五氯苯酚对污泥性能和功能基因表达水平的影响

氯酚废水是一类广泛存在于环境的典型工业废水,具有显著的生态毒性,为探讨废水中氯酚类化合物对污泥性能和功能基因表达水平的影响,采用HRT（水力停留时间）为8 h、SBR（间歇曝气的序批式生物反应器）处理进水浓度为2 mg/L的PCP（五氯苯酚）废水,并与处理不含PCP的废水作对比分析,探讨PCP对污染物去除和微生物菌群的影响,并分析PCP诱导下污泥中Pseudomonas功能基因的表达水平.结果表明:①1~90 d,进水浓度为2 mg/L的PCP严重抑制污泥活性,出水ρ（COD_Cr）超过100 mg/L,PCP降解去除缓慢,而对照组出水ρ（COD_Cr）在31.6 mg/L左右波动.90 d后,降解PCP的优势菌群富集,水相、泥相PCP被降解去除,但PCP的毒性作用使其出水ρ（COD_Cr）仍高于对照组.②经PCP长期驯化污泥富集的优势菌属为Chondromyces、Ignavibacterium、Thauera、Pseudoxanthomonas、Bosea、Achromobacter、Comamonas和Salimesophilobacter,均归属于变形菌门和厚壁菌门,在降解氯酚类污染物方面起着重要作用.③当处理PCP的SBR处于稳定运行阶段时,SBR运行周期末污泥中降解PCP的菌属Pseudomonas调控ATP水解酶（ATPase）、过氧化氢酶（CAT）和细胞色素p450（CYP450）的功能基因表达被激活,而调控超氧化物歧化酶（SODb）、氨单加氧酶（AM）、脱氯水解酶（HDLH）和甘油三磷酸脱氢酶（GAPDH）的功能基因表达被抑制,即活性污泥中微生物调控不同基因的表达受进水PCP的抑制或激活.研究显示:进水PCP诱导SBR富集的优势菌属可实现废水中PCP的去除,起到削减废水毒性的作用;通过分析不同优势菌属的相关功能基因表达,可加强对不同微生物降解污染物机理的认识.      

The effect of salinity on waste activated sludge alkaline fermentation and kinetic analysis

The effect of salinity on sludge alkaline fermentation at low temperature(20°C) was investigated, and a kinetic analysis was performed. Different doses of sodium chloride(Na Cl, 0–25 g/L) were added into the fermentation system. The batch-mode results showed that the soluble chemical oxygen demand(SCOD) increased with salinity. The hydrolysate(soluble protein, polysaccharide) and the acidification products(short chain fatty acids(SCFAs), NH+4–N, and PO_4~(3-)–P) increased with salinity initially, but slightly declined respectively at higher level salinity(20 g/L or 20–25 g/L). However, the hydrolytic acidification performance increased in the presence of salt compared to that without salt.Furthermore, the results of Haldane inhibition kinetics analysis showed that the salt enhanced the hydrolysis rate of particulate organic matter from sludge particulate and the specific utilization of hydrolysate, and decreased the specific utilization of SCFAs. Pearson correlation coefficient analysis indicated that the importance of polysaccharide on the accumulation of SCFAs was reduced with salt addition, but the importance of protein and NH+4–N on SCFA accumulation was increased.     

Decontamination of electronic waste-polluted soil by ultrasound-assisted soil washing

Laboratorial scale experiments were performed to evaluate the efficacy of a washing process using the combination of methyl-β-cyclodextrin (MCD) and tea saponin (TS) for simultaneous desorption of hydrophobic organic contaminants (HOCs) and heavy metals from an electronic waste (e-waste) site. Ultrasonically aided mixing of the field contaminated soil with a combination of MCD and TS solutions simultaneously mobilizes most of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and the analyte metal (Pb, Cu, and Ni) burdens. It is found that 15 g/L MCD and 10 g/L TS is an efficient reagent combination reconciling extraction performance and reagent costs. Under these conditions, the removal efficiencies of HOCs and heavy metals are 93.5 and 91.2 %, respectively, after 2 cycles of 60-min ultrasound-assisted washing cycles. By contrast, 86.3 % of HOCs and 88.4 % of metals are removed from the soil in the absence of ultrasound after 3 cycles of 120-min washing. The ultrasound-assisted soil washing could generate high removal efficiency and decrease the operating time significantly. Finally, the feasibility of regenerating and reusing the spent washing solution in extracting pollutants from the soil is also demonstrated. By application of this integrated technology, it is possible to recycle the washing solution for a purpose to reduce the consumption of surfactant solutions. Collectively, it has provided an effective and economic treatment of e-waste-polluted soil.