文摘
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Abstract
A two-stage UASB reactor was employed to remove sulfate from acrylic fiber manufacturing wastewater. Mesophilic operation (35¡À0.5¡ãC) was performed with hydraulic retention time (HRT) varied between 28 and 40 hr. Mixed liquor suspended solids (MLSS) in the reactor was maintained about 8000 mg/L. The results indicated that sulfate removal was enhanced with increasing the ratio of COD/SO242?/sup>. At low COD/SO2?/sup>4, the growth of the sulfate-reducing bacteria (SRB) was carbon-limited. The optimal sulfate removal efficiencies were 75 % when the HRT was no less than 38 hr. Sulfidogenesis mainly happened in the sulfate-reducing stage, while methanogenesis in the methane-producing stage. Microbes in sulfate-reducing stage performed granulation better than that in methane-producing stage. Higher extracellular polymeric substances (EPS) content in sulfate-reducing stage helped to adhere and connect the flocculent sludge particles together. SRB accounted for about 31 % both in sulfate-reducing stage and methane-producing stage at COD/SO2?/sup>4 ratio of 0.5, while it dropped dramatically from 34 % in sulfate-reducing stage to 10 % in methane-producing stage corresponding to the COD/SO2?/sup>4 ratio of 4.7. SRB and MPA were predominant in sulfate-reducing stage and methane-producing stage respectively.
