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

好氧活性污泥法是目前城市含碳废水生物处理中最常用的工艺。城市污水好氧处理技术具有很强的实用性，已在世界各地的无数处理设施中得到成功应用，但其主要缺点是会产生大量的剩余污泥。平均而言，每处理1000立方米的废水，传统的三氯化铝产生约80公斤的干EXS，这些EXS传统上是通过厌氧消化，然后进行土地利用或填埋来处理的。然而，现代的产能限制和严格的环境法规以及成本使这些选择无法持续地向前推进。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传统废水处理厂总运营成本的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。建议的研究是独一无二的，它融合了(1)通过厌氧保存池(HT)促进和选择ASP中生物产量较低的兼性微生物的好处和潜在的协同效应，以及(2)对部分HT污泥进行高或低强度的超声波(US)处理。高强度的超声会增加细胞的裂解和溶解，以促进隐蔽的生长和较低的生物量产量，而低强度的超声处理会伤害微生物细胞，将能量转移到维持新陈代谢，而不是同化生长，这也将导致新的生物质污泥的整体减少。结合这些有益系统以减少剩余污泥的目标将通过研究一种新的改进型连续ASP进行评估，该改进版本将厌氧高温与污泥循环线中的超声后处理相结合，然后再循环回ASP曝气池。最终出水水质和重要的剩余污泥特性，如脱水和沉降性，将被用来评估拟议处理系统产生的污泥的质量。此外，为了了解微生物迁移、隐形生长和增强维护代谢在HT+US改良的ASP中的作用，还将在每个步骤(HT、US后、ASP)的微生物水平上监测这一过程。将使用微生物活性、活性和压力测试的组合，以及分子指纹、种群测序和扫描电子显微镜来表征絮体形态，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.