Theoretical Analysis And Experimental Research On Removal Approaches Of BTEX In Paint-producing Wastewater

In recent years, with the development of the industry and rapid increase of industrial and mining enterprises, environmental pollution of benzene homologue compounds has been one of the extrusive problems. Benzene homologue compounds are volatile organic pollutants. They can transfer and transform in the environment, and will lead to environmental pollution. It has aroused extensive attention inside and overseas. At present, spot review experiment about transfer and transformation law of benzene homologue compounds during the process of industrial wastewater treatment is seldom relatively.In this paper transfer and transformation law of BTEX of paint-producing wastewater during the process of biological treatment, physical and chemical pretreatment was investigated. Simultaneously, simulant experiment went along. It was analysed that Several main running conditiones of oxidation ditch process exerted an influence on removal rate of BTEX. The research showed that:1. The removal rate of BTEX was high fairly .And the removal rate of benzene was 89.6%, the rest exceeded 99.0%. The quality of effluent could meet the first class of the national discharging standard(GB8978-1996). BTEX were removed mostly in floatation and oxidation ditch process. The removal of BTEX was unconspicuous in oil separation system, because oil separation was ineffective, and benzene, toluene, m-xylene were not adsorbed easily by suspend substance.2. The removal rate of BTEX was high in oxidation ditch process. The removal rate of benzene, toluene, ethylbenzene, o-xylene, m,p-xylene was 82.59%, 97.48%, 96.37%, 95.83%, 95.10% separately. In oxidation ditch process biodegradation was the most important removal manner of BTEX, to the exclusion of benzene, volatilization by surface aeration was the second, and surplus sludge sorption was little.3. Volatilization of BTEX was concentrated in the process of mechanical surface aeration of oxidation ditch and bubble stripping in floatation vessels. Surface volatilization in all vessels was less. According to compution, the emission of toluene to the ambient air was the largest.4. In oxidation ditch system biodegradation and volatilization by surface aeration heightened, and the removal rate of BTEX enhanced when DO concentration increased from 2～3mg/l to 4～6mg/l; The overall removal rate declined, as well as biodegradation rate, when MLSS decreased from 8.0g/l to 4.5g/l; Temperature influenced on microorganism of oxidation ditch on a certain extent,the biodegradation rate of BTEX declined in winter to the degree.This study provided scientific, applied and credible parameters for the design and running of correlative wastewater treatment process, and contributed to improvement of oxidation ditch process. It was significant to environmental protection and development of pollution prevention technique.