Diversity Of Bacterial Groups In A Hybrid Constructed Wetlandand Its Impact On The Nitrogen Cycle

With the development of the social,the integration of urban and rural areas become a inevitable trend,and rural urbanization is the only way to promote it.In this process,the destruction of water environment caused by the discharge of rural domestic sewage is becoming increasingly prominent. As a simple and effective technique for ecological wastewater treatment, because of the lower investment, simple process, easy control and environment beautification, Constructed wetlands?CW?will be widely using, especially suitable for the rural and small town areas,which are not stable and scattered in water quality and quantity.The study on the contribution of anaerobic ammonium oxidation and denitrification to nitrogen removal and the mechanism of denitrification in the study of the microbial community structure in the constructed wetland has a positive effect on the improvement of the nitrogen removal efficiency.This subject is based on a compound constructed wetlands,which is build by “VF+HF”technology,.On the basis of the relevant research of other numbers, to explore the microbial colony structure of lateral subsurface flow wetland unit, anaerobic ammonia oxidation and denitrification ratio and analysis and its seasonal variation.First of all,this article analysis the change regulation of the temperature in last year,and defined the six months?January to April,November to December?as Low temperature period,which temperature range between 9.7?²0.4?.defined the other six months?May to October? as low temperature period,which temperature range between 21.8? 31.7?.then analysis sewage treatment plant the rule of change of the indexes, and give a comparison of high and low temperature season analysis, the main conclusions are as follows:?1?The pH value between high temperature and low temperature period has little difference,which ranges between 7⁸ and conducive to the metabolism of various types of nitrogen removal microorganisms.It has a certain difference in the values of conductivity, turbidity, SS and other non nitrogen pollutant indexes between high temperature and low temperature period,but the general change regulation of the index value is basically the same.?2?The removal efficiency of pollutants in sewage treatment plants is good in different seasons,which is better in high temperature period. The concentration value of COD, TP, TN, NH3-N of sewage plant in high temperature period is better than low temperature period.Each pollutant index showed a gradual decrease in the whole process,but there is a slight accumulation of nitrate nitrogen in the wetland.?3?Compare the removal rate of each indicators of pollutants in various structures,we can find that no matter what season,the HF is the main place of the removal of nitrogen and phosphorus pollutants.Through the analysis of lateral subsurface flow wetland DO and ORP concentration value change can be found within the unit is a kind of aerobic, anaerobic and anoxic alternate cycle.?4?During the study period,the TN concentration of the effluent at high temperature is about ¹⁵.1 mg/L,which removal rate rich to 66.5%. And the TN concentration of the effluent at low temperature is about 19.8 mg/L,which removal rate rich to 61.4%.It appear a different degrees accumulation phenomenon of NO3-N,especially in the low temperature period,which concentration value reach to 4.06 mg/L.?5?This article choose one months at high temperature period and low temperature period to do Illumina high-throughput sequencing analysis in the filler of HSFWs bed,then analysis the microbial colony structure and relative quantitative. The results shows that the wetland microbial species is very rich no matter high temperature period or low temperature period.The major bacteria of high temperature period are Thiobacillus,Rhodocyclaceae,Anaerolineaceae and Limnobacteretc. The major bacteria of low temperature period are Thiobacillus,Bacillus,Lactococcus and Oceanobacillus etc.?6?Using the greatest homology method to identify the bacterial sequences associated with denitrification.We can find that there are 3¹⁵9 denitrification bacteria associated in high temperature period,which accounting for 33.26% of the total bacteria.And there are 8228 denitrification bacteria associated in high temperature period,which accounting for 41.93% of the total bacteria.Anammox bacteria only detected at high temperature period and only have 5series,which subordinate to Candidatus_Brocadia and accounting for 41.93% of the total bacteria.?7?Using ¹⁵ N isotope labeling, with the amount of 29N2 and 30N2 test by GC-MS to count, finding that during the experiment were there anammox reaction no matter high temperature period or low temperature period, but the reactivity and the contribution of denitrification is a little lower.