Performance of horizontal subsurface flow constructed wetland integrated with floating wetland and anaerobic baffled reactor in treating seed production wastewater

Abstract

Discharge of untreated or partially treated industrial wastewater is the major contributor to aquatic environmental pollution. Seed producing industrial wastewater is composed of high organic matter, nutrient, and suspended solids. Discharging inadequately treated seed production wastewater can cause severe environmental pollution because of high nutrients and organic matter in the wastewater. The performance of integrated wastewater treatment system composed of anaerobic baffled reactor (ABR), horizontal subsurface flow constructed wetland (HSSFCW), and floating constructed wetland (FCW) for removal of pollutants from seed production industrial wastewater was studied. In HSSFCW, Cyperus alternifolius were planted with four rhizomes in each square meter, and the FCW had four floating mats made from polyethylene foam planted with Vetiver grass. The wetlands were continuously fed from ABR receiving 25 m 3 /day wastewater from wastewater reservoir. The raw wastewater average organic loading rate was 0.208 kg COD/day. Wastewater samples from the inlet and outlet of each treatment unit were collected twice a week for three months. The performance of the system in removal of biochemical oxygen demand (BOD 5 ), chemical oxygen demand (COD), total suspended solids (TSS), turbidity, nitrate, phosphate, and ammonium were studied. The results showed that the system achieved an average removal efficiency of 95.52%, 94.57%, 86.23%, 76.56%, 82.35%, 76%, and 32.91% for BOD 5 , COD, TSS, turbidity, nitrate, phosphate, and ammonium respectively. Based on the results obtained the integrated system composed of ABR, HSSFCW, and FCW is a promising low-cost technology for treating wastewater from seed producing industries, and the treated wastewater can be used for irrigation.