title: Effects of multi-metal toxicity on the performance of sewage treatment system during the festival of colors (Holi) in India.
abstract: The present study investigated the effects of heavy metals (Ni, Zn, Cd, Cu, and Pb) toxicity on the performance of 18 MLD activated sludge process-based sewage treatment plant (STP) during celebration of Holi (festival of colors in India). The composite sampling (n = 32) was carried out during the entire study period. The findings show a significant decrease in chemical oxygen demand removal efficiency (20%) of activated sludge system, after receiving the heavy metals laden wastewater. A significant reduction of 40% and 60% were observed in MLVSS/MLSS ratio and specific oxygen uptake rate, which eventually led to a substantial decrease in biomass growth yield (from 0.54 to 0.17). The toxic effect of metals ions was also observed on protozoan population. Out of the 12 mixed liquor species recorded, only two ciliates species of Vorticella and Epistylis exhibited the greater tolerance against heavy metals toxicity. Furthermore, activated sludge shows the highest metal adsorption affinity for Cu, followed by Zn, Pb, Ni, and Cd (Cu > Zn > Pb > Ni > Cd). Finally, this study proves the robustness of activated sludge system against the sudden increase in heavy metal toxicity since it recovered the earlier good quality performance within 5 days.
authors.affiliation: Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee 247667, India. vinayiitrp@gmail.com
authors.forename: Vinay Kumar
authors.initials: VK
authors.lastname: Tyagi
authors.forename: Akanksha
authors.initials: A
authors.lastname: Bhatia
authors.forename: Rubia Zahid
authors.initials: RZ
authors.lastname: Gaur
authors.forename: Abid Ali
authors.initials: AA
authors.lastname: Khan
authors.forename: Muntajir
authors.initials: M
authors.lastname: Ali
authors.forename: Anwar
authors.initials: A
authors.lastname: Khursheed
authors.forename: Absar Ahmad
authors.initials: AA
authors.lastname: Kazmi
mesh_terms: D016798:Ciliophora / Q000187:drug effects; D007194:India; D019216:Metals, Heavy / Q000032:analysis / Q000633:toxicity*; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000737:chemistry* / Q000382:microbiology; D014871:Water Microbiology
chemical_list: D019216:Metals, Heavy; D012722:Sewage; D062065:Wastewater