Anaerobic Liquid Environments

Compared to investigations of polymer degradation under aerobic conditions, very little information is available in the literature for degradation of plastics under anaerobic conditions. Again most of the investigations published are focused on PHA. 

In 1992 Budwill and co-workers published a paper on the degradation of PHB and PHBV copolyesters in an anaerobic mineral medium inoculated with sewage sludge [23]. It could 

Anaerobic degradation of PHB and PHBV (8.4 mol% HV) in a mineral medium with sludge from a waste water plant of the sugar industry at 35 °C was tested by Reischwitz and co-workers [25]. In this case a significant degradation of the polyester powders (approximately 50 pm diameter) was observed also within three weeks, with no significant differences between PHB and PHBV. 

Urmeneta found an almost complete degradation of PHBV powder (7 mol% HV) in a liquid anaerobic slurry from a sweet water sediment within six weeks (at 15 °C) up to an 

An extensive investigation on the anaerobic degradability of a number of natural and synthetic polyesters was performed by Abou-Zeid [30]. Beside the poly(hydroxyalkanoates), PHB and PHBV (10 mol% HV) she tested PCL, the aliphatic homopolyester poly(butylene adipate) (SP4/6) and the copolyester poly(butylene adipate-co-butylene terephthalate) where about 40% of the diacid component consists of the aromatic terephthalic acid (BTA 40 60). Weight loss measurements of polymer films (40-74 pm thickness) in two different 

4 Degradation in Laboratory Tests with Optimised and Defined Liquid Media 

Despite the limitations of aqueous degradation tests discussed previously, these tests, usually performed in a carbon free, synthetic medium, have one important advantage - the possibility of establishing a reliable carbon balance. The polymer, as an energy and carbon source for the microorganisms, is not completely transformed into CO2, but a part of the polymer carbon is used to build new biomass or natural metabolic 

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Discussing the biodegradation of plastics in a liquid environment usually means natural degradation in freshwater (lakes, rivers), in a marine environment, or in aerobic and anaerobic sludges (wastewater treatment). However, many degradation... 

Bruno F, Curini A, Di Corcia A, Fochi I, Nazzari M, Samperi R (2002) Determination of surfactants and some of their metabolites in untreated and anaerobically digested sewage sludge by subcritical water extraction followed by liquid chromatography-mass spectrometry. Environ Sci Technol 36 4156—4161... 

The Bio-FGD process converts sulfur dioxide to sulfur via wet reduction (10). The sulfur dioxide gas and an aqueous solution of sodium hydroxide are contacted in an absorber. The sodium hydroxide reacts with the sulfur dioxide to form sodium sulfite. A sulfate-reducing bacteria converts the sodium sulfite to hydrogen sulfide in an anaerobic biological reactor. In a second bioreactor, the hydrogen sulfide is converted to elemental sulfur by Thiobacilh. The sulfur from the aerobic second reactor is separated from the solution and processed as a sulfur cake or liquid. The process, developed by Paques BV and Hoogovens Technical Services Energy and Environment BV, can achieve 98% sulfur recovery. This process is similar to the Thiopaq Bioscrubber process for hydrogen sulfide removal offered by Paques. 

Fermentations may be aerobic when the cells must be in the presence of an O2 environment or anaerobic when they cannot. Water is the standard fermentation medium and is also one of the products, as is carbon dioxide, which is removed from the liquid and leaves in a vapor product stream since it may have a negative effect on the cells. Other nutrients or media (sources of nitrogen, phosphorus, minerals, vitamins, etc.) typically must be supplied to keep the organisms happy and healthy. 

Lovley, D.R., Anaerobic benzene degradation, Biodegradation 11, 107—116, 2000 Snyder, R., Xenobiotic metabolism and the mechanism(s) of benzene toxicity. Drug Metab. Rev. 36, 531—547, 2004 Rana, S.V. and Verma, Y., Biochemical toxicity of benzene, J. Environ. Biol. 26,157—168, 2005 Lin, Y.S., McKelvey, W., Waidyanatha, S., and Rappaport, S.M., Variability of albumin adducts of 1,4-benzoquinone, a toxic metabolite of benzene, in human volunteers. Biomarkers 11,14-27, 2006 Baron, M. and Kowalewski, V.J., The liquid water-benzene system, J. Phys. Chem. A Mol. Spectrosc. Kinet. Environ. Gen. Theory 100, 7122-7129, 2006 Chambers, D.M., McElprang, D.O., Waterhouse, M.G., and Blount, B.C., An improved approach for accurate quantiation of benzene, toluene, ethylbenzene, zylene, and styrene in blood, Anal. Chem. 78, 5375-5383, 2006. 

Release of liquid ethylene glycol into the environment would be expected to result in volatilization of the substance. In the atmosphere, ethylene glycol is broken down photochemically to produce hydroxyl radicals with 2day half-life. Release into soil results in near complete aerobic biodegradation within 4 days. Under anaerobic conditions, complete degradation is expected within 7 days. 

BIOLOGICAL PROPERTIES Koc 20,146 not expected to leach persistent in the aquatic environment and concentrates in sediments will probably degrade very slowly soil and aerobic half-lives 1.64-2.0 yrs surface water half-life 125-250 days ground water half-life 3.29-4.0 yrs anaerobic half-life 6.58-8.0 yrs can be detected in water by EPA Method 610 methylene chloride extraction followed by high performance liquid chromatography (HPLC) with fluorescence or UV detection or gas chromatography, or EPA Method 625 gas chromatography plus mass spectrometry... 

H. halophila cells from a liquid culture in the late exponential phase with a high percentage of motile cells see Note 5) are incubated in a glass capillary. The open ends of the capillary are sealed with Vaseline to create an anaerobic environment in the capillary (22). 

Corrosion in ships can also be caused by MIC. In this type of corrosion, microbial organisms present in the environment can accelerate corrosion. For example, SRB, which are present in stagnant water of many harbors, can build up on the hulls of ships. Other corrosion-causing bacteria, such as acid-producing and anaerobic bacteria, are also present in ballast tanks as well as in the liquid products that some tankers carry. The microbes cause a localized change in the environment, which can promote aggressive pitting and other types of corrosion. 

The microfluid segments are always handled in capillaries and microchannels. In consequence, they are separated from the environment. Problems caused by contact to air like undesired evaporation of solvent and complete drying out are avoided. Undesired influences of humidity and oxygen from air on oxidation-sensitive compounds of anaerobic cells can be excluded or strongly suppressed. Also, undesired effects of contact between the components of handled samples and the wall surfaces can be significantly reduced or suppressed by the separation of samples inside segments from the walls due to the carrier liquid. 

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