Emission of Microbial Aerosols from Polluted Waters in Densely Populated Regions

The air surrounding three activated sludge tanks was sampled over a two year period for the emission of bacterial aerosols under a variety of climatic conditions and at varying distances upwind and downwind of the aerated tanks. All plants emitted species of enteric bacteria which are significant as index organisms and as frank pathogens. The emission pattern of these bacteria were influenced by distance from the plant and wind direction. Within the parameters of a plant, defined arbitrarily in this study by sampling sites less than 150 m upwind and less than 900 m downwind, distance from the source was the only reliable predictor of emissions, and no statistical significance was found in the differences between upwind and downwind samples at the same distances from the plant. Multiple regression analysis revealed no consistent influences of any environmental factor on emission rate, but relative humidity, wind speed, air temperature, and ozone levels showed some contribution on the bacterial count, while light intensity appeared to have little influence. The deposition and retention of enteric bacteria on foliage plants near aerated basins was used as an alternate sampling method, and it emphasized the potential hazard of these aerosols. This method confirmed the inability to predict the emission rate by climatic factors, but wind speed contributed directly to the counts, and there was a pronounced difference in the average counts of upwind and downwind samples. The LD50 in mice was the same for aerosolized Klebsiella pneumoniae as for a strain of Klebsiella pneumoniae recovered from the sputum of a patient with pneumonia. Escherichia, Enterobacter and Klebsiella were recovered from the respiratory tract of mice forced to inhale air at a sewage treatment plant when the respiratory organs were assayed immediately after exposure, but not when the assay followed a prolonged period of observation, during which there was also an absence of clinical symptoms. This investigation also included a pilot study of the numbers of viable cells in the colony forming units on plates exposed in an Andersen Sampler, and CFU was found to be an unreliable index of viable cell counts. The study concludes that bacterial aerosols are a hazard for residents living near package plants, and recommends adopting alternate methods of sewage treatment that would remove the emissions of numerous package plants from the environment of densely populated regions

ENVIRONMENTAL AND HEALTH STUDIES OF KENTUCKY BLACKBIRD ROOSTS

At the present time we are under contract from the Kentucky Environmental Quality Commission to study three aspects of Kentucky starling-blackbird roost problems: (1) a study of birds killed this coming winter through PA-14 treatments, to obtain more accurate data on species composition, sex ratios, kill success and food items; (2) a compilation of breeding and wintering data on Kentucky populations through analysis of U.S. Fish and Wildlife Service summer bird counts and banding returns; and (3) a study of spore dispersal of various fungal species, most notably Histoplasma capsulatum, from roost sites. The winter sampling is yet to be done, as sprayings most likely will not be undertaken until December. The analysis of population figures is complete and will be partially reported herein, as some data may be of significance for application to future management efforts. The histoplasmosis study began in June 1976 and will continue throughout the winter and spring; some preliminary results are deemed of significance to management efforts and are also reported herein

Enteric Virus Survival in Package Plants and the Upgrading of the Small Treatment Plants Using Ozone

Post-chlorinated effluent collected with a portable viral concentrator from four treatment plants in Jefferson County, Kentucky, yielded infective viral particles from three plants from spring through late fall. The pH, ,chlorine, turbidity, and coliform levels of these effluents indicated that viral persistence was correlated with inefficient processing which produced effluent environments that inhibited disinfection by chlorine. The disinfection potential of ozone was tested on secondary effluent and finished water seeded with poliovirus and Esaheriahia coli. Low doses of ozone inactivated viruses and bacteria in treated water, but not in effluent. The inactivation of bacteria by ozone does not appear to be caused by cell lysis. Inability of poliovirus to form plaques correlated with inhibition of capsid penetration. Electron micrographs revealed that ozone degrades capsids. Ozonation produced low levels of COD and TOC reduction in package plant effluent. Since the reaction rates were not a simple function of COD levels and ozone dose it would be difficult to standardize dose rates. The relative inefficiency of ozone in reduction of biological and non-biological pollutants in effluents, combined with its high cost, does not favor a recommendation for ozonation as a tack-on process to upgrade these plants