盐度入侵城市污水处理厂对淡水活性污泥的毒性抑制

Assessment on effect of salt toxicity on activity of activated sludge in wastewater treatment plant

盐度入侵城市污水处理厂改变了活性污泥的胞外渗透压环境,影响生物系统的生物活性和污染物降解能力。采用MUCT工艺处理真实生活污水,模拟了盐度入侵对系统处理效率的影响。并结合污染降解动力学和抑制动力学建立了盐度抑制模型,系统地评测了盐度对活性污泥功能性微生物的毒性抑制。结果表明,盐度入侵造成了功能性微生物的活性损失,干扰了正常的污水处理能力。毒性抑制显著地降低了好氧微生物的呼吸作用,以此作为毒性评估的依据会造成对抑制作用的高估。而以底物降解速率评估盐度毒性抑制可以很好地指示污水处理效率。盐度对有机物降解异养菌、硝化菌和反硝化菌抑制的IC50值分别是20.64g.L-1、11.61g.L-1、10.88g.L-1。

Invasion of salt into wastewater treatment plants can change intracellular osmotic pressure of bacteria and influence microbial activity and degradation ability in bio-treating system with activated sludge.Effect of salinity on treatment efficiency was simulated based on MUCT process for treating real saline sewage.A model was constructed by combining the pollutant degradation kinetics and the inhibition kinetics,by which the salt toxicity on functional microorganisms in activated sludge was evaluated.The results showed that intrusion of salt can cause its activity loss and disrupt normal removal of pollutants.And this toxicity can reduce significantly respiration of aerobic microorganisms,and evaluation on the effect of salt toxicity,based on the respiration inhibition,can be overestimated,while based on pollutant degradation rate it can properly be related to treatment efficiency and the real situation of treatment system.In this study,IC50 values of salt inhibition obtained for the degradation of organics heterotroph,nitrifiers and denitrifiers were 20.64 g·L^-1,11.61 g·L^-1,and 10.88 g·L^-1,respectively.