Table 6.2 (continued) Minimisation Clogging and prevention mechanism Renovation technique C u Measurements and techniques solutions and AOC) Adapt duration microbial • Microbial Basin drying or analyses on soil of wetting and • growth scraping drying cycles in and aquifer Improve • basins samples source- water • pretreatment, • Pumping especially • analyses nutrient Chlorine shock substrate • Photography • removal or dosing in (basins) and chlorine source Acid treatment down-hole • dosing water TV camera Heat Backwash • • survey more Wire brushing • N, Chemical and • frequently Multienzyme • AOC = assimilable organic carbon; MFI = membrane filtration index; N = nitrogen; = phosphorous; SEM = scanning electron microscope; TSS = total suspended solids; TV = television. Source: adapted from Pyne (1995), Pérez-Paricio and Carrera (1999). Box 6.1 Identification and management of chemical clogging Fresh, oxygenated, low-pH groundwater from a surficial aquifer on South Goulburn Island, Northern Territory, was injected into an underlying brackish sandstone aquifer known to contain pyrite. This resulted in clogging of the injection well by iron oxyhydroxides. This was largely anticipated during the feasibility phase of the project, on the basis of geochemical modelling drawn from source and receiving water-quality data and core sample mineralogical analyses. Clogging was subsequently controlled by installation of a dedicated pump, to enable weekly backwashing of the aquifer storage and recovery well (Pavelic et al 2002a). 6.1.3 Tools for predicting clogging Numerous techniques have been developed to predict clogging. These range in complexity from the measurement of simple water-quality indices through to sophisticated process-based modelling. A summary of the main techniques is given below. Measures of recharge water-quality parameters Measures of recharge water-quality parameters that are useful indicators of the clogging potential of managed aquifer recharge systems include: physical clogging • turbidity – total suspended solids – membrane filtration index – microbial clogging • total organic carbon – dissolved organic carbon –
Table 6.2 (continued) Clogging mechanism Minimisation and prevention Renovation technique Measurements and techniques Microbial growth • substrate in source water N, and AOC) • Improve source- water pretreatment, especially nutrient removal or chlorine dosing • Backwash more frequently • Adapt duration of wetting and drying cycles in basins • Pumping • Chlorine shock dosing • Acid treatment • Heat • Wire brushing • Multienzyme solutions • Basin drying or scraping • analyses • Photography (basins) and down-hole TV camera survey • Chemical and microbial analyses on soil and aquifer samples AOC = assimilable organic carbon; MFI = membrane filtration index; N = nitrogen; = phosphorous; SEM = scanning electron microscope; TSS = total suspended solids; TV = television. Source: adapted from Pyne (1995), Pérez-Paricio and Carrera (1999). Box 6.1 Identification and management of chemical clogging Fresh, oxygenated, low-pH groundwater from a surficial aquifer on South Goulburn Island, Northern Territory, was injected into an underlying brackish sandstone aquifer known to contain pyrite. This resulted in clogging of the injection well by iron oxyhydroxides. This was largely anticipated during the feasibility phase of the project, on the basis of geochemical modelling drawn from source and receiving water-quality data and core sample mineralogical analyses. Clogging was subsequently controlled by installation of a dedicated pump, to enable weekly backwashing of the aquifer storage and recovery well (Pavelic et al 2002a). 6.1.3 Tools for predicting clogging Numerous techniques have been developed to predict clogging. These range in complexity from the measurement of simple water-quality indices through to sophisticated process-based modelling. A summary of the main techniques is given below. Measures of recharge water-quality parameters Measures of recharge water-quality parameters that are useful indicators of the clogging potential of managed aquifer recharge systems include: • physical clogging – turbidity – total suspended solids – membrane filtration index • microbial clogging – total organic carbon – dissolved organic carbon C u
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