ABSTRACT
A human pathogen is any virus, microorganism, or substance capable of causing disease. By this definition, bacteria, parasites, viruses, microbial substances, fungi and other organisms are pathogens. The two general categories are primary and secondary pathogens. Fecal coliform, an indicator organism when present in large numbers, indicates the potential presence of pathogens. Intestinal pathogenic bacteria normally react to environmental conditions in a similar manner, as do conforms. Thus, fecal coliforms are good indicator organisms. The efficiency of removal varies with the different unit processes. It also depends on the organisms and their physical and biological properties. For example, many parasites survive the wastewater treatment process and accumulate in the solids fraction, termed sludge, as a result of their densities. The solids resulting from wastewater treatment must undergo further treatment prior to land application. Land application of biosolids requires the disinfection and stabilization of biosolids.
