Combined UASB-MBR system for the treatment of low-strength wastewater at ambient temperatures

Abstract

Over the last 30–40 years, increasingly stringent environmental legislation relating to freshwater conservation and pollution reduction has driven technological development in the water sector. On the other hand, the rising consideration of wastewater treatment as non-negligible greenhouse gas (GHG) sources, have become a highly important issue. This, along with various governmental, institutional and organisational incentive, has encouraged problem holders to consider the application of more sophisticated technologies. Anaerobic wastewater treatment process is well over 100 years old. It is a natural process in which a variety of different species from two entirely different biological kingdoms, the Bacteria and the Archaea, work together to convert organic wastes through a variety of intermediates into methane gas, an excellent source of energy. Apart from the significant reduction of organic matter content, pathogenic microorganisms are also eliminated. Additionally, the amount of excess sludge produced and nutrient requirements are far less than with aerobic treatment. However, although methane is a good renewable energy source, it is also a powerful greenhouse gas, and special attention should be paid especially if wastewater is treated at ambient temperatures.