碳酸氢钠对短带鞘藻-活性污泥共生体系在城镇污水脱氮除磷中的促进作用

Acceleration of NaHCO_(3)on the removal of nitrogen and phosphorus in urban sewage by the symbiosis system of Oedogonium brevicingulatum and activated sludge

藻菌共生技术在污水处理中具有高效低耗、资源可利用等特点。目前,我国城镇污水厂中进水COD普遍偏低,影响了出水一级A(GB 18918-2002)提标改造中脱氮除磷的效果。在构建短带鞘藻-活性污泥共生体系的基础上,采用补充外加碳源促进其对城镇污水的脱氮除磷效果。结果表明,短带鞘藻-活性污泥共生体系的优化工艺条件为藻菌干重比3∶1、初始生物量0.3 g·L^(-1)、曝气量0.2 L·min^(-1)、曝气间歇时间6 h∶6 h。经过比较,确定碳酸氢钠比乙酸钠、葡萄糖和碳酸钠更适合作为该共生体系的外加碳源。当碳酸氢钠投加量为100 mg·L^(-1)时,该体系对模拟中污水中氨氮(NH4+-N)、总氮(TN)、总磷(TP)和COD的去除率分别为98.7%、78.6%、71.6%和100%。Monod动力学方程计算拟合结果证实,碳酸氢钠对短带鞘藻生长的促进作用比对活性污泥显著。将该共生体系置于自行设计的固定化藻菌共生生物膜反应器处理某城镇污水厂污水,经外加碳酸氢钠提升进水中碳源浓度后,出水中氮磷等指标均可达到城镇污水处理厂污染物一级A排放标准。

The symbiosis system of algae and bacteria has the advantages of high efficiency,low consumption,and resource utilization in sewage treatment.However,the COD of most urban sewage treatment plants has been generally lower than expected thus reduces the removal rate of nitrogen and phosphorus in the upgrading process of achieving the level A discharged standard of urban sewage(GB 18918-2002).On the basis of constructing a symbiosis system of O.brevicingulatum and activated sludge,an external carbon source was used to promote its removal effect of nitrogen and phosphorus from urban sewage.The results showed that the optimized process conditions for the symbiosis system of O.brevicingulatum and activated sludge were as follow:the dry weight ratio of algae and bacteria was 3∶1,the initial biomass was 0.3 g·L^(-1),the aeration rate was 0.2 L·min^(-1),and the aeration and intermission interval was 6 h/6 h.After comparison of the four external carbon sources,NaHCO3 was determined as more suitable carbon source than CH3COONa,C6H12O6 and Na2CO3.Adding 100 mg·L^(-1)NaHCO3 in the simulated sewage,the removal rates of ammonia nitrogen(NH4+-N),total nitrogen(TN),total phosphorus(TP)and COD were 98.7%,78.6%,71.6%and 100%,respectively.Through evaluating the effect of NaHCO3 on the growth of O.brevicingulatum and activated sludge by Monod kinetic method,the growth acceleration of O.brevicingulatum by NaHCO3 was more than that of activated sludge.Furthermore,a selfdesigned biofilm reactor with the symbiosis system was used to treat actual urban sewage,the nitrogen and phosphorus indicators in the effluent could reach the level A discharged standard of urban sewage after when NaHCO3 was added to increase the carbon source concentration in the influent.