The Study Of Remediation Technology Of TNT Red Water Polluted Soil

2,4,6-Trinitrotoluene（TNT）red water is an alkaline wastewater generated during the purification process of crude TNT by sodium sulfite method.TNT red water is dark red with the characteristics of complex composition and toxicity and poor biodegradability.TNT red water leaked into the soil,causing soil pollution.It has brought great risks to the local environment and human health.Therefore,it’s very necessary to treat TNT red water polluted soil.In this thesis,TNT red water polluted soil is regarded as the treatment object.Firstly,thermal decomposition was adopted to treat soil polluted by TNT red water.The main studies focused on the various influence factors on removal efficiency of soil polluted by TNT red water,including reaction temperature,reaction time and mass of polluted soil samples.And then we could select and obtain the optimal reaction conditions according to the residual organic oxygen demand of polluted soil.It is formed a program for remediating the TNT red water polluted soil by using thermal decomposition technology.Secondly,we washed the soil polluted by TNT red water after the thermal decomposition and explored the best conditions.Thirdly,we treated the washing water with ion exchange process and determined the optimal conditions.Finally,it’s formed thermal decomposition+washing technology for the soil polluted by TNT red water.At the same time,we analyzed the soil samples before and after the thermal decomposition using GC-MS,X-ray fluorescence spectrometry（XRF）.At last,we carried on ecological function evaluation experiment on the soil with festuca arundinacea,and determined the optimal experiment program considering various factors.The results show that thermal decomposition processing the soil polluted by TNT red water can effectively reduce the content of organic matter in soil.The processing effect became obvious after the reaction temperature reached above 300℃.With the rising of reaction temperature,the residual organic oxygen demand of polluted soil decreases,and the color of washing water polluted soil samples becomes more and more shallow.With increasing the thermal decomposition time,the residual organic oxygen demand in soil decreases.With increasing the mass of polluted soil sample,the residual organic oxygen demand in soil increases.The results indicate that the optimal reaction temperature is500℃,the optimal reaction time is 10min and the optimal mass of polluted soil samples is30g.And the residual organic oxygen demand of soil polluted by TNT red water decreases to 0.1642mg·g^-1 from 15.75mg·g^-1 of the original polluted soil,the removal efficiency is98.96%at the optimal conditions.It can effectively reduce the content of salt in the soil using washing technology to wash the soil after thermal decomposition.The bigger the liquid-solid ratio,the longer the washing time,the more the number of washing,the better washing effect.Various factors were considered to determine the optimal conditions on washing method,and the optimal liquid-solid ratio is 8:1,the optimal washing time is 2 minutes and the optimal washing is 1.Ion exchange process can effectively reduce the content of salt in the washing wastewater.Firstly,732 strong-acid cation exchange resin was used to treat the washing wastewater,and the optimum dosage is 0.7g.Secondly,717 strong basic anion exchange resin was used to treat,and the optimum dosage is 0.9g.The washing water treated by ion exchange process can be reused to wash the soil after thermal decomposition.Soil ecological function evaluation experiments show that the thermal decomposition isn’t good at improvements the ecological functions of soil.Festuca arundinaceae can grow in the once washed soil after thermal decomposition.The soil can achieve restoration effect and restore the ecological functions of the soil.The soil after thermal decomposition with washing water treated by ion exchange process can still restore the ecological function.GC-MS test results show that many organic pollutants in the soil polluted by TNT red water disappeare completely after thermal decomposition,and the content of the remaining pollutants are also reduced significantly.XRF analysis results show that the main each element content is no much difference before and after the thermal decomposition of soil,but the Na and S elements in soil after washing are much less than before washing.It also proves that the main reasons of having no recovered the soil ecological function after the thermal decomposition is that it’s still contained excessive salt and alkali.The salt and alkali are soluted in the water.It can restore the ecological function of the soil after washing.