Paddy-soaked rice mill wastewater treatment by phycoremediation and feasibility study on use of algal biomass as biofertilizer

BACKGROUND: Sustainable wastewater management mostly implicates treatment cost, viability, and performance of an appropriate system, in addition to reuse and recycling, to meet the present social needs. In the current study, algal technology was coupled with paddy-soaked rice mill wastewater (PSRMW) treatment to enhance the efficient treatment and economic feasibility of algal-based eco-friendly products. Initially, the selected microalgae,Chlorella pyrenoidosa, were cultured in raceway ponds using PSRMW as a growth medium. Then, the harvested live algal biomass was carried forward to subsequent study, after primary seedling experiments of Indian okra (Abelmoschus angulosus), which involves soil amendment treatment samples T1 (control soil - no amendment), T2 (soil + live algal biomass), and T3 (soil + chemical fertilizer). RESULTS: The maximum ammoniacal nitrogen (NH3-N) and phosphate (PO4-P) removal of similar to 70% (average yield coefficient (Y-N): 5.78 mg biomass mg(-1) of N) and similar to 65% (Y-P: 14.13) were obtained from the phycoremediation experiments. The biochemical composition such as lipid, protein, and carbohydrate contents of harvested biomass were recorded as similar to 35%, similar to 30%, and similar to 9%, respectively. From the biofertilizer experiments, the maximum absolute growth rate (AGR) of 0.40 day(-1) was obtained in T2 plants with better growth characteristics of chlorophyll, fresh and dry shoot, root weights (which were similar to 30% more than that of T3), and control soil (T1) does not exhibit the plant growth as the soil was low in nutrients. CONCLUSION: The present study revealed the phycoremediation potential of C. pyrenoidosa in PSRMW treatment and the application of produced algal biomass as a soil amendment for the growth ofA. angulosus.(c) 2020 Society of Chemical Industry (SCI)