Comprehensive evaluation of microalgal based dairy effluent treatment process for clean water generation and other value added products.

The current study demonstrates a comprehensive investigation on clean water generation from raw dairy wastewater (RDW) using a robust microalgal strain, Ascochloris sp. ADW007 and its growth, biomass, and lipid productivities in outdoor conditions. Microalgal treatment studies were conducted in column photobioreactor (CPB) and flat-pate photobioreactor (FPB), where the volumetric algal biomass productivity in RDW was significantly increased in both CPB (0.284 ± 0.0017 g/L/d) and FPB (0.292 ± 0.0121 g/L/d) as compared to synthetic mediums viz., BG11 and TAP, respectively, with enhanced lipid content. Maximum lipid accumulation of 33.40% was obtained within 7 d growth. The volumetric and areal lipid productivities in CPB and FPB were 94 mg/L/d and 5.597 g/m2/d, and 98 mg/L/d and 9.754 g/m2/d, respectively. Chemiflocculation, filtration, and centrifugation techniques were employed for harvesting microalgal biomass. Among the flocculants, 0.08% (w/v) FeCl3 harvested >99% of algal cells within 5 min, while 0.03% (w/v) cetyl trimethyl ammonium bromide and 0.125% (w/v) sodium hydroxide harvested >96% of the cells in 30 and 60 min. After microalgal treatment, >80% of clean and odorless water was obtained with reduction in 94-96% of COD, 72-80% of nitrate and 80-97% of total phosphate, respectively. Highlights Utilization of 100% raw dairy wastewater without any treatment. Production of clean and odorless water for recycle and reuse. COD, nitrate and total phosphate reduction by 94-96%, 72-80%, and 80-97% after treatment. Microalgal treatment studies in simple column and flat-plate photobioreactors. Biomass and lipid production as other value added by-products.