UASB (Upflow Anaerobic Sludge Blanket) process – What is it? Pros and cons? 

UASB  is the process where the organic matters in the waste are degraded by methanogens to produce biogas. The specialty of this process is that the microbes aggregate and form granules. This process was invented in the 1980s by Prof. Lettinga.  Papop has contributed to the early development of this process by commercialize this process 25 years ago in Thailand. 

Afterwards, it has been developed until presently. The process is widely adopted and accepted in Thailand for the past 20 years as a proven technology for wastewater treatment. UASB reactor is characterized by bottom feed influent and effluent flow at the top. The granular sludge are formed by the adhesion of cocci and Spirillum bacteria which strengthen the granule. When the granule becomes very large, it is much larger and heavier than the floc in activated sludge. Hence, it can settle very well and fast in the wastewater. 

The design of the UASB reactor is critical as the flow rate has to be sufficiently high to bring food or organic matter to the inner part of the granule simultaneously expanding the sludge blanket, but not too high to wash out those granules from the reactor. 

Gas-Liquid-Solid Separator (GSS) or 3 Phase Separator has be installed at the top of the reactor to separate biogas, granular sludge and wastewater. It allows the granular sludge to safely fall back into the reactor, and the treated effluent to flow out over the weir at the top. 

The benefits of UASB process are highest COD removal efficiency up to 90%; methane content in the biogas up to 70%; simple operation and maintenance; high process stability; smaller foot print than the typical anaerobic lagoon; and sellable granular sludge. 

The limitations of UASB are as follows: require medium skilled operator who understand biological process; require frequent monitoring of wastewater parameters in the process; low Suspended Solids (SS) in the influent; require careful design of the distribution at the bottom to prevent clogging and simple maintenance particularly for wastewater with high SS and TDS. 

 

Source: Costa, A; Ely, C; Pennington, M.; Rock, S.; Staniec, C. and Turgeon, J.  2015. Anaerobic Digestion and its Application. United States Environmental Protection Agency Office of Research and Development. Cincinnati. 

 

Papop, led by Mr. Likit Nimtrakul and Dr. Seni Kanjanawong, has conducted research and development on the UASB process for the past 25 years. We still continue to improve and innovate to address all your waste issues. 

Papop is the leading green tech company in Thailand. If you are interested in cost saving, waste treatment or mitigating climate change through the use of renewable energy, please contact us at info@papop.com  l  LINE: @papop l Call: +66 2 570 5580.