Nightsoil treatment plant converted into a sequencing batch reactor to improve removal of pollutants and nutrients

• Published in: Water Science & Technology Vol. 35; no. 1; pp. 233 - 240
• Main Authors: Choi, E., Oa, S.-W., Lee, J.-J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: London Elsevier Ltd 1997; IWA Publishing
• Subjects: Aerobic capacity; Batch reactors; Chemical precipitation; Continuous flow; Denitrification; Energy conservation; Flow system; Fractionation; Hydrogen ions; Hydroxyapatite; Influents; Investment; Mineral nutrients; nightsoil; Nitrification; nitrogen removal; Nutrient flow; Nutrient removal; Nutrients; pH effects; Phosphates; Phosphorus; phosphorus removal; Piping; Pollutant removal; Pollutants; Precipitates; Removal; SBR; Sequencing batch reactor; Sludge; sludge fractionation; Struvite; sludge fractionation; nightsoil; SBR; struvite; Hydroxyapatite; nitrogen removal; phosphorus removal
• ISBN: 0080430937; 9780080430935
• ISSN: 0273-1223; 1996-9732
• DOI: 10.1016/S0273-1223(96)00901-8

An existing 2 stage aerobic nightsoil treatment plant (25m3/d capacity) was converted (modified) from a conventional continuous flow system to a single stage SBR unit for nutrient removal. 10 months study indicated organic and nutrient removal drastically improved. Heat released from decomposition of high strength influent kept liquid temperature above 15 °C for a complete nitrification even during winter period. Nutrient removal efficiencies were found to be greatly affected by pH changes due to denitrification and nitrification. Increased pH due to denitrification stimulated chemical precipitation as struvite and hydroxyapatite. In contrast, decreased pH in aerobic stage due to nitrification dissolved the previously formed precipitates resulting in increase of PO4-P. Sludge fractionation indicated phosphorus was removed about 42 % chemically and about 36 % biologically. Piping changes and timer installations were the major capital investments in this modification, but energy savings were estimated to be about 40 to 53 %. Additional savings in O&M could be expected from the improved effluent quality.