Up-Flow Anaerobic Sludge Blanket (UASB) Technology for Energy Recovery: A Review on State-of-the-Art and Recent Technological Advances

Abstract

Up-flow anaerobic sludge blanket (UASB) reactor belongs to high-rate systems, able to perform anaerobic reaction at reduced hydraulic retention time, if compared to traditional digesters. In this review, the most recent advances in UASB reactor applications are critically summarized and discussed, with outline on the most critical aspects for further possible future developments. Beside traditional anaerobic treatment of soluble and biodegradable substrates, research is actually focusing on the treatment of refractory and slowly degradable matrices, thanks to an improved understanding of microbial community composition and reactor hydrodynamics, together with utilization of powerful modeling tools. Innovative approaches include the use of UASB reactor for nitrogen removal, as well as for hydrogen and volatile fatty acid production. Co-digestion of complementary substrates available in the same territory is being extensively studied to increase biogas yield and provide smooth continuous operations in a circular economy perspective. Particular importance is being given to decentralized treatment, able to provide electricity and heat to local users with possible integration with other renewable energies. Proper pre-treatment application increases biogas yield, while a successive post-treatment is needed to meet required effluent standards, also from a toxicological perspective. An increased full-scale application of UASB technology is desirable to achieve circular economy and sustainability scopes, with efficient biogas exploitation, fulfilling renewable energy targets and green-house gases emission reduction, in particular in tropical countries, where limited reactor heating is required.

Demand-Response Application in Wastewater Treatment Plants Using Compressed Air Storage System: A Modelling Approach

“…AD has been largely recognized as a significant source of renewable energy from different organic sources, able to provide fully renewable biogas, that has a high potential energy value [36]. Traditionally, AD was known to be beneficial in large-scale WWTPs, where a sufficient amount of sludge is available to continuously feed the digester, avoiding discontinuous operations throughout the year [39].…”

“…Air (k air ) and soil (k soil ) heat transfer coefficients were taken from [34]. The digester operating temperature, t dig , was set at 35 • C (optimum mesophilic range [36]), while the mean influent sludge temperature, t s0 , was supposed to be 15 • C, consistently with regional climate data [35]. The geometrical characteristics of the digester (base area, A base , (m 2 ), and lateral area, A sup , (m 2 )) were calculated considering the real characteristics of the analyzed full-scale reactor.…”

Up Flow Anaerobic Sludge Blanket (UASB) In The Paper Industry

“…According to the Dictionary of Food Science and Technology, UASB is an anaerobic processing reactor by micro organisms that form suspended flocks at the bottom of the reactor. UASB process compared to aerobic processes, needs lower energy, is efficient at higher loads, requires less nutrients, and produce less sludge [11].…”

“…The formation of granular sludge that has good deposition ability at the reactor and shows a low Sludge Volume Index (SVI) are the main key to the success of the UASB reactor [11]. The UASB reactor is shown in the figure below.…”

“…Biogas formed from anaerobic metabolism will go up and cause the vertical stirring process in the reactor. Biogas helps mixture and contact between sludge and liquid waste, and the three phase separator located above is used to separate biogas, liquid waste and sludge [11].…”