FACTORS THAT AFFECT THE REMOVAL OF NITROGEN AND PHOSPHOROUS FROM PIGGERY WASTEWATER USING MICROALGAE –BACTERIA CONSORTIUM

Abstract

Currently, most piggery farms in Viet Nam use biogas tank as a primary wastewater treatment system. However, even after the anaerobic treatment process, the concentration of nutrients was still high and exceeded the national effluent standard. If the wastewater was directly discharged into the water bodies, it was certainly hazardous to the environment and causes eutrophication. To remove the residual nutrients, several processes have been used, mostly chemical processes. The disadvantages of those chemical processes are high cost and the increase in amount of sludge. In this study, the biological method using microalgae-bacteria consortium was applied for the removal of nitrogen and phosphorous from wastewater from biogas treatment process. This study focused on factors which affect nitrogen and phosphorous removal efficiency in a batch reactor using microalgae-bacterial consortium. Studying on Chlorella sp A8. Activated sludge co-cultivation at different ratio (Chl/AS) gave good results in hydraulic retention time of 20 to 24 hours when C/N in wastewater was 4/1(m/m). In the fully mixing condition, DO range from 0.3 - 0.5 mg O2/L, the highest removal efficiencies of COD was 71 - 76 %; NH4+-N was 40 - 47 % and PO43--P was 64 - 77 % at Chl /As was 1.5:1, 2.5:1 and 1:1( g/g).