Department of Chemical Engineering, University of Barcelona, C/Martí i Franquès 1, 6th Floor, 08028 Barcelona, Spain.
Department of Microbiology, University of Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain; The Water Research Institute, University of Barcelona, Av. Diagonal 684, 08034 Barcelona, Spain.
Water Res. 2014 Sep 15;61:119-29. doi: 10.1016/j.watres.2014.05.012. Epub 2014 May 22.
Waste activated sludge is slower to biodegrade under anaerobic conditions than is primary sludge due to the glycan strands present in microbial cell walls. The use of pre-treatments may help to disrupt cell membranes and improve waste activated sludge biodegradability. In the present study, the effect of ultrasound, low-temperature thermal and alkali pre-treatments on the rheology, hygienization and biodegradability of waste activated sludge was evaluated. The optimum condition of each pre-treatment was selected based on rheological criteria (reduction of steady state viscosity) and hygienization levels (reduction of Escherichia coli, somatic coliphages and spores of sulfite-reducing clostridia). The three pre-treatments were able to reduce the viscosity of the sludge, and this reduction was greater with increasing treatment intensity. However, only the alkali and thermal conditioning allowed the hygienization of the sludge, whereas the ultrasonication did not exhibit any notorious effect on microbial indicators populations. The selected optimum conditions were as follows: 27,000 kJ/kg TS for the ultrasound, 80 °C during 15 min for the thermal and 157 g NaOH/kg TS for the alkali. Afterward, the specific methane production was evaluated through biomethane potential tests at the specified optimum conditions. The alkali pre-treatment exhibited the greatest methane production increase (34%) followed by the ultrasonication (13%), whereas the thermal pre-treatment presented a methane potential similar to the untreated sludge. Finally, an assessment of the different treatment scenarios was conducted considering the results together with an energy balance, which revealed that the ultrasound and alkali treatments entailed higher costs.
在厌氧条件下，与初沉污泥相比，剩余活性污泥的生物降解速度较慢，这是由于微生物细胞壁中的糖链存在。使用预处理方法可以帮助破坏细胞膜并提高剩余活性污泥的生物降解性。本研究评估了超声、低温热和碱预处理对剩余活性污泥流变学、卫生化和生物降解性的影响。根据流变学标准（稳态粘度降低）和卫生化水平（大肠杆菌、体细胞噬菌体和亚硫酸盐还原梭菌孢子减少）选择每种预处理的最佳条件。三种预处理均能降低污泥的粘度，且处理强度越高，降低效果越明显。然而，只有碱和热处理能够使污泥卫生化，而超声处理对微生物指标种群没有明显影响。选择的最佳条件如下：超声处理为 27,000 kJ/kg TS，热处理为 80°C 持续 15 分钟，碱处理为 157 g NaOH/kg TS。之后，在指定的最佳条件下通过生物甲烷潜力测试评估特定甲烷产量。碱预处理表现出最大的甲烷产量增加（34%），其次是超声处理（13%），而热预处理的甲烷潜力与未处理的污泥相似。最后，综合考虑结果和能量平衡，对不同的处理方案进行了评估，结果表明超声和碱处理的成本更高。
