Biological treatment and toxicity of low concentrations of oily wastewater (bilgewater)

The biodegradability and toxicity of low concentrations of oily wastewater (bilgewater) were tested under simulated sanitary wastewater treatment conditions. This was done to establish the feasibility of a combined shipboard oily and nonoily wastewater treatment system. The biodegradability of oily wastewater was determined by proxy: C-14-labeled dodecane. toluene. and phenanthrene (representing alkane, aromatic, and polyaromatic compounds, respectively) were mineralized in petroleum fuels and lubricants. We found that low concentrations of oily wastewater components were mineralized. even in the presence of more abundant substrates (such as synthetic graywater, containing vegetable oil, detergent, gelatin. and starch). The toxic effects of diesel fuel and several other components of oily wastewater (such as surfactants and a synthetic lubricant) on a naive wastewater assemblage was also tested. In concentrations much higher than would be expected under normal shipboard conditions. we found no evidence of toxic effects of the bilgewater compounds tested. Thus. a combined shipboard bilgewater and sanitary wastewater system might be feasible.