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Performance Evaluation of a ‘Sequential‐Batch’ Temperature‐Phased Anaerobic Digestion (TPAD) Scheme for Producing Class A Biosolids
Author(s) -
Santha Harikishan,
Sandino Julián,
Shimp Gary F.,
Sung Shihwu
Publication year - 2006
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 - 10.2175/106143005x89977
Subject(s) - biosolids , mesophile , anaerobic digestion , alkalinity , biogas , sewage sludge , chemistry , pulp and paper industry , anaerobic exercise , volatile suspended solids , waste management , environmental science , sewage , environmental engineering , activated sludge , sewage treatment , methane , engineering , biology , physiology , genetics , organic chemistry , bacteria
Laboratory studies were conducted to evaluate the performance and operational stability of a Temperature‐Phased Anaerobic Digestion (TPAD) system modified to operate in the sequential‐batch mode. The system fed with a 40:60 mixture (dry weight) of primary sludge (PS) and waste activated sludge (WAS) at 5.5% solids showed stable performance with minimum variation in operational parameters such as biogas production, VFA to alkalinity ratio, pH, and foam accumulation at system retention times as short as 12 days. The maximum volatile solids removal (VSR) of 52.5% was achieved at a system retention time of 16 days. The system did not show any effects of “shock loading” at the retention times studied and outperformed a “conventional” mesophilic system operated at a longer retention time. The system was effective in reducing the densities of pathogenic indicator organisms in the biosolids to levels lower than those specified by U.S. EPA for Class A designation.