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Effect of Biopolymer on the Dewatering Characteristics of Autothermal Thermophilic Aerobic Digestion of Sludges
Author(s) -
Agarwal S.,
AbuOrf M. M.,
Novak J. T.
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 - 10.2175/106143005x94394
Subject(s) - biopolymer , dewatering , aerobic digestion , chemistry , digestion (alchemy) , polysaccharide , biosolids , extracellular polymeric substance , ferric , bentonite , anaerobic digestion , chromatography , chemical engineering , waste management , polymer , biochemistry , inorganic chemistry , methane , organic chemistry , bacteria , biology , engineering , biofilm , geotechnical engineering , genetics
Autothermal thermophilic aerobic digestion of sludge is known to produce poorly dewatering sludges. Laboratory studies were conducted to investigate the reasons for the poor dewatering. It was found that, during digestion, proteins and polysaccharides were released into solution, and that these could be linked to the deterioration in dewatering. The biopolymer release was accompanied by an increase in the monovalent‐to‐divalent (M/D) cation ratio. The degree to which the M/D caused deterioration of the sludges depended on the presence of iron in sludge. When the iron content was high, the release of protein and polysaccharides was low. When iron was low, the release of protein and polysaccharides increased linearly with the M/D ratio. The dose of conditioning chemicals, cationic polymer or ferric chloride, was related to the amount of colloidal biopolymer present in solution. The findings suggest that the addition of iron during the digestion process has the potential to produce better dewatering sludges.