Start-up and maturation phases of a full-scale, high-rate anaerobic pond bioreactor (R) plus improved facultative ponds to treat municipal wastewater

摘要

Results of the start-up and maturation phases of a full-scale, high-rate anaerobic pond bioreactor (HRAPB)(R) plus improved facultative ponds (IFPs) to treat municipal wastewater are presented (CODt: 759 mg L-1, CODf: 219 mg L-1, S-SO42-: 102 mg L-1, and Cr+: 1,500 mu gL(-1)). The start-up of the HRAPB (R) comprised, first, the application of a selective pressure increasing up-flow velocity rates. Second, batch stages between successive rates were allowed until 70% of the initial CODf was removed. The IFPs were left in batch and ended when in-pond Chlorophyll-a concentration reached 800 mu gL(-1). Subsequently, the system underwent gradual maturation and reached effluent concentrations of CODt: 223 mg L-1, CODf : 50mg L-1, and Cr+: 60 mu gL(-1). The actual efficiency of the system compared with the expected design efficiency was lower given the characteristics of the influent wastewater biochemical oxygen demand/chemical oxygen demand ratios < 0.4, presence of Cr+ > 1,000 mu gL(-1), and variations in both conductivity (500-4,500 mu Scm(-1)) and pH (6.5-10.5 units). Nonetheless, the system exhibited an adaptation state in less than 1.5 months and yielded an ST/SV ratio of 0.46, and specific methanogenic activity of 0.43 g-CH4-CODg(-1)SV(-1)d(-1) for HRAPB (R); the in-pond Chlorophyll-a was on average 1,200 mu gL(-1) in the IFPs, which demonstrated the robustness of these ecotechnologies in tropical conditions.