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Conventional on-site sanitationCourse 2 Unit 2

Lecturer: Mariska Ronteltapm.ronteltap@unesco-ihe.org

Part A OverviewPart A OverviewPart B Description of commonly used low-cost on-site excreta management systemsPart C Comparison with UDD toilet

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To be really precise, this presentation is about Conventional low-cost excreta management systems

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Course 2 Unit 2

Part A: Overview

Course 2 Unit 2

Clarification of terms:Latrine is used interchangeably with the term toiletLatrine is used interchangeably with the term toiletPit = Hole in the ground (not water tight)Vault = Container above ground (water tight)

What do we mean by conventional and on-site?

Conventional means here: Currently widely known and used Accepted by decision makers as a

potential option

On-site means: Not connected to sewer Treated at the site where people

live but this is not always strictly

true e g septic tankspotential option Usually it still often means little

consideration for sustainability (unfortunately)

UDD toilets could become part of conventional options in the future (this would be a good thing!)

true, e.g. septic tanks eventually need removal of faecal sludge to a centralised treatment plant

Decentralised is often used interchangeably with on-site

The opposite of on-site is called: off-site; or centralised systems; or sewer-based sanitation (the

only other alternative could be yto tanker the wastewater away)

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Reasons for having on-site sanitation systems rather than a sewer system To save construction and maintenance costs Because people cannot afford a connection to a sewer Many municipalities cannot afford construction and maintenance of an

expensive sewer system and a wastewater treatment plantM i i liti f h t t h bilit t i i f t tMunicipalities face huge costs to rehabilitate aging sewer infrastructure

older than 150 years (e.g. in Germany, UK) To save water (or because water is scarce or not reliably available);

however, not all on-site sanitation systems have low water use (e.g. septic tanks)

To serve remote locations (long distances) e.g. in Australia and in the US (in the US 50% of new houses use on-site

sanitation - I heard this at the conference in Aachen in 2007 but have no exact reference for this figure)

Because housing is only temporary or illegal (slums, refugee camps) Because it is more flexible with respect to population growth and decline Because people prefer not to mix excreta with water in order to make

containment of pathogens easier (in the case of a waterless on-site sanitation system)

Can you think of other reasons?

Reminder: Sanitation consists of 4 components

1. Excreta managementMany people think of only excreta

management when they talk about sanitation

2. Greywater managementMost often just dumped into the

street or gutter (mixing with rainwater, soil infiltration)

Less critical from public health point of view compared to item 1 but still needs consideration

3. Solid waste management4. Rainwater drainage

The remainder of this presentation will dealwith low-cost excreta management

Greywater = wastewater from kitchen, bath/shower, sinks, laundry (minimal excreta content) See Course 2 Unit 1 for greywater treatment aspects

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On-site sanitation is quite easy if

Population density is low(e.g. rural areas)

or costs are not important

Course 2 Unit 2

But big problems for:High population density and low income(peri-urban areas, slums)

this is the focus of this lecture: low-cost on-site

My rules of thumb:Low density: < 100 people/haPeri-urban areas: 100 240 people/ha (e.g. Lusaka, Zambia case)Slums: > 800 people/ha (e.g. Dhaka, Bangladesh)1 ha = 10,000 m2 = 0.01 km2 (1 soccer field = 0.7 ha)

What is the population density in your city?

sanitation in urban areas

Conventional low-cost excreta management methods (in approximate order of increasing system cost)

Excreta disposal method Needs faecal sludge mgmt.?

Can accept greywater?

Human dignity Public health risk

Open defecation No No Very low Very high

Course 2 Unit 2

Flying toilet No No Very low Very high

Bucket latrine Yes No Low High

Simple pit latrine Yes No Can be OK Medium

Ventilated improved pit (VIP) latrine Yes No OK Low

Urine-diversion dehydrating toilet* No but faecal matter collection

No OK Low

Pour-flush latrine with pit, aqua privy Yes No OK Low

Water-flush or pour-flush toilet with septic tank

Yes Yes OK Low

Water-flush toilet with holding tanks / cess pits

Yes Yes OK Low

* Not (yet) conventional but included for comparisonMore about costs: see Course 4 Unit 1 Financial aspects

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Course 2 Unit 2

Part B: Description of commonly used low-cost on-site excreta management systems

Course 2 Unit 2

(this part is excluding UDD toilets; UDD toilets are covered in detail in Part C)

Commonly-used on-site excreta management systems described in Part B

1 Open defecation1. Open defecation

2. Flying toilet3. Bucket latrine

4. Simple pit latrine5. Ventilated improved pit latrine

6. Pour-flush latrine with pit or septic tank

7. Aqua privy with septic tank

Remember: these are not counted as basic/improved sanitation in the MDGs

These can be counted as basic/improved sanitation in the MDGs if no open pit but pit with slab, not shared not

8. Water-flush toilet with septic tank

9. Water-flush toilet with holding tanks / cess pits

not shared, not public toilet and adequate treatment of faecal sludge (see Course 1 Unit 1 Part C on MDGs)

UDD toilets are not (yet) commonly used so they are not listed in this table here, but described in detail in Part C

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1. Open defecation About 2.4 billion people have no

access to basic sanitation (WHO/UNICEF, 2006) and many of these use openmany of these use open defecation (or bucket latrines, flying toilets)

Great public health risks unless population density is very low

Rain events flush faeces into receiving water bodies Example: Diarrhoea incidences

increase during rainy season inincrease during rainy season in peri-urban areas in Lusaka, Zambia

Open drain used as public toilet in Ouagadougou, Burkina Faso (Oct. 06)

2. Flying toilet

Defecate into plastic bags and throw these away

Main problems: Little human dignity and

comfort for the user Plastic bags can block open

drains Plastic bags can break and

spill their content animals and children can get in contact with fresh faeces

3 Bucket latrine Defecate and urinate into a

bucket which is regularly emptied manually

3. Bucket latrine

http://www.millennium-ark.net/News_Files/NBC/shelter.in.place.html

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What does faecal sludge from bucket latrines look like?

A worker in Kumasi

Course 2 Unit 2

A worker in Kumasi (Ghana) is transferring faecal sludge from a manhole, which is used to store faecal sludge from bucket latrines, to a bucket and then to a and then to a transport vehicle (Source: Vodounhessi (2006))

Note the lack of boots (but he does wear gloves which is good) Faecal sludge

4. Simple pit latrine User urinates and defecates into a toilet

placed over a hole (pit) in the ground Pit depth: 2 m or more, covered with

latrine slab Diameter of pit: 1 1.5 m (round or

square) The hole may be lined around the top to

prevent collapsing The pit is designed so that the liquid pit

content seeps into the ground Can be squatting (top photo) or sitting

(bottom photo)(bottom photo) Very common for:

Rural areas Peri-urban areas, slums, schools Emergency sanitation, refugee camps

Ouagadougou, Burkina Faso

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Reminder: How can pit latrines affect the groundwater?

Pit latrine Shallow drinking water well

(from Course 1 Unit 3)

Based on: Werner, Ch., Mang H.-P., Klingel, F. Bracken, P. (2004): General overview of ecosan. PowerPoint-Presentation. Deutsche Gesellschaft fr Technische Zusammenarbeit (GTZ) GmbH ecological sanitation programme.

Nitrate

Pathogens

Groundwater (clean)

Groundwater (polluted)

Question: so why dont we build fully lined pit latrines?

If a pit latrine was fully lined, it would no longer be a pit latrine p y , g pbut a holding tank

The pit would fill up very quickly with all the urine (remember: about 1.5 L/cap/d of urine)

Pits are only lined at the top and perhaps the side to prevent collapsing but never at the bottom

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5. Ventilated Improved Pit (VIP) Latrine VIP latrine is the same as

simple pit latrine but has a vent pipe and fly screen (reduces odour and fly b di )

Fly screenAir flowbreeding)

Toilet room and pit should be dark to not attract flies

Some VIPs are built as a double-pit structure (see next slide)

Vent pipe

screen

Super-structure

Source: Harvey et al. (2007)

Substructure / pit:Liquid seeps into the ground

Pits are not water tight as they would otherwise fill up too quickly

liquid (urine)

Double Pit VIP Latrine

Double pit improves conditions for pit emptying and potential for reuse compared to single pit

Pits are alternated every 6 months or (better) every 12

thmonths But lack of faecal sludge

management and potential for groundwater pollution are still problems

Source: http://web.mit.edu/urbanupgrading/waterandsanitation/resources/pdf-files

Pit: Liquid seeps into the ground (no separate urine collection)

Pit in use

(drying)

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Pit latrines in peri-urban areas of Lusaka, Zambia

Raised pit latrine due to rocky soil (note leaking on the side)Source: Mayumbelo (2006)

More photos from pit latrines in peri-urban areas of Lusaka

Photos by Kennedy Mayumbelo (Lusaka Water and Sewerage Company) March 2007: The pit Company), March 2007: The pit latrine is being used by three households, all on the same plot. There are a total of 14 people currently using it and it is leaking very badly from the sides (problem of construction). It is also full and the users said they only use it because they have no choice; as expected all the three households are tenants and the landlord lives elsewhere.

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Typical problems with pit latrines in peri-urban areas

High odour levels Fly breeding Overflowing

C ll i f it Collapsing of pits No space to dig new pits Difficult to dig new pits if ground is

rocky No systems to empty pits (lack of

faecal sludge management) Pit latrines have to be outdoors Pollution of groundwater which is

sed for drinking ater b singused for drinking water by using shallow wells (e.g. Lusaka, Zambia)

Pits are also used to dump rubbish

Have you ever used a pit latrine?

A collapsed pit latrine (photo by Linus Dagerskog, CREPA, taken in Ouagadougou, Burkina Faso)

Linus said: the most disgusting thing I have ever seen; a bubbling sludge, flies everywhere, and the house owner did not really know how to cover or fill it.

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A pit latrine where the hole is in the process of collapsing (seen in Maseru, capital of Lesotho (a small country

Course 2 Unit 2

( yinside of by South Africa), December 2006)

Photo: E. v. Mnch

Despite their popularity: pit latrines are actually not sustainable if The groundwater table is shallow Karst geology or ground that is underlain by pervious rock leading

to:a rapid rate of groundwater movement a rapid rate of groundwater movement

potential for groundwater contamination (in combination with shallow wells being used as a water supply source)

Area has a potential for flooding Soil type is rocky (hard to excavate) No space to dig new pits or no means to empty full pits and to treat

faecal sludge Population density is high Situation has lack of security (since pit latrines have to be built inSituation has lack of security (since pit latrines have to be built in

some distance from the settlements)

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Pit emptying

After some months or years of use (depending on the number of users and the size of the pit), a pit latrine fills up. It then needs to be either pabandoned or emptied.

Note: water needs to be added to make faecal sludge from pit latrines pumpable!

Methods for emptying: Manual emptying with buckets

(extremely high health risks!) Mechanised emptying with vacuum

tankers (see Course 2 Unit 3

Vacuum tanker collecting faecal sludge from septic tank

tankers (see Course 2 Unit 3 Storage and transport logistics)

Why are pit latrines so wide-spread in low income areas? Cheap and easy to construct and maintain Drop-and-forget mentality

Course 2 Unit 2

Can be appropriate solution if: population density is low; and soil conditions are suitable (not rocky, not sandy, easy to dig

but also stable); and area not prone to flooding; and groundwater table not shallow but rather deep; and

good general security (no harassment for women and good general security (no harassment for women and children at night)

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6. Pour-flush latrine with pit or septic tank

After defecation, a few litres of water must be poured into the bowl to flush the

Course 2 Unit 2

Pit under toilet Pit offset from toilet

bowl to flush the excreta into the pit or septic tank

Water acts as a hygienic seal (reducing odour and flies)

(The toilets squatting pan could be modified to include urine diversion as a first step towardsfirst step towards ecosan)

Source: Harvey et al. (2007)

7. Aqua Privy with septic tank

Simple latrine constructed over a septic tankseptic tank

Tank must be watertight to maintain constant liquid level in the tank

Tank can receive greywater

Nowadays less common (I have never seen one have you?)

Source: Harvey et al. (2007)

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8. Water-flush toilet with septic tank

Septic tanks: Underground tanks, usually one per

householdW k i j ti ith t fl h Work in conjunction with water-flush toilets

Combined settling, skimming and anaerobic digestion

Solution for the wealthy in developing countries (requires water for flushing)

Pre-treated, settled effluent usually infiltrated into ground (soakaway)g ( y )

Tanks need emptying Faecal sludge management often lacking

For an ecosan concept, septic tanks could be used just for greywater or just for blackwater (urine, faeces and small amount of water)

See Introduction to Anaerobic Treatment (Course 2 Unit 4) and Conventional Faecal Sludge Management (Course 2 Unit 7)

Underground septic tanks in Maseru, Lesotho (Dec. 2006)

Septic tank effluent discharged to soakaway or small-bore sewer(see Course 2 Unit 8 Small-bore sewer systems)

Source: http://web.mit.edu/urbanupgrading/waterandsanitation/resources/pdf-files

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Typical problems with septic tanks (particularly, but not only, in developing countries)

Effluent quality low and often not enough space for sustainable soil infiltration Tank is undersized (little anaerobic treatment occurring) a s u de s ed ( tt e a ae ob c t eat e t occu g) Population density has become too high capacity of soil to absorb

and treat liquid effluent is exceeded Pollution of groundwater is possible (effluent soak-aways most common)

Tank may be leaking (faecal sludge is leaking out); maintenance is neglected

Need regular emptying (typically every 5-10 years, depending on size and number of users)

Faecal sludge is overflowing together with the effluent Faecal sludge is overflowing together with the effluent Capacity for faecal sludge treatment lacking (resulting in illegal

dumping anywhere in the environment) Relatively expensive (not affordable for the poor) Need access roads for emptying trucks

Do you have your own experiences with septic tanks (e.g. at home or at work)? How often is it emptied (faecal sludge removed)? How do you know when to empty it? What is the effluent quality of your septic tank like? Is it good?

Course 2 Unit 2

What is the effluent quality of your septic tank like? Is it good? How do you know?

Is it ever giving you odour problems? Where is the faecal sludge taken to and how is it treated?

Such individual soil-based systems are difficult to monitor!

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9. Water-flush toilet with holding tank (also called cess pit or conservancy tank)

Needs watertight tank and frequent emptying

Sometimes cess pits are (illegally) converted into a(illegally) converted into a leaching pit by breaking through the base of the tank - so that the cesspit no longer fills up! This may be convenient for the owner but may lead to groundwater pollution

In the US the word

Source: http://web.mit.edu/urbanupgrading/waterandsanitation/resources/pdf-files

In the US, the word cesspool is used, but this is not a water-tight tank but allows infiltration

Faecal sludge management (FSM)

The following on-site systems result in the production of faecal sludge: Household pit latrines, bucket latrines Unsewered public toilets, e.g. aqua privies, pour flush, VIP,

cess pits Septic tanks (households, institutions, hotels,)

Faecal Sludge Management = FS transport, treatment, reuse

See separate lecture on FSM (Course 2 Unit 7 Faecal sludge management)Some handy rules of thumb:

Specific faecal sludge production (Heinss et al., 1998):1.0 L/cap/day from septic tanks0.2 L/cap/day from toilets without water use

Typical FS total solids content 25 g/L (Steiner et al., 2002)

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Proposed scenario Current situation= Faecal sludge crisis:

Faecal sludge management overview

uncontrolled disposalillegal dumping

(need to add water to empty pit by pumping)

Closing the loop

illegal dumping no beneficial

reuse

g

But how to deal with liquid effluent?

Course 2 Unit 2

Course 2 Unit 2

Part C: Comparison with UDD toilet

For cost comparisons see Course 4 Unit 1 (Financial aspects)

UDD toilet details are given in Course 1 Unit 3 and Course 1 Unit 4

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Example: Single vault urine-diversion dehydrating (UDD) toilet

This type of toilet is ypoften wrongly called composting toilet or ecosan toilet

Ecosan is not limited to a specific technology, hence UDD toilets or other

Source: http://web.mit.edu/urbanupgrading/waterandsanitation/resources/pdf-files

Removal of dried material

toilet types could be used in an ecosan project

(Double vault UDD toilet would normally have two vent pipes)

Advantages of a UDD toilet compared to a pit latrine

Can be indoors, because: No pit required (the pit would normally allow liquid to seep into

the ground)

Course 2 Unit 2

the ground) No odours (because urine and faeces are not mixed)

Suitable for areas with: High-density settlements Difficult soil conditions A danger of groundwater pollution

Easy to recycle excreta Does not require faecal sludge management (vacuum

tankers for pit emptying)tankers for pit emptying) Does not require regular digging of new pits Can be more portable (e.g. the Separett foldable UDD toilet

shown in Course 1 Unit 3 Part E)

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Disadvantages of a UDD toilet compared to a pit latrine Requires user training and awareness, e.g. must not urinate

into the faeces compartment (one should also provide waterless urinals for men)

C d d if t d tl

Course 2 Unit 2

Can produce odours if not used correctly Still relatively new concept amongst NGOs, municipalities,

universities, consultants, manufacturers, etc. Dried faecal matter must be removed once or twice per year Anal washing with water (if practised) must take place over a

drain which is separate from the faeces vault Urine must be collected, stored, transported and used as

fertiliser, or infiltrated into the ground or otherwise dealt withU i ll ti t i ld b t l Urine collection container could be stolen

Even the collected urine itself is known to have been stolen once people appreciate its value as a fertiliser (experience of CREPA in West Africa)!

How to select best on-site sanitation option?

Compare sustainability of available options (use sustainability p y p ( ycriteria, see Course 1 Unit 1) this includes: social, technical, economic, environmental, public health and institutional aspects; and/or

Use selection criteria based on local conditions (example on next slide)

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Example: Short-listing of options for peri-urban areas in Lusaka, Zambia (slide 1 of 2)

Selection criteria:1. Not pollute groundwater (groundwater is used as

drinking water)2 Not require water to transport waste (water is scarce 2. Not require water to transport waste (water is scarce

and expensive)3. Sanitise excreta to destroy pathogens (protect public

health)4. Cost effective low capital and O&M (people have low

income)

Short listed options:z Option 1: VIP latrine and downstream

processingz Option 2: Single-vault UDD toilet and

downstream processingSource: Mayumbelo (2006)

Note: Option 1 does not meet selection criterion 1 but is included to serve as a reference point in the cost analysis

Example contd: Decide on the implementation level (slide 2 of 2)

Household facility One toilet for 4 people

Course 2 Unit 2

One toilet for 4 people

Plot facility One toilet for all people living on one plot (12 in this case)

Communal facility One toilet block that is shared by a number of plots

Good compromise between convenience and cost

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And at the end: Summary of conflict between (conventional) onsite sanitation and urbanization

References for this presentation (slide 1 of 2) Harvey, P., Bastable, A., Ferron, S., Forster, T., Hoque, E., Morris, L., Piano, E., and Smith,

M. (2007) Excreta Disposal in Emergencies: A Field Manual, WEDC, Loughborough University Available: http://wedc.lboro.ac.uk/projects/new_projects3.php?id=15 *

Heinss, U., Larmie, S. A., and Strauss, M. (1998) Solids separation and pond systems for the treatment of faecal sludges in the tropics. Lessons learnt and recommendations for

li i d i EAWAG/SANDEC Db d f S it l dpreliminary design. EAWAG/SANDEC, Dbendorf, Switzerland. http://www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_ewm/downloads_ewm/solids_sep_and_pond_treatm.pdf *

Steiner, M., Montangero, A., Kon, D., and Strauss, M. (2002) Economic aspects of low-cost faecal sludge management. Estimation of collection, haulage, treatment and disposal /reuse cost, EAWAG/SANDEC, Dbendorf, Switzerland. http://www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_ewm/downloads_ewm/FSM_cost_report.pdf *

WHO/UNICEF (2006) Meeting the MDG Drinking Water and Sanitation Target The Urban and Rural Challenge of the Decade. WHO/UNICEF Joint Monitoring Programme (JMP) for Water Supply and Sanitation. Available: http://www.who.int/water_sanitation_health/monitoring/jmp2006/en/index.html (provided under Course 1 Unit 1 Assigned Reading)under Course 1 Unit 1 Assigned Reading)

* Provided on the I-LE for this course unit (Extra materials)

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References (slide 2 of 2)recent MSc theses at UNESCO-IHE

Mwase, H. (2006) The potential of ecosan to provide sustainable sanitation in emergency situations and to achieve quick wins in MDGs, MSc Thesis, UNESCO-IHE Institute for Water Education Delft The Netherlandsfor Water Education, Delft, The Netherlands

Mayumbelo, K. M. K. (2006) Cost analysis for applying ecosan in peri-urban areas to achieve the MDGs - Case study of Lusaka, Zambia, MSc Thesis MWI 2006-10, UNESCO-IHE Institute for Water Education, Delft, The Netherlands.

Vodounhessi, A. (2006) Financial and institutional challenges to make faecal sludge management integrated part of ecosan approach in West Africa Case study of Kumasi Ghana MScapproach in West Africa. Case study of Kumasi, Ghana. MSc Thesis WM 2006.05, UNESCO-IHE Institute for Water Education, Delft, The Netherlands.

The first two are also available from the GTZ literature database:http://www.gtz.de/en/themen/umwelt-infrastruktur/wasser/9835.htm