College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China.
College of Resources and Environment, Chengdu University of Information Technology, Chengdu, Sichuan, 610225, China.
J Environ Manage. 2020 Apr 1;259:109678. doi: 10.1016/j.jenvman.2019.109678. Epub 2019 Dec 5.
In this study, a biopolymer was harvested from piggery wastewater to treat biological sludge. Effectiveness of the combination of polyaluminum chloride (PAC) and this biopolymer in sludge dewatering was investigated and the dewatering mechanism was discussed. Results showed that as high as 3.11 g of biopolymer can be harvested from 1 L of piggery wastewater by cultivating Bacillus megaterium. After treated by PAC with a dosage of 1.5 g/L at pH point of 7.5, specific resistance to filtration (SRF), moisture content (MC), settled volume after 30 min (SV) and capillary suction time (CST) of the sludge were decreased to 3.4 × 10 m/kg, 84.5%, 79.8% and 65 s, respectively, and dry solid (DS) was increased to 21.4%, indicated that sludge dewatering was obviously enhanced by PAC. After further treated by 2 g/L of the biopolymer, SRF, MC, SV and CST were further decreased to 2.1 × 10 m/kg, 59.8%, 55.6% and 39 s, respectively, and DS was increased to 28.6%, indicated that sludge dewatering was further enhanced by the biopolymer. For the enhancing mechanism, on the one hand, the extracellular polymeric substances (EPS) was significantly disintegrated to release binding bound water, which was facilitating sludge dewatering; on the other hand, the synergistic effect of PAC coagulation and biopolymer flocculation, including charge neutralization and bridge-aggregation, were favorable to sludge dewatering. Additionally, we found that the dewatered sludge was helpful for remediation of chromium (Cr)(VI)-contaminated soil by raising soil pH and decreasing bioavailability of Cr(VI) in the soil, after remediated by 75 g/kg of the dewatered sludge for 60 days, the soil pH was increased from its initial value of 4.32-8.52, and the residue Cr(VI) in the soil extract was appeared as 2.2 mg/L.
在这项研究中，从养猪废水中收获了一种生物聚合物来处理生物污泥。研究了聚合氯化铝 (PAC) 和这种生物聚合物组合在污泥脱水方面的效果，并讨论了脱水机制。结果表明，通过培养巨大芽孢杆菌，从 1L 养猪废水中可以收获高达 3.11g 的生物聚合物。用 1.5g/L 的 PAC 在 pH 值为 7.5 处理后，污泥的比过滤阻力 (SRF)、水分含量 (MC)、30 分钟后沉降体积 (SV) 和毛细吸水时间 (CST) 分别降低到 3.4×10 m/kg、84.5%、79.8%和 65s，而干固体 (DS) 增加到 21.4%，表明 PAC 明显增强了污泥脱水效果。用 2g/L 的生物聚合物进一步处理后，SRF、MC、SV 和 CST 进一步降低到 2.1×10 m/kg、59.8%、55.6%和 39s，DS 增加到 28.6%，表明生物聚合物进一步增强了污泥脱水效果。对于增强机制，一方面，胞外聚合物物质 (EPS) 显著解体，释放结合水，有利于污泥脱水；另一方面，PAC 混凝和生物聚合物絮凝的协同作用，包括电荷中和和桥联聚集，有利于污泥脱水。此外，我们发现，经过 75g/kg 的脱水污泥修复 60 天后，脱水污泥有助于修复铬 (Cr)(VI) 污染土壤，提高土壤 pH 值并降低土壤中 Cr(VI)的生物利用度，土壤中 Cr(VI)的残留量从初始值 4.32-8.52 降低到 2.2mg/L。
