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Combined removal of sulfur compounds and nitrate by autotrophic denitrification in bioaugmented activated sludge system
Author(s) -
Manconi I.,
Carucci A.,
Lens P.
Publication year - 2007
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.21383
Subject(s) - thiosulfate , sulfide , chemistry , denitrifying bacteria , activated sludge , nitrate , sulfur , denitrification , nitrite , thiobacillus , hydrogen sulfide , inorganic chemistry , environmental chemistry , autotroph , sulfate reducing bacteria , sulfate , nuclear chemistry , nitrogen , environmental engineering , sewage treatment , organic chemistry , bacteria , biology , engineering , genetics
An autotrophic denitrification process using reduced sulfur compounds (thiosulfate and sulfide) as electron donor in an activated sludge system is proposed as an efficient and cost effective alternative to conventional heterotrophic denitrification for inorganic (or with low C/N ratio) wastewaters and for simultaneous removal of sulfide or thiosulfate and nitrate. A suspended culture of sulfur‐utilizing denitrifying bacteria was fast and efficiently established by bio‐augmentation of activated sludge with Thiobacillus denitrificans . The stoichiometry of the process and the key factors, i.e. N/S ratio, that enable combined sulfide and nitrogen removal, were determined. An optimum N/S ratio of 1 (100% nitrate removal without nitrite formation and low thiosulfate concentrations in the effluent) has been obtained during reactor operation with thiosulfate at a nitrate loading rate (NLR) of 17.18 mmol N L −1 d −1 . Complete nitrate and sulfide removal was achieved during reactor operation with sulfide at a NLR of 7.96 mmol N L −1 d −1 and at N/S ratio between 0.8 and 0.9, with oxidation of sulfide to sulfate. Complete nitrate removal while working at nitrate limiting conditions could be achieved by sulfide oxidation with low amounts of oxygen present in the influent, which kept the sulfide concentration below inhibitory levels. Biotechnol. Bioeng. 2007;98: 551–560. © 2007 Wiley Periodicals, Inc.