Pilot Study On The Treatment Of Sudden Ammonia Nitrogen And Formaldehyde Pollution By Chemical Oxidation And Abatement Device

In recent years,with the rapid industrialization and urbanization of our country,the environmental risk is high,and the sudden pollution of water environment in China has caused the adverse effects on people's production and life.Compared with conventional water pollution incidents,sudden environmental pollution incidents in water sources are characterized by urgency,uncertainty,threat and rapid response.In this study,ammonia nitrogen and formaldehyde,which are difficult to get good results,are selected as the characteristic pollutants,and the chemical oxidation reduction process of small test scale and pilot scale is carried out by using sodium hypochlorite as oxidant.The main results are as follows:(1)The main part of the chemical oxidation reduction device designed and developed is the sandwich net PVC pool and mixer,which is composed of the original pool,the oxidation pond and the dissolving pool.The original pool is square,the design size is 1.7m × 1.7m×1.5m;the oxidation pond and the medicine dissolution pool are round,and the diameter is 2m and the height is 1.32 m.The matching devices include water inlet pipe and drainage pipe connected to the pool,valves and three links,water pumps,flowmeters,turbidimeter and flow meter.The chemical oxidation reduction device designed and developed has good material performance and good use effect,which can better meet the requirements of emergency treatment equipment.(2)The result of ammonia nitrogen removal experiment shows that the optimum technological conditions for the oxidative removal of ammonia nitrogen by sodium hypochlorite are as follows: in the condition of normal p H,when the concentration of ammonia nitrogen in water is 5,10 and 20 times higher than the standard respectively,adding 1.7,1.9 and 15ml·L-1 of sodium hypochlorite respectively and then reacting 40 minutes can reduce the ammonia nitrogen concentration in the water to below the standard limit of 1.0 mg·L-1 for type ?of surface drinking water.Besides,A process for eliminating residual chlorine in water by H2O2 is proposed,which can reduce the concentration of residual chlorine rapidly.When the concentration of residual chlorine in the effluent is about 5 mg·L-1,25ul·L-1 hydrogen peroxide is added,and the residual chlorine concentration can be reduced to 0.2mg·L-1 below 30 minutes.(3)The experimental results of formaldehyde removal show that H2O2,Na Cl O and Ca(CIO)2 can be used as the best medicament for emergency treatment of formaldehyde wastewater.The optimum processing conditions under typical concentration are as follows: Under conditions of conventional p H and the reaction time of 30 min,when the concentration of formaldehyde in water exceed the standard of 10,20,50,100,200,500 and 1000 times,adding Ca(Cl O)2 20g· L-1,Na Cl O 100ml· L-1,Ca(Cl O)2 25g· L-1,Na Cl O 200ml· L-1,Ca(Cl O)2 100g· L-1,Na Cl O 300ml· L-1,Na Cl O 400ml· L-1 within the range of 0 to 20 degrees Celsius;and when the temperature is between 20 and 35 degrees Celsius,it is suitable to add H2O2,adding 60,100,120,250,400,600,800ml· L-1 respectively.After treatment,the formaldehyde concentration can be reduced to the standard limit value,the removal rate can reach more than 99%.(4)Pilot test on ammonia nitrogen and formaldehyde removal by comprehensive utilization of sodium hypochlorite as oxidant,the optimum parameters for the operation of the chemical oxidation device are as follows : the water inlet and the outlet are respectively designed at 9/10 and 1/2 of the effective depth of the water tank;The mechanical stirring paddle is selected in the device.The mixing time and speed are reasonably selected according to different characteristic pollutants,but controlling the stirring speed not lower than 60r·min-1,the stirring time not less than 1 minutes and the reaction time not less than 30 minutes.To sum up,the chemical oxidation reduction device in this study has good material performance and good use effect.It can meet the requirements of emergency treatment equipment well,and is of great significance to emergency treatment of environmental emergencies in water source.