The effect of anaerobic and aerobic wastewater treatment on faecal coliforms and antibiotic-resistant faecal coliforms.

The efficiency of anaerobic treatment of animal wastes and aerobic treatment of urban sewage in removing faecal coliforms and their effect on the antibiotic-resistant coliforms was evaluated in this study. A two reactor anaerobic digester and six activated sludge plants were studied. The concentrations of both faecal coliforms in sampling from influents and treated effluents were calculated to determine efficiency of plants during depuration treatments. Anaerobic and aerobic treatments resulted in 90% and 97% (arithmetic mean values) efficiency in removing faecal coliforms. Although neither anaerobic nor aerobic treatment seems to significantly increase the percentage of antibiotic-resistant bacteria, during the aerobic treatment of urban sewage there was a tendency for the percent of antibiotic-resistant bacteria to increase.