Study on Change and Control of Alkalinity in SHARON Process

The dynamic experiments were carried out to investigate the variation of alkalinity in SHARON process,as well as the relation of alkalinity to pH and volumetric removal rate of ammonia nitrogen.The results show that the maximum reaction rate of SHARON obtained at normal temperature and pH 7.37 is 1.64 kg/(m3·d).To maintain a suitable pH,the alkalinity needed would be raised as volumetric removal rate of ammonia nitrogen increases.The minimum alkalinity requirement in the system is 1 660 mgCaCO3/L,and the alkalinity equivalent is 5.41 mgCaCO3/mgN.A non-linear relation exists between pH and alkalinity.The pH change is relatively small in the range of 7.0 to 7.8,which favors the alkalinity control.The continuous or intermittent addition modes should be used to keep an optimal alkaline concentration of 1 770 to 2 008 mgCaCO3/L.