Methods of purifying oily water

Abstract

The article describes currently used methods of cleaning ship oil-containing waters and suggests a new method of their disposal. There are shown the specific features of the composition and properties of oil-containing waters, current requirements for the purification of oil-containing waters depending on the areas of operation of the vessel. The main reasons for oily waters emerging are given, as well as the main factors affecting the formation of oily waters on ships. A picture of a water-fuel emulsion under a microscope is illustrated. There are analyzed the methods of oil-containing water purification used on ships, their advantages and disadvantages. There is given a particular description of water purification methods: mechanical purification (straining, settling, centrifugation), physico-chemical purification (adsorption, coalescence, flotation), chemical purification (ozonation, electrochemical purification), biological purification and the method of thermal neutralization (wet burning, fire neutralization). There is presented one of the methods of mechanical wastewater treatment, namely, a scheme for primary treatment of oily waters using a grate, when the oily waters pass through numerous holes and are separated from foreign objects and large solid inclusions. Another example of mechanical wastewater treatment is the design of a clarifier with inclined plates through which the water flow passes along the plates and is divided into layers, which restrains mixing and facilitates settling oil products. A diagram of a coalescing filter (physico-chemical cleaning method) is also presented and its advantages are described. The comparative characteristics of the methods of utilization and neutralization of oily waters are given. Special attention is paid to the development and improvement of the technology of thermal neutralization of ship oil-containing waters. A method of utilization of oily waters by the heat of ship diesel exhaust gases is proposed.