventional mineral P-fertilizer.truvite has not yet been widely demanded as a fertilizer

One reason for the sluggish development of the struvitearket in Brandenburg may be the currently small quan-vite produced and marketed (400 t in 2011). Added toarth of knowledge about its availability, applicabilitys. Lowering the sales price of struvite could prove toful strategy for penetrating the fertilizer market, since

interviewed said that the price is the decisive factor,at struvite fullled the same requirements as the con-ineral P-fertilizer. For struvite producers, this could bele strategy, since they would mainly benet from lowerosts, while the revenues from struvite sales contributeo their added-value gains.

ion

rn of P nutrient from wastewater to crop production to an economical stewardship of the scarce P reserves.novations and innovative value chains for the instau-

utrient cycles may generate a higher added-value formies. In the value chain of wastewater treatment, then of struvite can reduce the loss of nutrients within the

treatment process. In the value chain of crop produc-lies a substitute for conventional mineral P-fertilizer asconventional mineral N- and Ca-fertilizer. At the samete precipitation reduces costs of wastewater treatment,radable product which is capable of generating revenue,es the costs of fertilization. We conclude that the valueastewater treatment and crop production can return aed-value by reinserting P and other nutrients into thecle.ing nutrient cycles requires the implementation of

well as institutional innovations. Our analysis suggestsnteraction and cooperation between actors in the valueutrient-recovery and re-use pose a challenge to estab-l nutrient cycles. The establishment of the P nutrientruvite precipitation is subject to the acceptance of theby all actors involved in the value chains. We arguetional arrangements for marketing can have a consid-ct on the distribution of added-value from establishingcles. In the case studied here, P-use within nutriento a higher added-value in crop production if struviterectly to farmers. However, direct sales to farmers are. A readjustment of the rules in use and governances essential to promoting personal interaction and coop-ween the involved actors in order to keep transaction

gements

ors owe special thanks to Alexander Schitkowsky fromWater Works for his advice and information on theatters of struvite production. Furthermore, the authors

colleagues Judy Libra, Katrin Daedlow and Tim Theobaldoperation and support. The research was carried outhe ELaN project, which was nanced by the German

Education and Research (grant no. 033L025B).

O. Maa et al. / Resources, Conservation and Recycling 87 (2014) 126136 135

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Added-value from innovative value chains by establishing nutrient cycles via struvite1 Introduction2 Theoretical concepts3 Materials and methods3.1 Boundaries of the investigation3.2 Case study3.3 Data collection and data analysis

4 Results4.1 Substitution potential of struvite for mineral P-fertilizer in Brandenburg4.2 Effect of struvite production on the added-value in the wastewater value chain4.3 Impact of struvite fertilization on the added-value from crop production4.4 Total effect on the added-value of struvite introduction in value chains in Brandenburg4.5 Distribution of added-value from struvite production and application

5 Discussion5.1 Changes in the value chains of wastewater treatment and crop production5.2 Cost, benefits and profitability5.3 Distribution of the added-value

6 ConclusionAcknowledgementsReferences