Enhanced Activated Sludge Minimization by Promoting Increased Maintenance Metabolism via Holding Tank Ultrasound Treatment

好氧活性污泥法（ASP）是目前最常用的城市含碳废水生物处理技术。虽然城市污水的好氧处理是强大的，并已成功地应用于世界各地的无数处理设施，其主要缺点是产生大量的剩余污泥（EXS）。平均而言，常规ASP每处理1000 m3废水产生约80 kg干EXS，传统上通过厌氧消化然后土地应用或填埋来处置EXS。然而，现代的产能限制和严格的环境法规以及成本使得这些解决方案无法持续发展。例如，渥太华市目前每天产生43.6干吨EXS，污泥处理和处置的总成本高达常规废水处理厂的总运行成本的40-65%（Perez-Elvira等人，2006年）。 缓解成本和污泥处理能力问题的理想解决方案是直接减少活性污泥法中的EXS。所提出的研究是独特的，并且混合了以下益处和潜在的协同效应：（1）通过厌氧保持罐（HT）促进和选择ASP中产生较低生物量的兼性微生物，以及（2）对HT污泥的一部分应用高或低强度超声（US）处理。高强度US增加细胞溶解和溶解，以促进隐蔽生长并降低生物质产量，而低强度US处理将伤害微生物细胞，将能量转移到维持代谢并远离同化生长，这也将导致新生物质污泥的总体减少。将这些有益的系统相结合，以减少剩余污泥的目标将通过调查一种新的修改版本的连续ASP，它集成了厌氧HT与后超声处理的污泥循环线之前，再循环回ASP曝气池进行评估。最终出水水质和重要的剩余污泥特性，如脱水性和沉降性，将用于评估拟议处理系统产生的污泥质量。此外，为了了解HT + US改良ASP中微生物转移、隐蔽生长和维持代谢增强的作用，还将在每个步骤（HT、US后、ASP）的微生物水平上监测该工艺。 将使用微生物活力、活性和压力测试的组合，以及分子指纹、群体测序和扫描电子显微镜来表征絮凝物形态，以最终表征微生物生态变化。

The aerobic activated sludge process (ASP) is the most commonly used technology for biological treatment of municipal carbonaceous wastewaters. While aerobic treatment of municipal wastewater is robust and has been successfully applied at countless treatment facilities around the world its main drawback is the production of large quantities of excess sludge (EXS). On average a conventional ASP produces about 80 kg of dry EXS for every 1000 m3 of wastewater treated, with the EXS being traditionally disposed of by anaerobic digestion followed by land application or landfilling . However, modern capacity restraints and stringent environmental regulations as well as costs make these options unsustainable solutions moving forward. For example, City of Ottawa currently generates 43.6 dry tonnes of EXS per day every day, with the total cost for sludge treatment and disposal being as high as 40-65% of the total operating cost of conventional wastewater treatment plants (Perez-Elvira, et al., 2006). The ideal solution to alleviate both cost and sludge treatment capacity problems would be the direct reduction of EXS within the activated sludge process. The proposed study is unique and blends the benefits and potential synergistic effects of (1) promoting and selecting for lower biomass producing facultative microbes in the ASP via an anaerobic holding tank (HT), and (2) applying high or low intensity ultrasound (US) treatment to a portion of the HT sludge. High intensity US increases cell lysis and solubilisation to promote cryptic growth and lower biomass yields while low intensity US treatment will wound the microbial cells diverting energy to maintenance metabolisms and away from assimilative growth that will also lead to an overall reduction of new biomass sludge. The goal of combining these beneficial systems to reduce excess sludge will be assessed by investigating a novel modified version of the continuous ASP which integrates an anerobic HT with post-sonication treatment in the sludge recycle line prior to recycling back to the ASP aeration basin. Final effluent quality and important residual sludge characteristics such as dewaterability and settleability will be used to assess the quality of the sludge produced by the proposed treatment systems. Additionally, in order to understand the roles of microbial shift, cryptic growth and enhanced maintenance metabolism within the HT + US modified ASP the process will also be monitored at the microbial level at each step (HT, post US, ASP). A combination of microbial viability, activity and stress tests will be used, as well as molecular fingerprinting, population sequencing and scanning electron microscopy to characterize floc morphology will be applied to ultimately characterize microbial ecological changes.