Experimental study on soil aquifer treatment for water quality improvement

Abstract

Laboratory fabricated soil column experiments were performed to differentiate among the mechanisms (i.e., adsorption, filtration, biodegradation) responsible for the changes in the water quality during Soil Aquifer Treatment (SAT). This study focuses on collecting and analyses the soil samples for its characterization. Similarly, treated wastewater was collected from sewage treatment plant, to characterize the quality before SAT. Then the study has been carried out with columns that are one meter in height and 6 cm diameter to understand the efficiency of the Soil Aquifer Treatment. Entire experiment has been carried out in the presence of sun light. Secondary treated wastewater has poured into soil column and collected at the outlet. Effluent from the column has been analyzed after SAT. After that the clogging layer specimens has taken from soil column and then the soil microbial concentration was estimated. The soil hydraulic conductivity was estimated, to characterize the mechanical and hydraulic behaviour of the clogging layer for before and after SAT. The relative significance of hydraulic loading in soil aquifer treatment system was analyzed and also the changes in the major soil components: Iron(Fe) and Manganese (Mn) oxides resulted from SAT application was measured. Maximum Chemical Oxygen Demand (COD) was reduced in 1.5 m unsaturated Vadoze depth Sandy Clay Loam (SCL) soil from 50.1 mg/l to 18.1 mg/l. During first wetting cycle of SAT, Dissolved Organic Carbon (DOC) was reduced from 12.5 mg/l to 6.5 mg/l. Nitrate(NO-3) and Nitrite(NO-2) was reduced 26 mg/l to 11.25 mg/l and 1.37 mg/l to 1 mg/l respectively. From adsorption studies, it was observed the clay soil has higher adsorption distribution coefficient. The relative hydraulic conductivity decline in SCL mixed clay soil was larger than SCL soil.