Reducing bioaerosol dispersion from wastewater treatment and its land application: a review and analysis

Wastewater treatment systems and spray irrigation of treated water may spread microorganisms such as bacteria and viruses through dispersion of aerosol particles. A recent review (Brooks, Josephson, Gerba, & Pepper, 2004) identifies appropriate reports. Teltsch and co-authors report findings that suggest effective management controls involve providing buffer zones, irrigating in the daytime and in times of low humidity, reducing microorganism levels in water used for spraying, and testing for multiple types of viruses and bacteria (Teltsch & Katzenelson, 1978; Teltsch, Shuval, & Tadmor, 1980; Teltsch, Kedmi, Bonnet, Borenzstajn-Rotem, & Katzenelson, 1980). Camann, Moore, Harding, and Sorber support these findings. They also note that fecal streptococci are hardier than fecal coliform and appear frequently in background samples, suggesting that this bacterium is a better indicator of background and downwind conditions than are fecal coliform bacteria. In their study, storage prior to spray irrigation reduced microorganism concentrations by 99 percent. Downwind concentrations of sprayed reservoir water were often comparable to background values (Camann, Moore, Harding, & Sorber, 1988). Italian researchers (Brandi, Sisti, & Amagliani, 2000; Carducci, Gemelli, Cantiani, Casini, & Rovini, 1999; Carducci et al., 2000) confirm variable die-away rates of microorganisms, observe a positive association between fecal streptococci and the presence of viruses, and recommend consideration of submerged aeration for sludge digestion at sewage treatment plants. No reports are available that measure dispersion of bioaerosols from wastewater consistently treated to meet contemporary disinfection standards.