Application And Demonstration Of Dispersed-Ozone Flotation (DOF) On Urban Wastewater Reclamation

In this study, we chose dispersed-ozone flotation (DOF) process as the method todo the urban wastewater advanced treatment pilot experiment and field applications forthe propose of wastewater reuse. DOF is a national patent technology (Invention patentnumber: ZL200410073500.4) which was researched by our research group in recentyears. DOF is a process which highly integrates chemical and phy-chemical treatmenttechnology, through a combination of low concentration ozone oxidation and a newdissolved air flotation technology, completes cohesion, oxidative bleaching, ozonedisinfection, flotation and other process in a single unit device, and closes automaticallyscum exclusion The total hydraulic retention time of the system was less than40minutes and substantial improvement in efficiency.The research result showed that the key parameters which affected the stableoperation of the dispersed-ozone flotation process were PAC dosage, ozone dosage,dissolved oxygen condition, slugging cycle and so on. In regard to the secondarybiological treatment effluent, the best operating conditions of the process as follows:PAC dosage amount was50mg/L, ozone dosage was3mg/L, dissolved oxygenpressure was0.3Mpa, the reflux ratio was50%,100minuets of the slugginginterval,and2minutes of slugging time.As the matter of the process characteristic, DOF has a good buffering capacity onthe load of the influent quality, especially about the loads of the color, turbidity,bacterial and E. coil etc. The results showed that the turbidity, color, TP and COD of theeffluent accorded with urban miscellaneous water quality standards (GB/T18920-2002) after advanced treatment by DOF. The study researched dewaterability of the scum after DOF by the way offlocculationand centrifugal. The results showed that the order of ability of affecting thedehydration effect: centrifugation time> centrifugation speed> flocculation dosage. Itwas summarized that the water content of the scum dropped from97.73%to86.71%and the reduction in volume to1/49by flocculation centrifugal dewatering whichgreatly reduced transportation costs and facilitates the subsequent processing of dross.For the shortage of water resources of Yanliang aviation industrial base in Xi’an,the ozone flotation technology as the core technology was applied to the sewagetreatment and reuse project of Yanliang aviation industrial base, which achieved thediversified use of reclaimed water and system optimization of water-deficient area.Thisproject uses the secondary effluentof the2500m3/d scale wastewater treatment plant asraw water, constructing a capacity of5000m3/d advanced wastewater treatment facility,the quality of effluent could meet the National City Reclaimed Water Quality Standard(GB/T18920-2002) and Industrial Water Quality Standard (GB/T19923-2005).Reclaimed water provides not only include the municipal water such as greening,watering, flushing and universities, residential area of water, it also provides industrialwater such as industrial circulating cooling water, boiler water, while the use of recycledwater storage tank with the fire reserves of water, thereby realizing diversified use ofreclaimed water and system optimization of water-deficient area.