| Conventional biological treatment processes such as activated sludge and trickling filters have been used to treat hazardous wastes. One innovation that has been used by some facilities is the sequencing batch reactor (SBR). The use of SBRs is not new, but recently they are being used for the treatment of hazardous and high strength industrial wastewaters. In wastewater treatment, microbial growth is usually described by the Monod equation. However, Monod kinetics will not be followed if a wastewater contains a mixture of toxic and inhibitory compounds. This project presents a mathematical model for the biodegradation of volatile organic compounds (VOCs) in a SBR including volatilization losses and competitive inhibition kinetics. The model is applied in the simulation of a SBR treating a mixture of two different substrates. The results obtained were also compared to those for a conventional activated sludge process operating under similar conditions.; The key parameter in this model was found to be the half-saturation constant for each substrate (KS), which greatly affects the response of both types of reactors. Differences in the K S values may cause some substrates to be removed from the wastewater more easily than others, because the inhibition effect is based on the value of this parameter. This model also quantifies the final fate of each individual pollutant during biological treatment. This can be a very important factor when using biological treatment for priority pollutants for which the maximum contaminant levels can be of the order of micrograms/liter. |
