Animal Waste, Water Quality and Human Health

170Animal Waste, Water Quality and Human HealthInterestingly, this study reported flow effects on FIO concentrations in sewageeffluents and the results are split into dry weather conditions and response torainfall events. Table 5.5 provides details on the sample numbers for each typeof treatment and Table 5.6 provides results of the FIO concentrations in thedifferent treatment systems by flow condition.Table 5.5 Types of sewage treatment/effluent reported in Kay et al. (2008).Level of treatment aSpecific effluent types aUntreated sewage (69) Crude sewage discharges (16)Storm sewage overflows b (53)Primary treatment (12) Primary settled sewage effluent (7)Stored settled sewage effluent (2)Settled septic tank effluent (3)Secondary treatment (67) Trickling filter effluent (38)Activated sludge effluent c (17)Oxidation ditch effluent (3)Trickling/sand filter effluent (1)Rotating biological contactor effluent (8)Tertiary treatment (14) Reedbed/grass plot effluent (6)Ultraviolet-disinfected effluent (8)a Figures in brackets indicate number of different treatment plants sampled (numbers of validenumerations (n) are shown in Table 5.6).b Specificeffluent types comprise treatment plant inlet overflows, stormwater retention tankoverflows and combined sewer overflows (CSOs); high-flow data only.c Activated sludge effluent includes deep-shaft activated sludge effluent at one site.5.4 MICROBIAL TRANSPORTBoth Clean Water Act TMDL investigations and EU Water Framework Directive(WFD) Programmes of Measures require information at the drainage basin scale.There has been work at this scale on the impacts of land use on stream FIOconcentration and transport.Bales et al. (1995) examined phage (a viral tracer) and FIO transport in anaquifer at Cape Cod, USA and reported phage attenuation higher than that forthe bacteria. The phages were easily remobilised, however, by enhanced flowwhich suggests continued viability whilst adsorbed to the sandy aquifer matrix.Sinton et al. (2005) reported vertical microbial tracer transport from areas ofslurry spreading to a 16.8 m deep aquifer in New Zealand. The breakthroughcurves suggested travel speeds of between 15.7 and 39.2 m.hr −1 . The tracers