SWINE MANURE CLEANUP CRITERIA CALCULATION FOR ODOR CAUSING VOLATILE ORGANIC-COMPOUNDS BASED ON MANURE-TO-VENTILATION AIR EXPOSURE PATHWAY

A mathematical model was derived to calculate swine manure cleanup cri teria for odor causing volatile organic compounds (VOCs) so that accep table total dose would not exceeded through the inhalation of ventilat ion air in swine housing for workers and pigs. A hypothetical scenario was used which assumed that subsurface contaminant in swine manure di ffuses through a layer of manure-air interface then is swept into the ventilated airspace via advection, where long-term inhalation of conta minant was assumed to occur. The philosophy of the transport model is to incorporate the age distribution of contaminated air and a first-or der decay of contaminant sources into the diffusion model for simulati on of air concentrations of VOCs and total exposure dose. A closed-for m solution is presented to allow a series of numerical experiments for investigating the effects of adsorption characteristics between manur e gas and manure, the mean age of contaminated air, effective diffusiv ity, and degradation coefficient on total dose. Swine manure cleanup c riteria based on non-exceedence of the total hazardous dose correspond ing to an acceptable risk from indoor inhalation of four selected VOCs of p-cresol hexane, toluene, and xylene were calculated in a typical pig unit. The model can be used in the future to compute the relative effectiveness of VOCs filtration systems and/or altered ventilation ra tes on the VOC exposure problem in animal housing.