title: Anaerobic treatment of Hong Kong leachate followed by chemical oxidation.
abstract: Landfill leachate of Hong Kong was first treated by the upflow anaerobic sludge blanket (UASB) process. At 37 degrees C, pH 7.1-8.5 and a HRT of 5.1-6.6 days, the process removed 66-90% of COD in the leachate for loading rates of 1-2.4 g-COD/l day depending on the strength of landfill leachate. The final effluent contained 1440-1910 mg-COD/l and 70-91 mg-BOD/l. About 92.5% of the total COD removed was converted to methane and the rest was converted to biomass with an average net growth yield of 0.053 g-VSS/g-COD-removed. The granules developed in the UASB reactor were 0.5-1.5 mm in size and exhibited good settleability. The UASB effluent was then further polished by two oxidation processes. The UASB-ozonation process removed 93.0% of the 12900 mg/l of COD from the raw leachate. The UASB-Fenton-ozonation process improved the COD removal efficiency to 99.3%. The final effluent had only 85 mg/l of COD and 10 mg/l of BOD5. Ozonation was most effectively conducted at pH 7-8 with the addition of 300 mg/l of H2O2 and for the duration of 30 min. Ozonation also significantly improved the biodegradability of the organic residues. Nearly 50% of these residues could be used as carbon source in denitrification.
authors.affiliation: Centre for Environmental Engineering Research, Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
authors.forename: H H P
authors.initials: HH
authors.lastname: Fang
authors.forename: I W C
authors.initials: IW
authors.lastname: Lau
authors.forename: P
authors.initials: P
authors.lastname: Wang
mesh_terms: D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors; D002244:Carbon / Q000737:chemistry / Q000378:metabolism; D006723:Hong Kong; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry / Q000378:metabolism; D009930:Organic Chemicals / Q000302:isolation & purification / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D010126:Ozone / Q000737:chemistry; D012037:Refuse Disposal / Q000379:methods*; D018508:Water Purification / Q000379:methods*
chemical_list: D009573:Nitrites; D009930:Organic Chemicals; D010126:Ozone; D002244:Carbon; D006861:Hydrogen Peroxide; D008697:Methane; D010100:Oxygen