Mixing and separation device for continuous flow bioassays with coal liquids.

Abstract

Efforts to increase United States' use of synthetic fuels, such as those derived from coal liquefaction, require examining potential toxicity of coal liquids that may eventually be released to the aquatic environment. Evaluation of potential long-term ecological effects must consider organism response to chronic exposure regimes. Since maintaining constant levels of the water soluble fraction (WSF) of coal liquids is complicated by presence of easily biodegradable phenolic compounds (DEGRAEVE et al. 1980), and since problems with low oxygen levels may occur with static tests, flow-through test systems must be employed. A serious problem with continuous flow studies of crude petroleum oils has been obtaining a consistent WSF. The test solution may contain dispersed oil and the character of the WSF may change during the testing period (CRADDOCK 1977). Although, batch-prepared WSFs of solvent refined coal (SRC) II materials were adequate for short-term continuous flow or static tests, a system was needed that would generate a stable WSF for long-term continuous flow bioassays. We developed a method to generate a reproducible stock solution for exposing aquatic organisms to sublethal concentrations of coal liquid WSFs under flowthrough conductions. Our apparatus extracts a primary WSF from a 2.9:1 blend of middle to heavy SRC II distillate, while separating and removing dispersed and floating insoluble materials. The WSF is efficiently extracted, thus reducing costs associated with waste treatment of the potentially hazardous materials. METHODS