Experimental Study Of Photocatalytic Technology In Calcium Carbide Wastewater Treatment

This paper is an experimental study about contamination degrading in calcium carbide wastewater through irradiating the catalyzer TiO₂ by UV.COD_Cr and the concentration of ammonia nitrogen is the criterion of water in the photocatalytic reaction.This paper reviews the main factors which affect the photocatalytic reaction,and also confirms the corresponding best values.The results of the experiment indicate that:after the photocatalytic reaction,the removal efficiency of COD_Cr and the ammonia nitrogen of the pretreated raw water is higher than the raw water which is not pretreated(Ultra-violet lamp is the lamp-house in this case);with increasing light strength,the removal efficiency of COD_Cr and the ammonia nitrogen in the water continues to grow;the optimum dose of the catalyzer is 1g/L;in alkali condition,the removel efficiency of COD_Cr and the ammonia nitrogen is higher in the photocatalytic reaction than in the acidic condition;the infusion of air can mix catalyzer and water sufficiently,further more,it can provide the oxygen needed in photocatalytic reaction,however,the over use of air will be a waste of energy.In the experiment,the optimum influx of air is 0.14 m³/(h·L);H₂O₂ and O₃, together with photocatalytic reaction,can degrade the contamination in the water.The results of the experiment also indicate that the optimum dose of H₂O₂ is 0.4 mL/L;with all the factors at the optimum condition,in the first 90min,the removal rate of COD_Cr and the ammonia nitrogen is very high,but in 3 hours,the removel efficiency of COD_Cr and the ammonia nitrogen will grow much slower and until then,the removal efficiency of COD_Cr is 84%,and the removal efficiency of ammonia nitrogen is 74%.On the basis of the study on degradation of COD_Cr and the ammonia nitrogen in aqueous suspension,this paper discusses the theory of inorganic nitrogen degradation by photocatalytic reaction.The study indicates that,in alkali condition,there are two ways to remove the ammonia nitrogen:blowing-off by the air and oxidation in the photocatalytic reaction.There are acetylene and sulfid to serve as the hole remover in calcium carbide wastewater,so the deoxidizing reaction of nitrate can go on smoothly,and the product is nitrogen,whose creating efficiency is very high.On the optimum condition of every factors,the removal efficiency of nitrate is about 60%in 3h,and the creating efficiency of nitrogen is up 90%.In the process of reaction,the blowing-off of ammonia nitrogen consumes a lot of OH^-,so the pH of the water decreases with the time goes by.In addition,the experiment explores the preparation of photocatalytic oxidation of modified TiO₂ film coating on fiberglass cloth surface,and evaluates the activity of the TiO₂ film.The experiment prepares the modified TiO₂ film by using fiberglass cloth (which has strong resistance to high temperature) and the ordinary fiberglass cloth as the carrier through the way of sol-gel.The result of the experiment indicates that in the reaction of photo-catalytic,by using the catalyzer with carrier that has strong resistance to high temperature,the removal efficiency of COD_Cr is 41%,and the removal efficiency of ammonia nitrogen is 39%in 3h,higher than the reaction with cartier of ordinary fiberglass cloth,in which the removal efficiency of COD_Cr is 35%,and the removal efficiency of ammonia nitrogen is 30%.