Nature provides valuable sanitation services

Much previous research shows that safe disposal of human waste has a positive impact on wellbeing, while preventing the degradation ecosystems. However, to date, role ecosystems themselves play in treating been largely neglected. We conceptualize nature plays waste—acting as pipeline and/or treatment plant. estimate is ~41.7 million tons per year worldwide, service worth at least 4.4 ± 3.0 billion USD year?1. demonstrate opportunities and challenges quantifying these “sanitation ecosystem services,” using 48 cities across globe worked example. In highlighting this, we are not marginalizing vital engineered infrastructure, but instead promoting better understanding how natural infrastructure interact within circular economy. This promising route for further may allow adaptive design management, reducing costs, improving effectiveness sustainability. While researchers practitioners have discussed many varied benefits environments provide humans (termed services),1Pascual U. Balvanera P. Díaz S. Pataki G. Roth E. Stenseke M. Watson R.T. Ba?ak Dessane Islar Kelemen et al.Valuing nature’s contributions people: IPBES approach.Curr. Opin. Environ. Sustain. 2017; 26–27: 7-16Crossref Scopus (590) Google Scholar formal concept evolved between 1970s 1990s.2Costanza R. de Groot Braat L. Kubiszewski I. Fioramonti Sutton Farber Grasso Twenty years services: far come do still need go?.Ecosyst. Serv. 28: 1-16Crossref (767) Before was often little more than an afterthought landscape development decisions, which were driven by economics resulting most services being degraded through unsustainable use.3Millennium Ecosystem AssessmentEcosystems Human Well-Being: Synthesis. Island Press, 2005Google The views from anthropocentric viewpoint, providing framework acknowledge, categorize, and, some cases, quantify monetize them.2Costanza Many other related terms also prevalent this field (including goods, environmental services, capital, nature's people, public payment services), fundamental basis similar. Some argued against approach concept, resenting utilitarian view nature—that only exists “service” humans.4McCauley D. Selling out nature.Nature. 2006; 443: 27-28Crossref PubMed (482) Others argue value nature, stating should preserve protect strictly “for its own sake,” “intrinsic value.”4McCauley consensus will help sustainability decision making (e.g., improved governance provision services).1Pascual Goal 6 2030 Agenda Sustainable Development recognizes importance ensuring availability sustainable management sanitation.5United Nations (2015). Transforming Our World: Development. RES/70/1 Adopted General Assembly.Google Traditionally, systems seen best way manage waste, physical, chemical, biological processes treat it turn into harmless products—6WWAP (2018). United World Water Report 2018: Nature-Based Solutions Water.Google Scholarthe process sanitation. recently recognized nature-based solutions essential if (SDG) be achieved.6WWAP Such services” identified Millennium Assessment (as “waste treatment”),3Millennium received attention since7Bardgett R.D. van der Putten W.H. Belowground biodiversity functioning.Nature. 2014; 515: 505-511Crossref (1139) so contributes sanitation understudied.8Jamwal Brown Kookana Drechsel McDonald Vörösmarty C.J. Vliet M.T.H. Bhaduri A. future urban clean water sanitation.One Earth. 2019; 1: 10-12Abstract Full Text PDF (1) To our knowledge, no paper quantified much safely managed nor continental/global scales. reviewed numerous disciplines covering literatures together foundation (see Box 1 example terminology used). For example, Web Science search either treatment” or “sanitation” “ecosystem service?” yielded 85 results December 17, 2018. Of papers: 48% relevant sanitation, focusing recreation, crop production, etc.). Thirty-six papers (42%) valued sanitation/waste (henceforth referred services) mostly benefit transfer methods9Costanza d’Arge Hannon B. Limburg K. Naeem O’Neill R.V. Paruelo J. al.The world’s capital.Nature. 1997; 387: 253-260Crossref (11704) (97%) China (67%). Benefit methods rely global values, typically obtained limited number studies, then applied different land covers world extrapolating few localized studies mangrove forests all globally). As such, known error prone because, functionally equal their differs according local economies.10Eigenbrod F. Armsworth P.R. Anderson B.J. Heinemeyer Gillings Roy D.B. Thomas C.D. Gaston K.J. Error propagation associated with transfer-based mapping services.Biol. Conserv. 2010; 143: 2487-2493Crossref (64) Scholar,11Eigenbrod proxy-based distribution services.J. Appl. Ecol. 47: 377-385Crossref (363) Finally, 4% reported impacts sewage nature; 6% documented included almost (five six papers) documenting constructed wetlands can (detailed below; Figure 1).Box 1Key definitions environmental, water, hygiene sectors•Ecosystem: community interacting organisms physical environment•Ecosystem service: derive nature1Pascual Scholar•Human waste: products digestive system12Rose C. Parker Jefferson Cartmell characterization feces urine: review literature inform advanced technology.Crit. Rev. Sci. Technol. 2015; 45: 1827-1879Crossref (448) Scholar•Treatment: used convert wastewater useful effluent (with negligible health issues), returned back cycle13Ameta S.C. Introduction.Adv. Oxid. Process. Waste Treat. 2018; : 1-12Google Scholar•Safely [sanitation]: informed excreta flow diagram (Figure 2)14JMP JMP Methodology 2017 Update & SDG Baselines.Google Scholar•Fecal sludge: fecal sludge comprises liquid semi-liquid contents pits vaults accumulating on-site installations, namely latrines septic tanks15Sandec (2008). Sandec Training Tool 1.0 – Module 5: Faecal Sludge Management (FSM).Google Scholar•Excreta diagram: expert-based diagrams capture physically flows city town, categorizes ten possible outcomes16SuSanASuSanA SFD Homepage.https://sfd.susana.org/Google Scholar,17Peal Evans Blackett Hawkins Heymans Fecal (FSM): analytical tools assessing FSM cities.J. Sanit. Hyg. Dev. 4: 371-383Crossref (54) •Ecosystem: Comparable searches fields [Box 1]) show similar data paucity. recently, Trimmer al.18Trimmer J.T. Miller D.C. Guest J.S. Resource recovery enhance services.Nat. 2: 681-690Crossref (20) acknowledge efficiently delivering likely uses concentrate increase delivery developing conceptual pathways resources recovered There extensive body attenuation aquifers, about industrial pollutants, although there focus nitrates waste.19Rivett M.O. Buss S.R. Morgan Smith J.W.N. Bemment Nitrate groundwater: biogeochemical controlling processes.Water Res. 2008; 42: 4215-4232Crossref (789) How poor damage frequently researched,20Camargo J.A. Alonso Á. Ecological toxicological effects inorganic nitrogen pollution aquatic ecosystems: assessment.Environ. Int. 32: 831-849Crossref (1177) finding technical managing waste. Expanding sewer networks challenging, especially when dense unplanned financial resource available.21Mara Pits, pipes, ponds—and me.Water 2013; 2105-2117Crossref (15) Thus empty pit latrines22Thye Y.P. Templeton M.R. Ali A critical technologies latrine emptying countries.Crit. 2011; 41: 1793-1819Crossref Scholar,23Rogers T.W. los Reyes F.L. Beckwith W.J. Borden R.C. Power earth auger modification extraction latrines.J. 72-80Crossref (8) concentrated stream24Semiyaga Okure M.A.E. Niwagaba C.B. Katukiza A.Y. Kansiime Decentralized options faecal slum areas Sub-Saharan Africa: technologies, practices end-uses.Resour. Recycl. 104: 109-119Crossref (34) Scholar,25Mallory Holm reuse low-income countries.Sustainability. 2020; 12: 8334Crossref (2) (known sludge) focus. focused alternative such composting toilets26Anand C.K. Apul D.S. Composting toilets sanitation—a review.Waste Manag. 34: 329-343Crossref (49) container-based toilets.27World Bank (2019). Evaluating Potential Container-Based Sanitation.Google each understudied. Due gaps ends up processed nature. 2017, people (14% population) where disposed situ 2 (>25% did access basic facilities—with 673 defecating open (i.e., behind bushes bodies water).28WHOSanitation Fact Sheet. 14 June 2019.https://www.who.int/en/news-room/fact-sheets/detail/sanitationDate: 2019Google present danger populations, contribute risk partially entirely. poorly understood difficult quantify—predominantly due deficiency—and, underappreciated. At make unquantified. recognize sanitation—introducing acting plant places 1). addition, discuss current valuing services. overall aim develop pathway ensure provided neither taken granted overwhelmed—the latter both release unsafe Here, two main mechanisms delivered, taking lead supporting (alongside infrastructure) (diluting away people), (adsorbing filtering via competition, die-off, predation, nitrates; 1).29Lawrence, A.R., Macdonald, M.J., Howard, A.G., Barrett, M.H., Pedley, S., Ahmed, K.M., Nalubega, (2001). Guidelines Assessing Risk Groundwater On-Site Where predominantly made minimal input propose acts facilitator. locations safe, proportion treated reducer). infrastructure. An harnesses oxidation anaerobic digestion)30Einschlag F.S.G. Water: Evaluation Management. InTech, 2011Crossref cases supporter Globally, approximately 711 (~9% connections connect plants; vast majority (>90%; >640 people) live areas.14JMP connected plants effective comply requirements, courses.14JMP instances, fill gap transporting high-risk conduit untreated sea, dilutes treats (discussed below). Evidence rivers readily available—between one-fifth one-third river stretches Asia, Africa, Latin America contain severe coliform pollution.31UNEPA Snapshot World’s Quality: Towards Global Assessment.2016Google course, source, (and waste) communities downstream reduced level remain unacceptably high populations32Narain Sanitation all.Nature. 2012; 486: 185Crossref necessary removed relocated account suffered users—this could specific sites challenging scale. Over 892 (~12% use facilities situ.14JMP Although, underestimate shared available excluded. Assuming wet mass 128 g person day,12Rose before entering groundwater). Accordingly, soil act filter, microbiota cleaning enter groundwater supplies, globally important. Lawrence al.29Lawrence, describe pathogens attenuated unsaturated soil. They adsorbed onto particles, particularly viruses carry electrical charge. Larger pathogens, protozoan cysts helminths, filtered. Pathogens take tortuous enhances dilution dispersion, increasing time reach groundwater. meantime they might die lack nutrients predated organisms. biologically plants29Lawrence, microorganisms.19Rivett It underpin services.3Millennium Research testing simple guidelines minimum separation distances sources29Lawrence, Scholar,33Daniels M.E. W.A. Schmidt W.-P. Clasen T. Jenkins M.W. Modeling Cryptosporidium Giardia ground surface sources rural India: associations latrines, livestock, damaged wells, rainfall patterns.Environ. 2016; 50: 7498-7507Crossref (21) Scholar, 34Verheyen Timmen-Wego Laudien Boussaad Sen Koc Uesbeck Mazou Pfister H. Detection adenoviruses rotaviruses drinking Benin, West Africa.Appl. Microbiol. 2009; 75: 2798-2801Crossref (59) 35Feighery, J.E. (2013). Combined Field Laboratory Investigation Transport Indicator Microorganisms Shallow Drinking Aquifer Bangladesh.Google 36Ravenscroft Mahmud Z.H. Islam M.S. Hossain A.K.M.Z. Zahid Saha G.C. Zulfiquar A.H.M. 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Nutrient transformations wetland receiving implications treatment.Water 1994; 29: 209-217Crossref (57) US.47Knight R.L. McKim Kohl H.R. Performance system management.J. (Water Pollut. Control Fed. 1987; 59: 746-754Google small evidence linked nutrient load flowing bodies.48Bolund Hunhammar areas.Ecol. Econ. 1999; 293-301Crossref (1518) Scholar,49Paludan Alexeyev F.E. Drews Fleischer Fuglsang Kindt Kowalski Moos Radlowski Stromfors al.Wetland reduce Sea eutrophication.Water 2002; 87-94Crossref fact, suggested mangroves economical services50WWAP (2017). 2017. Wastewater: Untapped Resource.Google government able rapidly populations require.51De Groot, R., Stuip, M., Finlayson, Davidson, N. (2006). Valuing Wetlands Guidance Benefits Derived Wetland Services.Google near Kampala, Uganda, Navikubo ~100,000 households (a 1.0–1.8 year?1) doing protects Murchison Bay Lake Victoria.51De Mississippi River diverted Gulf Mexico order remove nitrogen.52Engle V.D. Estimating wetlands.Wetlands. 31: 179-193Crossref (114) Muthurajawela integrated Sri Lanka receives domestic wastewater, trapping pathogenic accumulate