basic* methods of onsite sanitationcourses.washington.edu/onsite/basicmethodsofsanitation.pdfbasic*...

Basic* Methods of Onsite Sanitationpit latrines, dehydrating toilets, composting toilets

*simple, low-tech, affordable, practical, effective, feasible.......

What are 2 most commonly used sanitation technologies in use today?

What are 2 most commonly used sanitation technologies in use today?

Pit latrine – drop and store – basic Flush toilet – flush and discharge – more complex

Taken From: Ecological Sanitation, Winblad and Simpson-Hebert 2004

Problems with flush and discharge?

Problems with drop and store?

Problems with flush and discharge?

Problems with drop and store?

•VERY expensive•Scarce water resources•Not sustainable to treat drinking water for toilet flushing•Not always adequately treated at the end of the pipe

•High groundwater•Rocky ground•Densely populated areas•Areas where flooding occurs

Pathways for human exposure to pathogens?

Other “basic” onsite methods to:•contain toilet wastes to protect human and environmental health?•reduce pathogens making end products safe for reuse?

DehydratingComposting

Dehydrating toilets – how they work

Moisture needs to be <25% for pathogen reduction and odor controlAdd dry material after each use (ash, sawdust, husks, leaves, soil)Cover and leave to sit for period of timeEffective for arid climates, or humid climate with solar heater

Urine diverting toilets help with moisture reductionFew pathogens – urine is sterileStorage 1-3 months can render safe to useHigh in essential nutrients (87% of total nitrogen and 50% of total

phosphate) 2 ways to “fix” nitrogen

Urine diverting toilets

Clockwise from upper left, first three photos Chuck Henry

bench-type seat riser from El Alto, Bolivia

Urine diverting toilet with a lid with a smaller hole for children to use from Sweden


prefabricated squatting pan from China

Historical example from China

Historical example from Yemen


Urine collected by farmers and applied to crops, Sweden

Section and plan of a urine diverting toilet, Japan

Pictures Taken From: Ecological Sanitation, Winblad and Simpson-Hebert 2004*The Composting Toilet System Book, Del Porto and Steinfeld 2000

Generated in urineper person per day*:•11 g total N•1 g total P•2.5 g K•1.4 g Ca•0.1 g Mg


Vietnamdouble-vault vault

openings for removal


squatting slab for urine diversionpot for collecting urine

Dehydrating toilets

Zimbabweshallow pits


Dehydrating toilets

Sweden installed inside a house

urine is piped to an underground storage tank


Dehydrating toilets

Eco-toilet with processing chambersCuernavaca, Mexico


Dehydrating toilets

Ladakh, India.indoor, traditional dehydrating toilet


Dehydrating toilets

Yemenmulti-story urban house


Dehydrating toilets

What is compost?

Composting toilets

Picture taken from: http://www.tbray.org/ongoing/When/200x/2003/02/23/

Compost is a result of the decomposition of organic matter

Driven by microorganismsDecomposition is the chemical breakdown of compounds into more simple forms

Aerobic process

Oxidation reaction: Organic Matter Energy + CO2 (into atmosphere) + H2O + Minerals (released or immobilized into organisms)

Controlled application/acceleration of natural processes

Formation of stable, humus-like matter (“stable” => does not leach nutrients, does not rapidly decompose, pathogen reduction)

(Dehydrating toilet end-product is NOT stablized)

Picture taken from aggie-horticulture.tamu.edu/.../chapter1.html

Organisms consume organic matter and other organisms and excrete

inorganic wastes.

Inorganic nutrients are mobile and biologically available.

Organic nutrients are stored in

organisms and organic matter.

Organisms take up and retain

nutrients as they grow.

Mineralization and Immobilization

Image courtesy of the USDA-NRCS

What is a composting toilet?(biological toilet, dry toilet, waterless toilet, living toilet)

Containment and controlled compostNot saturated (e.g. septic system)Reduces mass to 10-30%Destroy pathogensResult in stable, humus product, soil conditioner

•Moisture•Carbon to nitrogen (C:N) ratio •Quality of particles (complexity of chemical bonds)•Porosity and particle size (surface area)•Oxygen (aerobic/anaerobic)•Temperature•Time•pH

Key Compost Process Variables

MoistureNeed 45-70% moisture, e.g. wet spongeUrine and flush contribute moisture

drain and removeevaporate with heatdry toilet or urine diverting toilets

Urine diverted and mixed urine and feces Taken From: Ecological Sanitation, Winblad and Simpson-Hebert 2004

C:NCarbon: 70-95% of a cell is water, the rest is mainly carbon-based compounds

Nitrogen: component of nucleic acid, protein, amino acids, enzymes, hormones,…

Stabilization of N:C:N > 30:1 ⇒ immobilize N (stored as organic) 30:1 < C:N < 20:1 ⇒ no net change in N availabilityC:N < 20:1 ⇒ mineralize N (volatilize, leaching)

Images Taken Fromwww.webelements.com

C:NUrine 0.8:1Feces 7.5:1

Microbes use a ratio of 25:1-30:1

Add C after each use (peat moss, sawdust)

Table Taken From: Brady and Weil 2002

Quality of Particles

Table Taken From: Brady and Weil 2002

Relative rates of degradationSugars, starches, simple proteins RapidCrude proteins ↑HemicelluloseCelluloseFats, waxes, etc ↓Lignins, phenolic compounds Very slow

Responsible actors:Rapid -> bacteriaSlow -> actinomycetes and fungiPassive -> fungi

The remaining stable organic matter is humus

Structure of Lignin Taken From:www.atmosphere.mpg.de/enid/3td.html

Quality of Particles

Figure taken from Henry 1996

Porosity and particle size

Smaller surface area -> easier to degradeLarger surface area -> more aeration

Porosity will decrease with decomposition (e.g. 60 to 35%)

Image Taken From http://earthnet-geonet.ca/glossary/display_term_e.php?term=porosity

OxygenKeep compost aerobic

Faster process

Prevent odors (e.g. H2S, NH3, CH4)

Temperature

Pathogen kill not due to heat in compost toilet (time + adverse environment)

Picture Taken From aggie-horticulture.tamu.edu/.../chapter1.html

-15 0 15 30 45 60 75 90

Mic

robi

al p

opul

atio

ns (p

ropa

gule

s/g)

Cryophiles

Mesophiles

Thermophiles

Temperature (°C)

Microbial activity doubles for every 10°C rise in temperature

Temperatures in a compost pile reach thermophilic, but composting toilet will normally be mesophilic due to heat lost to vent pipe, ambient temperature, etc

Hyperthermophile 65-110Thermophiles 40-70°CMesophiles 8-45°CPsychrophile -5-20°C

TimeStabilizationPathogen kill

7

8

9

6

5

4

10

pH

Days0 Lots

optimal for bacteria optimal for fungiRapid

decomposition (formation of

acids)

increase of acid using microbes

actinomicetes and fungi active

excessive nitrification

pH6.5-7.5Takes care of itself in “healthy”, aerobic, properly maintained

(release of organic acids)

Figure taken from Henry 1996

Toilet (waterless, micro-flush, urine diverting)

Components of composting toilets

Picture From The Composting Toilet System Book, Del Porto and Steinfeld 2000

•Vector control (screen, toilet seat seal)•Aesthetics (screen so you don’t see down in/odors•Odor control (positive pressure curtain blowing in•Heater (maintain temperature, evaporate liquids)•Compost access

Exhaust/ventilation/pipe/chimney

Fan

Composting areaLeachate

Can be used as fertilizer/soil conditioner

Check local regulations

End-product needs to be used with care

Further processing

Use in flower beds or above ground food crops vs. root food crops

End-product concerns

Design and management considerations•Climate

•Population density and settlement pattern

•Social and cultural valuesacceptance of compost use/handling of wastes, hygiene education, behavior change, type of toilet, location of toilet

•Economic

•Technical capacitybuilders, maintenance responsibility, infrastructure

•Institutional support educational, promotional, financial, codes and regulations, monitoring

•Capacityloading capacity, diurnal/seasonal loadings

Types of composting toilets•Self-contained vs. Centralized•Manufactured vs. Site-built•Batch vs. Continuous (1 or multiple chambers)•Active vs. Passive

Picture From The Composting Toilet System Book, Del Porto and Steinfeld 2000

Taken From: Richard Heinberg www.inthewake.org

Active compostingactively managed compost

thermophilic pathogen reduction3xs in the thermophilic range

The Humanure Handbook

liquid separation basket


Batchtypes of collection

solar heater

Cancun, Mexicodouble-vault composting toilet

Site-built, batch


Guangxi province, China, toilet is indoors and upstairs

double-vault processing chamber ground level


Site-built, batch

Indiadouble-vault toilet

urine diversionwater for cleaning and urine flow into the evapo-transpiration bed


Site-built, batch

Norway The ‘Carousel’ composting toilet


Centralized, manufactured, batch

West Bank, Palestine toilet indoor on first floor

Urine and greywater treated in septic tank


Site-built, centralized

Mexicomodeled after Clivus Multrum

http://www.solutions-site.org/artman/publish/article_66.shtml

Site-built, continuous

separate chute for kitchen food waste

Left, Taken From: Ecological Sanitation, Winblad and Simpson-Hebert 2004Right, Taken From: http://www.landcareresearch.co.nz/about/tamaki/sewage_wastewater.asp

Centralized, continuouscompost in basement

Clivus MultrumTrailhead Design

Manufactured, continuous

Pictures Taken From: http://www.phys.ufl.edu/~liz/waste.html

Centralized, continuous

basement composter

Pictures Taken From: http://www.rotaloo.co.uk/

Manufactured, centralized, batch system

Rotaloo collection system

Zimbabweurine-diversion, storage in container

solids collection in bucketusers add dry soil and wood ash

Urine-diversion


Guangxi province, China eco-san project

high standard of finishprefabricated squatting pan and tiled

floors and walls


Urine-diversion

Stockholmhousing cooperative

system adapted to existing building

Long drop systems


Inner Mongolia, ChinaUrine diverting

long-drop toilets multi-storey blocks of flats

China-Sweden Erdos Eco-Town Project, Taken From: Ecological Sanitation, Winblad and Simpson-Hebert 2004

Long drop systems

A composting machine serving the 18 apartments in ‘Ekoporten’.

Low flush toilets, composting/biogas

Schematic view of the vacuum–biogas system Lübeck– Flintenbreite


Large-scale

Photos of Choi Building toilet and composter can be seen at:http://www.clivusmultrum.com/projects/commercial/index.html

University of British Columbia – Choi Buildinghttp://www.iar.ubc.ca/choibuilding/matsuzaki.html

30,000 sq. ft. office complex NOT connected to sewer

BiolytixFlow-through vermicomposting system

http://www.biolytix.com/

Vermicomposting

References:Brady and Weil, The Nature and Property of Soils, 2002Del Porto and Steinfeld, The Composting Toilet System

Book 2000 Winblad and Simpson-Hebert, Ecological Sanitation, 2004

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