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Controlling Biosolids Phosphorus Content in Enhanced Biological Phosphorus Removal Reactors
Author(s) -
Chaparro Sean K.,
Noguera Daniel R.
Publication year - 2003
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143003x141042
Subject(s) - biosolids , phosphorus , phosphate , chemistry , enhanced biological phosphorus removal , sewage sludge , sewage treatment , mixing (physics) , activated sludge , pulp and paper industry , environmental chemistry , environmental engineering , environmental science , biochemistry , physics , organic chemistry , quantum mechanics , engineering
A methodology to reduce the phosphorus content of biosolids produced by enhanced biological phosphorus removal treatment plants was studied. The process consists of mixing phosphate‐rich waste activated sludge (WAS) with either primary sludge or the supernatant from a primary‐sludge gravity thickener under anaerobic conditions to induce the release of phosphate from WAS. The solubilized phosphate could then be chemically sequestered and removed from the biosolids. Bench‐scale phosphate release experiments were conducted with sludge from the Nine Springs Wastewater Treatment Plant (Madison, Wisconsin) at different mixing ratios. A WAS/primary sludge or WAS/supernatant mixing ratio of 1:1 (by volume) resulted in the highest phosphate release in the batch tests. For experiments with less than 50% WAS (by volume), the total phosphate release was directly proportional to the amount of WAS added. When the mixture contained more than 50% WAS, total phosphate release was limited by the volatile fatty acids (VFAs) available. For the Nine Springs plant, optimal biosolids phosphorus could be achieved using a primary sludge/WAS mixing ratio of 1.02 kg volatile suspended solids (VSS)/kg VSS or a supernatant VFA/WAS mixing ratio of 0.028 kg VFA/kg VSS. The expected reduction in phosphorus content would be 35 and 32% if primary sludge or supernatant, respectively, were used.