Study On N-PHenylglycinonitrile Production Wastewater Treatment

N-phenylglycinonitrile chemical wastewater is one of the refractory wastewater with high concentration, low biodegradability and high toxicity; the main components are anilines and cyanides which are harmful to organisms at low concentration ,difficult to treat and classed as hazardous pollutants. It was started from the raw water quality analysis, and found an aniline analysis method suitable for water quality characteristics in this study; from the experiment methods of bentonite purified,modified,wastewater treatment,and modified by cross-linking modification of sodium and iron,the mineral microstructure,physical and chemical properties of the unmodified or modified products were analyzed; it also explain its physical and chemical properties and mineral micro-structure of the relationship between changes after the bentonite was modified; montmorillonite iron and H₂O₂ combined as a promoter of aniline-acetonitrile wastewater pretreatment was studied, the optimal operating parameters were obtained, and the reaction mechanism was discussed; and then the experimental design, starting and stable operation of the research ,with the effluent at the pretreatment levels which was treated by two-phase anaerobic reactor was undertaken .As the complexity of the wastewater components, the detection process will interfere with each other,especially for the detection of the anilines existing in the wastewater. Therefore, the detection method of the aniline compounds in wastewater was studied firstly.So change the way to a more secure and more feasible method, it is the ultraviolet spectrophotomety, at pH=6.6, the aniline is determined at 230nm. It has a good linear relationship when the concentration of aniline range from 0³4.00 mg/L , related coefficients is 0.9998. The relative standard deviation of aniline is less than 5.0%, the rates of recovery of aniline is 98.55%～100.61%, so the results are satisfactory. Therefore, this method for the detection of anilines was used in the experiments.During the research of the wastewater pretreatment ,firstly, using Ca-bentonite as raw material, Na-bentonite was prepared by microwave radiation after purification, and the preparation conditions were as follows: using NaCl as modified regents,the reagent volume of 50% C₂H₅OH to the bentonite quality is 7:5(ml/g)and the reaction time is 4min, the experimental results showed that the CEC of Na-bentonite increased to 93mmol/100g after modification from 62.4mmol/100g which is useful to the Fe-pillared modified.Secondly, Na-bentonite is used as raw material.For the wastewater treatment limitation of organo-bentonite, using the Fe-pillared bentonite and H₂O₂ to treat the N-pHenylglycinonitrile chemical wastewater by oxiditon was tried, and the removal ability was investigated,too. The experimental results showed that the optimal treatment conditions were obtained as follows: pH value is about 4.0, added amount of H₂O₂ is 6.66g/L, amount of Fe-pillared bentonite added is 20g/L, temperature is 30℃,and treatment time is 60min, the removal rates of the COD_cr and aniline can reach 40.6%, 92.6% and the content of aniline is less than 500mg/L,the BOD₅/COD_cr increases to 0.32 which meets to the requirement of subsequent biochemical treatment. The effect of oxidation method by Fe-pillared bentonite and H₂O₂ had been improved effectively. Simultaneously, the reaction kinetics was studied.The structures of Na-bentonite, and Fe-pillared bentonite was investigated by XRD, IR and SEM respectively. Studies on X-ray diffraction date (XRD) demonstrated that the interlayer spacing was obviously enlarged through Fe-crosslinked modification; the results of infrared spectrum (IR) discovered that some new characteristic peaks appeared, and the basic structure didn't destroy; SEM indicated that the bentonite surface was packed with the modified groups via, which improved the treatment effect, therefore, the change of structure and properties of bentonite were useful to the treatment efficiency during modification.During the experiments of two-phase anaerobic treatment, firstly the original wastewaterwas diluted, accession the sludge from Coking Plant of ChongQing Iron and Steel Company ,then the sludge was inoculation cultured, to gradually increase the concentration of the influent,and the methanogenic phase was divided into two modes to run to gradually adapt to the wastewater sludge. After the success of the cultivation, the most proper value ranges of some important effect factors of this bio-chemical system had been determined. Fore phase of acid producing the proper condition is T=30～35℃,pH=6.0～6.5 HRT=24h and the capacity burden is 7.95COD_cr/m3d; fore phase of methane producing the condition is T=30～35℃,pH=8.0～8.5, HRT=48h, and the capacity burden of the two stages of methane producing are 4.65kgCOD/m3d and 3.38kgCOD/m3d respectively. In the two-phase anaerobic best running conditions, the treatment effect can be achieved67%. Simultaneously, the sludge flocculation body and the image of the microbe of bio-chemical stage had been studied. For the fragment of the sludge flocculation body, the sludge flocculation body from phase of acid producing compare with the phase of methane producing is more incompact, the microbe are exposed on the surface of the sludge contrast with the phase of methane producing. Fore the image of microbe, the main microbe in phase of acid producing are bacillus,Clostriolium and vibrio, on the other hand the methanococcus is the most contribution of the microbe in the phase of methane producing, there still have some methanobacterium been found.At last, under the operating conditions in the study,the outlet of physic-chemical stage had been put into the two-phase anaerobic stage for several periodicities, the data shows that the removal rate of aniline compound is 50% and the COD_cr is about 68%, and the removal of aniline is contributed only by the phase of acid producing but almost not by the phase of methane producing.