Shakeel Ahmad KhanGULSHAN KUMAR SHARMA2020-06-202020-06-202019http://krishikosh.egranth.ac.in/handle/1/5810147794T-10272Improvement of soil fertility and agricultural productivity is the need of today to meet the increasing demand for food security. To satisfy the need for environmental and food sustainability, we have to recycle and reuse of resources. The wastewater grown microalgae are exceptional in providing the NPK to the soil after phycoremediation and biofuel extraction. In the present study microalgae, Chlorella minutissima was selected for phycoremediation. C. minutissima reduced nitrate, ammonium, phosphate, and potassium content in sewage wastewater by 89 %, 48.2 %, 67.4 %, and 66.3 % respectively. The reduction in BOD, COD, and TDS was 93.2 %, 80.5 % and 94.3% respectively. Although, C. minutissima can effectively reduce the EC, TDS, P, K, NH4 + , NO3 - , BOD and COD within 15 days of inoculation. The algal biomass, urea and algal biomass with urea was applied to bay corn and spinach. The application of 100% N dose by algal biomass lead to higher or equivalent economic yield of spinach and baby corn as compared to yield obtained by supply of recommended dose of chemical fertilizer. The enzymes urease, nitrate reductase, and dehydrogenase were analysed in baby corn and spinach grown soil after 30 days of sowing. The soil supplied with 100 N by algae biomass (C. minutissima) significantly (P=0.05) increased the dehydrogenase activity in spinach grown soil. While the nitrate reductase activity in soil supplied with alga manure was maximum (0.13 mg NO2 -N produced g-1 soil 24 h-1) and significantly higher than other treatments in baby corn grown soil. Nitrate leaching was analysed during the experiment from 0-15 cm, 15-30 cm, 30-45 cm depth soil in column. The cumulative nitrate leaching was low (17.19 mg/L) in algae applied treatment, while highest (24.69 mg/L) in plot supplied with recommended dose of NPK. Hence algal manure is best in terms of complete utilization of N with minimal leaching. Therefore it can be concluded that phycoremediation coupled with manure production from algae biomass is sustainable practice to reduce pollution, recycling of wastewater, and improve the soil quality. Key words: Phycoremediation, Chlorella minutissima, Algae manure, Nitrate leaching, Spinach, Baby cornen-USnullThesis