UASB Performance and Perspectives in Urban Wastewater Treatment at Sub-Mesophilic Operating Temperature

Abstract

UASBs present several advantages compared to conventional wastewater treatment processes, including relatively low construction cost facilities, low excess sludge production, plain operation and maintenance, energy generation in the form of biogas, robustness in terms of COD removal efficiency, pH stability, and recovery time. Although anaerobic treatment is possible at every temperature, colder climates lead to lower process performance and biogas production. These factors can be critical in determining the applicability and sustainability of this technology for the treatment of urban wastewater at low operating temperature. The purpose of this study is the performance evaluation of a pilot-scale (2.75 m3) UASB reactor for treatment of urban wastewater at sub-mesophilic temperature (25 °C), below the optimal range for the process, as related to biogas production and organic matter removal. The results show that, despite lower methane production and COD removal efficiency compared to operation under ideal conditions, a UASB can still achieve satisfactory performance, and although not sufficient to grant effluent discharge requirements, it may be used as a pretreatment step for carbon removal with some degree of energy recovery. Options for UASB pretreatment applications in municipal WWTPs are discussed.

Use of expanded polystyrene (EPS) as a support media for trickling filters applied to wastewater treatment

“…This decrease is slightly below the values found in the literature and obtained in UASB reactors operated at full scale. There are several full-scale plants already in operation in Colombia, Brazil, Indonesia, India and Egypt and COD removals above 70% have been observed by several authors (Cecconet et al 2022;Lew et al 2003;Kalogo and Verstraete 2000;Chernicharo and Cardoso 1999;Souza and Foresti 1996).…”

Urban Wastewater Mining for Circular Resource Recovery: Approaches and Technology Analysis

“…Since the operating temperature has a primary impact on process kinetics, UASBs were initially applied mostly in tropical countries; however, due to low construction and operating costs, UASB-based sanitation has been adapted to cold and moderate climatic settings upon the proper modification of the operating parameters. At an operating temperature of 25 • C, well below the optimal anaerobic mesophilic range, COD conversion to CH 4 can reach 25-30% [97,98]. The combination of UASB and ASD can further improve process performance at low temperatures [99].…”

Análise da combustão de biometano a partir de resíduos sólidos urbanos para inserção na rede de gás natural

“…Além disso, a inserção de biometano na rede de gás pode diminuir consideravelmente a utilização de combustíveis de origem fóssil. Como consideração, o sucesso do biometano, visto o potencial, assim como o biogás, virá com a disponibilidade do mesmo a custos mais baixos e de diversas maneiras de aproveitamento, além disso, a disseminação das usinas ficará sujeita a melhoria na eficiência do processo, bem como para o surgimento de novas tecnologias de mistura e monitoramento (Cecconet et al, 2022).…”