生物膜法A~2/O~2焦化废水处理系统缺氧反应器工艺特性

以焦化厂废水处理系统气浮设备出水为试验废水水源,在中试规模上研究了生物膜法A2/O2(厌氧/缺氧/好氧/好氧)系统中缺氧反应器的工艺特性和效果。缺氧反应器为以陶粒作填料的上流式滤池。研究结果表明,缺氧反硝化对去除焦化废水中COD有重要作用。反硝化菌可利用一些好氧微生物和厌氧微生物都难以降解的焦化废水中的有机物作碳源,反硝化反应器可去除进水中40%的COD。缺氧反硝化反应器进水碳氮质量比在5以上就可基本满足焦化废水反硝化对碳源的需求。稳定运行状况下的NO3--N容积负荷不大于0.24 kg/(m3.d)。缺氧反应器的水力停留时间不小于24 h。系统进水COD、NH3-N的质量浓度分别在1 000～2 200、200～400 mg/L范围内,对系统进水不进行稀释的条件下,水解酸化反应器HRT为20 h,缺氧反应器HRT为24 h,一级好氧反应器和二级好氧反应器HRT均为48 h,二级好氧反应器硝化液回流比为3时,生物膜法A2/O2系统处理出水的COD和NH3-N可以同时达到《污水综合排放标准》(GB8978-1996)中的一级排放标准。

Process characteristics of anoxic reactor in biofilm A2/O2 system treating coking wastewater

With the effluent water from air-floating equipment of a coking wastewater treatment system as experimental source water,the process characteristics and effect of anoxic reactor in biofilm A2/O2(anaerobic/anoxic/aerobic/aerobic) system was studied based on the pilot-scale experiment.Ceramic pellets were packed in the anoxic reactors with an upflow-filter mode.The results of the study indicated that,anoxic denitrification played a very important role in COD removal from coking wastewater.Denitrification bacteria could use some organic matters which could hardly be degraded by aerobic and anaerobic microoganisms as carbon source,40% of COD could be removed by the denitrification reactor.The carbon source could basiclly satisfy the need for the denitrification of coking wastewater so long as the influent carbon-nitrogen ratio was above 5.The NO3——N volume loading was lower than 0.24 kg/(m3·d) under steady state operation.The hydraulic residence time of the anoxic reactor should be longer than 24 h.When the influent COD and NH3-N concentration of the system were 1 000-2 200,200-400 mg/L respectively,with no dilution,the HRT of the hydrolytic acidification reactor,anoxic reactor,first-stage aerobic reactor and second-stage aerobic reactor were 20,24,48 and 48 h respectively,and at a nitrifying recirculation ratio of 3,the mass concentration of COD and NH3-N in effluent water treated by biofilm A2/O2 system could meet the specification for grade 1 in intergrated wastewater discharge standard(GB 8978-1996).