Study On Ozone-biological Activated Carbon Process

With the increase of the intensity and scope of human activities, the phenomenon of organic pollution of raw water is becoming more and more serious, which has threatened the survival and development of human being.Meanwhile, the quality standards of drinking water are improving, the conventional process of water treatment has been difficult to make the water quality meet the requirements of the relevant standards. Organic pollution of the water seriously exceeded, in order to ensure the safety of urban water supply and improve water quality, several kinds of water advanced treatment process,one of these process is ozone- biological activated carbon process. The development of this process is very rapid.The process not only can remove the residual organic pollutants in raw water effectively, but also has a good effect on the removal of NH4-N and disinfection by-products. But there is little research on this processatlow temperature period and low turbidity water in the north of China. This paper takes NH4-N in raw water of Songhua River as the research object. The study was based on the conventional process of water treatment of the Songhua River waterworks.The removal of NH4-N was tested based on ozone-biological active carbonprocess, also the factors of the conventional water treatment adjustment were investigated. The possibility of further research on the advanced treatment technology in combination withthe conventional treatment process was explored.The results of this study provided theoretical and technical support for the waterworks of the northern and kept water plant stable operating.The conclusions are drawn based on the study on the removal rate of NH4-N by ozone biological activated carbon technology under low temperature conditions:1. The best(G,T) and the mixing was determined by updating the conventional coagulation and the conventional flocculating process under the low temperature conditions. The filterruns was 48 hours through updating filtration and thewash rate was 12 L /(m2·s). By updating the conventional process, not only the treatment effect is improved, but also the quality of the raw water inlet of the ozone activated carbon process.2. Pre-ozonation could improve the effect of coagulation and increase removal rate of turbidity, CODMnand NH4-N. The best dosage of pre-ozonationwas 1mg /L.The ozone can improve and enhance the effect of activated carbon process.The ozone- biological activated carbon processwas energy-saving technology.3. The activated carbon was characterized by iodine value and methylene blue value. The result was broken activated carbon property is superior to that of particles activated carbon. Compared with particles activated carbon,the removal rate of broken activated carbon on turbidity, CODMnand NH4-N were higher 16.54%, 15.88% and12.36%.4 The result of wash rate and time text on carbon filter showed that the optimal air wash rate of carbon filter was 10L/(m2?s) and the optimal time was 5min. The water wash rate was 12 L/(m2?s) and the optimal time was 10 min.5. The optimal wash runs was about 14 days, which got from the experiment of wash runs. In actual operationthe running effect of the carbon filter can be influenced by the frequencyof the wash runs.It was very important to adjustthe frequency of wash runs according to the actual change of turbidity.6. Ozone-biological activated carbon process can make the water to reach the biological stability and inhibit the breeding of E.coli and other microorganisms.This process can effectively remove the trihalomethanes precursors, which is the by-products of disinfection during chlorination adding into water. The rate of removing the by-products of disinfection was 49.3%, enough to enhance water purification water quality.It would ensure the safety of drinking water.7.The Ozone-biological activated carbon processhad been operating stably six months. This processcan make the turbidity, color, CODMn, NH4-N and other conventional indicators of emissions stabilize the standard, especially in low temperature, low turbidity period. The Ozone-biological activated carbon processcould be used as a recommended process for the Songhua River water plants as one kind of advance treatments, which could ensure the safety of drinking water and the demandof water supply for urban.