Coalescer And Advanced Filtration Designs For Removal Of Oil And Solvents

By Highland Tank

Abstract
The following is a discussion of recent developments in primary and secondary water treatment technologies for oil-water separation with coalescers and advanced filtration systems (AFS). These developments can rapidly remove oil and petroleum hydrocarbons from water to very low levels. Economic advantages for applications with stringent discharge requirements are reviewed including: marine bilge water, industrial wastewater, storm water treatment and re-use, and ground water remediation.

Introduction
Increasing interest for conserving the nation's water resources has directly affected many maritime, industrial and petroleum handling facilities. Industries face more stringent regulations covering the treatment and discharge of oily wastewater, while increased public pressure for the government to control harmful oil spills and pollutant discharges can potentially result in costly penalties.

Oily wastewater treatment: current technology
Industrial and petroleum handling activities produce wastewater containing oil, grease, floating debris and settleable solids. The method of treatment depends on the concentration, the type of contaminants in question, and the location of the discharge. The key to success for pumping, separating and treating oily wastewater on-site is properly configuring current technologies to limit operational costs and minimize the size and hazardous waste generation of the system.

A well designed and maintained oil/water separator (OWS) as the primary step, combined with an AFS secondary step, can economically pump, treat and meet most discharge limits and water quality standards for petroleum compounds.

Historically, it has been difficult and expensive to remove or "polish" petroleum for industrial discharge and re-use applications. The old economic rule of thumb in water treatment is that "50 percent of the cost is for removing the first 99 percent of the pollutants; the other 50 percent of cost is for removing the last one percent." Short of pumping and treating petroleum impacted water of this type, facilities must ship polluted water off-site for treatment at a licensed facility – an expensive option that may cost well over a dollar per gallon.