Greasy-Spoon Cleaner

The frenzied cooking and cleaning in a typical restaurant generates large volumes of water permeated with oil and grease. While big restaurants can afford their own wastewater treatment facilities, smaller establishments usually discharge wastewater straight into the closest sewer systems. Chemical engineers at the Hong Kong University of Science and Technology have developed a compact and inexpensive technology for cleaning restaurant wastewater.

The device consists of a set of catalysts and aluminum electrodes fitted inside a small tank. When the electrodes are powered up, the fine oil droplets in the wastewater fed to the tank shed their negative charges and begin to clump together. One electrode generates tiny hydrogen bubbles that carry the coagulated grime to the surface, where it can be skimmed off. Water purified by the process can be used for cleaning and other non-drinking purposes, according to project leader P. L. Yue. A Hong Kong-based company collaborating with Yue’s group expects to bring the technology to market in about two years.