Probabilistic Analysis of Sludge Land Application

Abstract

A Monte Carlo simulation approach is proposed for estimating the groundwater pollution risk from nitrate in percolation from sludge land application sites. The approach is used to estimate the probability that annual nitrate‐nitrogen concentrations will fail to meet a water quality standard. Failure probabilities and mean annual nitrate‐nitrogen concentrations were computed as functions of sludge application rates for 12 example systems in New York. The results for aerobic, anaerobic, and composted sludges indicated that application rates that are designed to limit mean nitrate‐nitrogen concentrations to no more than 10 mg/L during a system's operating life result in failure probabilities of 30–40%. Thus, although the average groundwater nitrate concentration will meet a water quality standard, the standard will be violated in three or four years out of ten.