Cu2+和Zn2+对活性污泥生长动力学的影响

Cu2+和Zn2+是污水处理工艺中经常遇到的金属离子,文章利用序批式实验研究了活性污泥在Cu2+和Zn2+作用下的生长模式.尽管微量的Cu2+和Zn2+对微生物的生长有益,但当它们达到一定的质量浓度时,均会对微生物的生长速率和COD的去除速率产生抑制作用.实验结果表明,活性污泥的产量在Cu2+的质量浓度为1～20 mg/L时均有所减少;而Zn2+的质量浓度只有超过5 mg/L时,才能使污泥产量降低,当Zn2+的质量浓度等于或低于5 mg/L时,它反而轻微促进微生物的生长速率和COD的去除速率.总体而言,根据微生物的比生长速率、基质比去除速率、活性污泥产率以及COD的去除效率等各方面的对比研究,结果表明,Cu2+的毒性比Zn2+强.

Growth kinetics of activated sludge in batch culture in the presence of Cu2+and Zn2+

The growth kinetics of activated sludge in batch culture in the presence of Cu~(2+)and Zn~(2+), which are the most common metal ions in wastewater treatment process,is investigated in this study. Though Cu~(2+) and Zn~(2+) in trace concentration are beneficial to the growth of microorganisms, they bring about inhibition effect on the growth kinetics at high concentration. Cu~(2+) inhibited the microorganism growth rate and the chemical oxygen demand(COD) removal rate,and consequently, decreased the yield of activated sludge at all tested concentration ranging from 1 mg/L to 20 mg/L. Zn~(2+) inhibited the microorganism growth rate, the COD removal rate and the yield of activated sludge at concentration over 5 mg/L; but at 5 mg/L, or less, it enhanced the microorganism growth rate and the COD removal rate slightly. Overall, Cu~(2+) was more toxic than Zn~(2+) according to their effect on the relative specific growth rate of microorganisms,the relative specific COD removal rate,the yield of activated sludge as well as the COD removal efficiency.