Phosphorus Material Flow andPhosphorus Material Flow andits Recovery from Wastewaterits Recovery from Wastewaterand Solid Wasteand Solid Waste

Masaki Takaoka1*, Kazuyuki Oshita1, Xiu CuiSun1, Kazutsugu Matsukawa2, Taku Fujiwara2

1:Department of Urban & Environmental Engineering, Graduate School ofEngineering, Kyoto University, Nishikyo-ku, Kyoto, 615-8540

2: Faculty of Agriculture and Agricultural Science Program, Graduate School ofIntegrated Arts and Sciences, Kochi University, Otsu 200, Monobe, Nankoku-shi, Kochi,783-8502

UNEP-DTIE-IETC, Regional Workshop on Waste Agricultural BiomassMarch 2-5th, 2010 at Global Environment Centre Foundation in Osaka

1

ContentContent

Current status of Phosphorus (P)Resources and Material Flow

Recovery from Wastewater

Recovery from Sewage Sludge

Recovery from Livestock Manure

Ongoing Research

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PhosphorusPhosphorus

Essetial element for plant growth as wellas Nitrogen(N) and Pottasium(K)

Important component in ATP(Adenosine Triphosphate)

Causing substance of eutrophication Low mobility and circularity Uneven distribution (Morocco:42%,

China:26%, America:7%)

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Estimate of Phosphate RockEstimate of Phosphate RockDepletionDepletion

0

10

20

30

40

50

60

0 100 200 300 400

Year

Am

ou

nt

of

Ph

osp

hat

eR

ock

(×1

09 t)

Reserve base

Reserves

Rateof In

crease

=0

%

1 %

2.6 %3 %

56.8 y

To establish PcycleFertilizer food human wastewater/wasteFertilizer/product

4

Phosphorus (P) is anexhaustible resource.Japan depends on foreigncountries for most of itsphosphorous supply.As high-gradephosphorus mines arebeing depleted,phosphorous recovery fromwaste streams becomeseven more important.

(Source: Steen I, 1998)

Phosphorus Material Flow inPhosphorus Material Flow inJapan(2000)Japan(2000)

Inflow to wastewater: 50,000 tonThe recovery potential from waste streams : about 260,000 ton-P/year,almost equivalent to the amount of phosphorus in imported fertilizers.

94*1000 ton in slag94*1000 ton in slag

5(Source: Kato etaI, 2003, Matsubae etal, 2008)

P Removal from WastewaterP Removal from Wastewater

Accumulation of P insludge

Recovery from sewagesludge

Various advancedwastewater treatmentsystem for P removal havebeen introduced inwastewater treatment plantdue to prevention ofeutrophication in closedwater area since 1970s.

Phosphorus removalmethods from wastewaterhave been developed(coagulation, AO, A2Oprocess, MAP, Crystallization,adsorption, etc.).

Input ratio of P to Tokyo bay (1999)

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P Recovery from WastewaterP Recovery from Wastewater

Technology Process Characteristics P Form

MAP Method

Magnesium Ammonium Phosphate(MAP, Struvite) is generated throughcrystallization among PO4

3-, NH4+,

Mg2+. Chemicals are added towastewater including high phosphorusconcentration such as digestersupernatant, and they are stirred,mixed with aeration.

Easy operation. Needlessto pretreat. Low runningcost. NH4

+ is simultaneouslyremoved. NH4

+is required.Not suitable for lowphosphorusconcentration water.

MAP

HAP Method

Hydroxyapatite (HAP) is generatedthrough crystallization among PO4

3-,Ca2+, OH-. Chemicals are added towastewater including low phosphorusconcentration such as secondaryeffluent, and they are sent tocrystallization reactor.

Few by-product. Lowrunning cost. Alreadyoperated in full scall.Degassing and Filtrationare required.Difficulty to maintainseeding grain.

HAP

7(Source: Kato etaI, 2007)

P Recovery from WastewaterP Recovery from Wastewater

Technology Process Characteristics P Form

Electrolysis

After immersing iron electrodeunder wastewater and passing DCelectricity, Fe2+ is eluted frompositive electrode, being oxidizedto Fe3+ by dissolved oxygen, andphosphate is precipitatedreacting with Fe3+.

Simple equipment. Alreadyapplied to household digestiontank. Possibility to small-scallfacilitied. Maintainance ofelectrode is required avoidingiron hydroxide layer generationon its surface.

FePO4

Adsorption

Secondary effluent is sent topacked tower filled with Zr,activated alumina adsorbent andphosphate is removed. Theadsorbent is reused.

Few sludge generation. Thereare adsorbent which hasreletively large adsorptioncapacity to phosphite,hypophosphite, polyphosphate.Easily affected by coexistingmaterials.

PhosphoricAcid,

CalciumPhosphate

8(Source: Kato etaI, 2007)

Sewage Sludge as BiomassSewage Sludge as BiomassResourceResource

Huge amount of waste, butboth a biomass resourceand a form of renewableenergy.

Technological developmentfor the efficient use ofsewage sludge and theresource recovery fromsewage sludge is required aspart of establishing asound material-cyclesociety and preventingglobal warming.

IndustrialWaste(wet basis)417 million tonIn 2004

9Source:MOE home page

Changes in volume ofChanges in volume ofsewage sludge generated andsewage sludge generated andits treatmentits treatment The volume of sewage

sludge in Japan hasbeen increasing withthe rise in the numberof people usingsewage treatmentsystems.

The amount of sewagesludge (dry basis)was approximately 2.2million tons in 2004.

Sludge recycle ratehas been increasingrapidly, achieving to67% in 2004.

0

20

40

60

80

100

0

0.5

1.0

1.5

2.0

2.5

1995 2000 2005Year

The amount of sludge

Sewer spread

Sludge recycle

Ra

te(%

)

Th

ea

mo

un

to

fslu

dg

e(m

illion

ton

-DS

)

Source:MLIT home page 10

Chart of Sewage SludgeChart of Sewage Sludgetreatment in Japantreatment in Japan

Thickening

Digestion

Dewatering

Drying

Incineration

Composting

Carbonizationgasfication

Melting

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Sewage SludgeSewage SludgeDisposal and UtilizationDisposal and Utilization

Unit: DS-ton at March 2005

55%12(Source: MLIT Homepage)

P Recovery from SewageP Recovery from SewageSludgeSludge

Technology Process Characteristics P Form

Hydrolysis,PhysicochemicalTreatment

Sulfuric acid is added tocentrifuged sludge hydrolyzing at150°C, pH1~2, and organicmatters and Heavy Metals areprecipitated. Iron salt is added tosupernatant recovering FePO4,and excess iron is reused asflocculant.

Organic matters in sludgecan be used as carbonresource for denitrification.Reducing sludge volume,sludge treatment cost.Flocculant cost andhydrolysis heat is required.

FePO4

ChemicalAddition

NaHS is added to pre-coagulatedsludge generated in primarysedimentation tank using ferricchloride, and FeS and phosphoricacid is generated. And calcium saltis added to its supernatantrecovering calcium phosphate. Acidis added to FeS recovering H2S

Reducing Organic load,electricity, tank volume canbe reduced through pre-coagulation. ONLY calciumsalt and acid is not reusable.H2S gas is toxic and itscontrol is required. Includingmany processes.

CalciumPhosphate

13(Source: Kato etaI, 2007)

P Recovery from Dewatered orP Recovery from Dewatered orCarbonized SludgeCarbonized Sludge

Technology Process Characteristics P Form

Compost ofDewateredsludge

Dewatered sludge is dried bydrum drying, and its dried sludgeis used as fertilizer and low-grade fuel.

Recovered materials excludesash dust, and are particulate,drying by combustion ofgenerated gas. Suitable fordewatered sludge including15~40 % of moisture content.

Fertilizer

AcidTreatment forcarbonizedsludge

Sulfuric acid is added tocarbonated sludge, extractingphosphorus, aluminium, andheavy metal at 90°C. Andalkali is added to extract,selectively recoveringphosphorus and heavy metal.

Phosphorus, Al, Fe, Mn can beremoved. Adsorptive capacityincreased 10 times than withoutacid treatment. Aluminium inrecovered material may affectplant growth.

CalciumPhosphate

HeatingTreatment forcarbonizedsludge

NaOH is added to carbonatedsludge including Si, Al, Ca,calcinating at 800°C,generating sodium phosphateand zeolite.

Carbonated sludge can beheated as fuel, recovering atlower temperature than sewagesludge ash. Application of zeoliteis unclear.

SodiumPhosphate

14(Source: Kato etaI, 2007)

P Recovery from IncinerationP Recovery from IncinerationAshAsh

Technology Process Summary Characteristics P Form

AcidTreatment

Sulfuric acid is added to ash,extracting phosphorus, heavymetals. And its supernatant is ion-exchanged recovering phosphate,FeCl3,KHSO4.

Recovered material is used asfertilizer, reducing ashgeneration. Ion-exchange isnoneconomic.

PhosphoricAcid

AlkaliTreatment

NaOH is added to ash, extractingphosphorus and alminum. AndCa(OH)2 is added to its supernatantrecovering HAP (Ca Aggregation)or the supernatant is cooledrecovering sodium phosphate (NaAggregation).

Phosphorus and aluminiumcan be selectively extracted,sodium aluminate solution afterrecovering phosphorus can beused as extraction chemical.Aluminum in recovered materialmay affect plant growth.

CalciumPhosphate,

SodiumPhosphate

15(Source: Kato etaI, 2007)

National Project (Metawater co. ltd.)National Project (Metawater co. ltd.)

(1)mixing incineration ash of sewage sludge with the alkaline reaction solution ina reaction tank to extract the phosphorus contained in incineration ash of sewage sludgein a liquid(2) separating the phosphorus-extracted liquid from the treated ash by solid-liquidseparation: adding a calcium component to the separated phosphorus-extracted liquid(3) withdrawing a calcium phosphate crystal from the calcium component-addedphosphorus-extracted liquid. 16(Source: SPIRIT21 LOTUS Project, 2007)

P Recovery from MeltingP Recovery from MeltingProcessProcess

Technology

Process Characteristics P Form

MeltingTreatment

Coke is added to ash, melting inreduction atmosphere at1250~1500°C, volatilizing yellowphosphor, then recovering liquidyellow phosphor with cooling orphosphorus oxide with combustingyellow phosphor gas.

Recovered yellow phosphor is highgrade (99.94 %) . Generated slagand metal can be used as materials.Arsenic is simultaneously volatilized.More arsenic in recoveredmaterial is included than in industrialyellow phosphor.

YellowPhosphor,

PhosphoricAcid

MgO, CaO, SiO2 are added to ash,melting them, generating slag aswell as fused phosphate.

Recovered slag can be used ascitrate soluble phosphorusfertilizer. Heavy metal concentrationmeets standard of fertilizer controllaw. Citrate solubility of P2O5 andMgO is inhibited due to Al2O3 in ash.

Fusedphosphate

17(Source: Kato etaI, 2007)

Manure as Biomass ResourceManure as Biomass Resource

IndustrialWaste417 million tonIn 2004

To stop excess feedingof manure-derived organicfertilizer and share it withother farming area, it isnecessary to recoverphosphorus from livestockmanure and make easyhandling fertilizer.

Chemical fertilizerBroilerHenSwineNon-Dairy CattleDairy Cattle

Ton/y

P2O5

Appropriate feeding Actual feeding

Largest amount of waste, 90% isrecycled as manure-derived organicfertilizer.But, in some part of Japan, actual Pinput in farming land is more thanthree times of appropriate feedingamount. This causes undergroundwater pollution.

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Source:Sekido etal, 2007

P Potential in LivestockP Potential in LivestockManureManure

Feces Urine

Volume P conc. P amount Volume P conc. P amount

(millionton/y)

(kg/ton-feces)

(1000ton/y)(millionton/y)

P(g/ton-urine)

P(1000ton/y)

Dairy Cattle 19.2 0.55 10.5 5.7 6.7 0.0

Non Dairy Cattle 19.8 2.3 46.3 7.2 121 0.9

Swine 8 4.3 34.8 14.9 527 7.9

Hen & Broiler 12.9 3.5 44.5 - - -

Sum 59.9 136.1 27.8 8.8

10% of the manureWastewater treatmentMethane FermentationIncinerationDryingCarbonization

P recoveryfrom Hen manureIncineration ash

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Development of an innovative water management systemwith decentralized water reclamation and cascadingmaterial-cycle for agricultural areas under theconsideration of climate change

Ongoing researchOngoing research

Global warming : closely related to consumption of resourcesand energy the most evident example of the influence of increasedenvironmental load.Effective countermeasures must be implemented worldwide.

Innovative cascading water/bio-resource recycling systems shouldbe developed to effectively utilize the diffused biomass in agriculturalareas and minimize the pollution loads discharged into water systemsfor guaranteeing the safety and security of both water and food.

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Cascade WaterBioCascade WaterBio--ResourceResourceRecycling SystemRecycling System

Prevention of nonpoint source pollution and production of valuable products fromwastes in agricultural areas will simultaneously be actualized by development of acascading water/bio-resource recycling system.

Farm productsMarine products

Feed forlivestock

Valuableproducts

Poly-L-lacticAcid

GarbageGraywater

Nitrogen/Phosphorusrecovery

Energy recovery

Water reclamation

Decentralizedwater reclamation system

RearingLivestock

Fishing IndustryAgricultureHouseholds

Waste

&Waste

water

Urine &feces

Urine &feces

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AcknowledgementAcknowledgement

We are very grateful for financial supportfrom

◦ Kajima Foundation

◦ CREST (Core Research of Evolutional Science &Technology) in Japan Science and Technology

◦ Global COE program( Human SecurityEngineering for Asian Megacities).

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