المُلخص التنفيذي
يشبه مِرحاض الدفْق الفاصل للبول Urine-Diverting Flush Toilet (UDFT) في مظهره مِرحاض الدفْق بالسيفون (و.5) عدا الفصل في فتحة المِرحاض، حيث تكون فتحة المِرحاض مُقسَّمة إلى قسمين لفصل البول عن البُراز. ويتوفر منه نماذج للجلوس المباشر على القاعدة، وأخرى للجلوس فوقها بوضعية القرفصاء.
يتم جمع البول في مصرف في الجزء الأمامي من المِرحاض، ويتم جمع البُراز في فتحة في جزء المِرحاض الخلفي. ويتم جمع البول بدون ماء، ولكن تُستخَدم كمية صغيرة من المياه لشطف مصرف البول عندما يتم دفْق المياه في المِرحاض. ويتدفْق البول إلى وحدة التخزين من أجل الاستخدام مرة أخرى أو المُعالجة، بينما يتم نزح البُراز بالمياه لتتم معالجته بعد ذلك.
| المُدخلات | المُخرَجات |
|---|---|
| البراز , البول ,مياة الدفق ,مياة تنظيف الشرج ,مواد التنظيف الجاف |
المياة البنية , البول |
اعتبارات التصميم
يتطلب هذا النظام عمل تصميم مزدوج للسباكة مزدوج؛ أي أنابيب منفصلة للبول والمياه البُنِّية )البُراز، مواد التنظيف الجافة ومياه الدفْق( ويجب تثبيت المِرحاض بعناية مع فهم كيف وأين يمكن أن تحدث الانسدادات بحيث يمكن منعها وإزالتها بسهولة. وينبغي أن تُستخدم الأنابيب البلاستيكية لتصريف البول، وذلك لمنع التآكل. وللحد من التكلس Scaling على جدار الأنابيب؛ يجب مراعاة أن تكون كافة الوصلات )الأنابيب( المتصلة بخزانات التخزين قصيرة قدر الإمكان، ويجب تثبيت الأنابيب -أينما كانت- بميل 1% على الأقل، ويجب تَجنُّب الزوايا القائمة)90 درجة(. وتُعتبر الأنابيب ذات قطر 50 ملليمتر مناسبة للمميول الحادة؛ لكونها سهلة الصيانة. وتُستخدم الأنابيب ذات القطر الأكبر > 75) ملليمتر (في وضع آخر، وخاصةً للميول البسيطة والنقاط التي يصعب الوصول إليها.
المُلاءَمَة
يعتبر مِرحاض الدفْق الفاصل للبول مناسبًا حينما يكون هناك ما يكفي من المياه للدفْق، وعندما توجد تقنية لمُعالجة المياه البُنِّية، وعندما يتم استخدام البول الذي تم جمعه. ولتحسين كفاءة الفصل يُوصَى بوجود مباول للرجال.
مراحيض الدفْق الفاصلة للبول مناسبة للاستخدامات العامة والخاصة على الرغم من أن هناك ضرورة للتدريب الجاد والتوعية الشاملة في الأماكن العامة؛ لضمان الاستخدام الصحيح والسليم، وكذلك للحد من الانسدادات.
وحيث إن هذه التقنية تتطلب أنابيب منفصلة لجمع البول والمياه البُنِّية فإن تركيب الأنابيب )أعمال السباكة( تكون أكثر تعقيدًا من مِراحيض الدفْق. كما أن التصميم المناسب وتركيب الأنابيب )أعمال السباكة( الخاصة بالبول أمر بالغ الأهمية ويتطلب خبرة عالية.
التشغيل والصيانة
كما هو الحال مع أي مِرحاض فإن النظافة اللائقة والصحيحة مهمة لفتحة )أو فتحات( المِرحاض و لمنع تراكم الأوساخ. وحيث إنه يتم تجميع البول بشكل مُنفصل، فقد تترسب الأملاح المعدنية المُكونة من مُركبَّات الكالسيوم والمغنيسيوم، وتتراكم في الأنابيب، وعلى الأسطح المُعرَّضة للبول باستمرار. ويُمكن أن يُمنع تراكم الأملاح المعدنية والتكلس Scaling بغسل الوعاء بحمض متوسط )على سبيل المثال، الخل (و/أو الماء الساخن، ويمكن استخدام حمض أقوى > 24% حمض الخليك Acetic أو محلول الصودا الكاوية )جزئين من الماء مع جزء واحد من الصودا( لإزالة الانسدادات، ومع ذلك ففي بعض الحالات قد يتطلَّب الأمر الإزالة اليدوية للانسدادات.
نظرة شمولية لتقنية الإصحاح البيئي
Urine Separation - Closing the Nutrient Cycle
This report presents the present state of knowledge about urine-separating toilets and systems for the recirculation of urine as an agricultural fertilizer. It contains a description of urine separation technology and how a system can be constructed for recirculating urine from residential districts to farmland. It also contains concrete recommendations about planning and management of the various components of the system.
JOHANSSON, M. (2000): Urine Separation - Closing the Nutrient Cycle. Final Report of the R&D Project: Source-Separated Human Urine - A Future Source of Fertilizer for Agriculture in the Stockholm Region. Stockholm: Stockholm Vatten, Stockholmshem & HSB National Federation URL [Accessed: 31.05.2019]Urine Diversion - One Step Towards Sustainable Sanitation
This report of Stockholm environment institute (SEI) presents the current state-of-the-art (2006) of urine-diverting systems, focusing on the Swedish experience and what can be learned from that experience. The intention is to inspire decision- and policy-makers to consider urine diversion for sanitation interventions aimed at meeting the sanitation target of the Millennium Development Goals.
KVARNSTROEM, E. EMILSSON, K. RICHERT STINTZING A. JOHANSSON, M. JOENSSON, H. PETERSENS, E. SCHOENNING, C. CHRISTENSEN, J. HELLSTROEM, D. QVARNSTROEM, L. RIDDERSTOLPE, P. DRANGERT, J.O. (2006): Urine Diversion - One Step Towards Sustainable Sanitation. (= EcoSanRes Publication Series ). Stockholm: Stockholm Environment Institute (SEI) URL [Accessed: 27.07.2010]Novaquatis final report. NoMix – A new approach to urban water management
From 2000 to 2006, the cross-cutting project Novaquatis explored the potential of urine source separation – also known as NoMix technology. Novaquatis comprises nine work packages, largely organized around the various stages of a nutrient cycle (e.g. user acceptation, sanitary technologies, storage and transport, urine treatment and fertiliser production, micropollutants in urine, urine-based fertilisers). The final report contains the results of all working packages as well as a practical guide for interested NoMix user.
LARSEN, T. A. LIENERT, J. (2007): Novaquatis final report. NoMix – A new approach to urban water management. Duebendorf: Swiss Federal Institute for Environmental Science (EAWAG) URL [Accessed: 12.05.2019]Technology Review of Urine Diversion Components
The publication explains the purposes of urine diversion, its benefits and challenges, urine precipitation, urine treatment and reuse in agriculture. Further, it provides an overview on design and operational aspects for equipment needed, such as waterless urinals and urine diversion toilets including supplier information and indicative costs. Overall, it pulls together scattered knowledge around the topic of urine diversion in a concise manner.
MUENCH, E. von WINKER, M. (2011): Technology Review of Urine Diversion Components. Overview of Urine Diversion Components such as Waterless Urinals, Urine Diversion Toilets, Urine Storage and Reuse Systems. Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH URL [Accessed: 11.05.2019]Technology Review of Urine-Diverting Dry Toilets (UDDTs)
This publication offers a complete overview of UDDT functions, design considerations, common operation and maintenance issues and generalised installation costs. Its focus is on applications in developing countries and countries in transition, although UDDTs are also applicable in developed countries.
RIECK, C. MUENCH, E. HOFFMANN, H. (2012): Technology Review of Urine-Diverting Dry Toilets (UDDTs). Overview on Design, Management, Maintenance and Costs. (= Technology Review ). Eschborn: German Agency for Technical Cooperation (GTZ) GmbH URL [Accessed: 11.05.2019]Closing the Loop between Sanitation and Agriculture in Accra, Ghana
Case study assessing the drivers and barriers for scaling-up the use of urine and faeces as an alternative fertilizer in urban agriculture in Accra.
TETTEY-LOWOR, F. (n.y): Closing the Loop between Sanitation and Agriculture in Accra, Ghana. (= Master Thesis ). Wageningen: Wageningen University URL [Accessed: 27.07.2010]Compendium of Sanitation Systems and Technologies. 2nd Revised Edition
This compendium gives a systematic overview on different sanitation systems and technologies and describes a wide range of available low-cost sanitation technologies.
TILLEY, E., ULRICH L., LÜTHI, C., REYMOND P. and ZURBRÜGG C. (2014): Compendium of Sanitation Systems and Technologies. 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag) URL [Accessed: 03.05.2023] PDFUrine and brownwater separation at the GTZ main office building, Eschborn, Germany
This case study is about a demonstration project in the headquarters of GTZ in Eschborn, Germany. The project consists of 50 urine-diversion flush toilets, 23 waterless urinals and 10 m³ urine storage tank.
WINKER, M. SADOUN, A. (2011): Urine and brownwater separation at the GTZ main office building, Eschborn, Germany. (= SuSanA - Case Studies ). Eschborn: Sustainable Sanitation Alliance (SuSanA) URL [Accessed: 12.05.2019]Compendium of Sanitation Systems and Technologies (Arabic)
This is the Arabic version of the Compendium of Sanitation Systems and Technologies. The Compendium gives a systematic overview on different sanitation systems and technologies and describes a wide range of available low-cost sanitation technologies.
TILLEY, E. ULRICH, L. LUETHI, C. REYMOND, P. SCHERTENLEIB, R. ZURBRUEGG, C. (2014): Compendium of Sanitation Systems and Technologies (Arabic). 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag) PDFMix or NoMix - A Closer Look at Urine Source Separation
Beside the headarticle about 'Novaquatis', an inter- and transdisciplinary Eawag project, investigated urine source separation and treatment as an option for modern wastewater management, there are more article about urine sepeartion and its development.
EAWAG (2007): Mix or NoMix - A Closer Look at Urine Source Separation. (= Eawag News , 63 ). Duebendorf: Swiss Federal Institute of Aquatic Science and Technology (EAWAG) URL [Accessed: 06.02.2012]Urine as Liquid Fertilizer in Agricultural Production in the Philippines
This field guide has been developed to accommodate the ever-increasing demand for more detailed and scientifically backed information on how to use urine in agricultural production. It is intended primarily for practitioners and experts in the water, sanitation, planning, and agriculture sectors, as well as local and national government officials from the various sectors, NGO and individuals interested and working in the field of agriculture and sustainable sanitation in the Philippines and the wider Southeast Asian region.
GENSCH, R. MISO, A. ITSCHON, G. (2011): Urine as Liquid Fertilizer in Agricultural Production in the Philippines. Cagayan de Oro: Sustainable Sanitation Center Xavier University (XU), the Philippine Sustainable Sanitation Knowledge Node, the Philippine Ecosan Network, and the Sustainable Sanitation Alliance (SuSanA) URL [Accessed: 07.05.2019]Urine Diversion - One Step Towards Sustainable Sanitation
This report of Stockholm environment institute (SEI) presents the current state-of-the-art (2006) of urine-diverting systems, focusing on the Swedish experience and what can be learned from that experience. The intention is to inspire decision- and policy-makers to consider urine diversion for sanitation interventions aimed at meeting the sanitation target of the Millennium Development Goals.
KVARNSTROEM, E. EMILSSON, K. RICHERT STINTZING A. JOHANSSON, M. JOENSSON, H. PETERSENS, E. SCHOENNING, C. CHRISTENSEN, J. HELLSTROEM, D. QVARNSTROEM, L. RIDDERSTOLPE, P. DRANGERT, J.O. (2006): Urine Diversion - One Step Towards Sustainable Sanitation. (= EcoSanRes Publication Series ). Stockholm: Stockholm Environment Institute (SEI) URL [Accessed: 27.07.2010]Appendix 1 for technology review of urine diversion components
This document contains a worldwide list of suppliers for waterless urinals. The tables of suppliers provided here are not complete listings but give only an indication of available products. If you spot errors or omissions, please contact the authors at ecosan@giz.de. In the brackets below each listing the date for provision of the information/last update of information is given. Please be aware that not all information is from 2011. An entry in this list does not imply a recommendation by GIZ. Costs are indicative only.
MUENCH, E., v. WINKER, M. GIZ (2011): Appendix 1 for technology review of urine diversion components. Worldwide listing of suppliers for waterless urinals. (= Technology Review ). Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH URL [Accessed: 31.05.2019]Appendix 2 of technology review of urine diversion components
This document contains a worldwide list of suppliers for urine diversion squatting pans. The tables of suppliers provided here are not complete listings but give only an indication of available products. If you spot errors or omissions, please contact the authors at ecosan@giz.de. In the brackets below each listing the date for provision of the information/last update of information is given. Please be aware that not all information is from 2011. An entry in this list does not imply a recommendation by GIZ. Costs are indicative only.
MUENCH, E., v. WINKER, M. GIZ (2011): Appendix 2 of technology review of urine diversion components. Worldwide listing of suppliers for urine diversion squatting pans (for UDDTs or for urine diversion flush toilets). (= Technology Review ). Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH URL [Accessed: 29.04.2011]Appendix 3 of technology review of urine diversion components
This document contains a worldwide list of suppliers for urine diversion pedestals/seats (for UDDTs or for UD flush toilets). The tables of suppliers provided here are not complete listings but give only an indication of available products. If you spot errors or omissions, please contact the authors at ecosan@giz.de. In the brackets below each listing the date for provision of the information/last update of information is given. Please be aware that not all information is from 2011. An entry in this list does not imply a recommendation by GIZ. Costs are indicative only.
MUENCH, E., v. WINKER, M. GIZ (2011): Appendix 3 of technology review of urine diversion components. Worldwide listing of suppliers for urine diversion pedestals/seats (for UDDTs or for UD flush toilets). (= Technology Review ). Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH URL [Accessed: 29.04.2011]How to Make Simple Pedestals
This presentation offers the chance to learn about how to make different kinds of pedestals.
MORGAN, P. SHANGWA, A. (2009): How to Make Simple Pedestals. The Chisungu Primary School Water and Sanitation project. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI) URL [Accessed: 31.05.2019]Technology Review of Urine-Diverting Dry Toilets (UDDTs)
This publication offers a complete overview of UDDT functions, design considerations, common operation and maintenance issues and generalised installation costs. Its focus is on applications in developing countries and countries in transition, although UDDTs are also applicable in developed countries.
RIECK, C. MUENCH, E. HOFFMANN, H. (2012): Technology Review of Urine-Diverting Dry Toilets (UDDTs). Overview on Design, Management, Maintenance and Costs. (= Technology Review ). Eschborn: German Agency for Technical Cooperation (GTZ) GmbH URL [Accessed: 11.05.2019]Compendium of Sanitation Systems and Technologies. 2nd Revised Edition
This compendium gives a systematic overview on different sanitation systems and technologies and describes a wide range of available low-cost sanitation technologies.
TILLEY, E., ULRICH L., LÜTHI, C., REYMOND P. and ZURBRÜGG C. (2014): Compendium of Sanitation Systems and Technologies. 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag) URL [Accessed: 03.05.2023] PDFHow to Manage Public Toilets and Showers
The purpose of this decision-making aid is to provide practical advice and recommendations for managing toilet blocks situated in public places. It is primarily aimed at local decision-makers in developing countries and at their partners (project planners and managers).
TOUBKISS, J. (2010): How to Manage Public Toilets and Showers. (= Six Methodological Guides for a Water and Sanitation Services' Development Strategy , 5 ). Cotonou and Paris: Partenariat pour le Développement Municipal (PDM) and Programme Solidarité Eau (pS-Eau) URL [Accessed: 19.10.2011]Maintenance Guide for Roediger NoMix Toilets
This maintenance guide for Roediger NoMix Toilets proposes a maintenance strategy based on the experiences at Eawag. It gives an introduction to NoMix toilets, maintenance instructions and problem solving.
UHLMANN, C. GOOSE, P. OSER, M. (2013): Maintenance Guide for Roediger NoMix Toilets. Duebendorf: Eawag URL [Accessed: 26.09.2013]Urine-diverting vacuum sanitation system, Beijing
Urine diversion vacuum flush toilets were installed in an urban building. Urine collected in the source-separation sitting/squatting toilets as well as the waterless urinals is drained by gravity. Faeces are withdrawn by vacuum suction. There is currently no reuse of urine and brownwater, but they flow to the sewer.
GERMER, J. (2009): Urine-diverting vacuum sanitation system, Beijing. (= SuSanA - Case Studies ). Eschborn: Sustainable Sanitation Alliance (SuSanA) URL [Accessed: 07.07.2010]Source separating sanitation in Olympic Forest Park, Beijing
Urine diversion low-flush toilets where installed in public toilet blocks of the Olympic park. Urine was collected for reuse and brownwater was treated in a septic tank and moving bed reactor before being transformed into compost. The aim of the system was to interlink the sanitation material flows as a water and nutrient source with the green areas of the park as a water and nutrient sink. Reduced water and energy demand as well as the substitution of fertilizer by urine and faeces-derived manure were expected advantages.
GERMER, J. KANGNING, X. (2009): Source separating sanitation in Olympic Forest Park, Beijing. (= SuSanA - Case Studies ). Eschborn: Sustainable Sanitation Alliance (SuSanA) URL [Accessed: 07.07.2010]NoMix-Toilettensysteme. Erste Monitorergebnisse vom Forum Chriesbach
The NoMix toilet systems of Eawag’s main building have been in operation for three years. So far, NoMix toilets, waterless urinals and urine pipes do not show any clogging problems and no odour problems occurred inside the building. However, outside the building, odour problems occurred because of ammonia gas emissions from the urine pipes. For the moment, the most important remaining problem for an efficient separation of urine and faeces is the correct use of the NoMix toilets by non-acquainted users.
GOOSSE, P. (2009): NoMix-Toilettensysteme. Erste Monitorergebnisse vom Forum Chriesbach. Duebendorf: Swiss Federal Institute for Environmental Science (EAWAG) URL [Accessed: 10.08.2010]Novaquatis final report. NoMix – A new approach to urban water management
From 2000 to 2006, the cross-cutting project Novaquatis explored the potential of urine source separation – also known as NoMix technology. Novaquatis comprises nine work packages, largely organized around the various stages of a nutrient cycle (e.g. user acceptation, sanitary technologies, storage and transport, urine treatment and fertiliser production, micropollutants in urine, urine-based fertilisers). The final report contains the results of all working packages as well as a practical guide for interested NoMix user.
LARSEN, T. A. LIENERT, J. (2007): Novaquatis final report. NoMix – A new approach to urban water management. Duebendorf: Swiss Federal Institute for Environmental Science (EAWAG) URL [Accessed: 12.05.2019]Urban Urine Diversion and Greywater Treatment System Linz, Austria
This case study discusses a medium-scale pilot project in a new urban area in Linz, Austria. General objectives were the creation of a sustainable settlement in a new city district (high demand for residential buildings) and the establishment of ecological buildings and low energy construction concepts. Among specific objectives was the implementation of innovative solutions for water supply and wastewater treatment with a reduction of the infrastructure costs for municipal wastewater treatment. Also, the aim was to establish a holistic sanitation approach enabling the use of nutrients contained in excreta or wastewater in agriculture and to research treatment of micropollutants in urine.
OLDENBURG, M. WERNER, C. SCHLICK, J. KLINGEL, F. (2009): Urban Urine Diversion and Greywater Treatment System Linz, Austria. (= SuSanA - Case Studies ). Eschborn: Sustainable Sanitation Alliance (SuSanA) URL [Accessed: 24.09.2013]Urine and brownwater separation at the GTZ main office building, Eschborn, Germany
This case study is about a demonstration project in the headquarters of GTZ in Eschborn, Germany. The project consists of 50 urine-diversion flush toilets, 23 waterless urinals and 10 m³ urine storage tank.
WINKER, M. SADOUN, A. (2011): Urine and brownwater separation at the GTZ main office building, Eschborn, Germany. (= SuSanA - Case Studies ). Eschborn: Sustainable Sanitation Alliance (SuSanA) URL [Accessed: 12.05.2019]The search for appropriate latrine solutions for flood-prone areas of Bangladesh
The appropriateness of latrine technology depends on groundwater table, geographical context and acceptance by the community. The current study discusses defferent technologies and solutions for excreta management in flood- and cyclone-prone areas of Bangladesh.
MORSCHED, G. ; SOBHAN, A. (2010): The search for appropriate latrine solutions for flood-prone areas of Bangladesh. المُدخلات: Waterlines: Volume 29 URL [Accessed: 25.11.2015]Ecological sanitation within GTZs main building in Eschborn - A demonstration and research project
PDF-presentation on urine diversion flush toilet systems at the GTZ headquarter.
RUED, S. ; WERNER, C. (2007): Ecological sanitation within GTZs main building in Eschborn - A demonstration and research project. المُدخلات: Proceedings of the International Conference on Sustainable Sanitation: Eco-Cities and Villages, 26-31 August 2007, Dongsheng/Erdos: URL [Accessed: 10.08.2010]How to Separate Urine
This flyer contains information about the importance of urine reuse. The nutrients in urine are easily taken up by plants. The fertilised plant will grow faster, develop more leaves and produce higher yields. Applying urine to crops instead of chemical fertilisers saves money and energy and produces a similar yield. One person produces about 500 liter urine per year.
WECF (2010): How to Separate Urine. Utrecht/Munich/Annemasse: Women in Europe for a Common Future URL [Accessed: 06.01.2011]Yellow is the new Green
This opinion contribution from Rose George published in the New York Times emphasises the enormous potential urine as a sustainable fertiliser source.
GEORGE, R. (2009): Yellow is the new Green. المُدخلات: The New Your Times: , 27. URL [Accessed: 27.07.2010]Gee Whiz: Human urine is shown to be an effective agricultural fertilizer
The Scientific American is a popular science magazine in the US. This article, written for laymen, states that urine not only promotes plant growth as well as industrial mineral fertilizers, but also saves energy.
GRUNBAUM, M. (2010): Gee Whiz: Human urine is shown to be an effective agricultural fertilizer. المُدخلات: Scientific American: Volume 30 URL [Accessed: 17.04.2012]http://www.berger-biotechnik.com/
German provider of pre-fabricated composting toilets.
http://www.dubbletten.nu
Homepage of a Swedish urine diversion flush toilet supplier (only in Swedish).
http://www.eawag.ch/forschung/sww/gruppen/rttc/
Introducing the Reinvent the Toilet Challenge project at Eawag in cooperation with EOOS and Makerere University in Uganda, funded by the Bill & Melinda Gates Foundation.
http://www.ecovita.net/
Ecovita is a U.S.-based ecological toilet supplier (waterless, urine separation flush toilets, urine diversion composting toilets, etc.).
http://www.flickr.com/photos/gtzecosan/sets/72157626481209996/
SuSanA Flickr picture collection on UDFT.
http://www.novaquatis.eawag.ch/
Novaquatis – a cross-cutting Eawag research project was concerned with urine source separation as a new element in wastewater management.
http://www.saniresch.de/
This is the main homepage of the SANIRESCH project (SANItaryRecycling ESCHborn) which focuses on the treatment and recycling of the urine, brown- and greywater collected at the headquarters of the German Technical Cooperation (GTZ) GmbH in Eschborn, Germany.
http://www.separett.com/
International supplier of urine diversion composting toilets.
http://wostman.se/
Homepage of a Swedish urine diversion flush toilet supplier.
A Better Toilet For A Cleaner World
The sanitation technology paradigm is under review, as past approaches are not sufficient or affordable to close the sanitation coverage gap. In 2011, the Bill & Melinda Gates Foundation (BMGF) launched the bold Reinvent the Toilet Challenge (RTTC) program to promote the development of radically new innovations to address the sanitation challenge on a large-scale. The RTTC is premised on the fact that ground-breaking improvements are required in toilet design and fecal sludge management to close the urban sanitation gap. The RTTC is focused on reinventing the flush toilet, a break-through public health invention that has not changed substantially since the first flush toilet patent was issued in 1775.