Understanding fundamental process mechanics of volatile fatty acid production in fermentation of primary sludge

自然水系统的富营养化是一个主要的地表水质量问题，可能是由于营养物如磷和氮的过量供应造成的，这些营养物支持藻类和水生植物的增殖。加拿大各地的政府正在努力寻找最具成本效益的立法限制城市污水处理废水中的营养物质，以管理接收沃茨的负荷。阿尔伯塔省政府目前正在对卡尔加里市（TMDL）实施每日最大总负荷限制。浓度限度不再适用，已实施额外的TMDL限度。这有效地限制了卡尔加里市运营的污水处理厂向弓河排放的总磷（TP）为240公斤/天。为了使城市根据历史和预测的人口增长率进行扩张，TP的浓度必须降低。虽然生物强化除磷（BEPR）工艺已被证明是一种有效的处理替代方案，但其固有的生物性质导致工艺效率和后续出水水质的变化。严格的污水质量标准的要求突出了需要更好的过程控制和优化，以实现更一致和有效的处理水平。在BEPH设施的设计中纳入初级污泥发酵器的重要性已经得到了明确的证明，特别是在具有温和气候和有机弱废水的地区，其中必须满足低于1 mg/L的严格的流出物磷标准。该单元工艺将初沉污泥中的复杂有机物质发酵成简单的含碳化合物，其中最重要的是挥发性脂肪酸（VFA）。初级污泥发酵罐VFA生产的优化是废水处理中一个相对较新的概念。该研究计划的主要目标是优化Bonnybrook全规模发酵罐系统的VFA生产。本研究计划的长期目标是首先阐明微生物在发酵初沉污泥中所采用的生化途径，并利用这一机制信息来克服其代谢系统所施加的限制，以抑制VFA的产生。这些新策略的开发将用于在全规模系统中改进和测试功效。这项研究不仅将改善和提高除磷工艺的功能性，而且还将提高可靠性，以确保不违反卡尔加里市批准运营污水处理厂的条件。

The eutrophication of natural water systems represents a major surface water quality problem and can result from an excess supply of nutrients such as phosphorus and nitrogen which support the proliferation of algae and aquatic plants. Municipalities across Canada are struggling with finding the most cost effective legislated limits for nutrients in municipal wastewater treatment effluents to manage loadings to receiving waters. The provincial government in Alberta is now enforcing Total Daily Maximum loadings limits for the City of Calgary (TMDL). The concentration limits are no longer suitable and additional TMDL limits have been implemented. This effectively limits the Wastewater treatment plants operated by the City of Calgary to 240 kg/d of Total Phosphorus (TP) discharged into the Bow river. In order for the City to expand based on historical and projected population growth rates, the concentrations of TP has to decrease in their effluents. Although Biologically Enhanced Phosphorus Removal (BEPR) processes have proven to be an effective treatment alternative, their inherent biological nature causes variability in process efficiency and subsequent effluent quality. The demands of stringent effluent quality criteria highlight the need for better process control and optimization to achieve a more consistent and effective level of treatment. The importance of incorporating primary sludge fermenters in the design of BEPH facilities has clearly been demonstrated, particularly in areas with temperate climates with organically weak wastewaters in which stringent effluent phosphorus standards, of below 1 mg/L, must be met. This unit process ferments the complex organic material found in primary sludge to simple carbonaceous compounds, the most important of which are Volatile Fatty Acids (VFA). Optimization of primary sludge fermenter VFA production is a relatively new concept in wastewater treatment. The main objective of this research program is to optimize the production of VFA from the Bonnybrook full scale fermenter systems. The long term objective of this research program is to first elucidate the biochemical pathways employed by microorganisms in fermenting primary sludge and to use this mechanistic information to overcome the limitations imposed by their metabolic systems to inhibit the production of VFA. The development of these new strategies will be used to improve and test the efficacy in a full scale system. This research would not only improve and enhance both the functional nature of the phosphorus removal process but also the reliability to ensure there are no violations of the conditions set out in the City of Calgary’s approval to operate wastewater treatment works.