Research On Biodegradability Of Dianilinodithiophosphoric Acid And Its Treatment Method

In mineral flotation, organic compound was used to mineral flotation. Amony them, large numbers of flotation reagent was lost with the flotation wastewater. The residual organic flotation reagents in flotation wastewater have serious toxic effects on the biological and plant in mine environment, and brought serious environmental problems. With increasing concern of mine environment, there is an urgent need to develop a technology to treat the organic flotation reagent in flotation wastewater. At present, a lot of research have been focused on the organic flotation reagent treatment, but there are still many shortage such as low efficiency, high cost, instability of treatment efficiency and low industrial application. Therefore, develops a organic flotation reagent treatment technology and studies on the treating law and mechanism of organic flotation reagent will provide some theoretical and technical guidance for solving the shortage of existing technology and developing effective, stability and low cost organic flotation reagent treatment technology.In this research, chemical oxidation and biodegradation of dianilinodithiophosphoric acid was studied. In the research of sodium hypochlorite oxidation, the optimum technological conditions were optimized and the intermediates and oxidation path of dianilinodithiophosphoric acid was studied. At the same time, the reason of poor TOC removal in dianilinodithiophosphoric acid oxidation by sodium hypochlorite in the previous study was discussed. In the research of biodegradation of dianilinodithiophosphoric acid, the biodegradation characteristic was studied by BOD5/CODcr method, static flask screening method, shake flask test and modified Sturm test (PCD). A self-made submerged membrane biological reaction (sMBR) was used to treat the dianilinodithiophosphoric acid. The operation conditions such as hydraulic detention time (HRT) was determine. Additionally, the effects of influent Dianilinodithiophosphoric acid on activated sludge characteristics and microbial communities structure was studied in order to provide theoretical and technology support for optimize the dianilinodithiophosphoric acid treating by sMBR in industrial application. Furthermore, biodegradation and transformation paths of dianilinodithiophosphoric acid in activated sludge were studied. From the present research, the main conclusions can be drawn as follows:(1) The result of the optimization of oxidation condition shows that the influences of operating factors followed the order of NaOCl dose>oxidation time>pH, and NaOCl dose had a drastic effect on the effect of dianilinodithiophosphoric acid oxidation. It deserves to note that at 100mg/L dianilinodithiophosphoric acid,84.54% could be removed under the optimal conditions:NaOCl concentration=1.25g/L, pH=4 and reaction time=60min.(2) The chemical oxidation pathways of dianilinodithiophosphoric acid show that cleavage of N-P bond takes place firstly resulting in the formation of aniline and dithiophosphate. Among them, dithiophosphate was further oxidation to inorganic phosphorus and sulfur. And the oxidation of aniline is divided into two classes:one is benzene ring was attack to produce 2,4,6-trichloroaniline and then further oxidized to 2,4,6-trichloronitrobenzol; the second one is the aniline was attack to produce aniline radical, and then produce the dimers, the dimers further oxidized to phthalic acid ester and further oxidation occur to form small molecules. By study the oxidation intermediate of dianilinodithiophosphoric acid, the reason of the poor TOC removal in dianilinodithiophosphoric acid oxidation by sodium hypochlorite is the stable substances such as 2,4,6-trichloroaniline produced by the oxidation.(3) The results of the BOD5/CODcr method, static flask screening method, shake flask test and modified Sturm test (PCD) shows that dianilinodithiophosphoric acid is a biodegradable organic compound, but its biodegradation degree is slightly larger than the refractory organic compounds’ and it can be degraded by microbial after domestication. And the primary biodegradation kinetic equation of dianilinodithiophosphoric acid is Ct=21.191e-0.01747t.(4) Under the condition of 3 h HRT, gas/water ratio is 10:1～12:1 in aerobic zone, 95±5mg/L dianilinodithiophosphoric acid is effectively removed by sMBR. High reagent loading has little effect on the dianilinodithiophosphoric acid removal, but it has a great influence on the COD removal. sMBR treatment effect is good and stable during the long time operation, but the removal efficiency of phosphorus is not good.(5) Dianilinodithiophosphoric acid has a great influence on the characteristic of activated sludge in sMBR. MLVSS/MLSS, sludge settling characteristics, filtering properties, viscosity and activity of activated sludge were getting worse with long time operation and increasing influent concentration. Increasing the dianilinodithiophosphoric acid concentration can accelerate the exudation of extracellular polymers, especially the loose bound extracellular polymers and soluble extracellular polymers. Meanwhile, increasing the dianilinodithiophosphoric acid concentration was major effect on the exudation of protein in extracellular polymers, and it is the main substances which affecting on the characteristics of the sludge.(6) The result of microbial community analysis show that Zoogloea, Clostridium, Sideroxydans lithotrophicus, Thiobacillu, Thauera aminoaromatica and Alicycliphilus denitrificans were the dominant microorganism communities in the treatment of dianilinodithiophosphoric acid, and they has the amazing ability to germinate in dianilinodithiophosphoric acid treatment system. Meanwhile the similar analysis, clustering analysis, diversity analysis and NMDS analysis show that the microorganism community has great changed with the operation time going. The different between microorganism community structure of A zone and O zone was getting larger with the system operation, especially when the influent dianilinodithiophosphoric acid increasing.(7) Dianilinodithiophosphoric acid transfer pathway was that dianilinodithiophosphoric acid was adsorbed by SMP firstly, and then passed through LB-EPS transfer to TB-EPS, finally concentration in TB-EPS and biodegraded by microorganism. The biodegradation pathways of dianilinodithiophosphoric acid shows that cleavage of N-P bond takes place firstly resulting in the formation of aniline and dithiophosphate. And then dithiophosphate was further oxidation to inorganic phosphorus and sulfur by Microorganisms such as Clostridium, microorganism such as Thauera aminoaromatica、Alicycliphilus denitrificans can oxidized the aniline through oxidized to phthalic acid compounds and finally mineralization by TCA cycle.