Soil Aquifer Treatment (SAT) facilitates to polish stormwater & treated wastewater and provides natural storage capacity prior to reuse or groundwater recharge. During subsurface passage of artificially infiltrated effluent, the effluent is subjected to physical, chemical and biological nutrient and pathogen removal. After underground storage, water can be extracted through recovery wells, (post-treated, if necessary) and re-used.
Design and Construction Principles
Design of the functioning of soil aquifer treatment (SAT)
During wet cycles, infiltration basins (also “recharge basins”) (for unconfined aquifers) or injection wells (for confined and unconfined aquifers) are loaded with treated effluent or stormwater (MELIN 2009; SAKTHIVADIVEL 2007), followed by dry cycles for percolation. Involving both aerobic and anaerobic milieus, SAT facilitates to polish water for indirect potable or irrigation uses, but also offers natural storage and buffering capacity. Partial removal of organic and inorganic nitrogen, organic carbon as well as significant reduction effects in terms of phosphorus, some non-aromatic organics (including polysaccharides and proteins), trace metals or pathogens have been observed (MIOTLINSKI et al. 2010; NRMMC 2010; JIMENEZ 2008). Relying on sub-surface transport and storage, this method is specifically valuable for areas with high evaporation rates (MIOTLINSKI et al. 2010). Design and performance of SAT systems strongly depend on influent quality, geo-hydrological characteristics of soil and aquifer and operational schedule of infiltration components (hydraulic loading, drying intervals) as well as intended reuse purpose (NRMMC 2010; NCSWS 2001), whereas the following general set-up can be proposed: (1) Capture Zone (2) Pre-treatment (e.g. horizontal, vertical and free-surface CWs, waste stabilisation ponds, USAB reactors or advanced treatment such as ASP or membrane filtration systems) (3) Recharge unit (4) Subsurface storage (in the aquifer) (5) Recovery well or GW-recharge (6) Post-treatment (and Disinfection) (7) End use: drinking water supply, irrigation/industry, discharge to ecosystems. Conventional systems are designed for retention times in the aquifer of up to 12 months, “Short SAT” systems rely on retention times of 30-60 days. Land use requirements vary with the infiltration method used (LOFTUS 2011; CIKUREL 2006).
Operation and Maintenance
O&M requirements strongly depend on design and complexity of the infiltration system, the aquifer, the characteristics of the treated effluent as well as on the extraction method. For simple systems, e.g. where roof run-off from single houses is infiltrated on a small-scale and extracted for non-potable uses, only limited expertise might be required (infiltration is management on behalf of the householder themselves). However, in these cases, a local authority should provide design requirements for the householders and also monitor regional effects on the aquifer. For more complex, large-scale systems, operation and regulation requires more expertise to guarantee for ecologically sustainable operation. This specifically refers to the issue of risk management, which requires a deep understanding of the system (NRMMC 2010). A common maintenance issue is the development of a clogging layer on the infiltration basin’s surface (or around the injection well) due to accumulation of biofilm, algae, suspended solids and chemical precipitates, resulting in the decline of the infiltration rate.
Following PITTOCK et al. (2009), the economically most favourable use of SAT output water is for substitution of potable water for uses such as irrigation, environmental restoration, cleaning, sanitation or industrial uses. Capital costs and running costs generally depend on the number of injection wells or recovery wells, or the area of infiltration ponds/galleries required to recharge/recover water at the required rate. In general, the higher the total costs per unit volume of recovered water, the lower the yields of the extraction well. Treatment processes required to avert clogging can cause a major part of the costs. Space can especially become very cost-relevant in urban settings where land prices are high (MOITLINSKI et al. 2010). Moreover, for large-scale systems, also investigation costs for understanding the soil profile and the aquifer dynamics can be substantial (NRMMC 2010).
Experiences in Europe and other Cities of the World
In Basel (Switzerland) water from the river Rhine is used to provide around 60% of the total drinking water demand (25 Mm³/y) applying SAT in the “Langen Erlen” – a former floodplain landscape in the city. Following rapid sand filtration, river water is applied on eleven forested recharge basins, whereas three sections (0.5 ha each) are consecutively flooded for ten days, followed by a drying period of 20 days. The vegetation on the recharge basins consists of typical floodplain plants (such as ash tree, alders, willows, bird cherry, reed canary grass and sedges) building up a floodplain forest ecosystem whose plant roots and soil fauna keep the soil permeability continuously high. The shade offered by the plants prevents strong warming of the upper soil layers and hereby also algae growth. The infiltration capacity (1-2 m³/m²/d) of the recharge basins has been constant for decades. With a surface area demand of around 10 m²/inh. the system is primarily suitable for areas with low land prices and/or large forests (RUETSCHI 2004). Another prominent example for large-scale SAT, is the Shafdan treatment in the Dan Region (Central Israel), where parts of the wastewater from seven cities is treated with SAT prior to re-use for irrigation in the South of the country. Infiltrating around 130-140 Mm³/y on a total area of 80 ha, this is one of the biggest reclamation sites applying SAT (CIKUREL 2006). The effluent percolates through a deep vadose zone (15-30 m) and is horizontally spread through the saturated zone. 1-2 days surface spreading is followed by 2-6 days drying period and a retention time in the aquifer of 6-12 months resulting in “accidental drinking water quality”. Facing increasing urbanisation pressure, a short SAT was introduced in combination with nano-filtration being superior to the conventional SAT technology in terms of land use, time parameters, and water quality (efficient removal of microorganisms and micro-pollutants) (LOFTUS 2011; CIKUREL 2006).
Experiences in India
Investigations on potentials and challenges of (pilot-scale) SAT applications have been undertaken in e.g. Ahmedabad (NEMA et al. 2001), Delhi (JAMWAL & MITTAL 2010); Chennai City (DEEPA & KRISHNAVENI 2012). In Ahmedabad a pilot project was jointly conducted by Physical Research Laboratory, National Environmental Engineering Research Institute (NEERI) and Ahmedabad Municipal Corporation. SAT was applied for purifying the municipal secondary treated water and augmentation of groundwater. During an experiment period of 138 days in the post-monsoon period of 1996, an average of 1,650 m3/d of primary settled sewage entered the pilot system, and a recovery rate of about 60% could be achieved. Analysis of the system performance proved a reduction in the cost of centralised recharge collection, treatment and disposal; rejuvenation and restoration of groundwater for agricultural use. SAKTHIVADIVEL (2007), who investigated potentials of various groundwater recharge approaches in India, proposes that aquifers best suited for artificial recharge are those, which can absorb and retain large quantities of water. For surface spreading schemes in the arid zone, recent river alluvium (where water table is subject to pronounced natural fluctuations) but also coastal dunes and deltas were identified as favourable sites. Another aspect that needs to be addressed is the public perception of SAT (or wastewater reuse in general). NIJHAWAN et al. (2013) investigated the public perception of wastewater reuse through artificial groundwater recharge in India based on public consultation through questionnaires. The idea of using wastewater for artificial groundwater recharge was supported by a large number of respondents. However, there was significant concern over the quality of treated municipal wastewater and the general feasibility of using this water for groundwater recharge. The authors emphasised on the need for extensive awareness raising and strict process monitoring to sufficiently protect groundwater bodies from pollution.
For further information please visit: Soil Aquifer Treatment
Future Scenarios for Soil Aquifer Treatment: Responding to Change. SWITCH Project Workshop on Learning Alliance
This presentation provides information on the SAT system in the Dan Region (central Israel) and its importance and potential for water reclamation in Israel.CIKUREL, H. (2006): Future Scenarios for Soil Aquifer Treatment: Responding to Change. SWITCH Project Workshop on Learning Alliance. Tel Aviv: Mekorot URL [Accessed: 11.08.2011]
Water Quality Performance of Soil Aquifer Treatment (SAT) Using Municipal Treated Wastewater of Chennai City, India
The aim of this study is to assess the treated waste water quality performance before and after SAT by using short term soil column development for aquifer recharge applications.DEEPA, K. ; KRISHNAVENI, K. (2012): Water Quality Performance of Soil Aquifer Treatment (SAT) Using Municipal Treated Wastewater of Chennai City, India. In: Journal of Environmental Hydrology 20, Paper 2: URL [Accessed: 17.04.2015]
icrobiological quality of the treated wastewater is an important parameter for its reuse. The data on the Fecal Coliform (FC) and Fecal Streptococcus (FS) at different stages of treatment in the Sewage Treatment Plants (STPs) in Delhi watershed is not available, therefore in the present study microbial profiling of STPs was carried out to assess the effluent quality for present and future reuse options. This study further evaluates the water quality profiles at different stages of treatment for l6 STPs in Delhi city.JAMWAL, P. ; MITTAL, A.K. (2010): Reuse of Treated Sewage in Delhi City: Microbial Evaluation of STPs and Reuse Options. In: Resources, Conservation and Recycling: Volume 54 , 211-221. URL [Accessed: 17.04.2015]
Tel Aviv, Israel. Treating Wastewater for Reuse Using Natural Systems. SWITCH Training Kit Case Study
This case study includes the challenges the Shafdan treatment plant in Israel has experienced since the 1970’s; the new technologies that are applied and the lessons learned.LOFTUS, A.C. (2011): Tel Aviv, Israel. Treating Wastewater for Reuse Using Natural Systems. SWITCH Training Kit Case Study. Freiburg: ICLEI European Secretariat GmbH URL [Accessed: 24.08.2011]
A pilot study was carried out in Sabarmati River bed at Ahmedabad, India for renovation of primary treated municipal wastewater through soil aquifer treatment (SAT) system. The infrastructure for the pilot SAT system comprised of two primary settling basins, two infiltration basins and two production wells located in the centre of infiltration basins for pumping out renovated wastewater.NEMA, P. ; OJHA, C.S. ; KUMAR, A. ; KHANNA, P. (2001): Techno-Economic Evaluation of Soil-Aquifer Treatment Using Primary Effluent at Ahmedabad, India. In: Water Research 35/9: , 2179-2190. URL [Accessed: 17.04.2015]
This publication is one of the three modules that comprise the second phase of the Australian Guidelines for Water Recycling, which address health and environmental risks associated with water recycling. The guidelines as a whole, including this module, are designed to provide an authoritative reference that can be used to support beneficial and sustainable recycling of waters generated from sewage, grey water and stormwater, which represent an underused resource. The guidelines describe and support a broad range of recycling options, without advocating particular choices. It is up to communities as a whole to make decisions on uses of recycled water at individual locations. The intent of these guidelines is simply to provide the scientific basis for implementing those decisions in a safe and sustainable manner.NRMMC Biotext (2009): Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 2). Managed Aquifer Recharge. (= National Water Quality Management Strategy Document , 24 ). Canberra: Natural Resource Management Ministerial Council, Environment Protection and Heritage Council, National Health and Medical Research Council URL [Accessed: 18.03.2015]
This paper presents the perception of people toward artificial recharge and determines the primary concerns among members of the public, so that these can be addressed while carrying out pilot studies. This is the first such public survey that has been carried out in India.NIJHAWAN, A. ; LABHASETWAR, P. ; JAIN, P. ; RAHATE, M. (2013): Public Consultation on Artificial Aquifer Recharge Using Treated Municipal Wastewater. In: Resources, Conservation and Recycling: Volume 70 , 20-24. URL [Accessed: 17.04.2015]
Reclaim Water. Water Reclamation Technologies for Safe Artificial Groundwater Recharge. Publishable Final Activity Report
This report presents results from eight technical pilot studies on aquifer recharge (including SAT) between 2005 and 2008 on five continents. The main objective of these studies was to assess the overall performance of these sites in recharging aquifers mainly for irrigation and potable water supply purposes by following contaminant fate throughout each scheme.MELIN, T. (2009): Reclaim Water. Water Reclamation Technologies for Safe Artificial Groundwater Recharge. Publishable Final Activity Report. Aachen: RWTH Aachen University URL [Accessed: 26.05.2019]
This study conducted in Alice Springs, the arid zone of central Australia, evaluated the performance of the SAT method, in particular rates of infiltration and changes in groundwater quality. It found that attenuation of nitrogen is low because the soil beneath the basin is aerobic and denitrification is inhibited. The report features many technical details and data analysis.MIOTLINSKI, K. BARRY, K. DILLON, P. (2010): Alice Springs SAT Project Hydrological and Water Quality Monitoring Report 2008-2009. CSIRO Water for a Healthy Country National Research Flagship URL [Accessed: 10.08.2011]
Interbasin Water Transfers and Water Scarcity in a Changing World – a Solution or a Pipedream? Frankfurt a
Chapter about the groundwater recharge movement in India.SAKTHIVADIVEL, R. (2007): The Groundwater Recharge Movement in India. Chapter 10. In: GIORDANO, M. ; VILLHOLTH, K.G. (2007): The Agricultural Groundwater Revolution. Opportunities and Threats to Development. Colombo and Wallingford: 195-210. URL [Accessed: 17.04.2015]
Compendium of Natural Water Systems and Treatment Technologies to cope with Water Shortages in Urbanised Areas in India
The Compendium of NaWaTech Technologies presents appropriate water and wastewater technologies that could enable the sustainable water management in Indian cities. It is intended as a reference for water professionals in charge of planning, designing and implementing sustainable water systems in the Indian urban scenario, based on a decentralised approach.BARRETO DILLON, L. ; DOYLE, L. ; LANGERGRABER, G. ; SATISH, S. ; POPHALI, G. (2013): Compendium of Natural Water Systems and Treatment Technologies to cope with Water Shortages in Urbanised Areas in India. Berlin: EPUBLI GMBH URL [Accessed: 11.12.2015]