Valorization of abattoir water discharge through phycoremediation for enhanced biomass and biodiesel production

Abstract

Phycoremediation has been discussed as a multipurpose strategy to refine various waste streams for sustainable algal biomass, value-added compounds, and biodiesel production. While phycoremediation has been explored for various wastewaters, there is still a research gap in systematical understanding the impact of abattoir water discharge (AWD) on both algal growth and biodiesel quality. The present study evaluated the potential of Chlorella sorokiniana to grow at different ratios of AWD, 30–90 %, v/v with conventional growth medium. Results showed that nutrient removal efficiency after 12 days of cultivation reached up to 85 % for total nitrogen, 78 % for total phosphorus, 70 % for potassium, and 65 % for sodium. Thus, all algae-treated AWD samples showed Kelly ratio (KR) values less than 1, confirming their suitability for direct application in soil irrigation. In addition, there were insignificant variations in algal growth and biomass yield across all treatments. Interestingly, carotenoids yield showed significant increase in all AWD ratios, with the highest recorded value of 0.750 mg L −1 at day 12 using 90 % AWD, compared to 0.523 mg L −1 in the control. Among various treatments, C. sorokiniana grown in 90 % AWD exhibited the highest lipid content of 201.6 mg g −1 algal dw (comparing to 180.6 mg g −1 dw in the control). The biodiesel derived from C. sorokiniana at different AWD ratios demonstrated promising characteristics due to enhancement of saturated fatty acids proportion, which resulted in lower iodine value, longer oxidation stability, and higher cetane number than the control. • Abattoir water discharge (AWD) was evaluated as a growth medium for microalgae. • Nutrient removal reached 85 % TN, 78 % TP, 70 % K, and 65 % Na within 12 days. • Carotenoid yield increased up to 44 % and lipid content increased by 11 % in AWD. • Superior lipid profiles in 90 % AWD led to enhanced biodiesel characteristics. • Biodiesel quality improved due to higher saturated fatty acids using AWD.