| In 2015 the State Council promulgated the "Water pollution control action plan",clearly pointed out that by 2020,the county sewage treatment rate reached about 85% and urban reached about 90%,all counties and key towns have capacity to sewage collection and treatment;The quality of water environment in the whole China would be improved periodicity,the serious pollution of water is greatly reduced.At present,the county sewage treatment rate is about 80%,the towns is less than 30% and villages is only 8%;There are 116 major lakes in China and 90 of them are eutrophication;736 main reservoirs in eutrophic state has 259.Studies have shown that algal blooms are often in the sewage collection and treatment is not perfect in urban and rural areas,to solve the problem of water environment in this area,we should select investment,processing process is simple,needs less maintenance,low operation cost.This paper is based on the "Vertical Flow + Horizontal Subsurface Flow" constructed wetland wastewater treatment plant.Analysis of seasonal variation of pollutants in wastewater treatment plant,variation law of dissolved oxygen and nitrogen pollutants in the HSFW,and explore the microbial diversity by high-throughput sequencing.Since the Chongqing summer is long,spring and autumn are short,so this paper consided direct use of temperature to division season.Analysis of temperature variation throughout the study period,the monthly average temperature higher than 25? into summer,the monthly average temperature between 15?~25? as warm season,the monthly average temperature below 15? into winter,so as to study the seasonal variation of the water pollution law.The main conclusions are as follows:(1)During the study,the constructed wetland wastewater treatment plant has a good effect on the removal of pollutants,the quality of the effluent water in summer is better than that in other seasons;The difference of pH value in summer,warm season and winter is very small,which is between 7 and 8;HSFW is the main pollutant removal unit in each season,and there is a significant accumulation of nitrate nitrogen when sewage flow through the HSFW;The sewage plant effluent SS and COD concentrations meet the "urban sewage treatment plant pollutant discharge standard"(GB18918-2002)the first level of A,effluent TN and NH4+ concentration meet the first level B,TP treatment effect is poor only to meet the effluent standard level two.(2)Based on the analysis of DO and ORP values of HSFW,it was found that the HSFW was in a state of aerobic,anoxic and anaerobic;Using COD instead of BOD,analysis the ratio of COD and TN removal in the HSFW,the summer is about 1.91:1,warm season is about 1.94:1,the winter is about 2.12:1;Compared with the traditional nitrification denitrification theory's C/N value,is less than 2.86:1.It is assumed that anammox may occur in the HSFW,and the response is more obvious in summer.(3)The high-throughput sequencing results showed the dominant bacteria in the HSFW successively were Anaerolineaceae,Thiobacillus,Nitrospira,Comamonadaceae,Xanthomonadales,Holophagaceae.Among them,Anaerolineaceae was proved to be able to degrade carbohydrates and other cellular materials in methanogenic biological systems;Thiobacillus and Nitrospira are belong to the biological denitrifying bacteria;Most Comamonadaceae can remove phenols,steroids and other pollutants.(4)The biological nitrogen removal sequences accounted for 24% of all gene sequences,the dominant bacteria was Thiobacillus;In addition,two anammox bacteria were detected,one with Candidatus Anammoxoglobus propionicus homology of 100%,another homology with Candidatus Brocadia fulgida reached 99%.It is speculated that the interaction between the traditional biological nitrogen removal and anammox reaction of the HSFW,in the microbial level is mainly Thiobacillus and Candidatus Anammoxoglobus propionicus,Candidatus Brocadia fulgida together. |
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