title: Improvement of activated sludge dewaterability by humus soil induced bioflocculation.
abstract: Effects of humus soil particles on the dewaterability of activated sludge were investigated. Cations leaching increased proportionally with the dosage of humus soil, and the leaching was not significant after 2 h. Divalent cations, Ca2+ and Mg2+, leaching from the humus soil played an important role in improving dewaterability of the biological sludge. On the contrary, dewaterability was not affected or slightly deteriorated by the monovalent cations, K+ and Na+ leached from the humus soil. Improvement in dewaterability of the sludge by addition of humus soil was higher than that of equivalent cations mixture. It seemed that the decrease of supracolloidal bio-particles (1 to 100 microm in diameter) resulted in diminishing of the blinding effect on cake and filter medium. SRF (specific resistance to filtration) of the humus soil added sludge varied in parallel with the M/D (monovalent to divalent cation) ratio, and the M/D ratio could be utilized as a useful tool for evaluation of the sludge dewatering characteristics. Long-term effects of humus soil on the improvement of activated sludge dewaterability were clearly identified by continuous operation results of a bench-scale MLE (Modified Ludzack Ettinger) system combined with a humus soil contactor. On the other hand, dewaterability of the control sludge was only slightly improved by a decrease in M/D ratio of the wastewater influent.
authors.affiliation: Department of Civil and Environmental Engineering, Sungkyunkwan University, Suwon, Kyunggi-Do, Korea.
authors.forename: Young-Gyun
authors.initials: YG
authors.lastname: Choi
authors.forename: Seong-Hong
authors.initials: SH
authors.lastname: Kim
authors.forename: Hee-Jun
authors.initials: HJ
authors.lastname: Kim
authors.forename: Gyu Dong
authors.initials: GD
authors.lastname: Kim
authors.forename: Tai-Hak
authors.initials: TH
authors.lastname: Chung
mesh_terms: D019149:Bioreactors; D002412:Cations / Q000737:chemistry; D005374:Filtration; D005427:Flocculation; D006812:Humic Substances; D010316:Particle Size; D012722:Sewage / Q000737:chemistry*; D012987:Soil; D014867:Water; D018508:Water Purification / Q000379:methods*
chemical_list: D002412:Cations; D006812:Humic Substances; D012722:Sewage; D012987:Soil; D014867:Water