A computational model is described which facilitates multi-parameter analyses of VOC emissions from sewers. The model, CORAL+, was used to simulate more than 3.6 million combinations of five system parameters, including sewer channel slope, relative depth of flow, pipe diameter, Henry's law coefficient, and headspace ventilation rate. Lumped results were analyzed using a graphical frequency array approach to identify parameter combinations that lead to potential VOC emission hot spots. Additional modeling was completed to provide examples of passive VOC emission reductions through control of system parameters. Computational results provide information related to combinations of parameters that either never or always lead to potential VOC emission hot spots, independent of the values associated with all other parameters. Results indicate that the common assumption of infinite ventilation can lead to significant overestimates of VOC emissions, and that controlled headspace ventilation can be used to reduce VOC emissions by an order of magnitude or more. This may be of significance with respect to reducing emissions from on-site industrial sewers by maintaining biodegradable VOCs in solution prior to discharge to a downstream biological treatment system. Results also suggest that VOC emissions are highly sensitive to wastewater flow rate, increasing as flow rate decreases. This is an important observation with respect to the fact that some municipalities encourage industrial discharges at night for purposes of flow equalization.

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