title: Hydrolysis of return sludge for production of easily biodegradable carbon: effect of pre-treatment, sludge age and temperature.
abstract: Return sludge from two Swedish and two Danish wastewater treatment plants were hydrolysed in laboratory reactors. Treatment plants with/without pre-sedimentation and with/without nitrification were represented. Soluble organic matter was produced from all types of sludge, but the yield was to a large extent dependent on what type of sludge was hydrolysed. Activated sludge from wastewater treatment plants without pre-treatment returned more soluble carbon after hydrolysis than sludge from treatment plants with pre-sedimentation. In addition, more soluble carbon was formed from non-nitrifying activated sludge than from nitrifying sludge. Moreover, the maximum yield of soluble COD at 10 degrees C was less than the yield at 20 degrees C. The initial hydrolysis rate was found to be between 0.35 and 1.8 mg soluble COD/(g VS x h). With the exception of one case, between 15 and 50% of the produced soluble COD was shown to be volatile fatty acids, a suitable carbon source for biological phosphorus removal. Nitrification rate measurements indicated that the viability of the activated sludge was not affected by the hydrolysis.
authors.affiliation: Water and Environmental Engineering, Department of Chemical Engineering, Lund Institute of Technology, P.O. Box 124, SE-221 00 Lund, Sweden. karin.jonsson@vateknik.lth.se
authors.forename: K
authors.initials: K
authors.lastname: Jönsson
authors.forename: J la C
authors.initials: Jl
authors.lastname: Jansen
mesh_terms: D000641:Ammonia / Q000032:analysis; D003718:Denmark; D006868:Hydrolysis; D009930:Organic Chemicals / Q000737:chemistry*; D010710:Phosphates / Q000032:analysis; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology*; D012995:Solubility; D013548:Sweden; D013696:Temperature; D013997:Time Factors; D018508:Water Purification / Q000379:methods*
chemical_list: D009930:Organic Chemicals; D010710:Phosphates; D012722:Sewage; D000641:Ammonia