Phosphorus recovery from sludge and ashes
Sustainable sludge handling
The projects is aimed on recovery of phosporus from sludge from
wastewater treatment plants.
Phosphorus recovery from sewage sludge has been studied in experimental
works by leaching SCWO, Super Critical Water Oxidation, residues,
sludge incineration ash and co-incineration of sludge and municipal
waste with acid and base.
Participating
persons:
Project leader
Erik
Levlin, PhD
Scientist
Bengt Hultman, Professor
Doctors student
Kristina Stark, Tekn. dr.
External cooperation partner
Agnes Mossakowska, Stockholm
Water Company.
Laboratory
Monica Löwén, research engineer
Land and
Water Chemical laboratory has been used for leaching work and
analysis of phosphorus content in leachates.
VA-Forsk
VA-Forsk have 2003 given grants for studying phosphorus recovery
by leaching ash from incineration and sludge residue from supercritical
water oxidation with acid and base. Leaching with base gave a small
contamination of metals in the phosphorus product and acid leaching
gave a high phosphorus recovery. The work have been reported in
VA-Forsk
2004-03.
Year
2004 grants have been given for further experiments. A two step
method for phosphorus recovery has ben studied, which combins the
high phosphorus recovery of the acid leaching with the small contamination
of metals of the leaching with base. In a first step the sludge
is leached with acid at pH 4. Therefter leaching in a second step
be made with base. The recovery at leaching with base is increased
when calcium which binds phosphorus at alkaline conditions, first
is leached at pH 4. Two step leaching gave more leaching of phosphate,
however, not as high as for leaching with acid.
The high per cent of leached phosphorus compared
to leached metals at leaching with acid and the lower cost for acid
(90 Euro/ton for HCl ) than for base (265 Euro/ton för NaOH)
makes leaching with acid less expensive than leaching with base.
If only metal phosphate is leached the dissolved amount of metal
will be 3 equivalents per mole P. Cost for acid leaching with HCl
is about 0.32 Euro/kg P (3 mole HCl per mole P) and upwards depending
on the amount of dissolved metals. Leaching Mora sludge incineration
ash with 1 M HCl dissolves about 3.49 equivalent metal ions per
mole phosphate, which gives a cost of 0.37 Euro/kg P. Cost for base
leaching with NaOH is about 1 Euro/kg P (3 mole NaOH per mole P).
The cost for chemicals for two-step leaching is estimated to 1.2
Euro/kg P and upwards. The work have been reported in VA-Forsk
2005-12 and at IWA Specialized Conference - Sustainable sludge
management 29-31 May 2006 in Moscow Russia.
MISTRA
Mistra finance 1999
to 2005 a PHD student within the Mistra programme Sustainable
Urban Water Management.
Doctors thesis:
Stark K. (2005) Phosphorus release and recovery from treated sludge.
Dep. Land and Water Resources Engineering, KTH, ISBN 91-7178-123-4.
Licenciate thesis:
Stark K. (2002) Phosphorus release from sewage sludge by use of
acids and bases. Dep. Land and Water Resources Engineering, KTH,
ISBN 91-7283-307-6.
Stockholm Water Company
Stockholm Water has until 2002 contributed to finansing the project.
Internationell presentations:
Poster
at 1st World Water Congress in Paris, 3 - 6 July 2000: Levlin, E.,
Löwén, M., Schmidt, E., Hultman, B. and Mossakowska,
A. Phosphorus recovery from sewage sludge incineration ash.
OH at 2nd World
Water Congress in Berlin 15-18 October 2001: Levlin, E., Löwén,
M., Stark, K. and Hultman, B. Effects of phosphorus recovery requirements
on Swedish sludge management.
The articel has also been published in Water Science and Technology
Vol 46, No. 4-5, pp. 435440. 2002.
Two posters at 3:d World Water Congress in Melbourne 7-12 April
2002:
- Poster:
Stark, K., Hultman, B., Levlin, E., Löwén, M. and
Mossakowska, A. Calculation of chemical needs in combined phosphorus
removal and recovery at Henriksdal WWTP, Sweden.
- Poster:
Stark, K., Hultman, B. and Levlin, E. New system technology for
combined phosphorus removal and recovery.
Presentation
at 2nd international Conference on Recovery of phosphates from sewage
and animal wastes, Noordwijkerhout Netherlands 12 - 13 mars, 2001
Hultman, B., Levlin, E., Mossakowska, A. and Stark, K. Effects of
wastewater treatment technology on phosphorus recovery from sludges
and ashes.
Reports from Stockholm Water Company:
- Hultman, B. Levlin, E., Löwén M. and Mossakowska,
M. Uthållig Slamhantering. Förstudie. Stockholm Vatten
AB, R. Nr 23 sept-97, 1997
- Levlin, E., Löwén, M., Schmidt, E., Hultman, B.
and Mossakowska, A. Fosforutvinning ur aska. Stockholm Vatten
AB, R. Nr 54 nov-98, 1998.
- Hultman, B., Levlin, E., Löwén, M., Mossakowska,
A. and Stark, K. Utvinning av fosfor och andra produkter ur slam
och aska, delrapport, Stockholm Vatten AB, R.
Nr 6 mars 2001.
- Hultman, B., Levlin, E., Löwén, M., Mossakowska,
A. and Stark, K. Utvinning av fosfor och andra produkter ur slam
och aska, Slutrapport. Stockholm Vatten AB, R
nr 02, feb 2002.
Swedish - Polish Research Co-operation
Papers about phosphorus recovery have been published in reports
from seminars of the Swedish
- Polish Research Co-operation:
Levlin E. Sustainable
sludge handling - Metal removal and phosphorus recovery, Report
No. 3, Advanced Wastewater reatment Nowy Targ, October 1-2, 1998.
Levlin E. Resources
recovery from incineration ashes, Report No. 5, Sustainable
municipal sludge and solid waste handling, Stockholm August 24,
1999.
Hultman B. and Löwén M. Combined
phosphorus removal and recovery and
Stark K. Phosphorus
release from sewage sludge by use of acids and bases, Report
No. 9, Wastewater, Sludge and Solid Waste Management, Nowy Targ
- Zakopane, October 24-26, 2001.
Hultman, B. Levlin, E. Plaza E.and Stark K.
Phosphorus recovery from sludge in Sweden - possibilities to meet
proposed goals in an efficient, sustainable and economical way
and
Levlin E. and Hultman B. Phosphorus
recovery from phosphate rich side-streams in wastewater treatment
plants, Report No. 10, Integration and optimisation of urban
sanitation systems, Gdansk, 23-25 March 2003.
Levlin E., Löwén M. and Stark K. Phosphorus
recovery from sludge incineration ash and Supercritical Water Oxidation
residues with use of acids and bases, Report No. 11, Integration
and optimisation of urban sanitation systems, Wisla October 25-28,
2003.
Levlin E. and Hultman B. Phosphorus
recovery from sewage sludge - Ideas for further studies to improve
leaching Report No 12. Integration and optimisation of urban
sanitation systems, Stockholm June 5-9, 2004.
Levlin E. Phosphorus
recovery from sewage sludge - Two-step leaching process with acid
and base, Report No 13, Krakow Mars 17-19, 2005.
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