Abstract
Up-flow Anaerobic Sludge Blanket (UASB) reactors are popular tools in wastewater treatment systems due to the ability to work with high feed rates and wastes with high concentration of organic contaminants. While full-scale industrial applications of UASB reactors are developed and described in the available literature, laboratory-scale designs utilized for treatability testing are not well described. The majority of published studies do not describe the laboratory UASB construction details or do use reactors that already had developed a trophic network in microbial consortia under laboratory environment and therefore are more stable. The absence of defined guidelines for geometry design, selection of materials, construction, operation rules, and, especially, the start-up conditions, significantly hamper researchers who desire to conduct treatability testing using UASB reactors in laboratory scale. In this article, we compiled and analyzed the information available in the refereed literature concerning UASB reactors used in laboratory environment, where information on geometry and/or operational conditions were provided in detail. We utilized the information available in the literature and the experience gained in our laboratory (Sustainable Waste to Bioproducts Engineering Center) to suggest a unified operation flowchart and for design, construction, operation, and monitoring for a laboratory-scale UASB reactors.
Highlights
Up-flow Anaerobic Sludge Blanket (UASB) reactor is an anaerobic digester for wastewater treatment, and its operational concept can be described as a vertical up-flow pumping of liquid substrate, including wastewater or growth media, through a layer of anaerobic sludge [1,2,3,4,5,6]
Organic Loading Rate (OLR) and Hydraulic Retention Time (HRT); Recycle ratio of effluent; Regulation of pH; Retention of biomass; and Despite the long history since the invention and description of the UASB concept by Lettinga et al [41] and increasing its application in industry, UASB laboratory scale reactors used for treatability studies are highly variable with regard to terminology, design, construction, and operation processes
While building those tables we focused on the geometry of the reactor and operational conditions including substrate strength expressed as Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), etc.; loading rates; volume of reactor; and effluent recycling rates
Summary
Up-flow Anaerobic Sludge Blanket (UASB) reactor is an anaerobic digester for wastewater treatment, and its operational concept can be described as a vertical up-flow pumping of liquid substrate, including wastewater or growth media, through a layer of anaerobic sludge [1,2,3,4,5,6]. Distributed in normal cross-section of the reactor, the substrate is pushed through the sludge layer (called a “digestion zone”) creating a vertical up-flow This process is concurrent with the decomposition of organic compounds of substrate and a formation of gaseous products. Despite the long history since the invention and description of the UASB concept by Lettinga et al [41] and increasing its application in industry, UASB laboratory scale reactors used for treatability studies are highly variable with regard to terminology, design, construction, and operation processes This lack of uniformity leads to different results regarding water quality indicators, for example, Chemical Oxygen Demand (COD), as well as bioenergy production, for example for biomethane and biohydrogen. These lack of uniformity with laboratory scale UASB reactors is addressed in this study and guidelines are provided for increasing the uniformity so that results are comparable across different laboratories and are more meaningful for scale up applications of the UASB reactor process
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