Technology review of composting toilets Basic overview of composting toilets (with or without urine diversion) 1 Imprint Published by: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH Sustainable sanitation - ecosan program Postfach 5180, 65726 Eschborn, Germany T +49 61 96 79-4220 F +49 61 96 79-80 4220 E [email protected] I www.giz.de/ecosan Place and date of publication: Eschborn, September 2011 Author: Wolfgang Berger Responsible editor: Dr. Elisabeth von Muench Acknowledgements: We thank Patrick Bracken and Jürgen Stäudel for Design: their critical comments and editing work during the Martina Winker (GIZ) reviewing process. Photos: Contact: Cover: © Wolfgang Berger, Emmanuel Morin Dr. Elisabeth von Muench, GIZ ([email protected]) Back: © Wolfgang Berger, Eduard Le Douarin 2 Contents 1 Summary and target audience .............................................................................................................................................. 5 2 Introduction ............................................................................................................................................................................. 5 2.1 Scope of this document ................................................................................................................................................... 5 2.2 General description .......................................................................................................................................................... 5 2.3 Functional principles ........................................................................................................................................................ 6 2.3.1 Biological composting process .................................................................................................................................. 6 2.3.2 Bulking material ........................................................................................................................................................ 6 2.3.3 Ventilation ................................................................................................................................................................. 6 2.3.4 Hygiene (pathogen removal) ..................................................................................................................................... 7 2.3.5 Optimum water content ............................................................................................................................................. 7 2.3.6 Management and reuse of leachate ......................................................................................................................... 8 2.4 Available technologies ..................................................................................................................................................... 8 2.4.1 Toilet and storage facility in one unit or separated .................................................................................................... 8 2.4.2 Single-vault or multiple-vault toilets .......................................................................................................................... 8 2.4.3 Urine diversion versus “mixed composting” .............................................................................................................. 8 2.5 Costs ................................................................................................................................................................................ 8 2.5.1 Owner-built or commercially manufactured............................................................................................................... 8 2.5.2 Low-tech or high-tech systems ................................................................................................................................. 9 2.5.3 Cost benefits ............................................................................................................................................................. 9 2.6 Worldwide applicability ..................................................................................................................................................... 9 3 General recommendations for operation ............................................................................................................................. 9 3.1 Overview .......................................................................................................................................................................... 9 3.2 Cleaning ........................................................................................................................................................................... 9 3.3 Maintenance .................................................................................................................................................................... 9 3.4 Composting and secondary treatment ........................................................................................................................... 10 3.5 Application and reuse of compost .................................................................................................................................. 10 3.6 Hygienic precautions and directives ............................................................................................................................... 10 4 Single-vault composting toilets .......................................................................................................................................... 11 4.1 Functional principles ...................................................................................................................................................... 11 4.1.1 The Arborloo ........................................................................................................................................................... 11 4.2 Operation and maintenance ........................................................................................................................................... 11 4.3 Extent of application ....................................................................................................................................................... 11 4.4 Hygiene (pathogen removal) .......................................................................................................................................... 12 4.5 Cost data ....................................................................................................................................................................... 12 4.6 Good practice examples ................................................................................................................................................ 12 5 Multiple-vault composting toilets ........................................................................................................................................ 12 5.1 Functional principles ...................................................................................................................................................... 12 5.1.1 Rotating multi-chamber ........................................................................................................................................... 12 5.1.2 Movable squatting plate .......................................................................................................................................... 13 5.1.3 Fossa alterna .......................................................................................................................................................... 13 5.2 Operation and maintenance ........................................................................................................................................... 13 5.3 Extent of application ....................................................................................................................................................... 13 5.4 Hygiene (pathogen removal) .......................................................................................................................................... 13 5.5 Cost data ....................................................................................................................................................................... 13 5.6 Good practice examples ................................................................................................................................................ 13 5.6.1 Example 1 – Sirdo Seco ......................................................................................................................................... 13 5.6.2 Example 2 – Pacific Island CCD toilet .................................................................................................................... 14 6 Mobile bucket or bin toilets followed by composting of the excreta ............................................................................... 14 6.1 Functional principles ...................................................................................................................................................... 14 6.2 Operation and maintenance ........................................................................................................................................... 15 6.3 Extent of application ......................................................................................................................................................