Significance of indicator bacteria in a regionalized wastewater treatment plant and receiving waters

A regional wastewater treatment plant was found to be discharging high conc entrations of fecal coliform bacteria in excess of acceptable surface water criteria. An investigation of the sources of those bacteria showed their o rigins to have been environmental, primarily from a pulp and paper mill. Fa lse positive and false negative fecal coliforms were also found and enumera ted. These bacteria were found to increase in numbers through the treatment plant, unlike sewage treatment plants in which they decrease to the efflue nt.