ABR-MAP-MBR组合工艺处理高浓度养殖废水研究

摘要

针对养殖废水高悬浮物、高有机物及高氨氮的特点,采用厌氧折流板反应器/磷酸铵镁沉淀/兼氧-好氧膜生物反应器(ABR-MAP-MBR)组合新工艺对其进行中试处理研究,考察生物反应器的启动运行条件;考察水力停留时间(HRT)、水温和溶解氧(DO)等运行参数对养殖场废水各阶段处理效果的影响;考察MAP沉淀法对ABR厌氧出水的NH4-N去除效果.结果表明:采用阶梯负荷启动策略,60 d完成ABR反应器的启动,厌氧环节在HRT为24 h、水温25～35℃时COD去除率达73.5%;磷酸铵镁沉淀过程中选择氯化镁、磷酸三钠作为沉淀剂,控制Mg2+∶NH4+∶PO3 4?摩尔比为1.2∶1∶0.95,pH为8.5～9.0条件下处理ABR厌氧出水,COD、NH4-N和PO 4 3?-P去除率分别为28.2%、85.4%和89.7%;通过对A/O-MBR反应器HRT和DO的条件优化,该单元的COD、SS、NH4-N和TN等指标的去除率分别为82.0%、95.2%、72.4%和67.7%(HRT=16 h,O区DO≥3.0 mg·L?1).经过组合工艺的综合处理,系统出水各项主要指标(SS、COD、TN和TP等)达到《畜禽养殖业污染物排放标准》(GB 18596—2001)一级排放标准,表明该新工艺在规模化养殖场废水处理中具有良好的应用前景.%Piggery wastewater is difficult to be treated due to its high concentrations of suspended solids (SS), organic matter and ammonia nitrogen. An integrated process was proposed to treat the piggery wastewater, which consists of anaerobic baffled reactor (ABR), magnesium-ammonium-phosphate precipitation (MAP) and anoxic/aerobic-membrane bioreactor (A/O MBR). The influences of ABR startup conditions, hydraulic retention time (HRT), water temperature, and dissolved oxygen (DO) on the performance of pollutants removal were investigated. The MAP were used to remove the NH4-N in the wastewater discharged from the ABR. Based on the strategy of stepped-loading, the ABR process startup was finished within 60 days and after that, a 73.5% of COD removal efficiency was achieved at the HRT of 24 h and temperature of 25—35℃. Effluents from the ABR were treated by the MAP using magnesium chloride and trisodium phosphate as precipitant. At the optimum conditions that the molar ratio of reagent dosing Mg2+∶NH4+∶PO4 3? was 1.2∶1∶0.95 at the pH value of 8.5—9.0, the removal efficiency of COD, NH4-N and PO3?4-P reached 28.2%, 85.4%, and 89.7% respectively. At an optimized HRT (16 h) and DO (≥3.0 mg·L?1) in the A/O-MBR, the removal efficiency of COD, SS, NH4-N and TN was 82.0%, 95.2%, 72.4% and 67.7%, respectively. As a result, the final effluent quality, including SS, COD, TN and TP, well met the first class standard of the "Discharge standard of pollutants for livestock and poultry breeding"(GB 18596—2001), demonstrating that the new integrated process proposed in this paper was very promising for the treatment of piggery wastewater.