Enhanced Treatment Of PVC Wastewater With Ozone Microbubble And Their Operation Efficiency Inon-site Pilot Plant

In view of the practical problems of high energy consumption in the treatment of polyvinyl chloride(PVC)centrifugal mother liquor wastewater in Hebei Shenghua Chemical Industrial Park,the operating parameters were optimized through laboratory tests and field tests.This study aimed to enhance the treatment of PVC centrifugal mother liquid wastewater using microbubble ozone catalytic oxidation process.In this paper,the effects of main parameters(e.g.microbubble size,ozone inlet flow rate,catalyst dosage)on the treatment efficiency of PVC centrifuge liquid wastewater were studyed.The purification efficiency of first-grade BAF was investigated,and the optimal aeration amount was determined.Meanwhile,the micro-bubble ozone catalytic oxidation process was combined with the two-stage BAF process,and energy saving and consumption reduction of this process were accessed based on the operation efficiency of the on-site pilot.In the microbubble ozone catalytic oxidation process,the influences of ozone microbubble size,ozone inlet flow rate and catalyst dosage on the treatment efficiency of PVC centrifuge liquid wastewater were studied.The results showed that the removal of organic matter in PVC wastewater was improved with the increase of ozone inflow rate,and the mass transfer efficiency of gas phase ozone to liquid phase was increased with the reduce of size ozone microbubbles.The removal rate of COD in PVC centrifugal mother liquid wastewater could reach 46.4%,when the optimal conditions of ozone inlet flow rate of 0.3 L/min,microporous aerator aperture of 0.5 μm and activated carbon catalyst dosage of 10 g/L and the mcrobubble ozone catalytic oxidation process were applied.The B/C value of PVC wastewater treated by microbubble ozone catalytic oxidation process increased from 0.45 to 0.88,indicating that the biodegradability was significantly improved,providing favorable conditions for subsequent biological treatment.In the pilot test system of microbubble ozone catalytic oxidation and two-stage BAF,the treatment efficiency of PVC centrifuge liquid mother wastewater was investigated.The results showed that the optimal dissolved oxygen(DO)and microporous aeration head sizes treatment of PVC centrifuge liquid wastewater in the first-stage BAF were 5 mg/L and 2 μm,respectively.In the optical conditions,the ammonia nitrogen concentration of the primary BAF effluent was maintained at 2.3 mg/L,the COD removal rate of the PVC mother liquor wastewater was 28.0%.The ozone microbubbles increased the COD removal rate of the ozone oxidation unit by 20.0%compared with the actual wastewater treatment plant.With the use of the ozone microbubbles,the dosage of ozone was reduced from 12 g/h to 8 g/h Meanwhile,the aeration of the first-stage BAF was optimized.The results indicated that the dissolved oxygen content of the BAF in the treatment of PVC centrifuged mother liquid wastewater plant was 7 mg/L.In this case,the dissolved oxygen amount could be controlled at 5 mg/L,saving about 30%of the electricity consumptionThe existing PVC centrifugal mother liquid wastewater treatment plant could save operating costs by 30%～40%via controlling the size of ozone microbubbles,using activated carbon as a catalyst,and reducing the aeration amount in BAF.