Treatment Of TNT Wastewater By Electrochemical Method

The wastewater of explosive factory include three kinds, they are TNT, HMX and RDX wastewater. The TNT wastewater is the most polluted and pulled out most. This wastewater is known by complicated composition, high density and difficulty to be degraded and great danger. It can make human body and mandibles impatient or chronic to be poisoned, and seep into the soil and water body.At present, Treatments of this wastewater mainly are extraction, flocculation, adsorption, ultrasonic, incineration, Fenton, ozone oxidization, light catalyst oxidization and the organic methods.Those methods seldom studied the TNT basic water, the objects were mainly the water with low concentration, and frequently mixed with pure substances, the processes are not only complicated, but also with low efficiency and high expenses.This article treats the TNT red and yellow wastewater of an explosive factory as object to study. With PbO₂/Ti electrode to electrolyse this water, there were no similar reports of this research, which belongs to Advanced Oxygen Process.The main contents of the experimentation are: study of the factors effecting the reaction, the possibility of treating the TNT red and yellow wastewater by electrochemical and flocculation methods, the best condition of those methods, the mechanism of the electrochemical methods and the electricity consume.Experiment the result enunciation:(1) factors Affect the reaction of TNT from high to low are slot electricvoltage, the support electrolyte density, the distance of the electrodes and the cathode material, and the ex- three all have something to do with charge density, which influents the color degree, CODCr, TNT and bio-chemical value heavily. With its increase, the later three increased continuously, the bio-chemical ability of the waste water also enlarges continuously.(2) The treatment of TNT red water varies with the concentration. The efficiency of the dilution after decline to 500% or more is lower obviously, particularly to color degree. This method has high removal of TNT while low removal of CODo(3) With the charge of 50mA/cm2, distance of electrodes 3cm, treating the TNT red water by electrochemical method 24h, TNT removal can be 100%, while the CODa low and after 24h treatment the bio-chemical value increased to 0.2. Additionally, under the same conditions, the removal of color, CODcr and TNT of the yellow water are respectively 85.8%, 60.8% and 98.7%.(4) The dynamic state and static state of the TNT red water are nearly the same.(5) The best the condition of the flocculation of the TNT red water is: pH 8, the PAM (10 g/ L) 150 mg/ L, the volume ratio of PAM and the aluminium sulfate (100 g/ L) are 1:3. under those conditions the removal of color, CODcr, TNT are respectively 32.7%, 45.1% and 67.1% while the yellow water are 41.9% and 33.1%.(6) The efficiency of electrochemistry- flocculation pretreatment of TNT red water and electrochemistry- flocculation treatment of TNT yellow water is obviously better than the pure electrochemistry and flocculation methods, but those are worse than flocculation- electrochemistry method. After those treatment, the removal of red water are respectively 57.4%, 70.9% and 87.2%, the yellow water are 95.8% (CODq) and99.1%(color).(7) The existence of the intermediate like aniline is proved up, the amount of which is abound to the charge density. The most likely degrade process is that the compounds of nitryl firstly deoxidized to aniline by the cathode then oxidized by the HO- created by the PbO/Ti.(8) The electricity consume of treating the yellow water by electrochemical method are high while the flocculation- electrochemistry method low, removal lkgCOD<, needs about 20 degree electricity. So this method has promising future in the industry. And for TNT red water, the power needed in both methods are low and worth to research in the future.