Municipal reclaimed water as makeup water for cooling systems: Water efficiency, biohazards, and reliability

Abstract

Municipal reclaimed water is increasingly being considered as a sustainable source of makeup water for cooling towers. However, many oil and gas facilities in the water scarce middle eastern regions still depend on non-renewable groundwater for operating cooling towers. Successful application of reclaimed water in a dry desert climate with very high temperature requires a critical understanding of several factors, including water efficiency, biohazards, equipment reliability, and economics. In particular, biohazard assessment, due to bacteria and virus contamination in hot weather, should be assessed to understand the human risks of utilizing reclaimed water. This study investigated the applicability of municipal reclaimed water as an alternative to groundwater for an industrial cooling system at an oil and gas facility in Saudi Arabia. Treated wastewater effluent from an activated sludge biological treatment process was utilized, as make up water for a 4.2 MW cooling tower. The results of this study showed that water efficiency can be increased using municipal reclaimed water instead of groundwater by increasing the cycle of concentration. The bacterial and enteric virus study indicated that the disinfection and biocide treatment was effective in controlling biological growth and minimizing associated risks to human health. The use of reclaimed water was economically viable with 27% reduction in water consumption.