Improving solids retention in upflow anaerobic sludge blanket reactors at low temperatures using lamella settlers

Lamella settlers were used to increase sludge concentration in pilot scale UASB reactors treating concentrated sewage at low temperature. The aim was to increase sludge retention time (SRT) and achieve better digestion in UASB reactors without the need for increasing the hydraulic retention time (HRT). Two modified UASB reactors were used for this purpose. In the first reactor, lamella settlers were installed in the settling zone of the UASB reactor and the reactor was named UASB-ESR1. In the second reactor, lamella settlers were installed underneath the gas liquid separator (GLS) and the reactor was named UASB-ESR2. The sludge concentration, sludge profile, and system performance of each reactor were monitored. The obtained sludge concentrations were 50 and 53 g TS/l for UASB-ESR1 and UASB-ESR2, respectively. The measured concentrations were almost double the concentrations reported for conventional UASB reactors ranging 16–26 g TS/l. The calculated SRT in the modified UASB reactors was 103 days in both reactors. The average total COD (COD tot ) and suspended COD (COD ss ) removal efficiencies were 38% and 60%, respectively for the UASB-ESR1. The average COD tot and COD ss removal efficiencies for the UASB-ESR2 were 41% and 62%, respectively. The modified reactors were considered at the startup period and the performances of the modified systems are expected to significantly improve when arriving at steady state conditions.

[1]  Nidal Mahmoud,et al.  Community onsite treatment of cold strong sewage in a UASB-septic tank. , 2009, Bioresource technology.

[2]  J. A. Álvarez,et al.  Start-up alternatives and performance of an UASB pilot plant treating diluted municipal wastewater at low temperature. , 2006, Bioresource technology.

[3]  S. C. Oliveira,et al.  Comparative performance evaluation of full-scale anaerobic and aerobic wastewater treatment processes in Brazil. , 2009, Water science and technology : a journal of the International Association on Water Pollution Research.

[4]  L. Borzacconi,et al.  Integrated anaerobic treatment of dairy industrial wastewater and sludge. , 2009, Water science and technology : a journal of the International Association on Water Pollution Research.

[5]  Gatze Lettinga,et al.  Granulation in UASB-reactors , 1983 .

[6]  Baozhen Wang,et al.  Performance of an anaerobic baffled reactor (ABR) as a hydrolysis-acidogenesis unit in treating landfill leachate mixed with municipal sewage , 2000 .

[7]  Grietje Zeeman,et al.  Effect of temperature on anaerobic treatment of black water in UASB-septic tank systems. , 2007, Bioresource technology.

[8]  P. Chudoba,et al.  A three-stage biofiltration process: performances of a pilot plant , 1998 .

[9]  D. Biau,et al.  Stormwater and lamella settlers: Efficiency and reality , 1999 .

[10]  Grietje Zeeman,et al.  Treatment of domestic sewage in a two-step anaerobic filter/anaerobic hybrid system at low temperature. , 2002, Water research.

[11]  C.P.L. Grady,et al.  Anaerobic treatment of domestic wastewater , 1986 .

[12]  Hideki Harada,et al.  Economic evaluation of sewage treatment processes in India. , 2007, Journal of environmental management.

[13]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .

[14]  Awwa,et al.  Standard Methods for the examination of water and wastewater , 1999 .

[15]  Qaisar Mahmood,et al.  Anaerobic domestic wastewater treatment with bamboo carrier anaerobic baffled reactor , 2008 .

[16]  Grietje Zeeman,et al.  The role of anaerobic digestion of domestic sewage in closing the water and nutrient cycle at community level , 1999 .

[17]  M. Fayyad,et al.  Anaerobic filter for polishing effluent of UASB reactor treating strong sewage at 23 8 C , 2009 .

[18]  L Florencio,et al.  Domestic sewage treatment in full-scale UASBB plant at Mangueira, Recife, Pernambuco. , 2001, Water science and technology : a journal of the International Association on Water Pollution Research.

[19]  Delia Teresa Sponza,et al.  Effect of increasing nitrobenzene loading rates on the performance of anaerobic migrating blanket reactor and sequential anaerobic migrating blanket reactor/completely stirred tank reactor system. , 2009, Journal of hazardous materials.

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

[21]  J. Wood,et al.  Using CFD Modeling to Improve the Inlet Hydraulics and Performance of a Storm-Water Clarifier , 2008 .

[22]  George Tchobanoglous,et al.  Small and decentralized wastewater management systems , 1998 .

[23]  G Zeeman,et al.  Potential of anaerobic digestion of complex waste(water). , 2001, Water science and technology : a journal of the International Association on Water Pollution Research.

[24]  S. Zeghal,et al.  Process control for nutrients removal using lamella sedimentation and floating media filtration , 1998 .

[25]  G Lettinga,et al.  Treatment of strong domestic sewage in a 96 m3 UASB reactor operated at ambient temperatures: two-stage versus single-stage reactor. , 2005, Bioresource technology.

[26]  W. Wiegant Experiences and potential of anaerobic wastewater treatment in tropical regions. , 2001, Water science and technology : a journal of the International Association on Water Pollution Research.

[27]  J. A. Álvarez,et al.  Anaerobic treatment of low-strength municipal wastewater by a two-stage pilot plant under psychrophilic conditions. , 2008, Bioresource technology.

[28]  O. Lekang,et al.  Biological lamella sedimentation used for wastewater treatment , 2001 .

[29]  T. Viraraghavan,et al.  Low-strength wastewater treatment by a UASB reactor , 1996 .