School of Environment, College of Engineering, University of Tehran, Tehran, Iran.
Gorgan University of Agricultural Sciences & Natural Resources, Golestan, Iran.
BMC Biotechnol. 2020 May 6;20(1):21. doi: 10.1186/s12896-020-00614-1.
This study investigated the feasibility of enhancing anaerobic digestion of sewage sludge with triple, dual, and individual pretreatment of waste activated sludge with heat, alkalinity, and hydrogen peroxide. These pretreatments disrupt sludge flocs, organisms' cell walls, extracellular polymeric substance, and intracellular organic matter, which increase biodegradability and hydrolysis rate of activate sludge. In addition, the influence of various variables on methane production was analyzed using the response surface methodology with the quadratic model. Eventually, an optimized temperature and chemical concentration for the highest methane production and lowest chemical usage is suggested.
The highest amount of methane production was obtained from the sludge pretreated with triple pretreatment (heat (90 °C), alkaline (pH = 12), and hydrogen peroxide (30 mg HO/g TS)), which had better performance with 96% higher methane production than that of the control sample with temperature of 25 °C approximately and a pH = 8. Response surface methodology with a quadratic model was also used for analyzing the influence of temperature, pH, and hydrogen peroxide concentration on anaerobic digestion efficiency. It was revealed that the optimized temperature, pH, and hydrogen peroxide concentration for maximizing methane production and solubilization of sludge and minimizing thermal energy and chemical additives of the pretreatments are 83.2 °C, pH = 10.6 and 34.8 mg HO/g TS, respectively, has the desirability of 0.67.
This study reveals that triple pretreatment of waste activated sludge performed better than dual and individual pretreatment, respectively, in all desirable output parameters including increasing methane production as the most important output, increasing in COD solubilization, protein and polysaccharide, and decreasing in VSS solubilization.
本研究探讨了用热、碱度和过氧化物分别、双重和三重预处理废活性污泥来增强污水污泥厌氧消化的可行性。这些预处理会破坏污泥絮体、生物细胞壁、细胞外聚合物和细胞内有机物，从而提高活性污泥的生物降解性和水解速率。此外，还使用二次模型的响应面法分析了各种变量对甲烷生成的影响。最终，建议提出了最佳的温度和化学浓度，以实现最高的甲烷产量和最低的化学用量。
从经过三重预处理（热（90°C）、碱度（pH=12）和过氧化物（30mg HO/g TS））的污泥中获得了最高量的甲烷生产，与温度约为 25°C 和 pH=8 的对照样品相比，甲烷产量提高了 96%。还使用二次模型的响应面法分析了温度、pH 和过氧化氢浓度对厌氧消化效率的影响。结果表明，优化甲烷产量、污泥溶解、最小化热能和预处理化学添加剂的温度、pH 和过氧化氢浓度分别为 83.2°C、pH=10.6 和 34.8mg HO/g TS，可取性为 0.67。
本研究表明，与单独和双重预处理相比，三重预处理废活性污泥在所有理想的输出参数方面表现更好，包括增加甲烷产量作为最重要的输出，增加 COD 溶解、蛋白质和多糖，减少 VSS 溶解。
