Benzene Distribution In Municipal Wastewater Treatment In Xi'an

The headspace-gas chromatography method was used to determine the type and concentration(or content)of benzene species in the urban wastewater treatment process,revealing the characteristics of the benzene series composition,concentration and time variation in the wastewater and sludge in the urban wastewater treatment process,and discussing the various treatments.The influence of the unit on the distribution of benzene in wastewater,and the influence of time increasing and temperature on the benzene series of dewatered sludge surface,providing certain research bases and sciences for the analysis and control of benzene series distribution and environmental impact in urban wastewater treatment plants.Benzene and toluene are commonly found in wastewater and sludge from municipal wastewater treatment plants.Due to the difference in influent water quality,the composition of other benzene series in the wastewater treatment plant varies.In January and March of 2017,the concentration of benzene series in wastewater was higher;in May and July,the concentration of benzene series in wastewater and some sludge gradually decreased;from July to November,the concentration of benzene series increased..The solubility concentrations of benzene and toluene in the primary wastewater treatment were higher than that in the total concentration ratio of 74.70%-96.28% and 40.58%-98.52% respectively.The variation of the concentration of benzene and toluene in wastewater from wastewater treatment plants has a strong correlation.In the process of urban wastewater treatment,the concentration of benzene series in the wastewater basically showed a downward trend.The decrease in the concentration of benzene series in the primary treatment is relatively small,which is mainly due to the effects of falling water,flow shear,aeration and sedimentation,etc.,leading to benzene series emission.The decrease in the concentration of benzene series in the anaerobic stage was mainly due to the effects of sludge adsorption,anaerobic stage hydrolysis and acidification.The moisture content of the dewatered sludge decreased with the increase of storage time and temperature,and the descending rate from small to large was: 30 °C <50 °C <80 °C <105 °C.Under normal temperature,the content of benzene and toluene in the surface layer of dewatered sludge showed a tendency to increase first,then level off or even decrease with the storage time(0-132 h).In the experimental range,with the increase of storage time(0-2 h),the content of benzene in the sludge increased at 30-80 °C,but the content of benzene increased rapidly at first and then decreased at 30-105 °C;The toluene content in dewatered sludge decreased at °C,and it decreased fastest at 105 °C.