Study On The Treatment Of Nitrogen Containing Wastewater By BAF Using Prepeared Carbon Release Media

Aimed at the problem of excess nitrogen emissions,the state published a plan named"Water pollution control action plan"in 2015,which decided to control some indicators,like total nitrogen,total phosphorus and others,because they play very important role to water quality.Moreover,the state decided to start a study included a binding index system for the total emission of pollutants in river basins and regions,and made it clear that during the"13th five-year plan"period?2016-2020?,the effluent into the rivers and coastal regional library of the eutrophication of lake and relevant cities should implement the control of total nitrogen emission.China is a big agricultural country,and there are a large number of agricultural waste every year,such as banana peel,orange peel,walnut shells and et al,most waste just as fuel or discarded,not only cause the waste of resources but also increase the environmental burden.In order to salve this problem,our team have did a lot of research on walnut shell,we found that the walnut shell with special frame structure can be used as microbial carrier,and has a good interpretation of carbon release performance,but the application of walnut shell for BAF found in the process of long-term operation,walnut shell BAF is easy to collapse and blocked aerator,not only increase the backwashing frequency and brings energy consumption.Therefore,this test will use walnut shell grinding to powder as a slow carbon release source,and add a new preparation way of zeolite,cement and aluminium powder to prepare a newal porosity and carbon release filter,inspecting PCRM performance and its application in the study of BAF with its interpretation of the basic performance and the effect of nitrogen removal efficiecy,carbon release efficiency and optimize the operation parameters of BAF,finally get the following conclusion:?1?The porosity&carbon release media?PRCM?between 5.0 to9.0 mm were prepared by natural zeolite powder,cement,walnut shell and alminite powder.It's porosity was 68.18%,and the apparent density was 1.65 g/cm³,the compressive strength intensity was 100.8N and the bulk density was 0.57 g/cm³,the apparent area was 10.49×10⁴ m²/g.The compositionanalysis of PCRM was used X-Ray Diffraction?XRD?,observed the inner and outer surface was used Scanning Electron Microscope?SEM?and investigated the adsorbing capacity of ammonia and carbon release performance of PCRM,the results showed that the rough external surface and highly internal porosity could make a good place for microorganismgrowth,and enhanced the biomass on the biofilm,however,the adsorbing capacity of the ammonia were1.65 mg N/g,and the the release rate of the carbon source of the unit quality was 0.68 mg/?g·h?.?2?The initiation test of the suspended membrane of BAF showed that the microorganism can successfully both hang on the surface of PCRM and the CAC;The COD removal rate of PCRM reactor and CAC reactor were 86%and 91%respectively.The ammonia removal rate of PCRM reactor and CAC reactor were 95%and 92%respectively.The change trend of ammonia nitrogen indicates that nitrification and denitrification were present in both reactors.The change of p H and DO indicated that the exsitance of nitrification and denitrification reaction in reactors,and the sufficient concentration of DO and high p H value were necessary conditions for the success of the film.?3?The study on the process parameters found that HRT had little effect on the processing of COD_crr in the reactors.When HRT was 48h,both BAFs wastewater indicators were stable and showed good removal efficiency,and ammonia nitrogen removal rate of PCRM and CAC BAFs were 100%and 73%respectively,total nitrogen removal rate were 73%and 61%respectively,and both BAFs have NO₃^--N accumulation and nitrate accumulation.Stop increase aeration time,by contrast,has a large influence on the accumulation of nitrate nitrogen,when stop aeration time for 12 h,both the reactor didn't have nitrate nitrogen or nitrate accumulation,the ammonia nitrogen of PCRM reactor and CAC reactor removal rate were 94%and 92%respectively;The total nitrogen removal rate increased significantly,and the total nitrogen removal rate of the PCRM reactor increased to 99%,and the total nitrogen removal rate of CAC increased to 96%,which reached the level A discharge standard of wastewater.?4?Chemical parameters along BAFs of the research results indicated that PCRM reactor and CAC reactor between 30 and 60 cm showed good microorganism performance,and the most abundant microorganism were 14.85 nmol/P and 11.94 nmol/P respectively measured by lipid phosphate method,and at this area nitrification and denitrification showed good performance,and nitrogen remove rate very high in this area.