多环芳烃类污染土壤热脱附修复技术应用研究

THERMAL DESORPTION TECHNOLOGY APPLIED TO REPAIR PAHs CONTAMINATED SOIL

针对传统热脱附工艺脱附时间长、处理成本高、尾气处理工艺不完善等问题,进行了电加热回转窑热脱附实验。研究发现:随着温度增高、时间增长,总PAHs去除率增加;10 min条件下350℃与500℃时总PAHs的去除率分别为98.83%和98.94%,土壤中PAHs可达到修复目标值;500℃时多环芳烃的去除率表现为低环PAHs>高环PAHs。在此基础上,通过集成形成1套集污染土壤预处理、热脱附、尾气净化、余热利用、自动化控制于一体的工艺技术,并建成年处理有机污染土壤18万t的热脱附生产线。在350和500℃条件下对1万余吨污染土壤进行热脱附处理后(≥10 min),总PAHs去除率分别为98.92%和99.95%,尾气排放指标均低于DB 11/501—2007《大气污染物综合排放标准》。

Aiming at the problem of long stripping time,high processing costs,imperfect exhaust gas treatment process in the traditional thermal desorption process,experiment of electric heating thermal desorption on rotary kiln was put forward. The study found that with increasing temperature and time,the removal rate of PAHs was increased. Processing for 10 min at 350 ℃ and 550 ℃,total PAHs removal rate reached 98. 83% and 98. 92%,respectively,in which the total of PAHs in the soil got close enough to the target values. The removal rate of PAHs were LMW-PAHs HMW-PAHs at 550 ℃. On the basis of the above experiment,a set of technological flow was designed that included soil pretreatment,thermal desorption,exhaust gas purification, residual heat utilization and automation control process and eventually formed the thermal desorption production line,which could dispose contaminated soil of 180,000 tons per annual. More than 10,000 tons of contaminated soil was treated under 350 ℃ and 550 ℃ for above 10 min with the removal rate of 98. 92% and 99. 95% of PAHs respectively. The concentration content indexes of Shougang thermal desorption exhaust gas could reach the Comprehensive Discharge Standard of Atmospheric Pollutants（ DB 11/501—2007）