Energy Optimization at Municipal Wastewater Treatment Plants

城市污水处理厂的能源优化

• 批准号: RGPIN-2017-04982
• 负责人: Nakhla, George
• 金额: $ 3.72万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=636618
• 关键词: Energy; Optimization; Municipal; Wastewater; Treatment

Most wastewater treatment plants in North America, are approaching their design life necessitating significant capital investment for expansion and upgrade to meet increasingly stringent effluent quality criteria while addressing increased energy costs and heightened needs for economic and environmental sustainability. According to the US EPA, municipal wastewater treatment plants (MWWTP) consume about 75 billion KWH annually, or 3% of the US electricity generated. Aeration energy accounts for about 60% of the overall energy consumption at MWWTP. Furthermore, biosolids processing and disposal costs account for 50%-60% of overall wastewater treatment costs. The main technical challenges facing the municipal wastewater sector relate to nutrients and biosolids management, as well as optimization of energy, necessitating a paradigm shift towards energy neutrality and resource recovery. In contrast to the first generation of biological nutrient (nitrogen and phosphorous) removal (BNR) processes, which remove N by oxidation of ammonia and organic nitrogen to nitrates and then denitrifying to nitrogen gas, second generation BNR processes which nitrify and denitrify through nitrite as well as anaerobically oxidizing ammonia with nitrites, not only offer significant energy savings of up to 40%, but also reduce the addition of much-needed extraneous organic carbon to supplement the wastewater organics for denitrification by as much as 90%. All the second-generation BNR processes employ suspended growth systems that require much higher hydraulic retention times and much larger bioreactor volumes compared to biofilm or fixed-film processes. Energy generation at MWWTP primarily involves anaerobic digestion. However, the efficiency of volatile solids reduction (VSR) in conventional digesters with hydraulic retention times of around 15-30 days, is typically around 50%. While recently, the biogas production from anaerobic digesters has been enhanced through co-digestion of food wastes with municipal biosolids, the fundamentals of synergism are not well understood. The overall long-term objective of the proposed research program is to minimize energy consumption at MWWTP through reduction of aeration energy for nitrogen removal and enhanced conversion of municipal biosolids to methane in anaerobic digestion. The project has three short-term objectives: (1) development of an integrated biofilm process i.e. a fluidized bed bioreactor that combines short-cut nitrification with anaerobic ammonia oxidation in a single reactor; (2) development of a high-rate biofilm anaerobic fluidized bed digester with ultrasonication, and (3) investigation of the fundamental process parameters contributing to the observed synergistic effects of co-digestion of food wastes and wastewater biosolids.

北美的大多数废水处理厂正在接近其设计寿命，需要大量的资本投资进行扩建和升级，以满足日益严格的污水质量标准，同时解决能源成本增加以及对经济和环境可持续性的更高需求。根据美国环保署的数据，城市污水处理厂（MWWTP）每年消耗约750亿千瓦时，占美国发电量的3%。曝气能耗约占MWWTP总能耗的60%。此外，生物固体处理和处置成本占总废水处理成本的50%-60%。城市废水处理部门面临的主要技术挑战涉及营养物和生物固体管理以及能源优化，因此需要向能源中性和资源回收转变。与第一代生物营养素相比，（氮和磷）去除（BNR）工艺，其通过将氨和有机氮氧化成硝酸盐然后硝化成氮气来去除N，第二代BNR工艺，其通过亚硝酸盐硝化和硝化以及用亚硝酸盐厌氧氧化氨，不仅提供高达40%的显著节能，而且还减少了为反硝化而补充废水有机物所急需的外来有机碳的添加量，高达90%。所有第二代BNR工艺都采用悬浮生长系统，与生物膜或固定膜工艺相比，悬浮生长系统需要更长的水力停留时间和更大的生物反应器体积。MWWTP的能源生产主要涉及厌氧消化。然而，在水力停留时间为约15-30天的常规蒸煮器中，挥发性固体减少（VSR）的效率通常为约50%。虽然最近，从厌氧消化池的沼气生产已经提高了通过共同消化的食物垃圾与城市生物固体，协同作用的基本原理还没有得到很好的理解。拟议的研究计划的总体长期目标是通过减少脱氮的曝气能量和提高城市生物固体在厌氧消化中向甲烷的转化来最大限度地减少MWWTP的能耗。本项目有三个近期目标：（1）开发一体化生物膜工艺，即在单一反应器中结合短程硝化和厌氧氨氧化的流化床生物反应器;（2）超声波处理高效生物膜厌氧流化床消化器的研制，和（3）调查有助于观察到的食物废物和废水生物固体的共消化的协同效应的基本工艺参数。