title: Sewage treatment in integrated system of UASB reactor and duckweed pond and reuse for aquaculture.
abstract: The performance of a laboratory-scale upflow anaerobic sludge blanket (UASB) reactor and a duckweed pond containing Lemna gibba was investigated for suitability for treating effluent for use in aquaculture. While treating low-strength sewage having a chemical oxygen demand (COD) of typically less than 200 mg/L, with an increase in hydraulic retention time (HRT) from 10.04 to 33.49 h, COD removal efficiency of the UASB reactor decreased owing to a decrease in organic loading rate (OLR) causing poor mixing in the reactor. However, even at the lower OLR (0.475 kg COD/(m3 x d)), the UASB reactor gave a removal efficiency of 68% for COD and 74% for biochemical oxygen demand (BOD). The maximum COD, BOD, ammonia-nitrogen and phosphate removal efficiencies of the duckweed pond were 40.77%, 38.01%, 61.87% and 88.57%, respectively. Decreasing the OLR by increasing the HRT resulted in an increase in efficiency of the duckweed pond for removal of ammonia-nitrogen and phosphate. The OLR of 0.005 kg COD/(m2 x d) and HRT of 108 h in the duckweed pond satisfied aquaculture quality requirements. A specific growth rate of 0.23% was observed for tilapia fish fed with duckweed harvested from the duckweed pond. The economic analysis proved that it was beneficial to use the integrated system of a UASB reactor and a duckweed pond for treatment of sewage.
authors.affiliation: Department of Agriculture and Food Engineering, Indian Institute of Technology (IIT), Kharagpur, India 721 302.
authors.forename: D P
authors.initials: DP
authors.lastname: Mohapatra
authors.forename: M M
authors.initials: MM
authors.lastname: Ghangrekar
authors.forename: A
authors.initials: A
authors.lastname: Mitra
authors.forename: S K
authors.initials: SK
authors.lastname: Brar
mesh_terms: D000818:Animals; D017756:Aquaculture / Q000191:economics; D001673:Biodegradation, Environmental; D056804:Biofuels / Q000032:analysis; D018533:Biomass; D019149:Bioreactors; D005240:Feasibility Studies; D019684:Magnoliopsida / Q000378:metabolism*; D008697:Methane / Q000032:analysis; D061005:Ponds; D012722:Sewage / Q000032:analysis; D017210:Tilapia / Q000254:growth & development*; D014867:Water / Q000032:analysis
chemical_list: D056804:Biofuels; D012722:Sewage; D014867:Water; D008697:Methane