Microbial Enhanced Denitrification Of Constructed Wetlands And Utilization Of Sludge Resources

Since the 1980 s,the rapid economic development has had a significant impact on the environment.The excessive use of pesticides and fertilizers and the direct discharge of sewage have caused serious pollution to the water environment.The main substance causing eutrophication of water bodies is ammonia nitrogen,which seriously harms residents.Drinking water is safe and healthy,and thus constrains economic development.The removal of ammonia nitrogen is receiving more and more attention.Sewage treatment is accompanied by the generation of sludge.The amount of sludge generated in China is large.Landfilling a large amount of sludge requires land occupation.At the same time,it has aggravated the tension of land resources in China.In recent years,illegal dumping of sludge has occurred.This paper studies the denitrification of domestic sewage and the utilization of dewatered sludge.The treatment method for denitrification of domestic sewage is to use the highefficiency nitrogen-removing strains of domesticated cultivation in the previous period as the strains.The effects of three different inoculation methods on the removal of nitrogen in each reactor were studied,and the optimal inoculation method was determined.The produced sludge is used for resource utilization,and part of it is used for composting treatment: urea is used as nitrogen source,bagasse is used as carbon source,and the two are mixed as a regulator according to a certain ratio,and bacteria and fungi composite functional bacteria are constructed at the same time.The sludge composting effect was studied;the other part was treated with bricks,and Dongguan Yongan Brick Factory was used as an experimental base to pre-treat the sludge by different methods,and finally the experiment of mixing bricks with fly ash and foundation pit in different proportions.research shows:(1)Domesticated and cultivated high-efficiency nitrogen-removing strains,taking the actual domestic sewage as the research object,ensuring that the ammonia nitrogen(NH4+-N)and total nitrogen(TN)in the effluent reach the Class A standard of the Pollutant Discharge Standard for Urban Sewage Treatment Plants.Claim.Compared with the non-bacterial nitrogen removal effect,the one-time addition and secondary addition experiments showed a significant improvement.The removal rates of NH4+-N and TN were the highest in the secondary bacteria addition group,which were 99.6% and 86.6%,respectively.(2)In the sludge composting experiment,the heavy metal content in the sludge did not exceed the standard,which satisfies the Class B standard of “Sludge Disposal of Agricultural Sludge in Urban Sewage Treatment Plant”(CJT 309-2009).When the initial carbon-nitrogen ratio of the composting system is 20:1,the nitrogen,phosphorus and potassium in the sludge after composting are concentrated,the content is high,and the nitrogen fixation effect is obvious.At the same time,the temperature change is similar to the change of microbial quantity,and composting is more successful.The inoculation method of inoculation of compound bacteria Y123 in batches has the best degradation effect.In the 28-day experiment,cellulose and lignin decreased by 58.51% and 51.19%,respectively,which was more than 5 times higher than the blank W0 degradation rate,and the compost product could be used for agricultural production.(3)In the sludge brick experiment,the sludge pretreatment in this experiment is divided into three groups.In the first group,the optimal addition amount of sludge is 10 by directly using 5%,10%,15%,20%(mass ratio)of sludge with a water content of 60% and fly ash and foundation pit.%;the second group is sludge drying treatment,using dried sludge to make bricks,the sludge moisture content is 30%,the addition amount is 10%;the third group is sludge roasting treatment,using roasting sludge system Brick,sludge moisture content of 20%,added amount of 10%.It has been proved by the blending experiment that the sludge blending experiment is successful,and the compressive strength test is carried out by the Guangdong Building Materials Product Quality Inspection Center,which all meet the MU10 grade requirements of China’s Sintered Bricks GBT5101-2017.