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There are alternative decentralised wastewater treatment systems that can be implemented in camps. One example is an aerobic baffled rector (ABR). ABR’s are not suitable for the acute or rapid response stage of an emergency because biological environment within the ABR takes time to establish (even if inoculated) and are more suited for transition and recovery periods as well as long-term sustainable solutions.

The primary advantage of choosing an ABR system is the lower operation and maintenance costs in comparison to a septic tank or holding tank. Because of the increased aerobic activity in the ABR system sludge accumulation is minimal and a well designed system will require desludging only every 6 months to 1 year.

An ABR can be considered an ‘improved’ septic tank that uses baffles to optimise treatment. Treatment of the wastewater takes place as it is forced to flow upward through a series of chambers, where pollutants are biologically degraded in an active sludge layer at the bottom of each chamber.

Pathogen and nutrient reduction is low in ABR’s; if high effluent standards are to be achieved, an additional treatment technology should be added (e.g. Planted Gravel Filter, Waste Stabilisation Ponds).

References & Further Reading A systematic overview on different sanitation systems and technologies including ABR’s and complementary technologies: Tilley, E., Ulrich, L., Lüthi, C., Reymond, Ph., Zurbrügg, C. (2014). Compendium of Sanitation Systems and Technologies - (2nd Revised Edition). Swiss Federal Institute of Aquatic Science and Technology (Eawag), Duebendorf, Switzerland

Comprehensive book about decentralised wastewater treatment systems: Ulrich, A. (Ed.), Reuter, S. (Ed.), Gutterer, B. (Ed.), Sasse, L., Panzerbieter, T. and Reckerzügel, T. (2009). Decentralised Wastewater Treatment Systems (DEWATS) and Sanitation in Developing Countries. A Practical Guide. WEDC, Loughborough University, Leicestershire, UK.

Analyses the appropriateness of anaerobic baffled reactors (ABRs) for on-site primary sanitation in low-income communities: Foxon, K. M., Pillay, S., Lalbahadur, T., Rodda, N., Holder, F. and Buckley, C. A. (2004). The Anaerobic Baffled Reactor (ABR): An Appropriate Technology for on-Site Sanitation. Water SA 30 (5) (Special Edition). Available at: www.wrc.org.za