Separation of Oil from Wastewater by Coal Adsorption-Column Flotation

In order to improve the separation efficiency of fine oil droplets from oily wastewater, a new process utilizing coal adsorption and column flotation has been developed. In this work, anthracite from Jincheng, China was used as an adsorbent for oil removal from wastewater. The effects of adsorption time, coal particle size distribution, the value of pH, and the oil concentration in wastewater on the adsorption capacity of anthracite were investigated by static experiments. A novel device named a cyclone-static microbubble flotation column was developed for the separation of oily wastewater, which combines the conventional hydrocyclone with a conventional flotation column. Coal adsorption-column flotation tests were carried out and scaled-up from a lab-scale (1 m(3)/day), to a pilot scale (30 m(3)/day), and to a full-scale (2000 m(3)/day) unit. Different operating parameters, such as coal dosage, feed rate, circulation pressure, and gas flow rate were studied. In full-scale tests of 2000 m(3)/day, oil removal of 97.70% with the treated effluent containing an oil concentration of 23.39 mg/L was obtained.