Kinetics of anaerobic treatment

O Rourke, J. T., "Kinetics of Anaerobic Treatment at Reduced Tempera-... 

Pavlostathis S. G., Giraldo-Gomez E. (1991) Kinetics of anaerobic treatment. Water Science and Technology. 24(8), p. 35-59. 

Pavlostathis SG, Giraldogomez E. Kinetics of anaerobic treatment - A critical-review. Crit Rev Environ Control 1991 21(5-6) 411-90. 

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). 

Nevertheless, a rapid disappearance of resistant bacteria was observed after stopping the antibiotic treatment (fig. 5). Different kinetics of disappearance were, however, observed. The aerobic species showed a more rapid return to the baseline sensitive status whereas the anaerobic bacteria, especially the Gram-negative rods, regained sensitivity to rifaximin more slowly. In any case, 3 months after the end of treatment resistant strains were no longer detectable in the feces [82], These results support the cyclic use of rifaximin that has been adopted by the investigators in the treatment of hepatic encephalopathy [77] and colonic diverticular disease [79]. 

Many wastewater flows in industry can not be treated by standard aerobic or anaerobic treatment methods due to the presence of relatively low concentration of toxic pollutants. Ozone can be used as a pretreatment step for the selective oxidation of these toxic pollutants. Due to the high costs of ozone it is important to minimise the loss of ozone due to reaction of ozone with non-toxic easily biodegradable compounds, ozone decay and discharge of ozone with the effluent from the ozone reactor. By means of a mathematical model, set up for a plug flow reactor and a continuos flow stirred tank reactor, it is possible to calculate more quantitatively the efficiency of the ozone use, independent of reaction kinetics, mass transfer rates of ozone and reactor type. The model predicts that the oxidation process is most efficiently realised by application of a plug flow reactor instead of a continuous flow stirred tank reactor. 

McCarty, P. L., "Kinetics of Waste Assimilation in Anaerobic Treatment, ... 

Anaerobic treatment, a multistep complex process, can be described from a kinetic viewpoint as a three-step process involving (1) hydrolysis of complex organic material (2) organic acid production (3) methane fermentation (2). In the first step complex organics are converted to less complex soluble organic compounds by enzymatic hydrolysis. In the... 

In anaerobic treatment, failure of this type is usually evidenced by the near cessation of methane production and decreased COD removal. Several investigators (5, 16, 17) have reported that kinetic failure is also characterized by a build-up in the concentration of long and short chain fatty acids, the predominate precursors of methane. McCarty (7) and O Rourke (3), in laboratory digestion studies on primary sewage sludge conducted at 35 °C, confirmed the fact that the fermentation of short and... 

Vieira, L.G.T., Zaiat. M.. Foresti, E., and Hokka, C.O., Estimation of intrinsic kinetic parameters in immobilized cell systems for anaerobic wastewater treatment, Biotech-nol.-Tech. 1996 vol. 10, no. 9. pp. 635-638. 

Determination of Kinetic and Stoichiometric Pseudo Constants As indicated above, these parameters are most important for predicting the performance of biologically based treatment systems. It would be ideal if tabulations of these were available for various industrial wastes as a function of pH temperature and nutrient levels. Unfortunately, little reliable data has been codified. Only certain trends have been established, and these are primarily the result of studies on municipal wastewater. For example, the yield coefficient Y has been shown to be much higher for systems that are aerobic (molecular oxygen as the electron acceptor) than for anaerobic systems (sulfate or carbon dioxide as the electron acceptors). Systems where oxidized nitrogen is the electron acceptor (termed anoxic) exhibit yield values intermediate between aerobic and... 

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