| Reclaimed water is a kind of water which can reach to a certain degree of water quality objectives,meet certain application requirements and can be used beneficially.The use of reclaimed water has become one of the important way to alleviate water shortages.At present,there are some problems in the use of reclaimed water as a supplementary water for urban landscape water body.According to the national standard(18921-2002 GB/T)of wastewater reclamation and utilization,the total nitrogen in the water concentration of the water is less than 15mg/L,which can meet the requirement of the water quality of the landscape.However,it is easy to produce the eutrophication when the water concentration requirement is used as the water source for landscape reuse.Therefore,the study of the depth of the recycled water in addition to nitrogen method,to further reduce the total nitrogen concentration of recycled water,the control of renewable water reuse for landscape water use is prone to eutrophication problem has a very important practical significance.The paper mainly studies the effect of the use of adsorbent and coagulant in the process of reclaimed water production to remove nitrogen from raw water.The adsorbent has bamboo charcoal,modified bamboo charcoal and bentonite,the coagulant has polymeric aluminum chloride(PAC),poly ferric sulfate(PFS)and aluminum sulfate.The experiment using single factor experiment and orthogonal method,the effects of adsorbent and mixing performance and effect on the removal of nitrate nitrogen in raw water coagulation.The experimental results are as follows:(1)Adsorption and coagulation method can remove the nitrate nitrogen in the water,the adsorption removal rate as high as 70%,coagulation method is 10%;Combination of the two methods of removal rate can reach more than 80%.Therefore,the adsorbent can be manufactured in reclaimed water coagulation sedimentation process with coagulant dosing,at the same time of removal of raw water turbidity,also removed the nitrate nitrogen in the water.(2)Modified bamboo charcoal is the best adsorbent for the removal of nitrogen in the three adsorbents.According to the processing technology of bamboo charcoal,it belongs to a kind of biological carbon,which indicates that the modified carbon is a better material for the removal of nitrate from water.In the previous experiment,also used activated carbon,activated carbon is almost no removal effect.The nitrogen removal efficiency of coagulant PAC was the best,the other two also had the effect of removal,and the difference between the three is not very large.(3)The primary and secondary factors that affect the removal efficiency of nitrogen in the water are as follows: the type of adsorbent > the dosage of the adsorbent > the coagulant dosage.The pH value of raw water coagulation and the hydraulic conditions also affect the removal of nitrate Under the optimum conditions,modified bamboo charcoal cast dosage of 5g /L,mixed flocculants PAC dosage was 40mg/L,the stirring speed 80r/min,stirring time is 75 min,water pH 8,in raw water total nitrogen removal rate can reach 88.64%.Raw water turbidity decreased from 3.2NTU to 0.18 NTU.The main reason for the eutrophication of the reclaimed water is excessive nitrogen and phosphorus,which plays a decisive role in the concentration of phosphorus.This paper is on the basis of the senior wu zhao yang’s paper reclaimed water phosphorus removal in the clay mineral and mixed combined application of coagulant in the reclaimed water phosphorus removal of the experimental research,further explore the recycled water in addition to nitrogen.Removal of nitrogen is more difficult than phosphorus removal in reclaimed water production,because after biochemical treatment most of the nitrogen in the wastewater was oxidized to nitrate.The removal of nitrate nitrogen in water is rare in China.The results of this paper provide some functions for nitrogen removal from reclaimed water. |
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