PURIFICATION OF HIGH-SALINITY WASTE-WATER BY ACTIVATED-SLUDGE PROCESS

The objective of the present work was the enhancement of the efficienc y of microbiological processes in purification of high-salinity oil-fi eld brine by adding the powdered activated carbon (PAC) to the bioreac tor and by diluting the brine with surface water. The investigation wa s carried out in a laboratory setup. Results show that the nature of p ollutants and the high salinity (about 29 g/l) of oil-field brine had an unfavourable effect on the activated sludge process. Higher hydraul ic loads (above 2.5 d(-1)) increased wash-out of the activated sludge from the bioreactor, so that an increased concentration of the suspend ed matter in the settler was observed. The addition of PAC to the bior eactor, combined with the dilution of oil-field brine with surface wat er, produced a substantial improvement in the sludge volume index. Als o, under the given conditions, it was possible to maintain the given c oncentration of the activated carbon in the bioreactor. The procedure involving PAC and dilution with surface water resulted in an increased rate of pollutant degradation. The positive effect of PAC on the proc ess of oil-field brine purification with the activated sludge was expl ained by the possibility of immobilization of microorganisms on the ac tivated carbon surface in the form of a biofilm.