Study On Combined Treatment Of Organic Matter And Ammonia Nitrogen In Landscape Water By Photocatalysis And Electrocatalysis

At present,landscape water treatment mainly adopts traditional treatment methods such as water diversion and water exchange method,circulating filtration method,dosing air flotation method,aeration and reoxygenation method,biological contact oxidation method and constructed wetland method.However,these methods have many problems,such as high operating cost,secondary pollution and long start-up time.In fact,the main pollutants that cause landscape water pollution are organic matter and ammonia nitrogen.As an advanced oxidation technology,photocatalytic technology has attracted wide attention in the field of organic matter degradation because it does not produce secondary pollution and has good treatment effects.In addition,electrocatalytic technology has become a research hotspot in recent years because of its advantages of mild operating conditions,convenient operation and management,and high efficiency in removing ammonia nitrogen.Therefore,this article combines photocatalytic technology and electrocatalytic technology to simultaneously remove organic matter and ammonia nitrogen in landscape water.As a widely used photocatalyst,titanium dioxide has the advantages of non-toxic,stable,cheap and easy to obtain.However,the recombination rate o f photogenerated electrons and holes is so high that it needs to be modified.In this paper,photoreduction and immersion methods were used to prepare different metals and metal oxides modified titanium dioxide,and the modified titanium dioxide was analyzed through a variety of physical and chemical characterizations.In addition,with humic acid as the target pollutant,the effects of metal loading,metal loading,catalyst dosage,and coexisting ions on the photocatalytic degradation effect were explored.When the supported cocatalyst was metallic platinum,the loading ratio was 1.0 wt%,and the catalyst dosage was 1.5 mg/L,the degradation of humic acid reached the optimal effect.In this paper,Ti/RuO₂,Ti/IrO₂ and Ti/RuO₂-IrO₂ were selected for the study of ammonia nitrogen removal.The composition,microstructure,metal valence and other properties of these electrodes were analyzed through physical and chemical characterization,and the electrochemical performance of the electrodes was analyzed through electrochemical tests.In addition,with ammonia nitrogen as the target pollutant,the influence of anode material,electrolyte concentration,current density and chloride ion concentration on the removal of ammonia nitrogen was explored.When the Ti/RuO₂-IrO₂ electrode was used as the anode,the electrolyte concentration was 5 mmol/L,the current density was 7 m A/cm²,and the chloride ion concentration was 100 mg/L,the ammonia nitrogen removal effect was the best.On the basis of the above achievements,the photocatalysis and electrocatalytic reaction system were amplified and then coupled and applied to investigate the efficiency of simultaneous removal of organic matter and ammonia nitrogen.Firstly,the method of supporting the catalyst was explored.When the porous alumina plate was used as the substrate and the polyvinylidene fluoride+N-methylpyrrolidone was used as the binder,the supporting effect was the best.Secondly,the photocatalytic reactor was scaled up.When the photocatalyst loading was 16mg/cm² and the light intensity was 5 m W/cm²,the degradation rate of humic acid reached up to 70%.Thirdly,the electrocatalytic reactor was enlarged and studied.When the electrode spacing was 2 cm and the number of electrode pairs was 2 pairs,the ammonia nitrogen degradation efficiency reached 100%.Finally,the photocatalytic and electrocatalytic coupling treatment of simulated landscape water was studied.Under static flow conditions,the removal rate of humic acid reached70%and the degradation rate of ammonia nitrogen reached 100%within 8 hours.Under circulating flow conditions,when the flow rate was 95 m L/min,the degradation rate of humic acid reached 75%and the removal rate of ammonia nitrogen reached 100%within 4 h.