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

Abstract

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.

Keywords:

• Chemiflocculation
• clean water
• microalgae cultivation
• photobioreactor
• raw dairy wastewater

Acknowledgments

The authors are thankful to the Director, Sardar Patel Renewable Energy Research Institute, Gujarat, India, for supporting this research.

Additional information

Funding

The research work is financially supported by Indian Council of Agricultural Research (ICAR), under All India Coordinated Research Project (AICRP) –EAAI program, Govt. of India with Grant Number VVN/RES/DRET-LBT/2018/1 and Department of Biotechnology (DBT), Govt. of India, Project Grant Number BT/PR8991/PBD/26/392/2013.