Domestic wastewater treatment by constructed wetland and microalgal treatment system for the production of value-added products

Abstract

ABSTRACT The main aim of this study is to treat domestic wastewater in a hybrid Vertical Flow Constructed Wetland (VFCW-4.2 m2) and Microalgal Treatment System (MTS-1 m2). The objective is not only to treat Domestic wastewater (DW) but also to produce value-added products from microalgal biomass. The domestic wastewater was initially treated by VFCW and the VFCW effluent was further phycoremediated by MTS. Canna indica was used for wetland vegetation and resident microalgal consortium from VFCW effluent was used in MTS. The VFCW and MTS was operated at 1 m3/day (HRT-0.25 m3/m2-day, OLR-400 g/m2-day) and 0.03 m3/day (HRT-0.03 m3/m2-day, OLR-400 g/m2-day), respectively. The integrated system was observed to remove 68.9% COD, 77.4% NH4-N, 75.8% TKN and 63.6% PO4-P. The harvested Naive Biomass (NB) was observed to contain 16.7% of lipids (W/W). The Residual Biomass after Lipid Extraction (RBLE) was used as a substrate for ethanol production. The observed yield of ethanol using RBLE as a substrate was 33.4%. NB, RBLE, and Residual Biomass after Lipid and Sugar Extraction (RBLSE) indicated net biomethane yield (mL/g VS) of 211.8, 134.6 and 107.7, respectively. The present study demonstrated an initial attempt of demonstrating a hybrid wastewater treatment system for the production of value-added products in terms of biofuel.