Membrane enhanced A/B staged biological processes to harvest energy and reuse municipal wastewater

最近，废水工业正在出现一种范式转变，将其从需要处理的废物流视为一种宝贵的资源，从中生产可重复使用的水，产生能源和回收其他宝贵资源。水环境研究基金会（Water Environmental Research Foundation）发表的一项基准能源研究得出结论，城市污水所含的能源大约是处理所需能源的十倍。然而，目前采用的大多数废水处理方法都是能源密集型的，因为需要提供大量的氧气来进行生物降解。同样，技术的进步为经济地从城市污水中回收不可再生磷提供了巨大的潜力。本研究的目的是开发和优化膜强化A/B阶段生物工艺（MeA/B），以最大限度地回收能量，同时为回收其他有价值的资源和废水再利用提供机会。阶段a生物反应器由厌氧区先于好氧区组成，具有以下特点：1)由于SRT极短，通过生物絮凝将废水中的有机物最大限度地转化为生物质；2)最大限度地减少污泥过度腐烂，以减少生物降解所需的氧气；3)生产富磷生物质，从而提供从后续污泥消化器的上清液中回收磷的机会。采用膜曝气生物膜反应器（MABR）工艺作为b级处理可进一步实现协同效应。MABR的无气泡曝气可以实现极高的氧传递效率。a级生物反应器对有机物的有效去除也有助于控制b级膜模块内严重的污泥堵塞问题。将进行广泛的实验，以研究MeA/B系统在污水质量、污泥产量和除磷方面的可行性。重点将放在阶段A A/O过程，通过确定影响生物质生物絮凝的关键因素，描述微生物生态和过程性能之间的基本相互作用，并制定改善污泥沉降性的策略。通过表征附着在膜表面的生物膜，测量氧传递速率和硝化效率来评价MABR工艺的性能。最后，将进行一系列的实验来量化生物化学计量学和动力学参数。然后将收集到的数据用作模型输入，以修改和校准新的集成流程模型。如果成功，该项目将为加拿大市政当局和私营水务工业提供一种生产能源的废水处理工艺，以及水再利用和磷回收的潜力。此外，该研究将更好地了解污泥的生物絮凝，并在短SRT生物反应器中建立微生物群落生态与工艺性能之间的联系。该项目还将产生改善污泥沉降性的有效策略。本研究建立的过程模型可用于膜强化A/B阶段生物工艺的设计和优化。最后，该项目将为3名博士研究生、3名硕士研究生和1名博士后提供培训机会，这些学生目前因加拿大水工业的快速发展而需求量很大。

Recently, a paradigm shift is emerging in wastewater industry, considering it from a waste stream that needs to be disposed of, to a valuable resource from which to produce reusable water, generate energy and recover other valuable resources. A benchmarking energy study published by Water Environmental Research Foundation concluded that municipal wastewater could contain approximately ten times the energy needed to treat it. Yet, most wastewater treatment practices currently being employed are very energy-intensive because of the necessity to supply a large amount of oxygen for biodegradation. Similarly, technological advance provides great potential to recover non-renewable phosphorous from municipal wastewater economically. The goal of this study is to develop and optimize membrane enhanced A/B staged biological process (MeA/B) that can maximize energy recovery, while providing the opportunities to recover other valuable resources and reuse wastewater. Stage-A bioreactor consisting of an anaerobic zone ahead of aerobic zone offers distinct features: 1) to maximize the conversion of organic matter in wastewater into biomass through bioflocculation because of extremely short SRT, 2) to minimize excessive sludge decay to reduce the oxygen demand for biodegradation, and 3) to produce phosphorous-rich biomass, thereby, providing an opportunity to recover it from the supernatant of subsequent sludge digesters. Further synergistic benefits could be realized by incorporating membrane aerated biofilm reactor (MABR) process as Stage-B treatment. The bubbleless aeration of MABR could achieve extremely high oxygen transfer efficiency. The effective removal of organic matter by Stage-A bioreactor also helps control serious sludge clogging problem within Stage-B membrane modules. Extensive experiments will be conducted to examine the feasibility of MeA/B system in terms of effluent quality, sludge production and phosphorous removal. Emphasis will be placed on Stage-A A/O process by identifying key factors affecting the bioflocculation of biomass, characterizing the fundamental interactions between the microbial ecology and process performance and, developing the strategies to improve sludge settleability. As well, the performance of MABR process will be assessed by characterizing the biofilm attached onto membrane surface and measuring oxygen transfer rate and nitrification efficiency. Finally, a series of experiments will be performed to quantify the biological stoichiometric and kinetic parameters. The collected data are then used as model inputs to modify and calibrate a new integrated process model.If successful, this project will provide Canadian municipalities and private water industry with an energy-producing wastewater treatment process in addition to the potential for water reuse and phosphorous recovery. As well, the research will provide a better understanding of the biofloculation of sludge and establish the linkage between microbial community ecology and process performance in short SRT bioreactors. This project will also result in effective strategies to improve sludge settleability. The process models developed from this research can aid in designing and optimizing membrane enhanced A/B staged biological processes when used in practice. Finally, this project will provide training opportunities for 3 PhD students, 3 MSc students and 1 post-doctoral fellow who are now in high demand because of rapid expansion of water industry in Canada.