Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia.
Study Program of Environmental Engineering, Department of Biology, Faculty of Science and Technology, Universitas Airlangga, Kampus C UNAIR, Jalan Mulyorejo, Surabaya 60115, Indonesia.
Sci Total Environ. 2022 Aug 25;836:155564. doi: 10.1016/j.scitotenv.2022.155564. Epub 2022 Apr 30.
Bioflocculants gain attention as alternatives to chemical flocculants because they are more environmentally friendly and highly biodegradable. This study aims to improve the bioflocculant production by Serratia marcescens using one-variable-at-a-time (OVAT) analysis and analyze its flocculating activity performance, toxicity, and the flocculation mechanism. The effect of multiple variables including initial inoculum size, pH, mixing speed, temperature, growth medium, and incubation period was assessed through OVAT. Flocculating activity was then determined via jar test analysis, and toxicity test was performed using Daphnia magna and Daphnia pulex. The flocculation mechanism was determined via particle size distribution and zeta potential analysis. The optimum conditions for the improved bioflocculant production were as follows: 10% v/v initial inoculum size, pH 7, mixing speed of 150 rpm, room temperature, nutrient broth medium, and 72 h of incubation period. Scanning electron microscopy showed flake-like intact structure with coarse surface. The produced bioflocculant showed flocculating activity of 48% in 5227 ± 580 NTU initial kaolin turbidity with 1 mg/L concentration and 5% v/v dosage of bioflocculant, following the second-order kinetics. Toxicity test to D. magna and D. pulex showed the 48 h LC values of 8.06 and 6.42 g/L, respectively; these values are greatly higher than the fabricated chemical flocculants. The flocculation process using bioflocculant produced by S. marcescens was suggested to occur via bridging mechanism because it greatly affected the particle size distribution. Results indicated that bioflocculant produced by S. marcescens is much environmentally friendly and has great potential for turbidity removal in water/wastewater.
生物絮凝剂因其更环保且高度可生物降解而成为化学絮凝剂的替代品，受到关注。本研究旨在通过单变量分析（OVAT）提高粘质沙雷氏菌产生生物絮凝剂的能力，并分析其絮凝活性、毒性和絮凝机理。通过 OVAT 评估了包括初始接种量、pH 值、混合速度、温度、生长培养基和培养时间在内的多个变量的影响。通过摇瓶试验分析确定絮凝活性，并用大型蚤和蚤状蚤进行毒性试验。通过粒度分布和zeta 电位分析确定絮凝机理。改进生物絮凝剂生产的最佳条件为：初始接种量 10%v/v、pH7、混合速度 150rpm、室温、营养肉汤培养基和 72h 培养时间。扫描电子显微镜显示片状完整结构，表面粗糙。所产生的生物絮凝剂在初始高岭土浊度为 5227±580NTU、浓度为 1mg/L、生物絮凝剂用量为 5%v/v 的条件下，具有 48%的絮凝活性，符合二级动力学。对大型蚤和蚤状蚤的毒性试验表明，48hLC 值分别为 8.06 和 6.42g/L，远高于所制备的化学絮凝剂。粘质沙雷氏菌产生的生物絮凝剂的絮凝过程被认为是通过桥联机制发生的，因为它对粒度分布有很大的影响。结果表明，粘质沙雷氏菌产生的生物絮凝剂对环境更加友好，在去除水/废水中的浊度方面具有很大的潜力。
