Experimental Study On Removal Of Nitrite In Drinking Water By Oxidation

At present, the nitrogen source pollution of groundwater and surface water is very serious in our country, the problem of nitrite in the drinking water industries has become a topic of concern. In our country, the limit value of nitrite in drinking water is stipulated in the first time in the drinking water health standard, but it is only a reference. So it is still necessary to study the concentration of nitrite nitrogen in drinking water, so as to ensure the health and safety of drinking water. The main purpose of this paper was to study the problem of nitrite's overproof in drinking water, due to nitrite nitrogen of a part of the water supply plants in the current country has far exceeded the relevant indexes. so it is necessary to carry on the analysis on the source of nitrite in water supply plants, and then we can take advantage of the experiments to solve the nitrite exceeded the problem for the best solution. The main purpose of this paper is to convert nitrate to nitrite by using oxidants. The results showed that the ozone(air) would not only make the concentration of nitrite nitrogen is decreased in simulated water sample, but also increase the concentration of nitrite nitrogen in simulated water sample. The reason is that the air contain large amounts of nitrogen, the high voltage discharge convert nitrogen oxides to nitrogen, which create nitrite by passing into water, so that the concentration of nitrite nitrogen in water is increased,,however the ozone(oxygen) make the concentration of nitrite nitrogen is decreased in simulated water sample.The purpose of this experiment was to study removal effect that common oxidants including chloros, hydrogen peroxide, chloramine-T and PMS, ozone(oxygen),UV/hydrogen peroxide, and UV/PMS remove nitrite nitrogen. We can know partial oxidants and nitrite nitrogen's best electronic mole ratio, chloros, chloramine-T,UV254/PMS and UV254/hydrogen peroxide and nitrite nitrogen's best electronic mole ratio ware 1:1, 3:1, 5:1 and 5:1. The ozone(oxygen) flowed through the simulated water sample by 20ml/min, the best concentration was 50 m L/L. Effect of various oxidants on the removal of nitrite nitrogen is that chloros> chloramine-T> UV254/PMS> UV/hydrogen peroxide> PMS> hydrogen peroxide. At the same time we also studied p H value,temperature and reaction time's effect on removal of nitrite nitrogen under the best electronic mole ratio. We can know through the experiment that p H value's effect on the UV254/PMS removing nitrite nitrogen was less, however, oxidation reaction time's effect was superior, with the increase of reaction time, the removal rate of the nitrite nitrogen was increased gradually. The p H value's effect on the chloros removing nitrite nitrogen waslarger, with the decrease of pH value, the removal rate of the nitrite nitrogen was increased gradually, when water p H value was 5.5 and 7.0, the reaction time on the removal rate has almost no effect, however, when water p H value was 8.5, the reaction time on the removal rate had a great impact. with the increase of oxidation time, the removal rate of the nitrite nitrogen was increased gradually. The water temperature effect on the chloros removing nitrite nitrogen was larger, with the increase of water temperature, the removal rate of the nitrite nitrogen was firstly increased and then decreased.The results showed that nitrite nitrogen removal rate increased with the increase of antioxidant additive amount, chloros' removal effect on nitrite nitrogen removal rate was good under the condition of the water temperature is 20 ? and acidic environment, the contact oxidation time is relatively short. Generally, 2min is appropriate, PMS and hydrogen peroxide's Removal ratio was improved significantly under UV254 light source,its removal rates are 98.2% and 97.27%. But it costs too much time to react. General, 50 min is appropriate, however, UV308/PMS, UV365/PMS, UV308/hydrogen peroxide and UV308/hydrogen peroxide's effect on the removal ratio of nitrite nitrogen isn't increased greatly. The hydrogen peroxide's removal ratio on nitrite nitrogen is decreased by the irradiation of UV308 and UV365 light source. This experiment also studied the kinetics of UV254/PMS oxidizing nitrite nitrogen, We found that the kinetic reaction equation follows the first order reaction kinetics by method of trials and errors, and its correlation coefficient R2 were greater than 0.987, the linear correlation was better.