Effect of low temperature on the performance of UASB reactor for municipal wastewater treatment: recent advances and future perspectives

Abstract

Upflow anaerobic sludge blanket (UASB) reactor is a widely used anaerobic treatment technology, which is essential in municipal sewage treatment, in tropical and subtropical areas. However, UASB reactors have been underutilized in low-temperate zones due to the poor performance of UASB reactors under psychrophilic conditions. This study has three primary purposes: to review the performance of UASB reactors with different parameters, to describe the limiting factors at low temperatures, and to prospect the future solutions. In the low-temperature environment, lower COD removal efficiency and production of methane in the UASB reactor have been observed in various studies. The key limiting factors are increased dissolved methane, decreased activity of methanogens and hydrolytic bacteria. This article proposed that five technologies could reduce the impact of low temperature on the treatment of municipal wastewater by the UASB reactor, which are denitrifying anaerobic methane oxidation (DAMO), direct interspecies electron transfer (DIET), bio-electrochemical systems (BES), pre-hydrolysis, and degassing membrane (DM). These technologies are promising to be developed into highly-efficient engineering strategies for treating municipal wastewater in the UASB reactor at low temperatures in the future.