Review of biofiltration processes relevant to water reclamation via aquifers

CSIRO advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific, and technical advice. To the extent permitted by law, CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it. Executive Summary The biological clogging of natural porous media, often in conjunction with physical or chemical clogging, is encountered during managed aquifer recharge (MAR). The biologically mediated clogging often observed in MAR applications is affected by the character and concentration of biodegradable organic matter (BOM) in source waters. Biofiltration is a water treatment technology used to reduce BOM concentrations in source waters and hence has potential to limit biologically mediated clogging in natural porous media. Furthermore, the biofiltration media may behave similarly to aquifer media, potentially allowing much more precise and simpler measurements of coincident processes of BOM uptake and removal. This could lead to an improved understanding of near well processes in aquifers where it manifests as well clogging. Slow sand filtration (SSF), a " low technology " form of biofiltration, is recognised as the earliest established water treatment technology for provision of safe drinking water. SSF is also recognised as a technology that is simple and robust and can be readily adopted where sufficient space is available. Applications of SSF range from provision of safe water in rural, remote, and developing communities to its integration within extensive tertiary treatment trains for achievement of specific water quality targets in high technology applications. SSF's robust character and generally simple technology highlight its potential as pretreatment for MAR, and is particularly in line with the UN Millennium goals for safe drinking water in the developing world. The design, construction, and operation of SSFs are well defined but, for safe potable water supply, are predominantly for pathogen and turbidity removal. Design features typically include the use of ~ 1m depth of sand filter media, with a uniform small grain size (~0.2 mm). An operational feature of …