Cost-effective treatment of sewage wastewater using microalgae Chlorella vulgaris and its application as bio-fertilizer

Abstract

The present study lays an emphasis on microalgae-based treatment of sewage wastewater using Chlorella vulgaris to remove toxic pollutants and nutrients from the wastewater, making it safely dischargeable and reusable as bio-fertilizer, with simultaneous biomass and lipid production. The sewage treatment experiment was carried out in a 50 L capacity outdoor open syntax tank. The results exhibited the survival efficiency of C. vulgaris in sewage wastewater generating 0.67 g/L biomass and 0.26 g/L lipid yields. Crucial environmental factors like light intensity and temperatures have played a key role in biomass growth, lipid accumulation and nutrient removal efficiencies of C. vulgaris. The concentrations of significant nutrients like nitrates, COD and BOD were reduced up to 93%, 95% and 92% respectively. Other nutrients and parameters were removed up to 90% on an average. The treated sewage wastewater was then supplied as a bio-fertilizer to grow Solanum lycopersicum (tomato) plants as a comparative to chemical fertilizer grown plants. The results obtained from the comparative analyses showed that the tomato plant grown with treated sewage wastewater showed efficient growth and productivities as good as the chemical fertilizer aided yields. This study proved that sewage can be a successful replacement to the chemical fertilizers. The details are ornately discussed inside the paper.