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'{{short description|Safe, beneficial use of human excreta mainly in agriculture (after treatment)}} [[File:Harvest of peppers at a SOIL experimental garden.jpg|thumb|upright=1.4|Harvest of [[capsicum]] grown with [[compost]] made from human excreta at an experimental garden in [[Haiti]]]] '''Reuse of human excreta''' is the safe, beneficial use of treated [[Human waste|human excreta]] after applying suitable treatment steps and risk management approaches that are customized for the intended reuse application. Beneficial uses of the treated excreta may focus on using the [[Plant nutrition|plant-available nutrients]] (mainly nitrogen, phosphorus and potassium) that are contained in the treated excreta. They may also make use of the organic matter and energy contained in the excreta. To a lesser extent, reuse of the excreta's water content might also take place, although this is better known as [[Reclaimed water|water reclamation]] from [[Wastewater|municipal wastewater]]. The intended reuse applications for the nutrient content may include: [[soil conditioner]] or [[fertilizer]] in [[agriculture]] or [[Horticulture|horticultural]] activities. Other reuse applications, which focus more on the organic matter content of the excreta, include use [[#Solid fuel, heat, electricity|as a fuel source]] or as an energy source in the form of [[biogas]]. There is a large and growing number of treatment options to make excreta safe and manageable for the intended reuse option.<ref name="tilley2" /> Some options include: Urine diversion and dehydration of feces ([[Urine-diverting dry toilet|urine-diverting dry toilets]]), composting ([[Composting toilet|composting toilets]] or external [[Compost|composting processes]]), [[sewage sludge treatment]] technologies and a range of [[Fecal sludge management|fecal sludge treatment]] processes. They all achieve various degrees of pathogen removal and reduction in water content for easier handling. Pathogens of concern are enteric bacteria, virus, protozoa, and [[Parasitic worm|helminth eggs]] in feces.<ref name="Harder 695–743">{{Cite journal|last1=Harder|first1=Robin|last2=Wielemaker|first2=Rosanne|last3=Larsen|first3=Tove A.|last4=Zeeman|first4=Grietje|last5=Öberg|first5=Gunilla|date=2019-04-18|title=Recycling nutrients contained in human excreta to agriculture: Pathways, processes, and products|journal=Critical Reviews in Environmental Science and Technology|volume=49|issue=8|pages=695–743|doi=10.1080/10643389.2018.1558889|issn=1064-3389|doi-access=free}}</ref> As the helminth eggs are the pathogens that are the most difficult to destroy with treatment processes, they are commonly used as an [[indicator organism]] in reuse schemes. Other health risks and environmental pollution aspects that need to be considered include spreading micropollutants, [[Environmental persistent pharmaceutical pollutant|pharmaceutical residues]] and [[nitrate]] in the environment which could cause [[groundwater pollution]] and thus potentially affect [[Drinking water quality standards|drinking water quality]]. There are several "human excreta derived fertilizers" which vary in their properties and fertilizing characteristics, for example: urine, dried feces, composted feces, [[Fecal sludge management|fecal sludge]], [[sewage]], [[sewage sludge]]. The nutrients and organic matter which are contained in human excreta or in domestic [[wastewater]] ([[sewage]]) have been used in agriculture in many countries for centuries. However, this practice is often carried out in an unregulated and unsafe manner in [[Developing country|developing countries]]. [[World Health Organization]] Guidelines from 2006 have set up a framework describing how this reuse can be done safely by following a "multiple barrier approach".<ref name="WHO2006">WHO (2006). [http://www.susana.org/en/resources/library/details/1004 WHO Guidelines for the Safe Use of Wastewater, Excreta and Greywater - Volume IV: Excreta and greywater use in agriculture]. World Health Organization (WHO), Geneva, Switzerland</ref> Such barriers might be selecting a suitable crop, farming methods, methods of applying the fertilizer and education of the farmers. {{TOC limit|3}} == Terminology == Human excreta, [[Fecal sludge management|fecal sludge]] and [[wastewater]] are often referred to as wastes (see also [[human waste]]). Within the concept of a [[circular economy]] in sanitation, an alternative term that is being used is "resource flows".<ref name=":5" />{{rp|10}} The final outputs from the [[sanitation]] treatment systems can be called "reuse products" or "other outputs".<ref name=":5" />{{rp|10}} These reuse products are general [[Fertilizer|fertilizers]], [[Soil conditioner|soil conditioners]], [[biomass]], water or energy. Reuse of human excreta focuses on the nutrient and organic matter content of human excreta unlike [[Reclaimed water|reuse of wastewater]] which focuses on the water content. An alternative term is "use of human excreta" rather than "[[reuse]]" as strictly speaking it is the ''first'' ''use'' of human excreta, not the second time that it is used.<ref name="WHO2006" /> == Technologies and approaches == [[File:Morestead Sewage Farm - geograph.org.uk - 57146.jpg|thumb|right|A [[sewage farm]] in Hampshire, England]] The resources available in wastewater and human excreta include water, [[Plant nutrition|plant nutrients]], [[organic matter]] and energy content. [[Sanitation]] systems that are designed for safe and effective [[Resource recovery|recovery of resources]] can play an important role in a community's overall [[Environmental resource management|resource management]]. Recovering the resources embedded in excreta and wastewater (like nutrients, water and energy) contributes to achieving [[Sustainable Development Goal 6]] and other [[Sustainable Development Goals|sustainable development goals]].<ref name=":10">{{Cite journal|last1=Andersson|first1=Kim|last2=Dickin|first2=Sarah|last3=Rosemarin|first3=Arno|date=2016-12-08|title=Towards "Sustainable" Sanitation: Challenges and Opportunities in Urban Areas|journal=Sustainability|language=en|volume=8|issue=12|pages=1289|doi=10.3390/su8121289|doi-access=free}}</ref> It can be efficient to combine wastewater and human excreta with other [[Biodegradable waste|organic waste]] such as [[manure]], food and crop waste for the purposes of resource recovery.<ref name="Andersson">Andersson, K., Rosemarin, A., Lamizana, B., Kvarnström, E., McConville, J., Seidu, R., Dickin, S. and Trimmer, C. (2016). [http://www.susana.org/en/resources/library/details/2636 Sanitation, Wastewater Management and Sustainability: from Waste Disposal to Resource Recovery]. Nairobi and Stockholm: United Nations Environment Programme and Stockholm Environment Institute. {{ISBN|978-92-807-3488-1}}</ref> === Treatment options === There is a large and growing number of treatment options to make excreta safe and manageable for the intended reuse option.<ref name="tilley2">{{cite book|last1=Tilley|first1=Elizabeth|url=http://www.eawag.ch/en/department/sandec/publications/compendium/|title=Compendium of Sanitation Systems and Technologies|last2=Ulrich|first2=Lukas|last3=Lüthi|first3=Christoph|last4=Reymond|first4=Philippe|last5=Zurbrügg|first5=Chris|publisher=Swiss Federal Institute of Aquatic Science and Technology (Eawag)|year=2014|isbn=978-3-906484-57-0|edition=2nd|location=Duebendorf, Switzerland|chapter=Septic tanks|chapter-url=http://ecompendium.sswm.info/sanitation-technologies/septic-tank?group_code=s}}</ref> Various technologies and practices, ranging in scale from a single rural household to a city, can be used to capture potentially valuable resources and make them available for safe, productive uses that support human well-being and broader [[sustainability]]. Some treatment options are listed below but there are many more:<ref name="tilley2" /> * Urine diversion and dehydration of feces (which is done with [[Urine-diverting dry toilet|urine-diverting dry toilets]]) * Composting ([[Composting toilet|composting toilets]] or external [[Compost|composting processes]]) *[[Sewage sludge treatment]] technologies, which is installed downstream of various [[wastewater treatment]] technologies * [[Fecal sludge management|Fecal sludge treatment]] processes, such as sludge drying beds, [[Constructed wetland|constructed wetlands]]. * [[Anaerobic digestion]] with biogas production * [[Waste-to-energy]] process * [[Omni Processor]] A guide by the [[Swedish University of Agricultural Sciences]] provides a list of treatment technologies for sanitation resource recovery: Vermicomposting and [[Vermifilter|vermifiltration]], black soldier fly composting, [[algae]] cultivation, [[microbial fuel cell]], nitrification and distillation of urine, [[struvite]] precipitation, incineration, [[carbonization]], solar drying, membranes, filters, alkaline dehydration of urine, ammonia sanitization/urea treatment, lime sanitization.<ref name=":5">McConville, J., Niwagaba, C., Nordin, A., Ahlström, M., Namboozo, V. and Kiffe, M. (2020). [https://www.susana.org/en/knowledge-hub/resources-and-publications/library/details/4008 Guide to Sanitation Resource-Recovery Products & Technologies: A supplement to the Compendium of Sanitation Systems and Technologies]. 1st Edition. Swedish University of Agricultural Sciences (SLU), Department of Energy and Technology, Uppsala, Sweden.</ref> === Reuse options === The most common type of reuse of excreta is as fertilizer and soil conditioner in agriculture. This is also called a "closing the loop" approach for [[sanitation]] with agriculture. It is a central aspect of the [[ecological sanitation]] approach. Reuse options depend on the form of the excreta that is being reused: it can be either excreta on its own or mixed with some water ([[Fecal sludge management|fecal sludge]])<ref name=":4">{{Cite journal|last1=Andriessen|first1=Nienke|last2=Ward|first2=Barbara J.|last3=Strande|first3=Linda|date=2019|title=To char or not to char? Review of technologies to produce solid fuels for resource recovery from faecal sludge|url=https://iwaponline.com/washdev/article/9/2/210/66755/To-char-or-not-to-char-Review-of-technologies-to|journal=Journal of Water, Sanitation and Hygiene for Development|language=en|volume=9|issue=2|pages=210–224|doi=10.2166/washdev.2019.184|issn=2043-9083|doi-access=free}}</ref> or mixed with much water (domestic wastewater or [[sewage]]). The most common types of excreta reuse include:<ref name="Andersson" /> * [[Fertilizer]] and irrigation water in agriculture, and horticulture: for example using [[Reclaimed water|recovered and treated water]] for irrigation; using composted excreta (and other organic waste) or appropriately treated [[biosolids]] as [[Organic fertilizer|fertilizer]] and [[soil conditioner]]; using treated source-separated urine as [[Urine#Fertilizer|fertilizer]]. * Energy: for example digesting feces and other organic waste to produce [[biogas]]; or producing combustible fuels. * Other: other emerging excreta reuse options include producing protein feeds for livestock using [[Hermetia illucens|black soldier fly larvae]], recovering organic matter for use as building materials or in paper production. Resource recovery from fecal sludge can take many forms, including as a fuel, soil amendment, building material, protein, animal fodder, and water for irrigation.<ref name=":4" /> Reuse products that can be recovered from sanitation systems include: Stored [[urine]], concentrated urine, sanitized [[Blackwater (waste)|blackwater]], digestate, nutrient solutions, dry urine, struvite, dried feces, [[Pit latrine|pit]] humus, dewatered sludge, [[compost]], ash from sludge, [[biochar]], nutrient-enriched filter material, [[algae]], [[Aquatic plant|macrophytes]], black soldier fly larvae, worms, [[Irrigation|irrigation water]], [[aquaculture]], biogas.<ref name=":5" /> == As fertilizer == [[File:Spinach experiments at the SOIL farm.jpg|thumb|Comparison of [[spinach]] field with (left) and without (right) [[compost]], experiments at the [[Sustainable Organic Integrated Livelihoods|SOIL]] farm in Port-au-Prince, Haiti]] [[File:Application of urine (4461921719).jpg|thumb|Application of urine on a field near Bonn, Germany, by means of flexible hose close to the soil]] [[File:Reuse of urine - fertilised and not fertilised basil experiment part I (3530514851).jpg|thumb|Basil plants: The plants on the right are not fertilized, while the plants on the left are fertilized with urine - in a nutrient-poor soil]] [[File:Fig 2 - REPULO - urine reuse - Philippines (6519920661).jpg|thumb|Application of urine on eggplants during a comprehensive urine application field testing study at Xavier University, Philippines]] === Comparison to other fertilizers === {{Further|Fertilizer|Organic fertilizer}} There is an untapped fertilizer resource in human excreta. In Africa, for example, the theoretical quantities of nutrients that can be recovered from human excreta are comparable with all current fertilizer use on the continent.<ref name="Andersson" />{{rp|16}} Therefore, reuse can support increased food production and also provide an alternative to chemical fertilizers, which is often unaffordable to small-holder farmers. However, nutritional value of human excreta largely depends on dietary input.<ref name="Harder 695–743" /> Mineral fertilizers are made from mining activities and can contain heavy metals. Phosphate ores contain heavy metals such as cadmium and uranium, which can reach the food chain via mineral phosphate fertilizer.<ref>Kratz, S. (2004) [https://web.archive.org/web/20140413142857/http://gevleugeldewoorden.nl/wp-content/uploads/2013/06/Uran-Tag-download-5.pdf Uran in Düngemitteln] (in German)''.'' Uran-Umwelt-Unbehagen: Statusseminar am 14. Oktober 2004, Bundesforschungsinstitut für Landwirtschaft (FAL), Institut für Pflanzenernährung und Bodenkunde, Germany.</ref> This does not apply to excreta-based fertilizers, which is an advantage. Fertilizing elements of organic fertilizers are mostly bound in carbonaceous reduced compounds. If these are already partially oxidized as in the compost, the fertilizing minerals are adsorbed on the degradation products ([[humic acids]]) etc. Thus, they exhibit a slow-release effect and are usually less rapidly leached compared to mineral fertilizers.<ref name="SRN">{{Cite journal|author=J. B. Sartain|year=2011|title=Food for turf: Slow-release nitrogen|url=http://www.grounds-mag.com/mag/grounds_maintenance_food_turf_slowrelease/|journal=Grounds Maintenance for Golf and Green Industries Professionals (Blog Post)}}</ref><ref>{{cite journal|last1=Diacono|first1=Mariangela|last2=Montemurro|first2=Francesco|year=2010|title=Long-term effects of organic amendments on soil fertility. A review|url=https://hal.archives-ouvertes.fr/hal-00886539/file/hal-00886539.pdf|journal=Agronomy for Sustainable Development|volume=30|issue=2|pages=401–422|doi=10.1051/agro/2009040|issn=1774-0746|s2cid=7493884}}<!--https://hal.archives-ouvertes.fr/hal-00886539/file/hal-00886539.pdf--></ref> === Urine === <!-- The third and fourth paragraph of this section is transcribed to [[urine]], please keep that in mind if you make changes --> [[Urine]] contains large quantities of [[nitrogen]] (mostly as [[urea]]), as well as reasonable quantities of dissolved [[potassium]].<ref name=Rose2015>{{cite journal|last1=Rose|first1=C|last2=Parker|first2=A|last3=Jefferson|first3=B|last4=Cartmell|first4=E|year=2015|title=The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology|journal=Critical Reviews in Environmental Science and Technology|volume=45|issue=17|pages=1827–1879|doi=10.1080/10643389.2014.1000761|pmc=4500995|pmid=26246784}}</ref> The nutrient concentrations in urine vary with diet.<ref name="Joensson">Joensson, H., Richert Stintzing, A., Vinneras, B., Salomon, E. (2004). [http://www.susana.org/en/resources/library/details/187 Guidelines on the Use of Urine and Faeces in Crop Production]. Stockholm Environment Institute, Sweden</ref> In particular, the nitrogen content in urine is related to quantity of protein in the diet: A [[High-protein diet|high protein diet]] results in high urea levels in urine. The nitrogen content in urine is proportional to the total food protein in the person's diet, and the phosphorus content is proportional to the sum of total food protein and vegetal food protein.<ref name=":6" />{{rp|5}} Urine's eight main ionic species (> 0.1 meq L−1) are [[cation]]s [[sodium|Na]], [[potassium|K]], [[ammonium|NH₄]], [[calcium|Ca]] and the [[anions]], [[chlor|Cl]], [[sulfate|SO₄]], [[phosphate|PO₄]] and [[bicarbonate|HCO₃]].<ref name="kirchmann1995">{{cite journal|last1=Kirchmann|first1=H.|last2=Pettersson|first2=S.|year=1995|title=Human urine - Chemical composition and fertilizer use efficiency|journal=Fertilizer Research|volume=40|issue=2|pages=149–154|doi=10.1007/bf00750100|s2cid=24528286|issn=0167-1731}}</ref> Urine typically contains 70% of the nitrogen and more than half the [[potassium]] found in [[sewage]], while making up less than 1% of the overall volume.<ref name=Rose2015 /> Typical design values for nutrients excreted with urine are: 4 kg nitrogen per person per year, 0.36 kg phosphorus per person per year and 1.0 kg potassium per person per year (these values were published as "proposed Swedish default values" in 2004).<ref name=":6">Jönsson, H., Richert Stintzing, A., Vinnerås, B. and Salomon, E. (2004) [https://www.susana.org/en/knowledge-hub/resources-and-publications/library/details/187 Guidelines on the use of urine and faeces in crop production], EcoSanRes Publications Series, Report 2004-2, Sweden [This source seems to truncate the Jönsson & Vinnerås (2004) table by omitting the potassium row. The full version may be found at the original source at [https://www.researchgate.net/publication/285858813 RG#285858813]<!-- -->]</ref>{{rp|5}} The amount of urine produced by an adult is around 0.8 to 1.5 L per day.<ref name="WHO2006" /> Based on the quantity of 1.5 L urine per day (or 550 L per year), the concentration values of macronutrients as follows: 7300 mg/L N; 670 mg/L P; 1800 mg/L K.<ref name=":6" />{{rp|5}}<ref name=":Winker" />{{rp|11}} These are design values but the actual values vary with diet.<ref name=Rose2015 /> Urine’s nutrient content, when expressed with the international fertilizer convention of N:P₂O₅:K₂O, is approximately 0.7:0.15:0.22.<ref name=":Winker" /> This means that urine is rather diluted as a fertilizer compared to manufactured nitrogen fertilizers such as [[Diammonium phosphate|di-ammonium-phosphate]]. It also means the transport costs are high as a lot of water needs to be transported.<ref name=":Winker" /> <section begin=urine /><!-- The third and fourth paragraph of this section is transcribed to [[urine]], please keep that in mind if you make changes -->Applying urine as fertilizer has been called "closing the cycle of agricultural nutrient flows" or ecological sanitation or [[ecosan]]. Urine fertilizer is usually applied diluted with water because undiluted urine can [[Fertilizer burn|chemically burn]] the leaves or roots of some plants, causing plant injury,<ref>H. M. Vines, & Wedding, R. T. (1960). Some Effects of Ammonia on Plant Metabolism and a Possible Mechanism for Ammonia Toxicity. ''Plant Physiology'', ''35''(6), 820–825. <nowiki>http://www.jstor.org/stable/4259670</nowiki></ref> particularly if the soil moisture content is low. The dilution also helps to reduce odor development following application. When diluted with water (at a 1:5 ratio for container-grown [[annual plant|annual]] crops with fresh growing medium each season or a 1:8 ratio for more general use), it can be applied directly to soil as a fertilizer.<ref name="Morgan">{{cite book |chapter-url=http://www.ecosanres.org/PM_Report.htm|title=An Ecological Approach to Sanitation in Africa: A Compilation of Experiences|last=Morgan|first=Peter|year=2004|edition=CD release|location=Aquamor, Harare, Zimbabwe|chapter=10. The Usefulness of urine|access-date=6 December 2011}}</ref><ref name="LiquidGold">{{cite book |url=http://www.liquidgoldbook.com/ |title=Liquid Gold: The Lore and Logic of Using Urine to Grow Plants |last=Steinfeld |first=Carol |publisher=Ecowaters Books |year=2004 |isbn=978-0-9666783-1-4 }}{{page needed|date=November 2017}}</ref> The fertilization effect of urine has been found to be comparable to that of commercial nitrogen fertilizers.<ref name="UrineSeparation">{{cite web|vauthors= Johansson M, Jönsson H, Höglund C, Richert Stintzing A, Rodhe L|title=Urine Separation – Closing the Nitrogen Cycle|publisher=Stockholm Water Company|year=2001|url=http://www.sswm.info/sites/default/files/reference_attachments/JOHANSSON%202000%20Urine%20Separation%20-%20Closing%20the%20Nutrient%20Cycle_0.pdf}} </ref><ref>{{Cite journal|last1=Pradhan|first1=Surendra K.|last2=Nerg|first2=Anne-Marja|last3=Sjöblom|first3=Annalena|last4=Holopainen|first4=Jarmo K.|last5=Heinonen-Tanski|first5=Helvi|date=2007|title=Use of Human Urine Fertilizer in Cultivation of Cabbage ( Brassica oleracea ) ––Impacts on Chemical, Microbial, and Flavor Quality|url=https://pubs.acs.org/doi/10.1021/jf0717891|journal=Journal of Agricultural and Food Chemistry|language=en|volume=55|issue=21|pages=8657–8663|doi=10.1021/jf0717891|pmid=17894454|issn=0021-8561}}</ref> Urine may contain pharmaceutical residues ([[environmental persistent pharmaceutical pollutant]]s).<ref name=":0">Winker, M. (2009). ''Pharmaceutical Residues in Urine and Potential Risks related to Usage as Fertiliser in Agriculture'' [TUHH University Library]. https://doi.org/10.15480/882.481</ref> Concentrations of heavy metals such as [[lead]], [[mercury (element)|mercury]], and [[cadmium]], commonly found in sewage sludge, are much lower in urine.<ref name="EcoEngNewsletter1"> {{cite web|author=Håkan Jönsson|date=2001-10-01|title=Urine Separation&nbsp;— Swedish Experiences|url=http://www.iees.ch/EcoEng011/EcoEng011_F1.html|url-status=dead|archive-url=https://web.archive.org/web/20090427000144/http://www.iees.ch/EcoEng011/EcoEng011_F1.html|archive-date=2009-04-27|access-date=2009-04-19|work=EcoEng Newsletter 1}}</ref> The general limitations to using urine as fertilizer depend mainly on the potential for buildup of excess nitrogen (due to the high ratio of that macronutrient),<ref name="Morgan" /> and inorganic [[salt (chemistry)|salt]]s such as [[sodium chloride]], which are also part of the wastes excreted by the [[renal system]]. [[Fertilizer burn|Over-fertilization]] with urine or other nitrogen fertilizers can result in too much ammonia for plants to absorb, acidic conditions, or other [[phytotoxicity]].<ref name=":0" /> Important parameters to consider while fertilizing with urine include salinity tolerance of the plant, soil composition, addition of other fertilizing compounds, and quantity of rainfall or other irrigation.<ref name="Joensson" /> It was reported in 1995 that urine nitrogen gaseous losses were relatively high and plant uptake lower than with labelled [[ammonium nitrate]].{{Cn|date={{subst:CURRENTMONTHNAME}} {{subst:CURRENTYEAR}}}} In contrast, [[phosphorus]] was utilized at a higher rate than soluble phosphate.<ref name="kirchmann1995" /> Urine can also be used safely as a source of nitrogen in carbon-rich [[compost]].<ref name="LiquidGold" /><section end=Hygiene /> <noinclude>Human urine can be collected with [[sanitation]] systems that utilize [[urinals]] or [[urine diversion]] toilets. If urine is to be separated and collected for use as a fertilizer in agriculture, then this can be done with [[sanitation]] systems that utilize waterless [[urinals]], [[Urine-diverting dry toilets|urine-diverting dry toilets (UDDTs)]] or [[urine diversion]] flush toilets.<ref name=":Winker" /> During storage, the urea in urine is rapidly hydrolyzed by [[urease]], creating [[ammonia]].<ref>Freney, J. R., Simpson, J. R., & Denmead, O. T. (1981). AMMONIA VOLATILIZATION. ''Ecological Bulletins'', ''33'', 291–302. http://www.jstor.org/stable/45128671</ref> Further treatment can be done with collected urine to stabilize the nitrogen and concentrate the fertilizer.<ref>{{cite journal |last1=Wald |first1=Chelsea |title=The urine revolution: how recycling pee could help to save the world |journal=Nature |date=10 February 2022 |volume=602 |issue=7896 |pages=202–206 |doi=10.1038/d41586-022-00338-6}}</ref> One low-tech solution to odor is to add [[citric acid]] or [[vinegar]] to the urine collection container, so that the urease is inactivated and any ammonia that do form are less volatile.<ref>{{cite web |title=Urine in my garden |url=http://richearthinstitute.org/wp-content/uploads/2021/05/UrineMyGarden_DIYGuide.pdf |website=Rich Earth Institute |quote=Minimize odors by adding white vinegar or citric acid to the urine collection container before any urine is added. We use 1-2 cups of white vinegar or 1 tablespoon of citric acid per 5-gallon container. Adding vinegar also helps reduce nitrogen loss (via ammonia volatilization) during short-term storage.}}</ref> The health risks of using urine as a source of fertilizer are generally regarded as negligible, especially when dispersed in soil rather than on the part of a plant that is consumed. Urine can be distributed via perforated hoses buried ~10 cm under the surface of the [[soil]] among crop plants, thus minimizing risk of odors, loss of nutrients due to votalization, or transmission of [[pathogen]]s.<ref>{{Cite web |last=Canaday |first=Chris |date=December 21, 2016 |title=Suggestions for sustainable sanitation |url=https://issuu.com/chriscana/docs/suggestions_for_sustainable_sanitat |archive-url=https://web.archive.org/web/20210728153705/https://issuu.com/chriscana/docs/suggestions_for_sustainable_sanitat |archive-date=2021-7-28 |access-date=2022-2-17 |website=Issuu |language=en}}</ref> There are potentially more environmental problems (such as [[eutrophication]] resulting from the influx of nutrient rich effluent into aquatic or marine ecosystems) and a higher energy consumption when urine is treated as part of [[sewage]] in [[Sewage treatment|sewage treatment plants]] compared with when it is used directly as a fertilizer resource.<ref>{{cite journal |pmid=12926619 |year=2003 |last1=Maurer |first1=M |title=Nutrients in urine: Energetic aspects of removal and recovery |journal=Water Science and Technology |volume=48 |issue=1 |pages=37–46 |last2=Schwegler |first2=P |last3=Larsen |first3=T. A |doi=10.2166/wst.2003.0011 |s2cid=24913408 |url=https://semanticscholar.org/paper/b2b61639f7344fc3e14d292088661d8586cbeb15 }}</ref><ref name="Ganrot">{{cite book|url=http://www.melica.se/pdf/PhD_thesis_Zsofia_Ganrot.pdf|title=Ph.D. Thesis: Urine processing for efficient nutrient recovery and reuse in agriculture|last=Ganrot|first=Zsofia|publisher=Goteborg University|year=2005|location=Goteborg, Sweden|page=170}}</ref> In developing countries, the use of raw sewage or [[Fecal sludge management|fecal sludge]] has been common throughout history, yet the application of pure urine to crops is still quite rare in 2021. This is despite many publications that advocate the use of urine as a fertilizer since at least 2001.<ref name="UrineSeparation" /><ref>Mara Grunbaum (2010) [http://www.scientificamerican.com/article.cfm?id=human-urine-is-an-effective-fertilizer Human urine is shown to be an effective agricultural fertilizer], Scientific American, Retrieved on 2011-12-07.</ref> Since about 2011, the [[Bill and Melinda Gates Foundation]] is providing funding for research involving sanitation systems that recover the nutrients in urine.<ref>von Muench, E., Spuhler, D., Surridge, T., Ekane, N., Andersson, K., Fidan, E. G., Rosemarin, A. (2013). [http://www.susana.org/en/resources/library/details/2126 Sustainable Sanitation Alliance members take a closer look at the Bill & Melinda Gates Foundation’s sanitation grants]. Sustainable Sanitation Practice (SSP) Journal, Issue 17, EcoSan Club, Austria</ref></noinclude> === Feces === According to the 2004 "proposed Swedish default values", an average adult excretes 0.55 kg nitrogen, 0.18 kg phosphorus, and 0.36 kg potassium as feces per year.<ref name=":6"/>{{rp|5}} ==== Dried feces ==== Reuse of dried [[feces]] (feces) from urine-diverting dry toilets after post-treatment can result in increased crop production through fertilizing effects of nitrogen, phosphorus, potassium and improved [[soil fertility]] through organic carbon.<ref name="Rieck1">Rieck, C., von Münch, E., Hoffmann, H. (2012). [http://www.susana.org/en/resources/library/details/874 Technology review of urine-diverting dry toilets (UDDTs) - Overview on design, management, maintenance and costs.] Deutsche Gesellschaft fuer Internationale Zusammenarbeit GmbH, Eschborn, Germany</ref> ==== Composted feces ==== {{Main|Uses of compost}} [[File:Cabbage grown in compost.jpg|thumb|[[Cabbage]] grown in excreta-based [[compost]] (left) and without soil amendments (right), [[Sustainable Organic Integrated Livelihoods|SOIL]] in Haiti]] [[Compost]] derived from [[composting toilets]] (where organic kitchen waste is in some cases also added to the composting toilet) has, in principle, the same uses as compost derived from other organic waste products, such as [[sewage sludge]] or municipal organic waste. One limiting factor may be legal restrictions due to the possibility that pathogens remain in the compost. In any case, the use of compost from composting toilets in one's own garden can be regarded as safe and is the main method of use for compost from composting toilets. Hygienic measures for handling of the compost must be applied by all those people who are exposed to it, e.g. wearing gloves and boots. Some of the [[urine]] will be part of the compost although some urine will be lost via leachate and evaporation. [[Urine]] can contain up to 90 percent of the [[nitrogen]], up to 50 percent of the [[phosphorus]], and up to 70 percent of the [[potassium]] present in human excreta.<ref>[http://www2.gtz.de/Dokumente/oe44/ecosan/en-fighting-urine-blindness-1998.pdf J.O. Drangert, Urine separation systems] {{webarchive|url=https://web.archive.org/web/20141222023233/http://www2.gtz.de/Dokumente/oe44/ecosan/en-fighting-urine-blindness-1998.pdf |date=2014-12-22 }}</ref> The nutrients in compost from a composting toilet have a higher plant availability than the product (dried feces) from a [[urine-diverting dry toilet]].<ref name="Berger">Berger, W. (2011). [http://www.susana.org/en/resources/library/details/878 Technology review of composting toilets - Basic overview of composting toilets (with or without urine diversion).] Deutsche Gesellschaft für Internationale Zusammenarbeit GmbH, Eschborn, Germany</ref> === Fecal sludge === {{Further|Fecal sludge management}} [[Fecal sludge management|Fecal sludge]] is defined as "coming from onsite sanitation technologies, and has not been transported through a sewer." Examples of onsite technologies include pit latrines, unsewered public ablution blocks, septic tanks and dry toilets. Fecal sludge can be treated by a variety of methods to render it suitable for reuse in agriculture. These include (usually carried out in combination) dewatering, thickening, drying (in sludge drying beds), [[composting]], pelletization, and [[anaerobic digestion]].<ref name="Ronteltap" /> === Municipal wastewater === {{Further|Reclaimed water|Sewage treatment#Reuse}} [[Reclaimed water]] can be reused for irrigation, industrial uses, replenishing natural water courses, water bodies, [[aquifer]]s and other potable and non-potable uses. These applications, however, focus usually on the water aspect, not on the nutrients and organic matter reuse aspect, which is the focus of "reuse of excreta". When wastewater is reused in agriculture, its nutrient (nitrogen and phosphorus) content may be useful for additional fertilizer application.<ref name="Otoo">{{Cite book|url=http://www.iwmi.cgiar.org/publications/other-publication-types/books-monographs/iwmi-jointly-published/resource-recovery-from-waste/|title=Resource recovery from waste: business models for energy, nutrient and water reuse in low- and middle-income countries|last1=Otoo|first1=Miriam|last2=Drechsel|first2=Pay|publisher=Routledge - Earthscan|year=2018|location=Oxon, UK}}</ref> Work by the [[International Water Management Institute]] and others has led to guidelines on how reuse of municipal wastewater in agriculture for irrigation and fertilizer application can be safely implemented in low income countries.<ref>{{cite book|title=Wastewater irrigation and health : assessing and mitigating risk in low-income countries|date=2010|publisher=Earthscan|location=London|isbn=978-1-84407-795-3|edition=London : Earthscan.|url=http://www.susana.org/en/resources/library/details/1782|last = Drechsel, P., Scott, C. A., Raschid-Sally, L., Redwood, M., Bahri, A. (eds.)}}</ref><ref name="WHO2006" /> === Sewage sludge === {{Main|Sewage sludge|Biosolids}} The use of treated [[sewage sludge]] (after treatment also called "[[biosolids]]") as a [[soil conditioner]] or fertilizer is possible but is a controversial topic in some countries (such as USA, some countries in Europe) due to the chemical pollutants it may contain, such as heavy metals and [[environmental persistent pharmaceutical pollutant]]s. [[Northumbrian Water]] in the [[United Kingdom]] uses two [[anaerobic digestion|biogas plants]] to produce what the company calls "poo power" - using [[sewage sludge]] to produce energy to generate income. [[Biogas]] production has reduced its pre 1996 [[Electricity generation#Turbines|electricity]] expenditure of 20 million [[pounds sterling|GBP]] by about 20%. [[Severn Trent]] and [[Wessex Water]] also have similar projects.<ref name="bbc news">{{Cite web|url=https://www.bbc.com/news/business-37981485|title=The firms turning poo into profit|date=16 November 2016|publisher=BBC News Business Section|access-date=17 November 2016}}</ref> === Sludge treatment liquids === {{Further|Sewage sludge treatment}} Sludge treatment liquids (after [[anaerobic digestion]]) can be used as an input source for a process to recover phosphorus in the form of [[struvite]] for use as fertilizer. For example, the Canadian company Ostara Nutrient Recovery Technologies is marketing a process based on controlled chemical precipitation of phosphorus in a fluidized bed reactor that recovers struvite in the form of crystalline pellets from sludge dewatering streams. The resulting crystalline product is sold to the [[agriculture]], [[turf]] and [[ornamental plant]]s sectors as fertilizer under the registered trade name "Crystal Green".<ref>{{Cite web|url = http://www.ostara.com/nutrient-management-solutions/pearl-process|title = Ostara Nutrient Management Solutions|access-date = 19 February 2015|publisher = Ostara, Vancouver, Canada|url-status = dead|archive-url = https://web.archive.org/web/20150219161148/http://www.ostara.com/nutrient-management-solutions/pearl-process|archive-date = 19 February 2015}}</ref> === Peak phosphorus === {{Further|Peak phosphorus}} In the case of phosphorus in particular, reuse of excreta is one known method to recover phosphorus to mitigate the looming shortage (also known as "[[peak phosphorus]]") of economical mined phosphorus. Mined phosphorus is a limited resource that is being used up for fertilizer production at an ever-increasing rate, which is threatening worldwide [[food security]]. Therefore, phosphorus from excreta-based fertilizers is an interesting alternative to fertilizers containing mined phosphate ore.<ref>Soil Association (2010). [http://www.susana.org/en/resources/library/details/1143 A rock and a hard place - Peak phosphorus and the threat to our food security]. Soil Association, Bristol, UK</ref> == Health and environmental aspects of agricultural use == === Pathogens === ==== Multiple barrier concept for safe use in agriculture ==== Research into how to make reuse of urine and feces safe in agriculture has been carried out in Sweden since the 1990s.<ref name="Joensson" /> In 2006 the [[World Health Organization]] (WHO) provided guidelines on safe reuse of wastewater, excreta and greywater.<ref name="WHO2006" /> The multiple barrier concept to reuse, which is the key cornerstone of this publication, has led to a clear understanding of how excreta reuse can be done safely. The concept is also used in water supply and food production, and is generally understood as a series of treatment steps and other safety precautions to prevent the spread of pathogens. The degree of treatment required for excreta-based fertilizers before they can safely be used in agriculture depends on a number of factors. It mainly depends on which other barriers will be put in place according to the multiple barrier concept. Such barriers might be selecting a suitable crop, farming methods, methods of applying the fertilizer, education of the farmers, and so forth.<ref name="Richert">Richert, A., Gensch, R., Jönsson, H., Stenström, T., Dagerskog, L. (2010). [http://www.susana.org/en/resources/library/details/757 Practical guidance on the use of urine in crop production]. Stockholm Environment Institute (SEI), Sweden</ref> For example, in the case of urine-diverting dry toilets secondary treatment of dried feces can be performed at community level rather than at household level and can include [[thermophilic composting]] where fecal material is composted at over 50&nbsp;°C, prolonged storage with the duration of 1.5 to two years, chemical treatment with ammonia from urine to inactivate the pathogens, solar sanitation for further drying or heat treatment to eliminate pathogens.<ref>Niwagaba, C. B. (2009). [http://www.susana.org/en/resources/library/details/703 Treatment technologies for human faeces and urine.] PhD thesis, Swedish University of Agricultural Sciences, Uppsala, Sweden</ref><ref name="Rieck1" /> [[File:Step 4- Final maturing (beginning) (5012011706).jpg|thumb|Gardeners of Fada N'Gourma in Burkina Faso apply dry excreta after mixing with other organic fertilizer (donkey manure, cow manure) and pure fertile soil, and after maturing for another 2 to 4 months]] Exposure of farm workers to untreated excreta constitutes a significant health risk due to its [[pathogen]] content. There can be a large amount of enteric bacteria, virus, protozoa, and [[Parasitic worm|helminth eggs]] in feces.<ref name="Harder 695–743"/> This risk also extends to consumers of crops fertilized with untreated excreta. Therefore, excreta needs to be appropriately treated before reuse, and health aspects need to be managed for all reuse applications as the excreta can contain [[pathogens]] even after treatment. ==== Treatment of excreta for pathogen removal ==== Temperature is a treatment parameter with an established relation to pathogen inactivation for all pathogen groups: Temperatures above 50°C have the potential to inactivate most pathogens.<ref name=":5" />{{rp|101}} Therefore, thermal sanitization is utilized in several technologies, such as thermophilic composting and thermophilic [[anaerobic digestion]] and potentially in sun drying. Alkaline conditions (pH value above 10) can also deactivate pathogens. This can be achieved with ammonia sanitization or lime treatment.<ref name=":5" />{{rp|101}} The treatment of excreta and wastewater for pathogen removal can take place: * at the toilet itself (for example, urine collected from [[urine-diverting dry toilets]] is often treated by simple storage at the household level); or * at a semi-centralized level (for example, by [[composting]]); or * at a fully centralized level at [[sewage treatment plants]] and [[sewage sludge treatment|sewage sludge treatment plants]]. ==== Indicator organisms ==== As an [[indicator organism]] in reuse schemes, [[helminth]] eggs are commonly used as these organisms are the most difficult to destroy in most treatment processes. The multiple barrier approach is recommended where e.g. lower levels of treatment may be acceptable when combined with other post-treatment barriers along the [[sanitation]] chain.<ref name="WHO2006" /> === Pharmaceutical residues === Excreta from humans contains [[hormones]] and [[pharmaceutical drug|pharmaceutical]] residues which could in theory enter the food chain via fertilized crops but are currently not fully removed by conventional wastewater treatment plants anyway and can enter drinking water sources via household wastewater (sewage).<ref name=":Winker">von Münch, E., Winker, M. (2011). [http://www.susana.org/en/resources/library/details/875 Technology review of urine diversion components - Overview on urine diversion components such as waterless urinals, urine diversion toilets, urine storage and reuse systems.] Gesellschaft für Internationale Zusammenarbeit GmbH</ref> In fact, the pharmaceutical residues in the excreta are degraded better in terrestrial systems (soil) than in aquatic systems.<ref name=":Winker"/> === Nitrate pollution === Only a fraction of the nitrogen-based fertilizers is converted to produce plant matter. The remainder accumulates in the soil or is lost as run-off.<ref name="Nasir">{{cite book |doi=10.1007/978-94-007-7814-6_5 |chapter=Eutrophication of Lakes |title=Eutrophication: Causes, Consequences and Control |pages=55–71 |year=2014 |last1=Callisto |first1=Marcos |last2=Molozzi |first2=Joseline |last3=Barbosa |first3=José Lucena Etham |isbn=978-94-007-7813-9 }}</ref> This also applies to excreta-based fertilizer since it also contains nitrogen. Excessive nitrogen which is not taken up by plants is transformed into nitrate which is easily leached.<ref>{{cite journal |doi=10.1146/annurev.arplant.59.032607.092932 |pmid=18444903 |title=Roots, Nitrogen Transformations, and Ecosystem Services |journal=Annual Review of Plant Biology |volume=59 |pages=341–63 |year=2008 |last1=Jackson |first1=Louise E |last2=Burger |first2=Martin |last3=Cavagnaro |first3=Timothy R |s2cid=6817866 |url=https://semanticscholar.org/paper/1b50c5358e1ae5dcbcd3916ba64417fef5c781ce }}</ref> High application rates combined with the high water-solubility of nitrate leads to increased [[Surface runoff#Agricultural issues|runoff]] into [[surface water]] as well as [[Leaching (agriculture)|leaching]] into [[groundwater]].<ref>{{cite web|author1=C. J. Rosen |author2=B. P. Horgan |name-list-style=amp |url=http://www.extension.umn.edu/distribution/horticulture/DG2923.html |title=Preventing Pollution Problems from Lawn and Garden Fertilizers |publisher=Extension.umn.edu |date=9 January 2009 |access-date=25 August 2010}}</ref><ref>{{cite journal |doi=10.1016/0169-7722(95)00067-4 |title=Fertilizer-N use efficiency and nitrate pollution of groundwater in developing countries |journal=Journal of Contaminant Hydrology |volume=20 |issue=3–4 |pages=167–84 |year=1995 |last1=Bijay-Singh |last2=Yadvinder-Singh |last3=Sekhon |first3=G.S |bibcode=1995JCHyd..20..167S }}</ref><ref>{{cite web |url=http://www.nofa.org/tnf/nitrogen.php |title=NOFA Interstate Council: The Natural Farmer. Ecologically Sound Nitrogen Management. Mark Schonbeck |publisher=Nofa.org |date=25 February 2004 |access-date=25 August 2010 |url-status=dead |archive-url=https://web.archive.org/web/20040324090920/http://www.nofa.org/tnf/nitrogen.php |archive-date=24 March 2004 }}</ref> Nitrate levels above 10&nbsp;mg/L (10 ppm) in groundwater can cause '[[blue baby syndrome]]' (acquired [[methemoglobinemia]]).<ref>{{cite journal |doi=10.1289/ehp.00108675 |pmid=10903623 |pmc=1638204 |title=Blue Babies and Nitrate-Contaminated Well Water |journal=Environmental Health Perspectives |volume=108 |issue=7 |pages=675–8 |year=2000 |last1=Knobeloch |first1=Lynda |last2=Salna |first2=Barbara |last3=Hogan |first3=Adam |last4=Postle |first4=Jeffrey |last5=Anderson |first5=Henry }}</ref> The nutrients, especially nitrates, in fertilizers can cause problems for [[Ecosystem|ecosystems]] and for human health if they are washed off into [[surface water]] or leached through the soil into groundwater. == Other uses== Apart from use in agriculture, there are other possible uses of excreta. For example, in the case of fecal sludge, it can be treated and then serve as protein ([[black soldier fly]] process), [[fodder]], fish food, building materials and [[biofuels]] ([[biogas]] from [[anaerobic digestion]], incineration or co-combustion of dried sludge, pyrolysis of fecal sludge, biodiesel from fecal sludge).<ref name="Ronteltap">{{cite book |editor1-first=Linda |editor1-last=Strande |editor2-first=Mariska |editor2-last=Ronteltap |editor3-first=Damir |editor3-last=Brdjanovic |title=Faecal sludge management: systems approach for implementation and operation |year=2013 |publisher=IWA Publishing |isbn=978-1-78040-472-1 |url=http://www.sandec.ch/fsm_book }}{{page needed|date=November 2017}}</ref><ref name="Andersson" /> === Solid fuel, heat, electricity === Pilot scale research in Uganda and Senegal has shown that it is viable to use dry feces as for combustion in industry, provided it has been dried to a minimum of 28% dry solids.<ref name="diener">{{cite journal |doi=10.1016/j.resconrec.2014.04.005 |title=A value proposition: Resource recovery from faecal sludge—Can it be the driver for improved sanitation? |journal=Resources, Conservation and Recycling |volume=88 |pages=32–8 |year=2014 |last1=Diener |first1=Stefan |last2=Semiyaga |first2=Swaib |last3=Niwagaba |first3=Charles B |last4=Muspratt |first4=Ashley Murray |last5=Gning |first5=Jean Birane |last6=Mbéguéré |first6=Mbaye |last7=Ennin |first7=Joseph Effah |last8=Zurbrugg |first8=Christian |last9=Strande |first9=Linda |url=https://www.dora.lib4ri.ch/eawag/islandora/object/eawag%3A9063/datastream/PDF/view |doi-access=free }}</ref> Dried sewage sludge can be burned in [[sludge incineration]] plants and generate heat and electricity (the [[waste-to-energy]] process is one example). Resource recovery of fecal sludge as a solid fuel has been found to have high market potential in [[Sub-Saharan Africa]].<ref name=":4" /> === Hydrogen fuel === {{Further|Hydrogen fuel}} Urine has also been investigated as a potential source of [[hydrogen fuel]].<ref name=Kuntke2014>{{cite journal |doi=10.1016/j.ijhydene.2013.10.089 |title=Hydrogen production and ammonium recovery from urine by a Microbial Electrolysis Cell |journal=International Journal of Hydrogen Energy |volume=39 |issue=10 |pages=4771–8 |year=2014 |last1=Kuntke |first1=P |last2=Sleutels |first2=T.H.J.A |last3=Saakes |first3=M |last4=Buisman |first4=C.J.N }}</ref><ref>{{cite journal |doi=10.1016/j.cattod.2012.02.009 |title=Electrolysis of urea and urine for solar hydrogen |journal=Catalysis Today |volume=199 |pages=2–7 |year=2013 |last1=Kim |first1=Jungwon |last2=Choi |first2=Won Joon K |last3=Choi |first3=Jina |last4=Hoffmann |first4=Michael R |last5=Park |first5=Hyunwoong |url=https://authors.library.caltech.edu/36173/7/mmc1.doc }}</ref> Urine was found to be a suitable wastewater for high rate hydrogen production in a [[Microbial electrolysis cell|Microbial Electrolysis Cell]] (MEC).<ref name=Kuntke2014 /> === Biogas === {{Further|Biogas}} Small-scale [[biogas]] plants are being utilized in many countries, including Ghana,<ref>{{cite journal |doi=10.1016/j.ejpe.2016.10.004 |title=Feasibility study for biogas integration into waste treatment plants in Ghana |journal=Egyptian Journal of Petroleum |volume=26 |issue=3 |pages=695–703 |year=2017 |last1=Mohammed |first1=M |last2=Egyir |first2=I.S |last3=Donkor |first3=A.K |last4=Amoah |first4=P |last5=Nyarko |first5=S |last6=Boateng |first6=K.K |last7=Ziwu |first7=C |doi-access=free }}</ref> Vietnam<ref>{{cite journal |doi=10.1016/j.jclepro.2015.09.114 |title=Addressing problems at small-scale biogas plants: A case study from central Vietnam |journal=Journal of Cleaner Production |volume=112 |pages=2784–92 |year=2016 |last1=Roubík |first1=Hynek |last2=Mazancová |first2=Jana |last3=Banout |first3=Jan |last4=Verner |first4=Vladimír }}</ref> and many others.<ref>{{cite journal |doi=10.1016/j.renene.2017.08.068 |title=Current approach to manure management for small-scale Southeast Asian farmers - Using Vietnamese biogas and non-biogas farms as an example |journal=Renewable Energy |volume=115 |pages=362–70 |year=2018 |last1=Roubík |first1=Hynek |last2=Mazancová |first2=Jana |last3=Phung |first3=Le Dinh |last4=Banout |first4=Jan }}1</ref> Larger centralized systems are being planned that mix animal and human feces to produce biogas.<ref name="diener" /> Biogas is also produced during [[sewage sludge treatment]] processes with [[anaerobic digestion]]. Here, it can be used for heating the digesters and for generating electricity.<ref>{{Cite web|url=https://www.endress.com/en/industry-expertise/water-&-wastewater/Sludge-treatment-and-disposal|title=Sludge treatment and disposal - efficient & safe {{!}} Endress+Hauser|website=www.endress.com|language=en|access-date=2018-03-14}}</ref> Biogas is an important waste-to-energy resource which plays a huge role in reducing environmental pollution and most importantly in reducing greenhouse gases effect caused by the waste. Utilization of raw material such as human waste for biogas generation is considered beneficial because it does not require additional starters such as microorganism seeds for methane production, and a supply of microorganisms occurs continuously during the feeding of raw materials.<ref>{{Cite journal|last1=Andriani|first1=Dian|last2=Wresta|first2=Arini|last3=Saepudin|first3=Aep|last4=Prawara|first4=Budi|date=2015-04-01|title=A Review of Recycling of Human Excreta to Energy through Biogas Generation: Indonesia Case|journal=Energy Procedia|series=2nd International Conference on Sustainable Energy Engineering and Application (ICSEEA) 2014 Sustainable Energy for Green Mobility|language=en|volume=68|pages=219–225|doi=10.1016/j.egypro.2015.03.250|issn=1876-6102|doi-access=free}}</ref> === Food source to produce protein for animal feed === Pilot facilities are being developed for feeding [[Hermetia illucens|Black Soldier Fly larvae]] with feces. The mature flies would then be a source of protein to be included in the production of feed for chickens in South Africa.<ref name="diener" /> Black soldier fly (BSF) bio-waste processing is a relatively new treatment technology that has received increasing attention over the last decades. Larvae grown on bio-waste can be a necessary raw material for animal feed production , and can therefore provide revenues for financially applicable waste management systems. In addition, when produced on bio-waste, insect-based feeds can be more sustainable than conventional feeds. <ref>{{Cite journal|date=2018-12-01|title=Decomposition of biowaste macronutrients, microbes, and chemicals in black soldier fly larval treatment: A review|journal=Waste Management|language=en|volume=82|pages=302–318|doi=10.1016/j.wasman.2018.10.022|issn=0956-053X|last1=Gold|first1=Moritz|last2=Tomberlin|first2=Jeffery K.|last3=Diener|first3=Stefan|last4=Zurbrügg|first4=Christian|last5=Mathys|first5=Alexander|pmid=30509593|doi-access=free}}</ref> ===Building materials=== It is known that additions of fecal matter up to 20% by dried weight in clay bricks does not make a significant functional difference to bricks.<ref name="diener" /> === Precious metals recovery === A Japanese sewage treatment facility extracts [[precious metal]]s from [[sewage sludge]]. This idea was also tested by the US Geological Survey (USGS) which found that the yearly sewage sludge generated by 1 million people contained 13 million dollars worth of precious metals.<ref>{{Cite news | url = https://www.reuters.com/article/us-gold-sewage-odd-idUSTRE50T56120090130 | title = Sewage yields more gold than top mines | date = 2009-01-30 | newspaper = Reuters | access-date = 2016-02-27 }}</ref> == History == {{Further|History of water supply and sanitation|Ecological sanitation#History}} The reuse of excreta as a fertilizer for growing crops has been practiced in many countries for a long time. == Society and culture == === Economics === Debate is ongoing about whether reuse of excreta is cost effective.<ref name=Paranipe2017 /> The terms "sanitation economy" and "toilet resources" have been introduced to describe the potential for selling products made from [[human feces]] or [[urine]].<ref name=Paranipe2017>{{Cite web|url=https://news.trust.org/item/20170919145350-bovq7|title=The rise of the sanitation economy: how business can help solve a global crisis|last=Paranipe|first=Nitin|date=19 September 2017|website=Thompson Reuters Foundation News|access-date=November 13, 2017}}</ref><ref>{{Cite book|url=http://www.toiletboard.org/media/30-Sanitation_Economy_Final.pdf|title=Introducing the Sanitation Economy|publisher=Toilet Board Coalition|year=2017}}</ref> ==== Sale of compost ==== The NGO [[Sustainable Organic Integrated Livelihoods|SOIL]] in [[Haiti]] began building [[urine-diverting dry toilet]]s and [[composting]] the waste produced for agricultural use in 2006.<ref>Christine Dell'Amore, [http://news.nationalgeographic.com/news/2011/10/111026-haiti-waste-poop-fertilizer-farms-soil-science-environment/ "Human Waste to Revive Haitian Farmland?"], ''The National Geographic'', October 26, 2011</ref> SOIL's two composting waste treatment facilities currently transform over 20,000 gallons (75,708 liters) of human excreta into organic, agricultural-grade compost every month.<ref>Jonathan Hera, [https://www.theglobeandmail.com/report-on-business/small-business/sb-growth/going-global/exam-question-inspires-award-winning-entrepreneur-to-launch-social-business-in-haiti/article21555235/ "Haiti Non-Profit Plumbs Solutions to World's Unmet Sanitation Needs"], "The Globe and the Mail", November 14, 2014</ref> The compost produced at these facilities is sold to farmers, organizations, businesses, and institutions around the country to help finance SOIL's waste treatment operations.<ref>Kramer, S., Preneta, N., Kilbride, A. (2013). [http://www.susana.org/en/resources/library/details/1862 Two papers from SOIL presented at the 36th WEDC International Conference], Nakuru, Kenya, 2013. SOIL, Haiti</ref> Crops grown with this soil amendment include spinach, peppers, sorghum, maize, and more. Each batch of compost produced is tested for the [[indicator organism]] ''[[E. coli]]'' to ensure that complete pathogen kill has taken place during the [[thermophilic]] composting process.<ref>Erica Lloyd, [https://www.oursoil.org/safety-first-the-new-and-improved-soil-lab/ "Safety First: The New and Improved SOIL Lab"], "SOIL blog", February 2, 2014</ref> === Policies === There is still a lack of examples of implemented policy where the reuse aspect is fully integrated in policy and advocacy.<ref name="SEI2009">SEI (2009). [http://www.susana.org/en/resources/library/details/1265 Sanitation policies and regulatory frameworks for reuse of nutrients in wastewater, human excreta and greywater] - Proceedings from SEI/EcoSanRes2 Workshop in Sweden. Stockholm Environment Institute, Sweden</ref> When considering drivers for policy change in this respect, the following lessons learned should be taken into consideration: Revising legislation does not necessarily lead to functioning reuse systems; it is important to describe the “institutional landscape” and involve all actors; parallel processes should be initiated at all levels of government (i.e. national, regional and local level); country specific strategies and approaches are needed; and strategies supporting newly developed policies need to be developed).<ref name="SEI2009" /> === Regulatory considerations === Regulations such as Global [[Good agricultural practice|Good Agricultural Practices]] may hinder export and import of agricultural products that have been grown with the application of human excreta-derived fertilisers.<ref name="Kvarn">Elisabeth Kvarnström, Linus Dagerskog, Anna Norström and Mats Johansson (2012) [http://www.siani.se/resources/report/nutrient-reuse-solution-multiplier Nutrient reuse as a solution multiplier] (SIANI policy brief 1.1), A policy brief by the SIANI Agriculture-Sanitation Expert Group, Sweden</ref><ref>{{Cite journal|last1=Moya|first1=Berta|last2=Parker|first2=Alison|last3=Sakrabani|first3=Ruben|date=2019|title=Challenges to the use of fertilisers derived from human excreta: The case of vegetable exports from Kenya to Europe and influence of certification systems|journal=Food Policy|language=en|volume=85|pages=72–78|doi=10.1016/j.foodpol.2019.05.001|doi-access=free}}</ref> ==== Urine use in organic farming in Europe ==== The [[European Union]] allows the use of source separated urine only in conventional farming within the EU, but not yet in organic farming. This is a situation that many agricultural experts, especially in Sweden, would like to see changed.<ref name="EcoEngNewsletter1"></ref> This ban may also reduce the options to use urine as a fertilizer in other countries if they wish to export their products to the EU.<ref name="Kvarn" /> ==== Dried feces from urine-diverting dry toilets in the U.S. ==== In the United States, the EPA regulation governs the management of [[sewage sludge]] but has no jurisdiction over the byproducts of a urine-diverting dry toilet. Oversight of these materials falls to the states.<ref>{{cite web|last1=EPA 832-F-99-066|first1=September 1999|title=Water Efficiency Technology Fact Sheet Composting Toilets|url=http://water.epa.gov/aboutow/owm/upload/2005_07_14_comp.pdf|website=United States Environmental Protection Agency|date=29 January 2013|publisher=Office of Water|access-date=3 January 2015}}</ref><ref>{{cite web|title=Title 40 - Protection of Environment Chapter I - Environmental Protection Agency, Subchapter 0 - Sewage sludge Part 503 - Standards for the use or disposal of sewage sludge|url=http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title40/40cfr503_main_02.tpl|publisher=U.S. Government Publishing Office|access-date=3 January 2015}}</ref> == Country examples == === China === Treatment disposal of human excreta can be categorized into three types: fertilizer use, discharge and biogas use. Discharge is the disposal of human excreta to soil, septic tank or water body.<ref>{{Cite journal|last1=Liu|first1=Ying|last2=Huang|first2=Ji-kun|last3=Zikhali|first3=Precious|date=2014-02-01|title=Use of Human Excreta as Manure in Rural China|journal=Journal of Integrative Agriculture|language=en|volume=13|issue=2|pages=434–442|doi=10.1016/S2095-3119(13)60407-4|issn=2095-3119|doi-access=free}}</ref> In China, with the impact of the long tradition, human excreta is often used as fertilizer for crops.<ref>{{Cite journal|last=Worster|first=Donald|date=2017|title=The Good Muck: Toward an Excremental History of China|url=http://www.environmentandsociety.org/perspectives/2017/5/good-muck-toward-excremental-history-china|journal=RCC Perspectives: Transformations in Environment and Society|volume=2|doi=10.5282/rcc/8135|doi-access=free}}</ref> The main application methods are direct usage for crops and fruits as basal or top application after fermentation in a ditch for a certain period, compost with crop stalk for basal application and direct usage as feed for fish in ponds.<ref>{{Cite journal|last=Shiming|first=Luo|date=2002|title=THE UTILIZATION OF HUMAN EXCRETA IN CHINESE AGRICULTURE AND THE CHALLENGE FACED|url=http://www.ecosanres.org/pdf_files/Nanning_PDFs/Eng/Luo%20Shiming%2010_C11rev.pdf|journal=South China Agricultural University, EcoSanRes}}</ref> On the other hand, as much as many people rely on human waste as an agricultural fertilizer, if the waste is not properly treated, the use of night soil may promote the spread of infectious diseases.<ref>{{Cite journal|last1=Carlton|first1=Elizabeth J.|last2=Liu|first2=Yang|last3=Zhong|first3=Bo|last4=Hubbard|first4=Alan|last5=Spear|first5=Robert C.|date=2015-01-15|title=Associations between Schistosomiasis and the Use of Human Waste as an Agricultural Fertilizer in China|journal=PLOS Neglected Tropical Diseases|volume=9|issue=1|pages=e0003444|doi=10.1371/journal.pntd.0003444|issn=1935-2727|pmc=4295866|pmid=25590142}}</ref> === India === Urine is used for making [[Jeevamrutha|bio-pesticides]] in addition to the application as organic manure in India. === Kenya === In Mukuru, Kenya, the slum dwellers are worst hit by the sanitation challenge due to a high population density and a lack of supporting infrastructure. Makeshift pit latrines, illegal toilet connections to the main sewer systems and lack of running water to support the flushable toilets present a sanitation nightmare in all Kenyan slums. The NGO Sanergy seeks to provide decent toilet facilities to Mukuru residents and uses the feces and urine from the toilets to provide fertilizer and energy for the market.<ref>Likoko, E. (2013) [http://uu.diva-portal.org/smash/get/diva2:638161/FULLTEXT01.pdf Ecological Management of Human Excreta in an Urban Slum: A case study of Mukuru in Kenya]. Master thesis in Sustainable Development at Uppsala University, Department of Earth Sciences, Uppsala University, Sweden, No. 148, 41 pp.</ref> === Uganda === Reuse of wastewater in agriculture is a common practice in the developing world. In a study in [[Kampala]], although famers were not using fecal sludge, 8% of farmers were using wastewater sludge as a soil amendment. Compost from animal manure and composted household waste are applied by many farmers as soil conditioners. On the other hand, farmers are already mixing their own feed because of limited trust in the feed industry and the quality of products.<ref>{{Cite journal|date=2014-07-01|title=A value proposition: Resource recovery from faecal sludge—Can it be the driver for improved sanitation?|journal=Resources, Conservation and Recycling|language=en|volume=88|pages=32–38|doi=10.1016/j.resconrec.2014.04.005|issn=0921-3449|last1=Diener|first1=Stefan|last2=Semiyaga|first2=Swaib|last3=Niwagaba|first3=Charles B.|last4=Muspratt|first4=Ashley Murray|last5=Gning|first5=Jean Birane|last6=Mbéguéré|first6=Mbaye|last7=Ennin|first7=Joseph Effah|last8=Zurbrugg|first8=Christian|last9=Strande|first9=Linda|doi-access=free}}</ref> Electricity demand is significantly more than the electricity generation and only a small margin of the population nationally has access to electricity. The pellets produced from fecal sludge are being used in gasification for electricity production. Converting fecal sludge for energy could contribute towards meeting present and future energy needs.<ref>{{Cite journal|date=2015|title=Production of Pellets and Electricity from Faecal Sludge|journal=Excreta and Wastewater Management|volume=16 / 2015|via=Sandec News}}</ref> In [[Tororo District]] in eastern Uganda - a region with severe [[land degradation]] problems - [[smallholding|smallholder farmers]] appreciated urine fertilization as a low-cost, low-risk practice. They found that it could contribute to significant yield increases. The importance of social norms and cultural perceptions needs to be recognized but these are not absolute barriers to adoption of the practice.<ref>{{cite journal|last1=Andersson|first1=Elina|year=2015|title=Turning waste into value: Using human urine to enrich soils for sustainable food production in Uganda|journal=Journal of Cleaner Production|volume=96|pages=290–8|doi=10.1016/j.jclepro.2014.01.070|doi-access=free}}</ref> === Ghana === In Ghana, the only wide scale implementation is small scale rural digesters, with about 200 biogas plants using human excreta and animal dung as feedstock. Linking up of public toilets with biogas digesters as a way of improving communal hygiene and combating hygiene-related communicable diseases including cholera and dysentery is also a notable solution within Ghana.<ref>{{Cite journal|date=2014-07-01|title=A value proposition: Resource recovery from faecal sludge—Can it be the driver for improved sanitation?|journal=Resources, Conservation and Recycling|language=en|volume=88|pages=32–38|doi=10.1016/j.resconrec.2014.04.005|issn=0921-3449|last1=Diener|first1=Stefan|last2=Semiyaga|first2=Swaib|last3=Niwagaba|first3=Charles B.|last4=Muspratt|first4=Ashley Murray|last5=Gning|first5=Jean Birane|last6=Mbéguéré|first6=Mbaye|last7=Ennin|first7=Joseph Effah|last8=Zurbrugg|first8=Christian|last9=Strande|first9=Linda|doi-access=free}}</ref> ==See also== *[[Manure]] *[[Ecological sanitation]] *[[Fecal sludge management]] *[[Night soil|Nightsoil]] *[[Resource recovery]] *[[Composting toilet]] *[[Compost]] == References == {{reflist}} == External links == {{offline|med}} *[http://www.susana.org/en/resources/library?vbl_2%5B%5D=&vbl_8%5B%5D=42 Documents on reuse of excreta] in the library of the [[Sustainable Sanitation Alliance]] *[https://www.flickr.com/photos/gtzecosan/collections/72157626218265344/ Photos on reuse of excreta] in photo database of the [[Sustainable Sanitation Alliance]] {{Recycling}} [[Category:Agriculture]] [[Category:Excretion]] [[Category:Repurposing]] [[Category:Sanitation]] [[Category:Feces]]'