Lead removal through biological sulfate reduction process.
The feasibility of lead removal through biological sulfate reduction process with ethanol as electron donor was investigated. Sulfide-rich effluent from biological process was used to remove lead as lead sulfide precipitate. The experiments were divided into two stages; Stage I startup and operation of sulfidogenic process in a UASB reactor and Stage II lead sulfide precipitation. In Stage I, the COD:S ratio was gradually reduced from 15:1 to 2:1. At the COD:S ratio of 2:1, sulfidogenic condition was achieved as identified by 80-85% of electron flow by sulfate reducing bacteria (SRB). COD and sulfate removal efficiency were approximately 78% and 50%, respectively. In Stage II, the effluent from UASB reactor containing sulfide in the range of 30-50 mg/L and lead-containing solution of 45-50 mg/L were fed continuously into the precipitation chamber in which the optimum pH for lead sulfide precipitation of 7.5-8.5 was maintained. It was found that lead removal of 85-95% was attained.
Hien Hoa
Tran Thi
TT
Environmental Engineering and Management, Asian Institute of Technology, Klong Luang, Pathumthani 12120, Thailand.
Liamleam
Warounsak
W
Annachhatre
Ajit P
AP
D011232:Chemical Precipitation; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000302:isolation & purification*; D010084:Oxidation-Reduction; D013431:Sulfates / Q000737:chemistry*
D013431:Sulfates; D007854:Lead