5.3.2 Operational monitoring for health risks Unacceptable risks from microbial infections can arise from even very brief, single exposures. Therefore, there is no room for even momentary failures in the barriers that protect users of recycled water from agents of disease. Fortunately, enough is known about most of the treatment processes and some of the usage control processes to ensure that operational monitoring can detect problems before excessive exposure has taken place. For example, this can mean online monitoring of processes such as filtration and disinfection. However, in lagoon systems, days to weeks may pass before water that has been tested will reach users, providing a window for less frequent monitoring and the use of microbial testing as part of operational monitoring. Table 5.4 gives further examples of operational monitoring and supporting programs. Table 5.4 Examples of operational monitoring and supporting programs for health risks Process step to be monitored Operational monitoring Supporting programs Media filtration plant Turbidity downstream of system • Head loss across system Instrument calibration • • pH and temperature Asset maintenance program • • Instrument calibration Primary settling system Flow rate through the system • • Asset maintenance program Solids depth • • Secondary treatment system Flow rate through the system Instrument calibration • • Sludge blanket depth Asset maintenance program • • Lagoon Flow rate through the system • Toxic blue-green algal levels and toxin • concentrations Instrument calibration • Microbial indicator concentrations Asset maintenance program • • Membrane plant Turbidity downstream of system • Head loss across system Instrument calibration • • Particle counts on outlet Asset maintenance program • • Ultraviolet (UV) plant Turbidity upstream • UV transmissivity • UV intensity and/or calculated dose • Flow rate • Ballast functionality • Lamp power • Lamp status Instrument calibration • • Cleaning frequency Asset maintenance program • • Chlorination plant Turbidity upstream • Free chlorine, temperature and pH at • Instrument calibration downstream monitoring point • Flow rate to enable calculation of Ct Asset maintenance program • • Over-irrigation control Soil moisture content Instrument calibration • • Irrigation time Asset maintenance program • • Accidental ingestion control Timing of irrigation • Direction of sprinkler throw before • application Wind direction before application • Presence, currency and comprehension • of user agreements Presence, integrity and clarity of • fittings, signage and other end-user controls Instrument calibration • Asset maintenance program •
5.3.2 Operational monitoring for health risks Unacceptable risks from microbial infections can arise from even very brief, single exposures. Therefore, there is no room for even momentary failures in the barriers that protect users of recycled water from agents of disease. Fortunately, enough is known about most of the treatment processes and some of the usage control processes to ensure that operational monitoring can detect problems before excessive exposure has taken place. For example, this can mean online monitoring of processes such as filtration and disinfection. However, in lagoon systems, days to weeks may pass before water that has been tested will reach users, providing a window for less frequent monitoring and the use of microbial testing as part of operational monitoring. Table 5.4 gives further examples of operational monitoring and supporting programs. Table 5.4 Examples of operational monitoring and supporting programs for health risks Process step to be monitored Operational monitoring Supporting programs Media filtration plant • Turbidity downstream of system • Head loss across system • pH and temperature Primary settling system • Flow rate through the system • Solids depth Secondary treatment system • Flow rate through the system • Sludge blanket depth Lagoon • Flow rate through the system • Toxic blue-green algal levels and toxin concentrations • Microbial indicator concentrations Membrane plant • Turbidity downstream of system • Head loss across system • Particle counts on outlet Ultraviolet (UV) plant • Turbidity upstream • UV transmissivity • UV intensity and/or calculated dose • Flow rate • Ballast functionality • Lamp power • Lamp status • Cleaning frequency Chlorination plant • Turbidity upstream • Free chlorine, temperature and pH at downstream monitoring point • Flow rate to enable calculation of Ct Over-irrigation control • Soil moisture content • Irrigation time Accidental ingestion control • Timing of irrigation • Direction of sprinkler throw before application • Wind direction before application • Presence, currency and comprehension of user agreements • Presence, integrity and clarity of fittings, signage and other end-user controls • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program
water-recycling-guidelines-full-21.docx