Study On Filtration Through Single Or Double Beds To Remove NH₄⁺-N From Drinking Water

After the innovation, the economy of our country develops rapidly while treatment of the city sewerage and industry waste water can't adapt it. The result is that some sewage having not been treated is let into the water resource directly, causing water quality worsen and zoology destroyed. The seven largest water systems,the main lakes and reservoirs have been polluted seriously and mostly. Ammoniac nitrogen not only brings certain threat to the safety of the drinking water but also causes great damage to water treatment technology.The test chooses three kinds of mediums: sand,anthracite coal and activated carbon, all of which are representative. This paper has done deeply study to the removal rule of activated carbon filter, activated carbon / sand filter and anthracite coal/ sand filter to ammoniac nitrogen from drinking water.The test is carried out by two phases. The first one is done in the third water works of Harbin with the main content studying turbidity and organic matters removal effect of the filters, while the second one is done in laboratory with the main content studying the start-up, the ammoniac nitrogen removal effect and the backwashing of filters.The results of the study are as follows: the fresh start-up of the activated carbon filter and activated carbon / sand filter needs about 80 days, and because of low concentration of organic matters in the influent, nitration has happened in the upper, besides, the afresh start-up of the filters has the same characters with the fresh start-up but the time needed is shortened greatly, one tenth of the time needed for the fresh start-up,only 8 days in the test to get the removal effect back. The filtration can keep the turbidity bellow 1NTU, while average of the effluent Permanganate Index is less than 3mg/L and average of the effluent TOC fluctuates unobviously, according with requirement for organic matters in the drinking water standard; Removal of ammonia nitrogen and removal rule of ammonia nitrogen along the filter are all affected by medium,ammonia nitrogen concentration of influent,water temperature,pH value and filtration velocity, and at the same time, low dissolved oxygen,low water temperature and a certain range of pH values can cause great accumulation of nitrous nitrogen. It can be ensured that time of the backwashing is 10 mins and the cycle is 6～8 days. The removal rate of ammonia can get right 4h after the backwashing and falls slowly 6days after it which can also make the filter run periodically well and the removal rate of ammonia nitrogen rise wholly and slowly.