Evaluating water quality changes in wastewater reuse using pilot-scale experiments

The pilot-scale experimental study described in this paper was designed to evaluate water quality changes in wastewater reuse applications and, thus, to determine the water quality treatment requirements for environmentally safe applications. For this evaluation, two types of pilot-scale systems (an activated sludge treatment unit and two soil columns) were set up at the U.S. EPA Test & Evaluation (T&E) Facility in Cincinnati, Ohio. The activated sludge treatment unit was used to simulate contaminant behaviors in conventional municipal wastewater treatment systems, while the soil columns were constructed to investigate contaminant fate and transport in land applications for wastewater reuse. Aldicarb, a pesticide that is sometimes found in low concentrations in groundwater and surface water was used as the target contaminant to evaluate its fate and transport in both the activated sludge treatment unit and the soil columns. Atomic force microscopy (AFM) was used to observe the surface morphologies of extracellular polysaccharides (biofilms) on quartz coupons inserted within the soil columns. Fourier Transform Infrared (FTIR) spectroscopy experiments were also conducted to provide information regarding the mechanism of binding/transformation that may be occurring inside the soil columns.