Capacity Of Municipal Wastewater Purification And Lipid Contents Of Chlorella Ellipsoidea Gren And C.pyrenoidosa Chick

Microalgae can be used for wastewater treatment and bioremediation to capture carbon,nitrogen and phosphorus.It can accumulate lipids as part of their biomass for biodiesel fuels.Biotechnology of sewage resources and bioenergy are active area of research.The biotechnology of growing algae on wastewater for production of biodiesel will have profound effects on environmental,social and economic benefits.Wastewater purification capacity and lipid contents of Chlorella ellipsoidea Gren and C.pyrenoidosa Chick were investigated in this paper.The results were as follows:By using single factor method the effects of ammonia-nitrogen concentration,COD concentration,cell loading,and density of bioreactor and starvation time on wastewater removal efficiency in airlift bioreactor by immobilized Chlorella were studied.The results showed that the optimal removal efficiency of ammonia-nitrogen was 99.80% and 99.20% by C.ellipsoidea and C.pyrenoidosa after 96 h.Orthophosphorus removal efficiency reached to100% after 24 h by two species.COD removal efficiency was 87.50% after 96 h.The optimal removal efficiencies of COD,ammonia-nitrogen and orthophosphorus were obtained at the conditions as below: ammonia-nitrogen,30 mg/L;orthophosphorus,3 mg/L;COD,100 mg/L;cell density,5 million algae cells per bead and 150 beads per 150 mL bioreactor.The effects of above factors on the lipid contents of C.ellipsoidea and C.pyrenoidosa were investigated by the method of organic solvent extraction.The results showed that lipid contents of C.ellipsoidea was increased from 14.27% to 21.50% when ammonia-nitrogen concentration was increased from 10mg/L to 30 mg/L.Lipid contents of C.pyrenoidosa was increased from 13.92% to 21.99% when starvation time was 48 h.While lipid contents of C.pyrenoidosa was increased from 12.38% to 21.92%,when COD concentration reached to100mg/L.Lipid contents of algae decreased with the increasing cell loading.Bioreactor density has little effects on lipid contents of algae.The peak values of lipid contents were22.32% and 21.93% of C.ellipsoidea and C.pyrenoidosa when the optimal wastewater treatment condition as follows,ammonia-nitrogen,30mg/L,orthophosphorus,3 mg/L;COD,100mg/L;cell density,2.5 million cells per bead and 100 beads per 150 mL bioreactor.