Improving performance and operational control of UASB reactors via proper sludge and scum discharge routines

This study aimed to evaluate the impact of implementing routines of sludge and scum withdrawal in full-scale Upflow Anaerobic Sludge Blanket (UASB) reactors on the operational control and on the improvement of final effluent quality. The work was developed at Laboreaux STP (Population Equivalent = 70,000 inhabitants), located in the city of Itabira, in the state of Minas Gerais – Brazil. Two operating conditions were tested for hydrostatic scum removal, varying the pressure in the gas line and the height of the scum layer within the three phase separator. The effective removal of scum was only achieved in the three phase separators located near to the discharge line, indicating the necessity for improvements in the discharge system. Applying the concepts of minimum and maximum sludge mass in the UASB reactors at Laboreaux STP resulted in a dramatic improvement in the effluent quality of the reactors. In the periods when the reactor operated with quantities of biomass below the maximum established limit (10,000 kgST), the average concentrations of TSS, BOD and COD were below 109, 44 and 153 mg L−1, respectively.

[1]  G. Zeeman,et al.  The effect of operational conditions on the hydrodynamic characteristics of the sludge bed in UASB reactors. , 2011, Water science and technology : a journal of the International Association on Water Pollution Research.

[2]  C. L. Souza,et al.  Production and characterization of scum and its role in odour control in UASB reactors treating domestic wastewater. , 2006, Water science and technology : a journal of the International Association on Water Pollution Research.

[3]  C A L Chernicharo,et al.  Feasibility of UASB/trickling filter systems without final clarifiers for the treatment of domestic wastewater in small communities in Brazil. , 2011, Water science and technology : a journal of the International Association on Water Pollution Research.

[4]  L C S Lobato,et al.  Experience with the design and start up of two full-scale UASB plants in Brazil: enhancements and drawbacks. , 2009, Water science and technology : a journal of the International Association on Water Pollution Research.

[5]  Hideki Harada,et al.  Prospects for a self-sustainable sewage treatment system: a case study on full-scale UASB system in India's Yamuna River Basin. , 2006, Journal of environmental management.

[6]  G Lettinga,et al.  Effect of SRT and temperature on biological conversions and the related scum-forming potential. , 2005, Water research.

[7]  C A L Chernicharo,et al.  Control of scum accumulation in a double stage biogas collection (DSBC) UASB reactor treating domestic wastewater. , 2009, Water science and technology : a journal of the International Association on Water Pollution Research.

[8]  Gatze Lettinga,et al.  UASB Process design for various types of wastewaters. , 1991 .