Irreversible sorption of natural hydrocarbons to sediments; experimental observations and model predictions

Article Abstract:

A study has developed and used a semiempirical irreversible sorption isotherm model to correlate most field observations regarding contaminant release in the sediment or solid phase. The study is founded on the notion that desorption is not the opposite of adsorption, as a significant fraction of some contaminants is bound into sediments irreversibly. The study utilized and tested various chemicals including an aromatic compound, a halogenated aromatic compounds, two polycyclic aromatic hydrocarbons, two polychlorinated biphenyls, and a chlorinated pesticide, as well as various types of sediments containing different organic contents. The isotherm equation developed comprises a linear term to represent reversible sorption, and a Langmuirian-type term to represent irreversible sorption.

Comment:

Irreversible sorption isotherm model has been dvlpd to explain field observations on contaminant release in sediment/solid phase

All Other Miscellaneous Waste Management Services, Environmental Control NEC, Environmental management

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Enrichment of high-rate PCE dechlorination and comparative study of lactate, methanol, and hydrogen as electron donors to sustain activity

Article Abstract:

Lactate, methanol and hydrogen were used as electron donors to sustain rapid rates of tetracholroethene (PCE) dechlorination in mixed cultures of anaerobic bacteria. Researchers at Rice University in Houston, TX, found no notable difference among the electron donors in terms of the extent of dechlorination. Over time, the researchers recovered PCE as about 80% vinyl chloride and 20% ethene, regardless of electrod donor used. The study also found rates and extents of PCE dechlorination to have improved over time in systems containing high molecular hydrogen pressures in the presence of an active methanogenic community.

Comment:

Electron donors sustain rapid rates of tetrachloroethene dechlorination in mixed cultures

Refuse Systems, Waste Collection, Waste management industry

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Characterization of landfill gas composition at the Fresh Kills municipal solid-waste landfill

Article Abstract:

Nonmethane organic compound (NMOC) measurement data in a Fresh Kills, NY, municipal solid waste landfill, suggests that gas composition in the landfill is equal to the composition of gas passing through passive vents and soil cover. The study involves collection of more than 250 separate gas samples, analyzed for around 150 various analytes. The landfill was found to have an average total NMOC value of 438 ppmv (as hexane) as compared to the regulatory default of 4000 ppmv. The data also showed spatial, temporal, and measurement variability in the gas composition.

Comment:

Nonmethane organic compound data suggests that gas composition is equal to gas passing through passive vents & soil cover

Basic Chemical Manufacturing, Organic Chemicals, Organic compounds

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