NITROGEN AND PHOSPHORUS REMOVAL FROM SEWAGE EFFLUENT WITH HIGH SALINITY BY CHLORELLA-SALINA

Cells of Chlorella salina CU1 are able to grow well in domestic sewage effluent having salinities as high as 16 ppt. By using controlled C. salina CU1 cultures, it is possible to remove the nitrogen and phosphorus from the sewage effluent before it is discharged into marine coastal water. With a retention time of 8 days, 86% to 100% NH3-N, 98% NO3--N and 98% PO43--P are removed from the sewage effluent under laboratory conditions. It is also found that cells of C. salina CU1 prefer ammonia to nitrates as nitrogen source. Uptake of nitrates by the cells occurs only after the ammonia in the sewage effluent has been reduced to levels below 0·5 ppm. Ammonia at higher concentrations completely inhibits the nitrate uptake by the algal cells. Since cells of C. salina CU1 have a high protein content (44%), it is proposed that this unicellular green alga can be used to serve the dual function of wastewater purification and waste recycling through the production of algal protein from sewage effluent having high salinities. © 1979.