Kumar Rajneesh, Saini Gurvinder Kaur, Jawed Mohammad
Centre for the Environment, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
Centre for the Environment, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India; Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
Chemosphere. 2024 Mar;352:141324. doi: 10.1016/j.chemosphere.2024.141324. Epub 2024 Jan 29.
Non-agricultural sources of pesticides in urban areas are responsible for their presence in domestic wastewater. Therefore, pesticides are typically found in sewage treatment plants in developed and developing countries as micro-pollutant. The presence of pesticides in the wastewater can impart stress on the aerobic sludge biomass and disrupt the functioning of the plant. However, there exists a knowledge gap regarding the resilience of aerobic sludge biomass towards stress due to the presence of pesticides in the wastewater. This study investigated the impact of chlorpyrifos (CPS) - a widely used pesticide, on sludge biomass and explored its recovery capability when CPS is discontinued in the influent. Four duplicate reactors were operated with different CPS concentrations ranging from 50 to 200 mg/L. Chemical oxygen demand (COD) removal for reactors has ranged within 18-73 % at the steady state of the stressed phase, whereas COD removal for the control reactor was 91 %. CPS stress slightly inhibited filamentous biomass growth. Biomass activity and cell viability have decreased significantly, whereas biochemical contents have varied slightly under CPS stress. The activities of the enzymes dehydrogenase and urease were significantly inhibited when compared to catalase and protease. Amplified ribosomal DNA restriction analysis reflected changes in the microbial community. The discontinuation of CPS has allowed aerobic sludge biomass to recover in its organic degradation capability (COD removal of more than 88 % at steady-state conditions of recovery phase operation), biomass growth, and cell viability. In addition, enzyme activities have retrieved to their original levels, and 78-93 % similarity of microbial community structure has been displayed between CPS-exposed and control reactor biomasses. Overall, the present study has indicated the orderly changes in the quality of aerobic sludge biomass under CPS stress through physico-chemical and biological characteristics. The study also has highlighted the self-recovery of sludge biomass characteristics stressed with different concentrations of CPS.
城市地区农药的非农业来源是其存在于生活污水中的原因。因此，在发达国家和发展中国家的污水处理厂中，农药通常作为微污染物被发现。废水中农药的存在会给好氧污泥生物质带来压力，并扰乱工厂的运行。然而，关于废水中农药的存在对好氧污泥生物质抗逆性的认识还存在差距。本研究调查了广泛使用的农药毒死蜱（CPS）对污泥生物质的影响，并探讨了进水停止添加CPS后其恢复能力。四个重复反应器在50至200mg/L的不同CPS浓度下运行。在应激阶段的稳态下，反应器的化学需氧量（COD）去除率在18%-73%范围内，而对照反应器的COD去除率为91%。CPS应激轻微抑制丝状生物质的生长。生物质活性和细胞活力显著下降，而在CPS应激下生化成分略有变化。与过氧化氢酶和蛋白酶相比，脱氢酶和脲酶的活性受到显著抑制。核糖体DNA扩增限制性分析反映了微生物群落的变化。停止添加CPS后，好氧污泥生物质的有机降解能力（在恢复阶段运行的稳态条件下COD去除率超过88%）、生物质生长和细胞活力得以恢复。此外，酶活性恢复到原来的水平，暴露于CPS的反应器和对照反应器的生物质之间显示出78%-93%的微生物群落结构相似性。总体而言，本研究通过物理化学和生物学特性表明了CPS应激下好氧污泥生物质质量的有序变化。该研究还强调了不同浓度CPS应激下污泥生物质特性的自我恢复。
