Sea Water For Flushing The Local Sewage Denitrification Studies

In this paper, the nitrification of wastewater from flushing toilet with seawater by SBR in bench-scale has been studied. The effects of its salinity on the nitrogen removal efficiency and short-circuit nitrification have been focused. In addition, the experiment has been carried to detect how impact of some factors such as temperature, FA, pH on the treatment performance.The effects of salinity on the nitrogen removal efficiency indicate:The effects of salinity on the nitrogen removal efficiency are negligible when domestic sewage contains seawater lower than 35%. And the system can sustain high nitrogen removal efficiency (>80%)when the proportion of seawater lower than 60%.The concentration of NH3-N after treated can fulfil the first level of Integrated Wastewater Discharge Standard. But when the domestic sewage contains seawater higher than 60%, the nitrogen removal efficiency begins to decrease.The effects of salinity on the short-circuit nitrification indicate:The short-circuit nitrification is achieved when the domestic sewage contains seawater higher than 30%. It means that over 10.5g/L salinity can inhibit the growth of nitrobacteria. And the nitrogen removal efficiency begins to decrease when the proportion of seawater exceed 60%, that means 21g/L salinity can also inhibit the growth of nitrosomonas.The effects of some factors such as temperature, FA, pH on the treatment performance indicate:The short-circuit nitrification of the domestic sewage is achieved when the temperature is over 30℃.The results reveal that high temperature can increase nitrogen removal efficiency by denitrification via nitrite.The short-circuit nitrification of the domestic sewage isn't achieved when the pH is higher than 8.0, FA is higher than 5mg/l.So it is uncertain only use the high pH and FA to achieve the short-circuit nitrification.