Comparison of the quantity and quality of the microbiological content of sludge in countries with low and high content of pathogens

Abstract

The parasites present in the residual sludge generated by the diverse treatment processes of residual water vary, depending on the socioeconomic and epidemiological conditions of different communities. And although data exist at the global level regarding the microbiological quality of sludge, these data are practically nonexistent in developing countries. Therefore, this project compares the content of the four principal groups of parasites in residual sludge from the United States and Mexico. The marked differences between the orders of magnitude found in the two countries (coliphages 103-106 and 1.3 × 105 PFU/gTS, fecal coliforms 107-1010 and 107, Salmonella typhi 106-108 and 103 MPN/gTS, Giardia lamblia 102-104 and 102 cysts/gTS and helminth ova from 73-177 and <1 to 10 viable HO/gTS, respectively) will permit proposing real, effective and economical stabilization processes (undoubtedly different from those of industrialized countries), and will thus take advantage of the benefits represented by the reuse and disposal of sludge, in addition to developing regulations in agreement with the conditions of each region.