High Efficiency Aeration Technology And Its Application In Coking Wastewater Treatment

In recent years,the water quality discharge standards of coking wastewaterhave become increasingly high,and the development of efficient pre-treatmentand biochemical treatment processes has become the focus of coking wastewater treatment.Aeration technology plays an important role in pretreatment and biochemical treatment,but there is a problem of high energy consumption in aeration.Therefore,improving the efficiency of dissolved oxygen in aeration is of great significance.In this study,a new type of air-fluid oscillator was developed for aeration system.The stable flow into the aerator was changed into oscillating flow.With the total mass transfer coefficient of standard oxygen as the index,the influence of factors such as type of aeration disc,length of feedback channel of the oscillator,air flow on the efficiency of aerated dissolved oxygen was investigated.The internal flow field of the oscillator was simulated by fluent software,and the oscillating principle and influencing conditions were analyzed.The results show that the fluid has stable wall attachment in the oscillator,and the pressure acting on the fluid at the control end causes periodic change of flow direction,which results in fluid oscillation.Clean water aeration test shows that the oscillating flow of EPDM microporous aeration disc can increase the total mass transfer coefficient of standard oxygen by 114.6%compared with the steady flow under the optimum oscillator feedback channel length and air flow rate.Oscillating flow reduces both bubble size and bubble size,resulting in a 42.6% decrease in average bubble size.Coking is pretreated by air floatation with the system of "air oscillator + EPDM disc aeration".Field test shows that increasing aeration and adding demulsifier can improve oil removal efficiency.Under the optimum conditions,the aeration oil removal rates of oscillating flow and stable flow are 81.41%,44.89%,COD removal rates are 55%,8%,ammonia nitrogen removal rates are 67%,8%,and the maximum removal rates of volatile phenols are 23% and 3% respectively.At the same time,compared with the stable flow air flotation pretreatment,the oscillating flow aeration flotation system can significantly improve the biodegradability of wastewater.The system of "air oscillator + EPDM disc aeration" is used to improve the efficiency of aerobic biochemical treatment of coking wastewater.Field test shows that EPDM micro-porous aeration disc aeration system is better than phase titanium disc under the best operating condition of air oscillator.Compared with the steady flow,the COD removal rates of the two improved by 166% and 31% respectively.Fluent software is used to simulate the structure parameters of the fluid oscillator under actual operating conditions.The results show that when the oscillator is amplified,the width of the inlet section and the arc of the splitting should be minimized while the overall size is scaled up.The research technology can be used for technical transformation of coking pretreatment system and biochemical treatment system,and simulation technology can be used to guide the design and manufacture of high-efficiency industrial aeration equipment.