Microbial characterization of municipal wastewater at a spray irrigation site: the Lubbock infection surveillance study

The objective of the Lubbock Infection Surveillance Study (LISS) was to identify possible adverse effects on human health from slow-rate land application of wastewater. During a 3-year study wastewater applied to a 1478-ha site from either the transit pipeline or on-site storage reservoirs was analyzed for indicator bacteria, bacteriophages, enteric viruses, and selected physical and chemical parameters. Irrigation wastewater used before reservoir completion had a composition equivalent to a typical medium strength untreated wastewater with fecal coliform levels exceeding $10^{6}/100$ mL and virus levels ranging from 100 to 1000 pfu/L. Impoundment of this wastewater reduced coliform levels by as much as 99% and lowered viral levels to less than 10 pfu/L.