| In recent years,the improvement of aeration system in biological aeration tank of sewage treatment plant has never stopped,mainly aimed at the innovation of control system and aerator.This research is the first aeration method of partial pressure aeration,which makes full use of the air pressure produced by the blower,rearranges the aeration pipe and aerator on the basis of traditional aeration mode,and achieves high oxygen mass transfer performance.In this study,the double pressure and average aeration volume of the partial pressure aerator column and the traditional aeration reaction column were set up as the comparison object,and the fresh water aeration and oxygen filling experiment was carried out.Then,the SBR process was used to simulate the working conditions of the municipal sewage treatment plant to compare the preparation wastewater and the domestic sewage.At the same time,the properties of activated sludge were tested after the reaction column was operated for one month.Finally,the paper returns to the operation mechanism,explores the structural characteristics and advantages of the partial pressure aeration mode,and takes the Tangwang sewage treatment plant of Yangzhou as a case to transform the biological aeration tank with partial pressure aeration to carry out economic analysis.Through the research,the main contents and conclusions are as follows:(1)Through the experiment of aeration with clean water,the partial pressure aeration has been proved to have good oxygen transfer performance and has the potential of energy saving.The effective water depth is 3.2m for the partial pressure aeration column,and the average total oxygen transfer coefficient KLA(20)is 5.3 h-1 at different water depth positions;The oxygen filling rate EO was 0.0012 kg/h;The efficiency of oxygen transfer was EA 14.35%;The efficiency of oxygen charge Ep is 6.18 kg/kw*h,and there is a gap in the oxygen transfer performance in different regions in the interior,and the lower part is lower than the upper part.In the same height of the reaction column,the oxygen mass transfer performance of the two aeration modes is similar.Generally,the oxygen transfer coefficient,oxygen filling rate and oxygen utilization ratio of partial pressure aeration are 10.1%,10.4%and 10.6%lower than that of the traditional aeration column,and the performance gap of the upper part is smaller than that of the lower part.The average oxygen utilization rate of the pressure separated aerator at the same height is 19.3%higher than that of the traditional aerator,and the gap in the upper part is more obvious.(2)SBR process was used in the aeration stage,and partial pressure aeration was used to treat the preparation wastewater and domestic sewage.Compared with the traditional aeration,it showed a better pollutant removal effect.The results show that the degradation rate of pollutants in 60 min before partial pressure aeration is lower than that of traditional aeration,which has obvious delay,but the removal rate of pollutants in the wastewater reaches a stable value almost at the same time in 150 min.and the removal rates of total nitrogen,total phosphorus and COD in the prepared wastewater reach 63.8%,96%and 90%respectively;The removal rates of total nitrogen,total phosphorus and COD in domestic sewage are 64%,95%and 83.5%respectively.All pollutants have good degradation effect.The removal rate of total nitrogen is higher than that of traditional aeration,and the phenomenon of simultaneous nitrification and denitrification(SND)is more obvious.The overall effluent quality is similar to that of traditional aeration column.(3)After one month continuous operation of SBR process,the activated sludge indexes in the partial pressure aeration reaction column kept good.The sludge concentration SS was 3890 mg/L;The sludge settling ratio SV30 is 28%;The SVI was 71.2ml/g;The concentration of VSS was 2768 mg/L;The VSS/SS ratio is 71%,and the organic content of activated sludge in partial pressure aeration column is about 3%lower than that in traditional aeration.The results show that the partial pressure aeration has a positive feedback effect on activated sludge.(4)The partial pressure aeration system is improved on the basis of traditional aeration,which has the effect of energy saving and carbon reduction.This arrangement can reduce the waste of air pressure generated by the blower on the upper layer of the aeration tank.Through theoretical calculation,the two-layer partial pressure and equal aeration can theoretically reduce the power consumption of the blower by 25%.Taking Yangzhou Tangwang sewage treatment plant as an example,the daily power consumption of the blower in the aeration tank can be saved by about 7275.6 kW·h,which is equivalent to about 2910.24 kg standard coal,About 5711.35 kg CO2 emission was reduced;More complicated partial pressure aeration can reduce more electricity in theory,but considering the requirements of water quality and simplification,experiments and economic analysis are still needed.(5)If the biological aeration tank of Yangzhou Tangwang sewage treatment plant is reformed by partial pressure aeration,roughly 8512 EDI microporous aerators are needed;6 roots blowers;There are several PVC pipes,and the material cost is about 0.41 million yuan.The annual electricity cost of the blowers used in the sewage treatment plant is about 6.444 million yuan.After the completion of the plant,about 1.611 million can be saved from the electricity cost of the blowers every year.The income within one year can exceed the material cost required for the transformation,which has a huge application prospect. |
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