Nonaqueous liquid wastes

The panel meeting was organized and conducted to facilitate development of sample preparation protocols for mutagenicity testing of six media air, drinking water, nonaqueous liquid wastes, soils and sediments, waste solids, and waste water. The meeting objectives were established by the sponsors and were as follows ... 

Nonaqueous liquid wastes Liquids whose major component is not water. These materials range from soluble organic liquids (e.g., acetone) to insoluble organic liquids (e.g., dichloromethane) and liquids such as light to heavy oils. 

Nonaqueous Liquid Wastes Protocol. Nonaqueous liquid wastes were defined to include samples that range from water-soluble organic liquids to immiscible oils. Only a limited amount of data are available on the applicability of this protocol (Figure 4) to compounds other than oils or petroleum products. This medium differs from other environmental media because mutagenic materials are often concentrated in organic liquids. Therefore, this protocol incorporates dilution steps rather than the concentration techniques used in the other media protocols. This protocol is also unique because of the opportunity to test neat samples or samples diluted with DMSO rather than sample components isolated with an absorbent or extracted with a solvent. For this reason, samples treated with this protocol should contain polar compounds and/or volatile compounds that would be lost when the other protocols are used. 

The panel meeting participants unanimously agreed that the nonaqueous liquid wastes protocol is a synthesized protocol that assembles portions of a number of proven methods. There is a good indication that the various hybridized components will be applicable to a range of nonaqueous liquids however, this observation is based on data from the testing of discrete types of oily compounds. Further... 

Figure 4. Flow scheme for the preparation of nonaqueous liquid wastes.

Sitar, N., Hunt, J. R., and Udell, K. S., 1987, Movement of Nonaqueous Liquids in Ground-water In Proceedings of Geotechnical Practice for Waste Disposal, ASCE, Ann Arbor, MI, pp. 205-223. 

Protocols for preparing six environmental sample types prior to the Ames Salmonella assay were proposed at a recent panel discussion sponsored by the U.S. Environmental Protection Agency (USEPA) and the U.S. Army. Air particles, soil-sediment, and solid waste are extracted with dichloromethane, concentrated, and solvent exchanged into dimethyl sulfoxide (DMSO). Organics in water and waste water are absorbed onto XAD columns, then eluted with hexane-acetone, solvent reduced, and exchanged into DM SO. Nonaqueous liquids are assayed directly and as concentrates before they are solvent exchanged to DMSO. If bacterial toxicity or lack of dose response is observed in the Ames assay of extracts, the extracts are fractionated prior to solvent exchange. These are interim methods and have not been subjected to policy review of the USEPA or the U.S. Army. 

Environmental Waters and Waste Waters. This medium is multi-phasic and covers a wide range of constituents, including aqueous and nonaqueous liquids and dissolved and suspended solids. The protocol (Figure 3) is limited to solvent-extractable organic compounds however, not all compounds will be recoverable and/or stable under the protocol s methods. An overall scheme was developed and incorporated in the protocol to link the variety of components of this medium to the other protocols. 

Waste solids are defined as heterogeneous materials that range from sticky, viscous, or tarry material to dry solid particulates. Special techniques for the treatment of oily, gummy, and adhesive materials (e.g., addition of anhydrous sodium sulfate or silica gel) are specified in the protocol. The gravity phase-separation procedure (24 h at 4 °C) developed by the Environmental Waters and Waste Water Work Group is incorporated by reference to address the removal of liquids from waste solids samples. The waste solids protocol can also be applied to solids partitioned from aqueous or nonaqueous liquids or from gaseous media. 

Flocculation and sedimentation arc two processes used to separate waste streams that contain both a liquid and a solid phase. Both are well-developed, highly competitive processes, which arc oflcii used in the complete treatment of waste streams. They may also be used instead of, or in addition to, filtration. Some applications include the removal of suspended solid particles and soluble heavy metals from aqueous streams. Many industries use both processes in the rcmowal of pollutants from their wastewaters. These processes work best when the waste stream contains a low concentration of the contaminating solids. Although they are applicable to a wide variety of aqueous waste streams, these processes arc not generally used to treat nonaqueous or semisolid waste streams such as sludges and slurries. 

Liquid-liquid extraction or liquid-solid extraction for aqueous samples (and soxhlett extraction or sonication for nonaqueous samples), followed by sample concentration, cleanup, and determination by GC or GC/MS. Direct injection, waste dilution, or other extraction techniques, depending on the sample matrices, may be used. 

Many pilot studies and field cases have been summarized an effort has been made to select these studies and cases so that each one addresses unique issues. This book also proposes some new concepts and ideas or hypotheses. Several of them need to be validated by further research, and some may stimulate other research interests. From this standpoint, this book could be useful to researchers. The basic theories and sample calculations should help students and professionals who are less experienced in this area. This book also may be used by environmental engineering professionals who work on cleaning up wastes and nonaqueous phase liquids (NAPE). In addition, an effort has been made to strike an ideal balance between theory and practice in addition, extensive references are provided. 

---