An integrated process for the production of oil-bearing Chlorella variabilis for lipid extraction utilizing by-products of Jatropha methyl ester production from whole seeds of Jatropha, wherein growth of Chlorella variabilis is carried out in single stage under mixotrophic conditions in combination with either agitated or static conditions and the process comprising the steps of: i. providing deoiled cake as by-product of Jatropha methyl ester production having 4-6 % (w/w) nitrogen of Jatropha seeds; ii. hydrolysating the deoiled cake as provided in step (i) with hot acidic aqueous solution followed by adjusting pH in the range of 5.5 to 8.5 with alkaline materials to obtain a nitrogen-rich Jatropha oil cake hydrolysate (JOCH); iii. providing methanol-depleted crude glycerol layer as by-product of Jatropha methyl ester production, which is prepared by mopping up methanol from a glycerol layer obtained as by-product of Jatropha methyl ester production; iv. adding 1-5% (w/v) of the methanol-depleted crude glycerol layer as provided in step (iii) to 1-10% (v/v) of Jatropha oil cake hydrolysate as obtained in step (ii) to prepare growth-and-production medium for Chlorella variabilis; v. inoculating 1-10% (v/v) of the Chlorella variabilis seed culture into growth-and-production medium as obtained in step (iv) and incubating for a period in the range of 7 to 15 days at a pH in the range of 7.0-8.0 at a temperature in the range of 25-40°C to obtain lipid containing biomass; or, as optional alternative, inoculating 1-10% (v/v) of the Chlorella variabilis seed culture on the 1 st day of seed culture inoculation with tap water, for initial 4 to 10 days incubation with only seawater or 1:2 diluted seawater in tap water and after 4 th to 10 th day subsequently adding methanol-depleted crude glycerol layer as provided in step (iii) to obtain lipid containing biomass; or, as optional alternative, inoculating 1-10% (v/v) of the Chlorella variabilis seed culture into growth-and-production medium as obtained in step (iv) and adding UV-specific dye during outdoor biomass production to protect from UV damage at the temperature in the range of 40°C-50°C maintaining the viability of the culture, and incubating for a period in the range of 7 to 15 days at a pH in the range of 7.0-8.0 at a temperature in the range of 25-40°C to obtain lipid containing biomass; vi. drying the biomass as obtained in step (v) in sun or directly using the wet biomass for lipid extraction; and vii. extracting the lipid from biomass as obtained in step (vi). i. providing deoiled cake as by-product of Jatropha methyl ester production having 4-6 % (w/w) nitrogen of Jatropha seeds; ii. hydrolysating the deoiled cake as provided in step (i) with hot acidic aqueous solution followed by adjusting pH in the range of 5.5 to 8.5 with alkaline materials to obtain a nitrogen-rich Jatropha oil cake hydrolysate (JOCH); iii. providing methanol-depleted crude glycerol layer as by-product of Jatropha methyl ester production, which is prepared by mopping up methanol from a glycerol layer obtained as by-product of Jatropha methyl ester production; iv. adding 1-5% (w/v) of the methanol-depleted crude glycerol layer as provided in step (iii) to 1-10% (v/v) of Jatropha oil cake hydrolysate as obtained in step (ii) to prepare growth-and-production medium for Chlorella variabilis; v. inoculating 1-10% (v/v) of the Chlorella variabilis seed culture into growth-and-production medium as obtained in step (iv) and incubating for a period in the range of 7 to 15 days at a pH in the range of 7.0-8.0 at a temperature in the range of 25-40°C to obtain lipid containing biomass; or, as optional alternative, inoculating 1-10% (v/v) of the Chlorella variabilis seed culture on the 1 st day of seed culture inoculation with tap water, for initial 4 to 10 days incubation with only seawater or 1:2 diluted seawater in tap water and after 4 th to 10 th day subsequently adding methanol-depleted crude glycerol layer as provided in step (iii) to obtain lipid containing biomass; or, as optional alternative, inoculating 1-10% (v/v) of the Chlorella variabilis seed culture into growth-and-production medium as obtained in step (iv) and adding UV-specific dye during outdoor biomass production to protect from UV damage at the temperature in the range of 40°C-50°C maintaining the viability of the culture, and incubating for a period in the range of 7 to 15 days at a pH in the range of 7.0-8.0 at a temperature in the range of 25-40°C to obtain lipid containing biomass; vi. drying the biomass as obtained in step (v) in sun or directly using the wet biomass for lipid extraction; and vii. extracting the lipid from biomass as obtained in step (vi).