Table 3.8 (continued) Log Indicative treatment process Log On-site preventive measures Expo- Water quality objectivesc reduction reductions sure targets achievable reduct- (V, P, B)a by ionb treatment (V, P, B) Nonfood crops trees, turf, woodlots, flowers — 5.0 Secondary treatment or primary 0.5–1.0 Public in vicinity of irrigation area <10 000 cfu/100 mL E. coli • treatment with lagoon detention 3.5 0.5–2.0 No access and drip irrigation 6.0 • 4.0 1.0–3.0 No access during irrigation and, if spray 5.0 • irrigation, minimum 25–30 m buffer distance between irrigation area and nearest point of public access, and spray drift control (eg through part cycle sprinklers with 180° inward throw, vegetation screening, or anemometer switching or Extended buffer distances to >50 m • B = enteric bacteria; BOD = biochemical oxygen demand; cfu = colony forming unit; Ct = disinfectant concentration × time; P = enteric protozoa; SS =suspended solid; V = enteric virus; UV = ultraviolet a Log reduction targets are minimum reductions required from raw sewage based on 95th percentiles from Table 3.7. Exposure reductions are those achievable by on-site measures as listed in Table 3.3. b c Water quality objectives represent medians for numbers of and means for other parameters. E. coli d BOD and SS are an indication of secondary treatment effectiveness. Aim is to demonstrate reliability of disinfection and ability to consistently achieve microbial quality e f Log reductions for public in the vicinity of commercial food crop irrigation areas should comply with total log reductions required for municipal use.
Table 3.8 (continued) Log reduction targets Indicative treatment process Log reductions achievable On-site preventive measures Expo- sure reduct- Water quality objectivesc (V, P, B)a by ionb treatment (V, P, B) Nonfood crops — trees, turf, woodlots, flowers 5.0 Secondary treatment or primary 0.5–1.0 Public in vicinity of irrigation area • E. coli <10 000 cfu/100 mL 3.5 treatment with lagoon detention 0.5–2.0 • No access and drip irrigation 6.0 4.0 1.0–3.0 • No access during irrigation and, if spray 5.0 irrigation, minimum 25–30 m buffer distance between irrigation area and nearest point of public access, and spray drift control (eg through part cycle sprinklers with 180° inward throw, vegetation screening, or anemometer switching or • Extended buffer distances to >50 m B = enteric bacteria; BOD = biochemical oxygen demand; cfu = colony forming unit; Ct = disinfectant concentration × time; P = enteric protozoa; SS =suspended solid; V = enteric virus; UV = ultraviolet a Log reduction targets are minimum reductions required from raw sewage based on 95th percentiles from Table 3.7. b Exposure reductions are those achievable by on-site measures as listed in Table 3.3. c Water quality objectives represent medians for numbers of E. coli and means for other parameters. d BOD and SS are an indication of secondary treatment effectiveness. e Aim is to demonstrate reliability of disinfection and ability to consistently achieve microbial quality f Log reductions for public in the vicinity of commercial food crop irrigation areas should comply with total log reductions required for municipal use.