Cu2+和Ni2+对水解-MBR工艺处理效能的影响特性

为降低电镀废水中重金属对生物处理系统的冲击,采用水解-膜生物反应器(MBR)组合工艺对电镀综合废水进行处理,以重金属离子Cu~(2+)、Ni~(2+)为代表,重点研究不同质量浓度的重金属冲击下对水解-MBR工艺处理电镀废水效能的影响,以及水中DOMs与微生物活性的变化情况.结果表明:在Cu~(2+)、Ni~(2+)质量浓度5~20 mg/L冲击下,水解-MBR组合工艺对COD和NH_4~+-N去除效率分别在75%和45%以上.硝化细菌抗重金属冲击能力较差,水解-MBR组合工艺对重金属Cu~(2+)、Ni~(2+)的耐受质量浓度可达20 mg/L,而单纯MBR工艺仅为10 mg/L.水解反应器可将污水中HPI大部分转化为HPO-A,改善难降解有机物可生化性,芳香族化合物的含量明显降低.随着重金属Cu~(2+)、Ni~(2+)质量浓度的升高,MBR反应器内活性污泥的SOUR值逐步下降,但水解-MBR工艺SOUR受重金属的抑制率均比单独MBR工艺低5%左右.由于水解使重金属毒性减弱,水解-MBR系统中微生物的活性较高,系统中EPS含量和出水质量浓度均显著低于单独MBR工艺,且可以有效减少膜表面胶体物质和溶解性有机物形成,降低污泥滤饼层的形成速度,有效减缓膜污染的速率.

Influence characteristics of Cu2+ and Ni2+ on the treatment efficiency of hydrolysis-MBR process

In order to reduce the impact of heavy metals on the biological treatment system of electroplating wastewater, a lab-scale process combined with hydrolysis reactor and membrane bioreactor (MBR) was used to treat electroplating wastewater. Taking Cu²⁺ and Ni²⁺ as research objects, the effects of different metal concentrations on the electroplating wastewater treatment were studied, and the changes of DOMs and microbial activity in water were analysed simultaneously. The experimental results showed that the removal efficiencies of COD and NH₄⁺-N were above 75% and 45%, respectively, when the concentration of Ni²⁺and Cu²⁺ was 5-20 mg/L. Nitrification bacteria''s ability to resist heavy metal impact was weak. The tolerance concentration of Ni²⁺ in hydrolysis reactor combined with MBR was 20 mg/L and only 10 mg/L in MBR. The hydrolysis reactor could convert most of HPI into HPO-A, which could improve the biodegradability of refractory organic compounds, and the content of aromatic compounds was obviously decreased. With the increase of Ni²⁺ and Cu²⁺, the SOUR value of activated sludge in MBR reactor was gradually decreased, but the inhibition rate of SOUR in hydrolysis reactor combined with MBR was 5% lower than that in MBR. Due to the hydrolysis, the toxicity of heavy metals decreased. In hydrolysis reactor combined with MBR, the activity of microorganism was higher, and the content of EPS and the effluent concentration were significantly lower than those in MBR. The formation of colloid, dissolved organic matter and sludge cake layer could be reduced effectively, which retarded the rate of membrane fouling.