Removal Of High Concentration Inorganic Nitrogen From Industrial Wastewater And Nitrogen And Phosphorus Enrichment And Resource Utilization

With the concentration of urban population and the development of industry and agriculture,the problem of eutrophication of water has become increasingly prominent.The Pollution of nitrogen and phosphorus is the main cause for water ultranutrition.In recent years,strict requirements for the control and handling of the total nitrogen are being raised.The control of inorganic nitrogen,especially nitrate nitrogen and ammonia nitrogen,is the top priority.The dissertation was mainly about the removal of nitrate nitrogen from high concentrated nitrate wastewater,the adsorption of nitrate nitrogen and the enrichment and reuse of iron,phosphorus and nitrogen.The main contents of this study were summarized as follows:Because of treatment cost and rising the nitrogen conversion rate,it is still a challenge to remove the highly-concentrated nitrate from wastewater,Herein,a micro-batteries composed of nascent zero-valent iron and activated carbon can obviously improve the efficiency of nitrate reduction.After the contents of nitrate from 4600 mg/L to 9.52 mg/L,which is less than the national let level.In addition,sodium borohydride as reducing agent,ferrous iron is reduced many times could increase the removal efficiency of nitrate.Compared with existing iron powder,after processing of nitrate the concentration of ferrous iron was only 10.75%.And,its nitrogen content reaches as high as 63.24% in the reduction product.The reason for the increase in efficiency of treatment lies in the new nascent iron has more active sites and stronger reducing ability.The presence of electrons produced by ferric-carbon micro-electrolysis and the presence of hydrogen produced by the reaction of sodium borohydride due to the nitrogen conversion rate increased.Therefore,the method is an effective highly concentrated nitrate removal method.Due to the existence of ammonia nitrogen in industrial wastewater and partial conversion to ammonia nitrogen after the removal of nitrate,the ammonia concentration in the actual wastewater exceeds the standard and needs to be treated,and we hope to enrich and recover the ammonia nitrogen in the wastewater.In this study,for ammonia nitrogen adsorption,the adsorption amount of the chitosan iron(II)complex reached 23.9mg/g,which was 47.53% higher than that of chitosan.After 30 min,the concentration of ammonia in wastewater decreased from 40.8 mg/L to 14.5 mg/L,which was lower than the national emission standard.The reaction was rapid and efficient,no by-products are formed during the reaction,which is favorable for environmental treatment.However,the chitosan iron complex has great adsorption efficiency on low concentration of ammonia nitrogen,and the removal rate was about 98%.We applied it to natural water bodies with excessive ammonia levels.The results showed that at static conditions,1 g/L chitosan iron(II)complex could reduce the 4.63 mg/L ammonia in water to 2.0 mg/L.It was worthy mentioning that the chitosan iron(II)complex is formed by chitosan coordinated with the iron ions in the wastewater of the plant supernatant.(3)On the basis of the foregoing,the experiment was improved to explore the adsorption capacity of chitosan iron(II)complexes on phosphates,and the performance of chitosan iron(II)complexes was proved to be better through comparison with the adsorption efficiency of chitosan.It has higher adsorption capacity(70.5 mg/g)and better pH adaptability(higher adsorption at each pH).The kinetic experiments show that the adsorption process is completed by physical adsorption and chemical adsorption.Infrared spectroscopy shows that chitosan can coordinate with phosphorus after coordination with iron,and the complex is formed to make the structure more stable and difficult to desorption.After adsorption saturated with phosphate,the material was used for the adsorption of ammonia nitrogen.Three elements favoring plant growth were successfully enriched in the chitosan complex.Aquatic mung bean seedlings were cultured using chitosan complexes,it was proved to promote the seedlings,and the promotion efficiency was sustainable.This result significantly proved that our study not only removes many kinds of pollutants in water,but also realizes the recycling and reuse of resources.