Study On Characteristics Of Tidal-continuous Flow Combined Constructed Wetland For Polluted River Water Purification

The current water pollution problem is a global problem,China's river pollution is also increasingly serious,showing a wide range of pollution and a high degree of characteristics.Water pollution has been a serious threat to people's health,river pollution control,especially the treatment of highly polluted river water has been widely concerned by all parties.A variety of river regulation works have been carried out.Compared with physical,chemical and biological methods,ecological technology,especially constructed wetland technology,has shown adventages.Constructed wetland is more and more highly respected in the treatment of high pollution river water because it is stable,efficient,convenient and low cost.Tidal flow constructed wetland has been used in some projects because of their good oxygenation effect.Because of the lack of anaerobic denitrification in this form of wetlands,there is no advantage in the removal of nitrogen.This paper studies the treatment of high-polluted river water by constructing tidal-continuous vertical flow combined constructed wetland.The main contents of the study are as follows:the study on the removal characteristics of organic pollutants from the polluted river water by the tidal-continuous vertical flow combined constructed wetland combination process;the removal characteristics of the pollutants in the high-polluted river water by the combined wetland combination process;downgrade process simulation analysis in tidal-continuous vertical flow combined constructed wetland.The different modes of operation in the two-stage vertical flow constructed wetlands are used to change the environmental characteristics of different constructed wetland units to improve the purification performance of constructed wetlands.Further,the purification rules of constructed wetlands are analyzed to explore the adaptability of combined constructed wetland to polluted river treatment in northwest China,so as to provide reference for the optimal combination of constructed wetland.Research indicates:?1?we set the soap river water as the research object,which organic matter seriously exceeds about 5 times of the minimum standard on the surface water and nutrient exceeds about 10 times.The removal rates of COD,BOD₅,SS,soluble TP,suspended TP,TP,ammonia nitrogen,organic nitrogen and total nitrogen are 85.60%,94.70%,98.70%,81.30%,89.20%,85.60%,87.70%,88.00%and 74.13%respectively in tidal-continuous vertical flow combined constructed wetland,and the removal effect is very good.?2?The dissolved oxygen in the tidal flow wetland is up to 2.5mg/L,and the dissolved oxygen in the continuous vertical wetland is less than 0.5mg/L,which is favorable for the nitrification-denitrification environment.The tidal-continuous vertical flow combined constructed wetland has high biomass,in particular,the tidal flow wetland is three times of the traditional vertical flow wetland.Removal efficiency of organic matter and nitrogen is high and stable.?3?Plants and substrates play an important role in the removal of nitrogen and phosphorus.Strong adsorption of slag and gravel,with reed complex root structure,can achieve the majority of phosphorus and suspended solids removed.The contribution rate of nitrogen and phosphorus in the plants with high root yield and high oxygen consumption is 19.8%and 17.9%,respectively.?4?Under low temperature,the microbial activity and the ability of substrate to adsorb phosphorus are decreased,which affected the denitrification effect.but low temperature has little effect on the removal rate of organic matter and suspended matter.?5?DO is the main influencing factor of wetland treatment effect.Alkalinity has inhibitory effect on denitrifying bacteria suitable for neutral environment.Wetland bacteria are not sensitive to ORP changes.For high-polluted river water,the effect of artificial wetland on the denitrification of highly polluted river water is not affected by the concentration of organic matter.?6?The tidal flow wetland can enhance the anti-load impact ability,reduce the inlet load of the follow-up wetland,improve the processing efficiency of the follow-up wetland,and reduce the risk of jamming.This combination of constructed wetland has long-term stable and efficient treatment of high-polluted river water.?7?The monod model can be used to describe the denitrification removel of tidal-continuous vertical flow combined wetland,which is better than the first-order dynamic model.