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Jesъs Rodrнguez–Martнnez*, Josй A. Rodrнguez–de la Garza, Yolanda Garza–Garcнa

Kinetic assessment of the volatile fatty acids as a strategy to maintain the sustainability of the biodegradation of chemical oxygen demand of easily acidifying wastewater

Abstract

Kinetics of the production and consumption of volatile fatty acids (VFA) such as acetic-, propionic-, butyric- acid and alcohols during anaerobic digestion of model wastewater was studied under different concentrations of sorbitol (g/l) as carbon source, pH, temperature and granular sludge (GS). Methane production was measured. Higher COD removal and methane production were obtained at 3.5–7.5 g sorbitol/l, with an initial pH of 9–9.5, and at 30–37 °C with 4.18–5.02 g/l of VSS. At these conditions VFA and alcohols were consumed more and produced three times more methane than with 1.7 g/l VSS of granular sludge as inoculum. A strong relation between methanogenic activity, COD removal efficiency was observed for all the initial COD concentrations studied. The methanogenic stage was inhibited by the presence intermediary products such as VFA in excess, which caused a drop in pH and inhibited methanogenesis. This fact demonstrated the importance of monitoring the production and consumption of VFA as a direct indicator for the physiological condition of the reactor. The treatment of easily acidifying wastewater like used in this case can be achieved with a detailed kinetic study on the production and consumption of intermediary products to establish the optimum parameters for higher efficiency of COD removal and methane production.
Moscow University Chemistry Bulletin.
2006, Vol. 47, No. 2, P. 97
   

Copyright (C) Chemistry Dept., Moscow State University, 2002
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