Study On Shortcut Nitrification-Denitrification And Influence Factor In Hypersaline Wastewater Treatment By MBR

With development and application of the comprehensive utilization of seawater in coastal cities, more and more saline wastewater has been produced and becomes an important pollution sources. Toilet-flush seawater and other wastewater from districts, islands, ships and warships contain many organic and inorganic nitrogen compounds. Too much nitrogen compounds entering into seawater will make water quality worsen, accelerate the process of eutrophication, trigger red tide, which will impact the development of fishing industry and endanger human health. Therefore, we must pay more attention to the nitrogen pollution in seawater and the research on high-efficiency denitrification pathways. As a new highly efficient denitrification technology, shortcut nitrification-denitrification technology has been given attention by many scholars, which has the merits such as low energy consumption, saving carbon and reducing the reactor volumes. Membrane bioreactor as a new wastewater treatment technology, with the advantage of focus on equipment, small footprint, good effluent quality and less amount of sludge, is very suitable for biological treatment of toilet-flush seawater from islands, districts, ships and other special occasions. Combining shortcut nitrification-denitrification technology with membrane bioreactor can fully play these two highly effective technologies to remove all the characteristics of organic matter and ammonia, so as to better solve the treatment question of saline wastewater after utilization of seawate. Therefore this study has important theoretical significance and broad prospects.Based on experiments, the paper investigated the influence of salinity, temperature, pH, dissolved oxygen concentration and ammonia loading to shortcut nitrification-denitrification, determined the conditions in which shortcut nitrification-denitrification was achieved in hypersaline wastewater treatment by MBR, and studied the principle of shortcut nitrification-denitrification in MBR.Results show that the shortcut nitrification-denitrification occurs in MBR with salinity in the range of toilet-flush seawater. The optimal operating conditions are that the temperature is 30℃or so, the unit area aeration amount is 0.67m3/(h·m2), the pH value is 7.5~9. According to the difference of nitrate bacteria and nitrite bacteria in physiological mechanism and reaction characteristic, we can add inhibitors into reactor or control the reaction conditions to make more greatly impact on nitrate bacteria, and then change the form of nitrification.