Development And Application Of The Improved BFBR Process

With the improvement of the quality of life,the discharge of domestic sewage is also increasing year by year,but a considerable part of it is discharged without treatment.In recent years,the eutrophication of inland waters in China has become more and more serious.As a result,the frequency of water blooms has become higher and higher,and the landscape and use of surface water have been reduced.This not only increases the pressure on the environment.It also poses a threat to people's survival and health.As a new sewage treatment process,BFBR?Bio-Film Biological-Reactor?adopts certain artificial technical measures?including aeration,setting biological fillers,planting emergent plants,etc.?to create the growth of microorganisms and emergent plants.Appropriate conditions accelerate their growth and metabolism,utilize biological fillers and a large amount of microorganisms in the roots of emergent water plants to decompose organic matter in the water and convert it into stable organic matter,thereby purifying sewage.Based on the BFBR process,this article replaces the traditional aeration device with a micro-nano bubble generator independently researched and designed by the research group,aiming at better promoting the growth of emergent plants and making it more effective in the process of sewage treatment.The role of sewage treatment is more thorough.In recent years,micro-nano bubbles have received attention due to their unique properties,especially in the environmental protection industry,and have been widely used.The physicochemical properties of micro-and nano-scale air bubbles produced by micro-nanometer bubble generators are very different from those of ordinary-sized air bubbles.In this paper,we studied the effect of micro-nano bubble aeration and common aeration on dissolved oxygen in water.We found that micro-nano aeration can dissolve more oxygen into the water and make the dissolved oxygen in the water supersaturated and maintain a long time.This article also studied the micro-nano bubbles to promote the growth of the emergent water plant Iris pseudacorus L.It was found that the use of micro-nano bubbles in the growth process of Iris pseudacorus L.grows faster than ordinary aeration.In the same growth cycle,the use of micro-nano bubble aerationin the plant height,root length and other indicators showed a clear advantage.The improved BFBR process combines micro-nanometer bubble aeration,emergent water plants,and biofillers into a complete system that shows good results in the treatment of domestic sewage.?1?After the aeration of the micro-nano bubble machine,the dissolved oxygen in the water rises from 0 mg/L to 11.3 mg/L in a short time,and the dissolved oxygen in the water reaches an oversaturated state.At the same time,the dissolved oxygen in the water during normal aeration increased from 0 mg/L to9.07 mg/L,which did not cause the water to be in a saturated state of dissolved oxygen.The reason is that the diameter of micro-nano bubbles is much smaller than the diameter of ordinary aeration bubbles,and the residence time in water is longer than that of ordinary aeration bubbles.The size effect of micro-nano bubbles leads to a higher gas-liquid mass transfer rate and its surface.Tension will tear the micro-nanometer bubbles,so that the dissolved oxygen saturation state of the water body still has a high rate of gas-liquid mass transfer,eventually leading to the presence of dissolved oxygen in the water supersaturated state.Within three hours after the aeration was stopped,the dissolved oxygen in the micro-nano bubble aerated water dropped from 11.3 mg/L to 10.8 mg/L,and was still in a state of supersaturated dissolved oxygen.It is proved that the use of micro-nanometer aeration can not only make more oxygen dissolved in water,but also make the dissolved oxygen in water have a long root time,laying a solid foundation for the subsequent experiments.?2?It was found through experiments that the growth of the emergent plant Iris pseudacorus L.in the two environments of micro-nano bubble aeration and normal aeration has a great difference.The experimental results show that the root length of yellow iris growing for 30 days in the micro-nano bubble aeration environment reaches 46 roots in the range of 4⁸cm,accounting for 76.6%of the total.Most of them are well developed,and the whole tends to be ripe and pass through.The root length of common aerated Iris pseudacorus L is mainly in the range of 1 to 6 cm,accounting for 85%of the total,and it is generally biased towards the newly emerged young roots.The high concentration of Iris pseudacorus L.plants growing in the micro-nano bubble aeration environment is 18 to 26 cm,accounting for 85%of the total number of yellow iris,and only 10%of the Iris pseudacorus L.plant height is less than 18 cm,compared to the normal aeration environment.The plant height of the growing yellow iris is concentrated at 14-22cm,in addition to 15%of the yellow iris below 14cm.It can be seen that the plant height and root length in the micro-nanometer aeration environment are more advantageous than the yellow acacia growing in the common aeration environment,and the growth is faster and the development is better.In the BFBR process,the emergent plants bear the heavy responsibility of removing N,P and other elements from the water.The growth status of these plants will directly affect the treatment of the sewage.?3?The improved BFBR process shows good results in the treatment of domestic sewage,among which CODcr,TN,and NH₃-N all meet the Class I A standard in the Urban Pollutants Discharge Standard for Pollutants.The removal rates reached 91.12%,82.21%,and 89.10%,respectively,and the TP and SS indicators also reached the Class I B standard standard in the Urban Pollutants Discharge Standard for Pollutants.Compared with the BFBR process using ordinary aeration,the quality of effluent water has been significantly improved,and domestic sewage can be directly discharged after being treated with the modified BFBR process.