Thakkar Shivani, Bhatt Megha Deepesh, Patel Vishu, Mishra Anant Kumar, Vaishnav Pujan Bhupendra
Gujarat State Fertilizers & Chemicals Ltd., Fertilizer Nagar, Vadodara, Gujarat, 391750, India.
Environ Sci Pollut Res Int. 2025 Jul 31. doi: 10.1007/s11356-025-36782-w.
This research dives into highlighting potential usage of cow dung as a co-substrate to reduce the organic carbon load of toxic industrial effluents through batch and semi continuous anaerobic process. One such effluent stream is released during caprolactam manufacturing having pH of about 2, 0.4% ammonical nitrogen, and COD up to 55,000 mg/L which varies often. In this study, a series of laboratory-scale experiments followed by pilot level experiments were laid to treat highly toxic industrial effluent in different ratios using cow dung as co-substrate in an anaerobic setup. The basic parameters to analyze the performance of system were chemical oxygen demand (COD) removal efficiency, reduction in ammonium sulfate concentration, biogas production and methane constitution within it, and effluent quality. Reduction in COD and ammonium sulfate concentration was observed to be 42.9% and 23.2% respectively at lab level, while methane concentration in biogas was improved from 39.5 to 69.5% after day 7 of the reaction. Furthermore, pilot scale trials were laid to verify the results of similar treatments on large scale, and they confirmed the lab scale results positively by observing a reduction of COD up to 43.8%, ammonical nitrogen by 18.7%, and methane production improvised from 36.7 to 76.32% after day 7 of the reaction. Semi- continuous reactor trial that was carried out for 22 days showed reduction in COD and ammonical nitrogen by 38.5% and 37.5% respectively which stayed consistent up to the 22nd day. This study contributes to the evolving body of knowledge on anaerobic digestion, particularly for the treatment of highly toxic caprolactam plant effluents, and highlights the value of cow dung slurry as an effective and sustainable co-substrate.
本研究深入探讨了牛粪作为共底物的潜在用途，通过间歇式和半连续厌氧工艺来降低有毒工业废水的有机碳负荷。己内酰胺生产过程中会排放出一种这样的废水，其pH值约为2，氨氮含量为0.4%，化学需氧量（COD）高达55000mg/L且经常变化。在本研究中，进行了一系列实验室规模的实验，随后开展了中试规模的实验，在厌氧装置中使用牛粪作为共底物，以不同比例处理高毒性工业废水。分析系统性能的基本参数包括化学需氧量（COD）去除效率、硫酸铵浓度的降低、沼气产量及其内部的甲烷组成，以及出水水质。在实验室规模下，观察到COD和硫酸铵浓度的降低分别为42.9%和23.2%，而反应7天后，沼气中的甲烷浓度从39.5%提高到了69.5%。此外，进行了中试规模试验以大规模验证类似处理的结果，通过观察发现，反应7天后，COD降低了43.8%，氨氮降低了18.7%，甲烷产量从36.7%提高到了76.32%，从而肯定地证实了实验室规模的结果。进行了22天的半连续反应器试验表明，COD和氨氮分别降低了38.5%和37.5%，直至第22天保持稳定。本研究为厌氧消化不断发展的知识体系做出了贡献，特别是对于高毒性己内酰胺工厂废水的处理，并突出了牛粪浆作为一种有效且可持续的共底物的价值。
