Poultry litter extract as solid waste supplement for enhanced microalgal biomass production and wastewater treatment

Wastewater and livestock waste can be used as a cheap source of nutrients for microalgae growth. In this work, a cocktail waste medium (CWM) was developed using 75% Chhalera municipal wastewater (C-MWW), 25% Parag dairy wastewater (P-DWW), and 15 g L^-1 of poultry litter extract (PLE-15) for low-cost cultivation of Chlorella sp. BRE4. The highest specific growth rate of 0.57 day^-1 and biomass productivity of 315 mg L^-1 day^-1 was found in CWM. Microalgae grown in the photobioreactor with the strategic supply of PLE (PBR-4) resulted in the highest lipid productivity of 113.5 mg L^-1 day^-1, which was 1.3 and 5.4 times of PBR-3 (PLE supplemented since day 1) and PBR-1 (no additional PLE), respectively. The carbohydrate content (30.45%) in PBR-4 showed a 1.33-fold increase than PBR-1, confirming the suitability of the strategy for enhancing carbohydrates and lipids simultaneously. The high removal percentage of total nitrogen (92.6%) and phosphorus (97.4%) from CWM under strategic supply conditions demonstrated Chlorella sp. BRE4 is a suitable candidate for waste valorization and biofuel production.