AWWA ACE69058

There are an estimated 29,528 facilities in the U.S. that discharge wastewater containing metal working lubricants (MWL). Waste MWL typically contain about 1 - 5% oil, 10 - 20% solids, and 80 to 90% water. MWL are made up of mineral oil, fatty acids, tall oil, and additives such as surfactants, anti-corrosion agents, biocides, and dispersants. Stricter environmental regulations and increasing consciousness towards wastewater reuse lead to reconsideration of the "conventional" wastewater treatment processes. The "conventional" wastewater treatment systems such as chemical emulsion breaking and gravity separation, chemical emulsion breaking followed by dissolved air flotation (DAF) treatment, and free oil removal and ultra filtration (UF) are typically used for treating oily wastewater in the automotive industry. All these systems produce effluent that is close to equivalent; however, none are considered as effective when treating synthetic or semi-synthetic MWL. To meet the regulatory standards for oily wastewater, biological treatment using membrane reactors has been identified as the most common solution. A better understanding of the MWL chemistry, environmental health and safety issues, and review of existing treatment technologies are important steps for assessing the effectiveness and associated costs for treating the oily wastewater. This paper discusses all of these elements and relates to the economic effect on industry as well as the environmental effect on the natural resources. Includes 10 references, tables, figures.