Table 3.8 (continued) Water quality objectivesc Log Indicative treatment process Log On-site preventive measures Expo- reduction reductions sure targets achievable reduct- (V, P, B)a by ionb treatment (V, P, B) Landscape irrigation trees, shrubs, public gardens, etc — BOD <20 mg/Ld 5.0 Secondary treatment or primary 0.5–2.0 Combinations of: • treatment with lagoon detention 3.5 0.5–2.0 SS <30 mg/ Ld microspray 2.0 • • 4.0 1.0–3.0 <1000 cfu/100 mL (if not drip irrigation 4.0 E. coli • • disinfected) no public access 3.0 • Commercial food crops consumed raw or unprocessed 6.0 Advanced treatment to achieve total 6.0 None required, although pathogen 0.5 To be determined on case-by-case • • pathogen removal required (eg reduction will occur between harvesting basis, depending on technologies 5.0 5.0 V, secondary, filtration and disinfection) and sale Could include turbidity criteria for 5.0 5.0 • The recycled water can be used for all crop filtration, disinfectant Ct or dose (UV) • applications, including spray irrigation of <1 per 100 mL E. coli • salad crops Commercial food crops days lagoon detention and and no harvest of wet or dropped produce day V, B 6.0 3.0 disinfection Crops with ground contact with skins 5.0 • removed before consumption (eg BOD <20 mg/Ld 5.0 • watermelons) if spray irrigation, — 3.0–4.0 SS <30 mg/ Ld • minimum 2 days between final irrigation 2.0–4.0 Disinfectant residual (eg minimum • 3.0–4.0 and harvest chlorine residual) or UV dosee >6.0 — Pathogen reduction between harvesting and • <100 cfu/100 mL E. coli drip • sale Consumers Public in vicinity of irrigation area5 with Crops with limited or no ground • >25 0.5/ contact and eaten raw (eg No access and drip or subsurface irrigation 6.0 • No access during irrigation and if spray • 4.0 irrigation, minimum 25–30 m buffer
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) Landscape irrigation — trees, shrubs, public gardens, etc 5.0 Secondary treatment or primary 0.5–2.0 Combinations of: • BOD <20 mg/Ld 3.5 treatment with lagoon detention 0.5–2.0 • microspray 2.0 • SS <30 mg/ Ld 4.0 1.0–3.0 • drip irrigation 4.0 • E. coli <1000 cfu/100 mL (if not • no public access 3.0 disinfected) Commercial food crops consumed raw or unprocessed 6.0 Advanced treatment to achieve total 6.0 • None required, although pathogen 0.5 • To be determined on case-by-case 5.0 pathogen removal required (eg 5.0 reduction will occur between harvesting V, basis, depending on technologies 5.0 secondary, filtration and disinfection) 5.0 and sale • The recycled water can be used for all crop • Could include turbidity criteria for filtration, disinfectant Ct or dose (UV) applications, including spray irrigation of • E. coli <1 per 100 mL Commercial food crops salad crops 6.0 5.0 5.0 with >25 days lagoon detention and disinfection 3.0–4.0 2.0–4.0 >6.0 Consumers • Crops with limited or no ground contact and eaten raw (eg — drip and no harvest of wet or dropped produce • Crops with ground contact with skins removed before consumption (eg watermelons) — if spray irrigation, minimum 2 days between final irrigation and harvest • Pathogen reduction between harvesting and sale Public in vicinity of irrigation area5 3.0 3.0–4.0 0.5/ day V, B • BOD <20 mg/Ld • SS <30 mg/ Ld • Disinfectant residual (eg minimum chlorine residual) or UV dosee • E. coli <100 cfu/100 mL • No access and drip or subsurface irrigation 6.0 • No access during irrigation and if spray 4.0 irrigation, minimum 25–30 m buffer