Study On Treatment Technology Of Low Concentration Refractory Organic Chemical Wastewater

In this paper,the ozone-copper catalytic oxidation+PACT(powder activated carbon-activated sludge process)+denitrnfication sludge process is used to degrade the COD(chemical oxygen demand)of the wastewater.The efrects of ozone catalytic oxidation on COD removal were discussed by changing the catalyst type,dosage,reaction contact time and influent pH.Contrast the Aerobic biofilm method,aerobic sludge method and PACT to remove COD and ammonia nitrogen,change the type and dosage of powdered activated carbon in PACT,and explore the influencing factors of PACT to remove COD.By changing the dosage of carbon source,denitrification can remove the nitrate nitrogen to achieve the best effect;GC-MS is used to determine the changes of volatile organic compounds in water,and the removal of volatile organic compounds in each stage is understood from the microscopic point of view.Through research,the following conclusions are obtained:(1)For refractory wastewater,COD effluent reaches 92mg/L through ozone/copper wire catalytic oxidation+PACT+denitrification sludge process.The influent indicators of industrial wastewater are:COD 287mg/L,ammonia nitrogen 49mg/L,nitrate nitrogen and nitrite nitrogen close to 0 mg/L.The final effluent values are:COD 92mg/L,ammonia nitrogen 1.07mg/L,nitrate nitrogen 1.5 mg/L,and nitrite nitrogen 0.45mg/L.(2)The best catalyst for the catalytic oxidation of ozone is copper wire,the COD effluent is 180.6mg/L,and the biodegradability is optimal.The synergistic oxidation of ozone to remove COD is affected by the type of material,reaction time,dosage,and initial pH.The catalytic oxidation of ozone catalyst is the fastest in the first 20mim and tends to be stable in the later period.Ozone-catalyzed oxidation is better than acidic conditions under alkaline conditions.The conditions of over-alkali are not conducive to ozone-catalyzed oxidation to remove COD.Ozone catalyst catalyzed ozone oxidation COD removal rate increases first and then tends to be gentle as the catalyst input increases,and excessive catalyst loading will reduce COD removal rate.When catalytic oxidation is used to remove COD,the metal catalyst is superior to the non-metal catalyst.The catalytic activity of the metal catalyst is better than that of the non-metal catalyst.(3)When the aerobic treatment of ozone/copper wire catalyzed oxidation of water,the COD removal effect was ranked as PACT>aerobic membrane method>aerobic sludge method,and PACT(modified shell carbon)was the best to remove COD.The COD effluent was 100mg/L.When the residence time is 6h,the removal of COD can achieve better results.The rate is about 26%,and the removal rate of COD by the aerobic sludge method is about 24%.When PACT method uses fruit shell powder activated carbon,bamboo powder activated carbon and modified fruit shell powder activated carbon,the effect of modified fruit shell powder activated carbon is the best;the modified fruit shell powder activated carbon dosage is best at 50mg/L.The removal rate of COD can reach about 45%;at the same time,ammonia nitrogen can be converted into nitrate nitrogen.(4)When denitrifying treatment of nitrate nitrogen,the effect was best when extermal sodium acetate 140mg/L was added.The final effluent of nitrate nitrogen was 1.5mg/L,and the final effluent of COD was 92mg/L.When denitrification is used to remove nitrate nitrogen,the degraded nitrate nitrogen is about 4mg/L;when the carbon source(anhydrous sodium acetate)COD is 120mg/L,the nitrate nitrogen has 8mg/L residual.When the dosage is 160mg/L,the removal of nitrate nitrogen reaches the desired effect,but the effluent COD rises to about 1 lOmg/L;when the dosage is 140mg/L,the removal of nitrate nitrogen is the best.(5)After the wastewater is treated by the combined process of ozone/copper wire catalytic oxidation+PACT+denitrification sludge method,the total amount of organic matter in the water is reduced.Main substances in wastewater are alcohols,esters,ketones,olefins,alkanes.aldehydes,acids,phenols,pyridines and naphthoquinones.Ozone copper wire catalytic oxidation method produces a large number of hydroxyl radicals.It can oxidize some macromolecular organic substances such as ethylhexyl benzoate,diisobutyl phthalate,octyl ethylene glycol mono-n-dodecyl ester,and oxidized carotenoids into small molecular organic substances,and the removal rate is higher than Single ozone oxidation is beneficial for biological treatment.Compared with the removal of organic matter by aerobic sludge method,the PACT removal of volatile organic compounds is basically the same,but the removal of organic matter PACT is higher than that of aerobic sludge method.