Effect of lighting cycles and wastewater concentrations on biomass growth and lipid content of green microalgae in laundry wastewater treatment

Laundry wastewater contains high levels of detergents and nutrients, making it suitable for microalgae cultivation. This study aimed to evaluate green microalgae's potential for treating laundry wastewater by reducing BOD, COD, phosphate, pH, and temperature and analyzing lipid content under varying lighting cycles. Microalgae were cultured in photobioreactors at 100 %, 75 %, and 50 % (v/v) wastewater concentrations with aeration and stirring over 12 days under 24 h, 12 h, no-light, and solar lighting conditions. The results showed the optimal condition at 100 % (v/v) concentration with 24 h lighting, achieving 7.07 g-DW/L biomass and reducing BOD, COD, and phosphate by 99 %, 93 %, and 99.64 %, respectively. Due to stress-induced lipid accumulation, lipid content peaked at 41.66 % under no-light conditions. The microalgae cultivation effectively reduced wastewater temperature by 33 % and met the domestic wastewater quality standards set by the Ministry of Environment and Forestry. This study highlights the dual benefits of pollution control and biodiesel feedstock production, demonstrating scalability and cost-effectiveness for sustainable wastewater treatment and biofuel generation. Further research is recommended to explore economic feasibility and optimize lipid production for industrial applications.