Upflow Anaerobic Sludge Blanket Reactor (UASB) Process Design
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This document discusses the Upflow Anaerobic Sludge Blanket (UASB) reactor process for treating agro-food industrial wastewater. The UASB reactor has several advantages for wastewater treatment including low land demand, few process steps, lower energy requirements, and lower operating costs compared to other processes. However, it also has some limitations such as methane and odor emissions if not designed properly and insufficient pathogen removal without post-treatment. The document then describes agro-food wastewater characteristics and assumptions for UASB reactor sizing calculations to treat this type of wastewater.
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Upflow Anaerobic Sludge Blanket Reactor (UASB) Process Design
- 1. Upflow Anaerobic Sludge Blanket Reactor (UASB) Roja Kompany, Term Project,ENGR546
- 2. Description of the process 2
- 4. Advantages o low land demand (due to superior flocculation and settling properties) o few process steps (sludge and wastewater are treated jointly) o less power requirement for BOD reduction o Less CH4 emissions o low operating cost and maintenance 4
- 5. Limitations o methane and odour emissions (also of end- products) in case of inappropriate plant design or operation o economically not feasible in colder climates with sewage temperature lower than 15°C o insufficient pathogen removal without appropriate post-treatment 5
- 6. Characteristics of agro-food industrial wastewater 6
- 9. 9
- 10. UASB Sizing- Process design calculations 10
- 12. Ref. 1. Bal AS, Dhagat NN.,Upflow anaerobic sludge blanket reactor--a review. Indian J Environ Health. 2001 Apr;43(2):1-82. 2. Rajagopal, R.; Cata Saady NM; Torrijos M.; Thanikal J.V.; Hung Y.T. Sustainable Agro-Food Industrial Wastewater Treatment Using High Rate Anaerobic Process. Water. 2013, 5, 292- 311 3. Koupaie EH - Term Project Report: Design of Sequential anaerobic/aerobic treatment of petrochemical wastewater, University of British Columbia Okanagan,2013 4. Metcalf&Eddy, Wastewater engineering: treatment and resource recovery, Metcalf & Eddy, Inc. 15th. ed,, (2014) 12
- 13. Thank you! 13
Editor's Notes
- I designed an upflow anaerobic sludge blanket (UASB) type digester
- Here, the organic matter in the sewage is subject to anaerobic degradation by the bacteria contained in the sludge blanket, with methanogenic (“methane building”) bacteria producing CH4 during the degradation processes. In order to prevent unwanted sludge discharge, separation devices (deflectors) are installed that prevent the further upward movement of the sludge and force it to sink back into the bed. The gas is collected in gas holders installed in the upper part of the reactor; for gas rising close to the reactor walls.
- UASB reactor is separated in three phases: granules, liquid and gas (left). They can be in three geometrical shapes circular ,rectangular or mixed (right). cylindrical shape is mostly used only for small reactors. But square reactors provide an optimum relation between wall length and treated surface. In other word, they are the most economic rectangular construction model. In a typical UASB unit, no special media is used since the sludge granules themselves act as the 'media' and stay in suspension. So that two main features mainly influencing the treatment performance are -the distribution of the wastewater in the reactor and -the “3-phase-separation”of sludge, gas and water.
- Speaking of the UASB technology in general, they offer a number of advantages and disadvantages in comparison with treatment alternatives such as oxidation pond systems or aerobic processes (e.g. activated sludge). Low land demand because We have lower low degree of mechanisation and few process steps as sludge and wastewater are treated together
- Here, the main parameters of the agro-food industrial wastewater are compared such as total solids (TS), total nitrogen (TN), total phosphorus (TP) and BOD and COD.. These wastewaters vary from low (wash water from sugar mill or dairy effluents) to high strength substrates (cheese, winery and olive mill wastewaters), particularly in terms of organic matter and available nutrients. And I consider it as a reference to choose the sewage values
- So that for this project I have assumed an Agro-Food type wastewater with almost high substrate concentration as the influent, and modified it from other similar sewages to reach the values here.
- These are the assumptions for several design parameters which are determined from previous experimental data.
- The produced biogas consists of approximately 75 percent methane also we determine the Alkalinity or calcium carbonate required to maintain a pH value of 7.
- This is the detail of computations for tank size, HRT, SRT and other parameters. Also the by product, methane, can be utilised as renewable source of energy to generate electricity, which were estimated in kilowatt-hour here, and is roughly enough for a family to have electricity for 4 month.
- All parameters and criteria to efficiently design a UASB were followed and lead to a dimension of the tank here with a volume of 550 cubic meter which is enough to continuously treat this sewage type.