Microbiological characterization of the biological treatment of aircraft paint stripping wastewater.

Research on the treatment of potentially toxic wastewater produced at six US Navy aircraft paint stripping facilities has been conducted. The composition of the wastewater treated consisted of methylene chloride and phenol in concentrations of about 5000 and 1800 mg/l, respectively, and other organic compounds in a total concentration of 2200 mg/l. Biological treatment is an important means by which toxic or hazardous organic compounds can be economically converted to less noxious materials. Engineering studies conducted in the laboratory with activated sludge reactors and rotating biological contactors (RBC) demonstrated that both suspended and attached growths can be effective biological methods to treat this paint stripping wastewater when blended with domestic wastewater up to about 50% by volume. These studies were complemented with analyses of the bacterial communities inhabiting the treatment systems. The number and the genera of the microorganisms present in the blended wastewater, as well as their ability to biodegrade the potentially toxic organics were studied. The results indicate that paint stripping wastewater is able to support large bacterial populations consisting of various gram-negative rods and coccibacilli and a few gram-positive bacilli. Members of the genera Pseudomonas and Bacillus are suspected to play an important role in initiating the biodegradation process.