Study On The Factors Affecting The Anion Surfactants Removal In The Subsurface Constructed Wetlands

Because of its special property, good performance and low price, anion surfactant is the most widely used in many area. The consumption of anion surfactants amounts to about 70% of all surfactants used in detergent industry. Due to their heavy use in laundry and cleaning products, anion surfactants are widespread in the environment. Anion surfactants may affect the ecosystem, and they can affect the hydrophily propagations and the terraneous propagations. There are many methods to treat the wastewater containing anion surfactants, in which constructed wetland is a new process for removal of anion surfactants. Constructed wetland treatment technology involved the physical, chemical, and biological processes with low cost, ease operation, and good performance. At present, there are many reports on the constructed wetlands for the treatment of organic matters in the wastewater, however, there are few reports on the constructed wetland for the removal of anion surfactants.The purpose of the present study is to investigate the effect of constructed wetland configuration and operation factors on efficiency of treatment system for anion surfactants. The major contents are described as follows:1 Development of a reversed-phase high performance liquid chromatography-UV method to determine linear alkylbenzene sulphonate in wastewater sample.A reversed-phase high performance liquid chromatography-UV method has been developed for the determination of linear alkylbenzene sulphonate in wastewater. The proposed method promises simplicity, fastness, good selectivity and low-cost. The effects of methanol content, the type and concentrations of electrolytes, pH and flow rate of the mobile phase are optimized, and the optimal HPLC conditions are obtained. The experimental results show that the linear range for linear alkylbenzene sulphonate is between 5 and 18000μg/L, the detection limit (3σ) for analyte is 1.32μg/L under optimized conditions, and the relative standard deviation (RSD) is 4.4 % for 10 mg/L linear alkylbenzene sulphonate (n=11). The proposed method has been applied successfully in the analysis of linear alkylbenzene sulphonate in wastewater samples from constructed wetland.2 The effects of configuration and operation factors of constructed wetland system on efficiency of treatment system for anion surfactants removal is investigated. Through one year (from Sep.2005 to Sep.2006) study in a pilot-scale constructed wetland system, the major conclusions are summarized as follows:1) Several factors which influence the removal of LAS in constructed wetland system, such as hydraulic loading rate (HLR) , bed shapes, granular medium size, water depth and season were studied. The results show that hydraulic loading rate (HLR) and season are two major factors affecting removal of the linear alkylbenzene sulphonate( LAS) in the constructed wetland system. ANOVA statistical analysis shows that HLR and season performance significant differences affecting removal of LAS (p<0.05). But no significant differences are observed between the bed shapes,the two water depths and the granular medium size(p>0.05). So it can be concluded that hydraulic loading rate (HLR) and temperature are two major factors controlling removal of the linear alkylbenzene sulphonate (LAS) in this study.2) Kinetic simulation of LAS in constructed wetland system revealed that zero-order reaction kinetics may simulate the removal of the LAS in wetland of this research much well.