Department of Civil and Environmental Engineering, Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution (Hong Kong Branch) and Water Technology Center, The Hong Kong University of Science and Technology, Hong Kong, China; Wastewater Technology Lab, Fok Ying Tung Graduate School, The Hong Kong University of Science and Technology, Guangdong, China.
Water Research Group, Department of Civil Engineering, University of Cape Town, Cape Town, South Africa.
Water Res. 2021 Feb 1;189:116608. doi: 10.1016/j.watres.2020.116608. Epub 2020 Nov 6.
An energy-/cost-efficient and environment-friendly in-situ sludge reduction process, called the sulfidogenic oxic-settling anaerobic (SOSA) was developed recently. However, the underpinning mechanism of sludge reduction by the SOSA process remains elusive. This paper investigated the possible mechanisms of sludge reduction through biomass cultivation in three lab-scale experimental systems: one anoxic-oxic CAS process with a long sludge retention time (SRT) and extended aeration (EAO) process, and two EAO-based in-situ sludge reduction processes, i.e., the conventional oxic-settling anaerobic (COSA) process and the new SOSA process. These three comparative biosystems were operated with identical influent and reactor configurations as well as the same biomass concentrations and SRTs (approximately 5 g/L and 46 days, respectively), and the sludge interchange ratios (between the CAS and side-stream reactors) in COSA and SOSA were both 10% per day. Three systems all achieved high organic (>93%) and total nitrogen (TN) (>74%) removal efficiencies. SOSA produced 29% and 20% less sludge than EAO and COSA, respectively, simultaneously consumed 14% and 8% more oxygen than EAO and COSA, indicating that the sludge reduction in SOSA was not only caused by EAO-based aerobic digestion in the mainstream and conventional anaerobic reactions in the side-stream, but more importantly due to the bioaugmentation of sulfidogenesis. The roles of sulfidogenesis were further studied in batch tests, and the key findings were as follows: i) the SOSA biomass had a faster endogenous decay rate (0.097 d) than that of the COSA biomass (0.045 d), and ii) sulfidogenesis accelerated anaerobic solubilization, hydrolysis, acidogenesis and acetogenesis by 2.3 - 3.1 times, 6 - 22 %, 22 - 60% and 6 - 22%, respectively. Overall, the mechanisms of sludge reduction in SOSA were unraveled in this study which will help promote its full-scale application in future.
一种节能/成本效益和环保的原位污泥减量工艺，称为产硫化物好氧-沉淀厌氧（SOSA）工艺，最近被开发出来。然而，SOSA 工艺的污泥减量的基本原理仍不清楚。本文通过在三个实验室规模的实验系统中培养生物质，研究了污泥减量的可能机制：一个缺氧-好氧连续流活性污泥法（CAS）工艺，具有较长的污泥停留时间（SRT）和延长曝气（EAO）过程，以及两个基于 EAO 的原位污泥减量工艺，即传统好氧-沉淀厌氧（COSA）工艺和新的 SOSA 工艺。这三个比较生物系统采用相同的进水和反应器配置以及相同的生物质浓度和 SRT（分别约为 5 g/L 和 46 天）运行，并且在 COSA 和 SOSA 中，CAS 和侧流反应器之间的污泥交换率（SIR）均为每天 10%。三个系统均实现了高有机物（>93%）和总氮（TN）（>74%）去除效率。与 EAO 和 COSA 相比，SOSA 分别产生了 29%和 20%更少的污泥，同时比 EAO 和 COSA 分别多消耗了 14%和 8%的氧气，这表明 SOSA 中的污泥减少不仅是由于主流中的 EAO 基于有氧消化和侧流中的传统厌氧反应，更重要的是由于硫化物生物增强作用。在批处理试验中进一步研究了硫化物生物增强作用的作用，主要发现如下：i）SOSA 生物量的内源衰减率（0.097 d）高于 COSA 生物量（0.045 d），ii）硫化物生物增强作用分别加速了厌氧溶解、水解、产酸和产乙酸 2.3-3.1 倍、6-22%、22-60%和 6-22%。总体而言，本研究揭示了 SOSA 中污泥减少的机制，这将有助于促进其在未来的大规模应用。
