Post-treatment of effluents from UASB reactor treating industrial wastewater sediment by constructed wetland

Abstract

ABSTRACTThe improvement of water quality parameters by wetland systems is an increasingly global practice. In the present study, the utilization of a treatment method comprising of an upflow anaerobic sludge blanket (UASB) reactor followed by a surface flow (SF) and a vertical flow (VF) wetland (hybrid wetland) in the arrangement has been tested experimentally. Lemna minor was used in wetland units at a planting density about 3 kg wet m−2. The UASB reactor effluents were diluted with tap water to keep the influent chemical oxygen demand (COD) at about 1000 mg L−1 and then fed semi-continuously to lab-scale hybrid wetland system. Removal efficiency ranged from 80 to 93% treatment for COD and biochemical oxygen demand (BOD5), about 92–98% for total phosphorus (TP) treatment and total Kjeldahl nitrogen (TKN), and except Hg (approximately 83%), heavy metal removal was over 90%. Post-treatment of UASB reactor effluents with hybrid wetland provided a high COD, BOD5, TKN, ammonia–nitrogen, TP and phosphate–phosphorus removal and efficiently removed heavy metals (Hg, Cr, Zn, Al, As, Cd, Co, Cu, Pb and Ni). In addition to this, the bioconcentration factor of these heavy metals by the L. minor was also studied in the present study.