Removal Of N-Containing Organic Compounds In Wastewater By A Bio-inspired Technology

With the rapid development of pharmaceutical industry,a large number of pharmaceutical wastewaters has caused serious impact on the ecological environment.Nitrogen-containing organic compounds entering the water environment will lead to its eutrophication.At the same time,N-containing organic compounds are oxidized to nitrate and nitrite,which will affect the survival of aquatic organisms,and then damage the water ecological environment,and ultimately harm human health.At present,although scholars at home and abroad have explored a lot of treatment methods for wastewater containing organic nitrogen,to develop more economical,efficient and green treatment methods is still their goal.In this study,the common microorganisms in water such as Rhodospirillum rubrum,Rhodopseudomonas palustris,Escherichia coli,Staphylococcus aureus,Bacillus subtilis and Pseudomonas adaceae were selected to investigate their ability to degrade N-containing organic compounds in wastewater.The results showed that a better degradation of N-containing organic compounds was achieved with irradiation than without irradiation,and an aerobic environment was more appropriate for the degradation of N-containing organic compounds than an anoxic one.Among them,Rhodopseudomonas palustris showed the best ability for the degradation of di?n?butylamine under aerobic conditions,with the removal rates of total nitrogen and total organic carbon 46.2%and 30.4%,respectively.A kind of green and clean biomimetic catalysis systems,photo–Fe³⁺/Mn³⁺/Co³⁺–O₂（e.g.p H 8–8.5）and photo–Fe³⁺/Mn³⁺/Co³⁺–NO₃^–（e.g.p H 4–4.5）,was developed and applied to the degradation of N-containing organic compounds.The results showed that:under the alkaline condition,the catalytic system exerted an effect function on the degradation of tri-n-propylamine,with the removal rates of total nitrogen and total organic carbon 87.7%and 79.5%,respectively.However,sodium ethylenediamine tetraacetate（EDTA）showed a better degradation under acidic condition than under acidic condition.The degradation can be attributed to the charge transfer between transition metal ions and hydroxide ions or EDTA molecules（LMCT）,generating hydroxyl radicals or other active free radicals,and thus causing organic nitrogen-containing compounds oxidized and degraded.In addition,in order to avoid secondary pollution caused by NO_X due to degradation under acidic conditions,a cobalt/manganese composite was designed,which made EDTA reach a similar degradation under alkaline condition to that under acid condition.In addition,the experiments showed that the N-containing organic compounds treated by the catalytic system were partly decomposed to small molecular substances which are easier to be utilized by microorganisms,so the biodegradability of the wastewater was improved.The BOD₅/COD values of the treated acrylamide and caprolactam wastewater are greater than 0.3,indicating that the wastewaters have changed from refractory to easily biodegradable ones.The"biomimetic"method developed in this study not only retains the environmentally friendly advantages of the biological treatment method,but also speeds up the treatment process.The biodegradability of wastewater containing organic nitrogen can be improved after"biomimetic"treatment,which implies that no new toxic and harmful substances are produced in the treatment process.This process can replace the time-consuming microbial acclimation process,and create conditions for“butt-to-butt”biological treatment,and therefore possess a good application prospect.