Phosphate removal and phosphate recovery: Towards Sustainable Development

Dees Lijmbach, President Technical Committee, Chris Thornton, co-ordinator,CEEP Centre Européen d’Etudes des Polyphosphates

COPPERAS - November 2000

Phosphorus recycling is as old as agriculture

How did phosphorus recycling break down in Europe?

• The growth of cities (16th Century onwards) • The introduction of sewage collection and treatment systems • Decline in agricultural re-use of sewage biosolids

Modern society conducts phosphorus from the land and out to the rivers and sea

Why re-visit phosphorus recycling now?

• Phosphate rock reserves and costs • Impurities in phosphate rock • Increasingly, phosphate removal from waste water will be required by law • Opportunity to improve waste water treatment economics/ sludge cycle • Sewage and animal wastes are, potentially, a rich source of pure phosphate

(45,000 and 200,000 tonnes of P per annum, respectively in UK)

Why re-visit phosphorus recycling now?

• Agricultural spreading is the BEST way to recycle phosphorus (and nitrogen values, biosolids, …) • But this option is declining across Europe : - concentration of cities / storage - transport problems - competition from animal manures - legislative and social pressure re contaminants • Also, the P:N ratio in sewage sludge is higher than agronomic requirements

% Depletion

Depletion of Phosphate Rock Reserves

0 20 40 60 80 100 1996 2000 2010 2020 2030 2040 2050 2060 2070 High growth Medium growth Low growth Conservation scenario

Phosphate Rock - Main Impurities

o y I a J n M e 2 ( ( ) 5 8 ( ) ( ) ( ) ( ) ( ) 5 B a K a Y o 3 3 1 9 1 2 2 2 8 1 8 7 1 2 o A T a e l u l i a a a 4 4 3 9

Phosphoric acid analyses trace impurities

• • • • • • • • • • • • • • Acid from Morocco phosphate rock ppm Al 200 Cd Cr Fe Mg 40 357 1600 5700 Na Ni 1700 67 Ti 108 Zn 880 Mn Cu As Organic C 10 23 5 50 • • • • • • • • • • • • • • Acid from Geestmerambacht recovered phosphates ppm Al 950 Cd Cr Fe Mg <6 8 1260 4200 Na Ni 360 8 Ti 8 Zn 310 Mn Cu As 560 17 2 Organic C >2000

Possible pathways for P-recovery - 1

• Precipitation of a recyclable phosphate product from liquors in wwtp: - calcium phosphate -> P-industry - struvite (magnesium ammonium phosphate) -> fertiliser use - synergy with biological P-removal high-P side streams, P release in digesters, avoidance of struvite deposit problems) - other possible technologies may allow precipitation from wwtp main stream - ion exchangers, membranes ...

Full scale phosphate recovery (as calcium phosphates) from sewage : DHV Crystalactor® at Geestmerambacht sewage works, near Edam, Holland (230,000 pe.)

Full scale struvite recovery plant, Shimane Prefecture, Japan. Capacity : 45.000 m 2 /day.

Unitika Ltd / Japan Sewage Works Agency

Phosphorus Recovery: Remaining technical/economic concerns

• Chemistry of P-recovery by CaP or struvite precipitation looks simple but is poorly understood.

• Inadequate knowledge of reaction kinetics.

• Existing reactor designs are far from optimised.

• Further LCA , economic & logistic evaluation is needed.

Despite this:

• There are already about a dozen demonstration scale and full scale plants operating world-wide.

• Small amounts of recovered phosphate are already reaching industry.

Possible pathways for P-recovery - 2

• Recovery of phosphates in combination with existing chemical P-stripping - chemical constraints: - no known recycling pathway to date for iron phosphates - aluminium phosphates can be recycled in Thermphos’ Vlissingen furnaces, Holland - physical constraints : - how to recover a low-water, recyclable product and not a “sludge”, - need to separate phosphate product from sludge biosolids

Possible pathways for P-recovery - 3

• Recovery from sewage sludges or sludge incineration ashes - problems : - iron (from chemical P-stripping/flocculants used in sewage treatment) - copper (from diffuse sources : piping, diet ...)

CEEP and P recovery

• The European detergent and technical phosphate industry is committed to “making it happen” and is leading research in the area . • Contacts with water companies and regulators • Promotion - communications : SCOPE Newsletter, P-recovery conference (Holland, 12th-14th March 2001) • EU 5th Framework Proposal CYCLOPHOS addressing precipitation of calcium phosphate and struvite • Possibilities for co-operation with INCOPA ?

Cyclophos Industrial Partners

• •

Water Industry:

- CIWEM - Berlin Wasser - Lyonnaise des Eaux - Thames, Anglian, Yorkshire, Severn Trent - Canal Isabel II - STOWA - Polish water industry - Posch and Partners - WS Atkins

National regulators:

- UK Environment Agency - Spanish Environment Ministry - Swedish Environmental Protection Agency

Phosphorus Recovery: current CEEP research

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Scenarios for struvite recovery economics Imperial College, London

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Feasibility of P-recovery and recycling in Benelux STOWA/Thermphos/Haskoning

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Economics and sludge management implications Office Internationale de l’Eau

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Sludge production implications INSA Toulouse, France

Phosphorus Recovery: current CEEP research

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Precipitation reactor design parameters LAGEP/Uinversité Lyon II, France

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P-recovery potential in different areas of 3 bio-P wwtps CSIC Madrid/ Canal Isabel II Water Company

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Struvite formation in STW Imperial College (joint project with UK water industry).

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Testing of full-scale struvite precipitation reactor at Treviso bio-P sewage works, Italy (Ancona, Verona, Venice Universities)

Phosphorus Recovery: current CEEP research

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Testing of a pilot scale struvite reactor at Zarbze sewage works, Poland, Lodz Technical University Bielsko Biéla

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Crystallisation of calcium phosphates using calcite seed Karlsruhe Research Centre

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Precipitation of calcium phosphates - Centre for Ecology & Hydrology, UK and Natural history Museum, London

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Recovery of phosphates by reversible adsorption onto fly ash, Bath University, UK

Phosphorus Recovery: current CEEP research

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Biologically induced P precipitation in combination with biological P-removal from sewage Queens University, Belfast.

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Application of REM-NUT ion exchange for P recovery from sewage works main stream Bari Polytechnic, Italy

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Pathways for P recovery from sewage sludges Swedish Royal Institute of Technology

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Phosphorus separation and recovery in animal manures Institute of Grassland & Environmental Research, UK.

Recovery of P from iron compounds ?

Results of an initial experiment using sulfate reducing bacteria to solubilise phosphates from iron phosphate sludge, Jan Suschka, Lodz Tech. Univ, Bielsko Biéla, Poland 9 2000

A sustainable future in recycling phosphates