title: Sludge reduction with Tubificidae and the impact on the performance of the wastewater treatment process.
abstract: To reduce excess sludge, a Tubificidae reactor was combined with an integrated oxidation ditch with vertical circle (IODVC), and a new integrated system was developed for wastewater treatment. A pilot-scale of this integrated system was tested to investigate the sludge reduction with Tubificidae and the impact on effluent quality and sludge production. The dominant worm was Branchnria Sowerbyi in the Tubificidae reactor after inoculation of Branchnria Sowerbyi and Limnodrilns sp., and the maximal volume density of wet Tubificidae in vessels of the Tubificidae reactor was 17600 g/m3. Two operational modes, treating the excess sludge (first mode) and the returned sludge (second mode) of IODVC by the Tubificidae reactor, were used in this experiment. The results showed that the excess sludge reduction rate was 46.4% in the first mode, and the average sludge yield of the integrated system was 6.19 x 10(-5) kg SS/kg COD in the second mode. Though the sludge returned to IODVC via the Tubificidae reactor, it had little impact on the effluent quality and the sludge characteristics of the IODVC. No new type of recalcitrant substance in the supernatant was discharged into the environment when the sludge was treated by Tubificidae. The experimental results also indicated that no significant changes occurred on the viscosity, specific resistance, and the floc size distribution of the sludge.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. gxs0122@126.com
authors.forename: Xue-Song
authors.initials: XS
authors.lastname: Guo
authors.forename: Jun-Xin
authors.initials: JX
authors.lastname: Liu
authors.forename: Yuan-Song
authors.initials: YS
authors.lastname: Wei
authors.forename: Lin
authors.initials: L
authors.lastname: Li
mesh_terms: D000818:Animals; D019149:Bioreactors; D009835:Oligochaeta / Q000502:physiology*; D010316:Particle Size; D012722:Sewage; D014783:Viscosity; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D012722:Sewage