Development Of A Slow-Release Organic Carbon Source And Evaluation Of Water Purification Performance Of The Carbon Source Combined With Bacteria-Loaded Capsules

Nitrogen pollution,which is the most common and serious phenomenon in river pollution,can lead to eutrophication of water bodies and has been taken more and more seriously.Recently,many scholars have paid close attention to nitrogen removal problem of sewage with low carbon to nitrogen ratio and strived to develop an advanced and high efficient denitrification process which is simple and easy to operate with no secondary pollution.In the biological treatment of wastewater with low carbon and high nitrogen,an indispensable and effective manner is to artificially add carbon resource and microbial inoculum.In order to achieve efficient nitrogen-removal and hence high water-clarifying performance,the immobilized sustained-release carbon source was developed and then the water purifying capacity of a novel management strategy,which integrated the carbon source and water purification bacteria-embedded solid capsules,was investigated in this study.The main results are as follows.（1）For the development of slow release carbon source,the material A and B were used as the main scaffold material and sodium acetate was used as the carbon source and embedded with carrier materials.Then the influence of factors such as the ratio of adding materials,the processing temperature,the type and dosage of the auxiliary agent,and the product morphology on the release performance of sodium acetate was studied.Finally,a slow release carbon source with excellent sustained release properties was obtained.The release of sodium acetate has obvious linear characteristics.Scanning electron microscopy（SEM）was carried out to analyze micro-morphological changes to the entrapments before and after release of the carbon source.It is presumed that the carrier material of slow release carbon source should be coated on the surface of sodium acetate particles in the form of lamellar layer,the visible pore-rich multi-lamellar structure is formed and the skeleton structure of the embedding material remains intact after the dissolution of sodium acetate from the lamellae.（2）The bacteria-embedded solid capsules were divided into two categories W-capsule and B-capsule which included Pseudomonas stutzeri ADH1,Enterobacter sp.AOZ1 and Bacillus subtilis BSK9.（3）The water purification simulation experiments were performed on river sewage.Sewage treated using instant/sustained-release carbon source and bacteria with/without embedding were tested as comparable controls.Untreated sewage was also tested as a negative control（NC）.The obtained results showed that extensive wood shaving-like structures formed inside the entrapments after the release of sodium acetate;the TN remove rate of the sewage treated with sustained-release carbon source was 60.21%,and the COD kept less than 20（mg/L）;for the sewage treated with W-capsule and the combination of sustained-release carbon source and bacteria-embedded capsules,the TN remove rate was 39.10%and 85.21%.It was significantly important that comparing to the NC,instant carbon source-treated group and instant bacteria-treated group,the TN remove rate had been enhanced by 68.72%,66.22%and 67.00%,respectively,with the novel strategy.Therefore,it is concluded demonstrated that the novel combinatorial strategy in the current study is highly efficient in the nitrogen removal of river sewage,and has promising potential for popularization and application.The results of the main component analysis based on DGGE showed that the addition of slow release carbon source or water purification bacteria agent could change the bacterial community structure in water.（4）The field application experiment of slow release carbon source was conducted in the biofilter of Xiao Tongcun of Jinhua.It can be concluded that the removal rate of NH₄⁺-N was increased by 49.83%,of TN was 34.92%,and the COD was kept below 20mg/L after adding the slow release carbon source.And in the field experiment of Tan Shuqu,the removal rates of NH₄⁺-N,TN and COD were31.55%,16.88%and 19.04%.It can be seen that slow release carbon sources can still denitrify effectively in the field and without causing secondary pollution.