Anaerobic sulphate reduction

Applicable for sulphate reduction in waste water discharged to sensitive waterbodies. 

Typically, seep pore fluids are depleted in sulphate and enriched in reduced sulphur compounds, primarily H2S (e.g. Masuzawa etal., 1992 Aharon, 2000). 

This has been attributed to the anaerobic respiration by microorganisms like Desulfovibrio in seep sediments (Aharon, 2000) they use the abundant reduced carbon forms as electron donors and seawater-derived S042 as an electron acceptor. In addition to H2S, this metabolism can also produce carbonate species and ammonia whose concentration and type depend on the nature of the reduced carbon substrates and on the buffering capacity of the environment. Sulphate and H2S often show a linear, inverse relationship in profiles of seep sediment pore fluids, further indicating the link between sulphate reduction and H2S production (Aharon, 2000). 

Aharon and Fu (2000) found significantly elevated rates of sulphate reduction in crude oil and methane seeps overlain by chemosynthetic fauna of bacterial mats and mussel beds, compared to non-seep sediments. The intensity of sulphate reduction can be gauged from the observed rapid decrease of sulphate below the sediment/water interface and the highly elevated values of H2S in pore fluids (Aharon, 2000). 

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BAT is to use anaerobic sulphate reduction techniques for sensitive waterbodies (see Section 12.7.7)... 

Albuquerque MGE, Lopes AT, Serralheiro ML et al (2005) Biological sulphate reduction and redox mediator effects on azo dye decolourisation in anaerobic-aerobic sequencing batch reactors. Enzyme Microb Technol 36 790-799... 

Air-dry samples thoroughly at room temperature, which should not exceed 40°C (loss of Hg ) place the sample on the bag and turn over as necessary. Use gloves Any residual humidity will promote anaerobic reactions, including sulphate reduction, and must be avoided. When samples are properly dried, transfer to a new bag, if necessary (field bag may still be wet), seal and send to LAB IV. 

Nauhaus K., Boetius A., Kruger M., and Widdel F. (2002) In vitro demonstration of anaerobic oxidation of methane coupled to sulphate reduction in sediment from a marine gas hydrate area. Environ. Microbiol. 4, 296-305. 

Sulphate reduction major process in anaerobic marine sediments, especially on continental shelves 2CH20 + S042" -> H2S + 2HC03 -77... 

This process is most important in marine sediments where the pore waters contain appreciable amounts of dissolved sulphate. Bacterial sulphate reduction (BSR) operates when the pore waters are devoid of dissolved oxygen (i.e. anoxic). In euxinic basins the sediment experiences BSR diagenesis directly at the sediment-water interface (Fig. 1) in other words, no oxic and suboxic phases are encountered (Curtis, 1987). Sulphate reduction is aided by anaerobic bacteria, as follows ... 

The availability of substrates and the competition for them between various anaerobes is important. Sulphate is plentiful in marine environments (c.28 irnol I-1) and so sulphate reduction is the dominant anaerobic process (Jorgensen 1982) and accounts for c.50% of carbon oxidation in marine shelf sediments (compared... 

While little is known of their identity, they are clearly involved in methanogenesis, sulphate reduction and oxidation of sulphide and methane, the latter both aerobically and anaerobically (see Section 3.2). Seep microorganisms are also partially responsible for massive carbonate precipitation on the seafloor (see Section 3.3). 

Devol, A.H. and Ahmend, S.I., 1981. Are high rates of sulphate reduction associated with anaerobic oxidation of methane Nature, 291 407-408. 

Oxidation-reduction potential Because of the interest in bacterial corrosion under anaerobic conditions, the oxidation-reduction situation in the soil was suggested as an indication of expected corrosion rates. The work of Starkey and Wight , McVey , and others led to the development and testing of the so-called redox probe. The probe with platinum electrodes and copper sulphate reference cells has been described as difficult to clean. Hence, results are difficult to reproduce. At the present time this procedure does not seem adapted to use in field tests. Of more importance is the fact that the data obtained by the redox method simply indicate anaerobic situations in the soil. Such data would be effective in predicting anaerobic corrosion by sulphate-reducing bacteria, but would fail to give any information regarding other types of corrosion. 

This is a simplified treatment but it serves to illustrate the electrochemical nature of rusting and the essential parts played by moisture and oxygen. The kinetics of the process are influenced by a number of factors, which will be discussed later. Although the presence of oxygen is usually essential, severe corrosion may occur under anaerobic conditions in the presence of sulphate-reducing bacteria Desulphovibrio desulphuricans) which are present in soils and water. The anodic reaction is the same, i.e. the formation of ferrous ions. The cathodic reaction is complex but it results in the reduction of inorganic sulphates to sulphides and the eventual formation of rust and ferrous sulphide (FeS). 

Diniz PE, Lopes AT, Lino AR (2002) Anaerobic reduction of a sulfonated azo dye Congo Red by sulphate reducing bacteria. Appl Biochem Biotechnol 97 147-163... 

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