| Nitrobenzene is an indispensable and important chemical raw material in the production process of styrene,and the market demand is large.Combined with the actual production situation,this paper studies the treatment of nitrobenzene production wastewater,which has high academic value and practical value,and has important reference significance for the treatment of similar organic wastewater with similar water quality.Firstly,the source and water quality of nitrobenzene production wastewater were investigated and analyzed by gas chromatography-mass spectrometry(GC-MS),and the main components of the wastewater were determined.According to the characteristics of the production process,in line with the principles of energy saving,emission reduction,clean production and circular economy,the technological line of wastewater classification treatment is adopted.According to the different sources of wastewater and the water quality,the treatment process combined with the pretreatment and biological treatment is adopted,and the treatment process is put forward according to the process of extraction advanced oxidation biochemistry.Through the laboratory test,the optimum technological conditions are determined,and the processing ability of the whole process is understood and mastered,which can provide scientific basis for the subsequent experiment and practical application of the wastewater.This paper deals with the treatment of nitrobenzene production wastewater by extraction.By qualitative and quantitative analysis,the main organic pollutants in the production wastewater are nitrobenzene,which have high toxicity and have been listed in the world "environmental priority control of toxic organic pollutants".Nitrobenzene contained in waste water is the raw material,intermediate and even crude product in the process of production.Effective and rational treatment of wastewater containing nitrobenzene and recycling of raw materials is one of the important topics of comprehensive utilization of resources and environmental protection.The effects of initial pH value,diluent,extraction time,extraction time and other factors on the extraction process were investigated.The optimum extraction conditions of the wastewater are as follows: using kerosene as a diluent and three butyl phosphate as an extractant,the extraction time is 30 min,the concentration of the extractant is 70%,the extraction is compared with the ratio of oil to water(oil / water ratio)1:5,and the extraction operation is carried out directly with the original water pH,in which the extraction progression is selected two grades.Results after extraction,the chroma of wastewater decreased from 10000 to 2000,the removal rate of COD was 67.2%,and the biodegradability of wastewater increased from 0.13 to 0.23 after extraction.The apparent color of waste water changed from brown to light brown.In addition,the back extraction process and the regeneration of the extractant are also studied.The basic parameters of the stripping process are as follows: the best extraction effect is achieved when the optimum oil / water ratio is 5:2 and the concentration of NaOH is 20%.And the selected extractant has good performance.After 8 extraction in the experiment,the degradation failure phenomenon has not appeared.It is proved that the extractant has good anti fatigue property.It is worth popularizing in the project.In this paper,the technological conditions of micro electrolysis and Fenton treating wastewater are studied.The Fe/C ratio is 1.2,the micro electrolysis reaction time is 120 min,the influent pH value is 3,the H2O2 dosage is 4ml/L,the Fenton reaction time is 150 min,the wastewater treatment effect is better,the COD removal rate is about 60%.The micro electrolysis-Fenton process is a very good method for the pretreatment of nitrobenzene containing wastewater.The operation cost is low and the operation is simple.After pretreatment with micro electrolysis,the biodegradability of-Fenton increased greatly from 0.19 to 0.30,and the effluent water quality had reached the level of biochemical treatment.In this paper,ozone catalytic method was used to treat nitrobenzene production wastewater,concentrated acid water extracted by meridian extraction and diluted acid water after micro electrolysis-Fenton.Catalytic ozonation was used for pretreatment to further improve the biodegradability.In this study,a new catalyst,activated carbon supported titanium dioxide,was used to improve the catalytic efficiency of ozone.The experimental results show that the COD removal rate of catalytic ozonation is 34% higher than that of ozonation alone,which proves the obvious catalytic effect of the new catalyst.Because the pH value is an important control parameter of ozone catalysis,the effect of initial pH on the treatment effect is studied experimentally.With the increase of initial pH,the removal rate of COD increases gradually,and when the solution is converted from acid to neutral,the increase of the removal rate is smaller than that from neutral to alkaline,and the alkaline environment is more beneficial to the degradation of organic substances by the basic environment.The mechanism of catalytic ozonation was investigated by investigating the adsorption properties of the catalysts.The removal efficiency of COD by catalytic ozonation is significantly higher than that of catalyst.The reaction mechanism was deduced by adding OH capture agent tert butyl alcohol.The experimental results showed that the addition of tert-butanol made catalytic ozonation,which decreased the removal rate of COD in wastewater obviously and had great influence,which indicated that the catalytic reaction process followed the free radical reaction mechanism.Hydroxyl radical formation is the main reason for catalytic ozonation initiated by hydroxyl groups on the catalyst surface.The influence factors of biochemical reaction on the treatment of nitrobenzene production wastewater were studied in this paper.The BOD/COD of the treated wastewater was over 0.3,and the biodegradability was good.Therefore,Moving-Bed Biofilm Reactor(MBBR)is used to treat nitrobenzene wastewater.The activated sludge which can be used for degradation of nitrobenzene production wastewater was domesticated by the improved COD loading method.When the influent concentration of wastewater is 1000-1800mg/L,the removal rate of COD can reach more than 60%.Microscopic examination revealed that there were a large number of protozoans and metazoans such as roving insects,cysts and rotifers in active sludge flocs,and were very active.The pre-hanging membrane method was used to film and start the reactor.After running for 3 days,the COD removal rate of the system reached a stable state of about 90%.In addition,the effects of reactor stability and HRT on the removal efficiency of the reactor were investigated,and the relevant parameters were determined.When the influent concentration changes at 300mg/L-600mg/L,the overall treatment effect of the reactor is relatively stable.With the prolongation of HRT,the removal efficiency of COD gradually increased.Considering the effect and operating cost,HRT is selected for 24 hours.The microorganism distribution in the MBBR bioreactor was studied.The results showed that the microbes in the MBBR reactor accounted for 64.5% of the total microbial biomass,and the average of the suspended microbes accounted for 35.5%.The biomass changes periodically during the reaction period,resulting in periodic changes in the biomass and suspended biomass,but has little effect on the effluent COD. |
