Overview of technologies for ecosan (toilets and treatment)

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Course 1 Unit 1Part A B C D

Teacher

Mariska Ronteltapm.ronteltap@unesco-ihe.org

Course 1 Unit 3

Overview of technologies for ecosan (toilets and treatment)

Content of Part 1 (this file):Part A: General issues: groundwater pollution and urine precipitationPart B: Overview of technologies for ecosan conceptPart C: Waterless urinals

Content of Part 2 (separate file to keep file size < 10 MB):Part D: Overview of toilet typesPart E: UDD toiletsPart F: UD water-flush toilets

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Course 1 Unit 3

Part A: General issues:

A1: Groundwater pollution from on-site sanitation

A2: Blockages from urine precipitation

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These two issues are NOT related to each other; they are just put together here because they are common fundamental issues that come up regularly in ecosan work

Course 1 Unit 3

Potential for groundwater pollution from different types of on-site sanitation

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Needs to be prevented at all costs!

A1: Groundwater pollution

Treatment type Possible form of pollution

Conventional on-site sanitation (see Course 2 Unit 2)

Urine from pit latrines

Faecal sludge leaking from septic tanks

Nitrate

Faeces leachate from pit latrines

Septic tank effluent, leaking septic tanks, uncontrolled greywater infiltration

Pathogens and nitrate

Ecosan

Urine from UDD toilets if it is infiltrated into the soil and soil conditions not suitable

Nitrate

Fertiliser run-off if over-fertilised with ecosan products or not managed properly

NitratePathogens if sanitisation was not complete

How can septic tanks affect the groundwater?

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Ground level Ground level

Effluent to soil infiltration (normal)

Wastewater from house

Soil (unsaturated zone)

Faecal sludge (if “leaking septic tank”)

The effluent from septic tanks is commonly infiltrated into the ground (on purpose).But faecal sludge is NOT meant to leak out from the septic tank (but often does if not designed properly). More on septic tanks: Course 2 Unit 2 “Conventional on-site sanitation” and Course 2 Unit 4 “Introduction to anaerobic treatment technologies”

Groundwater (aquifer)

How can pit latrines affect the groundwater?

6Based on: Werner, Ch., Mang H.-P., Klingel, F. Bracken, P. (2004): General overview of ecosan. PowerPoint-Presentation. Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH ecological sanitation programme.

Pit latrine Shallow drinking water well

Course 1 Unit 3

Example picture to show the reality of the previous slide: peri-urban area in Lusaka, Zambia

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Shallow well to collect drinking water

Pit latrine

Do you have your own examples for this sort of practice?

Photo: Kennedy Mayumbelo, Lusaka Water and Sewerage Company (2006)

The problem of increased nitrate levels in groundwater

Soil bacteria convert the urea in urine first to ammonia, then to nitrate (this process is called nitrification)

Remember: ammonia = NH3

ammonium = NH4

nitrate = NO3

The safe limit for nitrate in drinking water is: 50 mg/L (WHO, 2004) Methemoglobinemia in infants (also called “blue baby syndrom”,

attributed primarily to excessive nitrate intake from drinking well water)

Example: Khorezm, Uzbekistan: tube well samples up to 250 mg/L nitrate (Herbst, 2006)

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Note: Sanitary engineers use nitrate-N, which is the nitrogen content of nitrate. Therefore, 50 mg/L of nitrate = 50 * 14/62 = 11.3 mgN/L (also called NO3-N)

Why is groundwater pollution a potential problem?

Groundwater may be source of drinking water (e.g. shallow wells) – a problem if polluted with nitrate and pathogens

Polluted groundwater can contaminate surface waters, e.g. rivers and springs, via groundwater movements

Can take a long time before effect is noticed See Course 2 Unit 9 (“Urban groundwater pollution”) for

more information

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What do you know about groundwater pollution in the city where you live?

Urine precipitation fundamentals The commonly called “urine stone” consists of calcite (CaCO3),

hydroxyapatite (HAP, Ca5(PO4)3(OH)) and struvite (MgNH4PO4 6 H⋅ 2O) 

Hardness in water favors precipitation of struvite But urine also precipitates without addition of water or Mg and Ca

contained in flushing water The trigger of precipitation in undiluted urine is the hydrolysis of urea by

bacterial urease. This process starts quite quickly when urine gets in contact with the bacteria producing urease that grow in urine pipes

In very fresh urine there is no precipitation, but that precipitation starts as soon as urine is stagnant and in contact with bacteria

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A2: Urine precipitation

Research results on urine precipitation are available from the Novaquatis research project of Eawag on UD flush toilets (http://www.novaquatis.eawag.ch/publikationen/final_report_E)

See also posting by Florian Klingel (ex-GTZ ecosan team) on the EcosanRes Discussion Forum on 12 October 2006

Course 1 Unit 3

Two types of urine pipe blockages

“Soft” blockages caused by precipitation on hair and paper fibre – this is the most common type of blockage in urine-diverting toilets It is a result of fibres and other particles entering the piping system and

of chemical precipitation of struvite (MgNH4PO4) and calcium phosphates (Ca10(PO4)6(OH)2) from the urine caused by the increase in pH which occurs when urea is converted to ammonia.

The precipitation also forms a viscous sludge, which will slowly flow towards the tank provided that the slope of the pipes is correct.

“Hard” blockages, caused by precipitation directly on the pipe wall

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Example of “soft blockages”

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Source: Håkan Jönsson on EcosanRes Discussion Forum, 11 Oct. 2006(photos: Marilena Cernat)

A blocked/non-sealing rubber seal from UDD toilet (after 7 years of use)

The pipe below the rubber seal

Course 1 Unit 3

Example 1 of a “hard blockage”: Urine precipitates in outlet section of waterless urinal

13Photo: 30 August 2006 in UNESCO-IHE building after approx. 5 months of use

Each urinal has two plastic insert pipes, which are removed to replace the blue blocking liquid (this liquid just drains to the sewer) Uridan urinal with oil-based

blue blocking fluid

Example 2 of a “hard blockage”: Urine pipes from waterless urinals and NoMix toilets

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Pipes can be blocked by urine scale here shown in magnification (photo: Kai Udert)Source: http://www.novaquatis.eawag.ch/arbeitspakete/nova2/index

Urine precipitation in waterless urinals (see also Part C of this presentation)

As a guideline: No or low precipitation:  waterless urinals with rubber odour seal and good

slope of urine pipes (no stagnation of urine) or urinals flushed with rainwater

Some precipitation: waterless urinals with oil seal, urinals flushed with large volume of hard water

Strong precipitation:  urinals flushed with low volume of hard water, waterless urinals with insufficient slope in the pipes. 

For further details see this document:

http://www2.gtz.de/Dokumente/oe44/ecosan/en-biologically-induced-precipitation-urine-collecting-system-2003.pdf

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Removing and preventing urine pipe blockages

Removing blockages: Mechanically by a drain auger or Chemically by use of strong solutions of caustic soda (2 parts

of water to 1 part of soda) or acetic acid (>24%).

Preventing blockages: Preventative cleaning as indicated above All urine pipes to have good gradients (at least 1%, more if

possible) Avoid pipe segments where urine is stagnant

See also Course 2 Unit 3 “Storage and transport logistics”

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Course 1 Unit 3

Course 1 Unit 3

Part B: Overview of technologies for ecosan concept

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Course 1 Unit 3

For comparison: the conventional sewer-based sanitation approach

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rainwater domestic + industrial wastewater

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Flush toilets discharging to conventional sewer systems (combined or separate for rain water)

Biological treatment processes:Activated sludge plantsTrickling filters, other attached growth processesLagoonsMembrane bioreactors

Often: no reuse at all (in industrialised countries)Sometimes effluent is reused for irrigation (agricultural, golf courses) and sludge (biosolids) is reused in agriculture

dis

-ch

arg

e

None

None

Stormwater drains

Receiving water body

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Activated sludge wastewater treatment plant in

Amsterdam, the Netherlands

Conventional wastewater treatment plants (WWTPs)

Conventional centralised wastewater treatment systems

Centralised sewer system and treatment Some recovery of nutrients and water possible e.g.

through reuse of wastewater

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Course 1 Unit 3

Some characteristics of conventional WWTPs

Rely on a water-borne sewer system Use lots of potable water for flushing human and industrial waste

away Result in a high volume of wastewater with relatively low

concentrations of pollutants Can result in products for reuse (treated effluent and sludge) but

this is not usually the main aim Can work well if financial and institutional capacity is in place More suited to centralised approaches than to decentralised

approaches Approx. 80% of investment cost is in sewers (20% in WWTP)

Sewers leak to varying degrees (see Course 1 Unit 1 Part A)

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Per capita water consumption for different countries (this is the total water consumption, except for USA where the value quoted is only the

indoor water use)

22Source: Metcalf & Eddy (2003), page 160 & 163

260

130

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50 42.525

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260 L/cap/d = 94,900 L/cap/year

What is the value in your country? How much does it vary within your country?

Typical values in the Netherlands:Wastewater production: 120 L/cap/dOf this from toilet flushing: 40 L/cap/d

Typical distribution of residential interior water use in the US

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26%

22%17%

16%

14%

2%2%1%

Toilet flushing

Clothes washing

Shower

Faucet (tap)

Leakage

Other domestic

Bath

Dishwashing

Source: Metcalf & Eddy (2003),page 160

Total mean indoor water use:260 L/cap/d

For more details see Course 5 “Urban water demand management measures”

Course 1 Unit 3

Overview of ecosan approach

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Org. solid waste rainwater greywater urine faeces

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Aim: If feasible and appropriate, separate collection of (most) waste components, with minimal dilution water.Collection system may already lead to (partial) treatment.

Aim: Treatment that will allow safe reuse (safe for public health and for environment); pathogen destruction is a key requirement

Aim: Beneficial reuse which recycles nutrients and organic matter to the soil or aquaculture

Overview of ecosan technology components

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organic solid waste

rainwater

greywaterurinefaeces

collecti

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treatm

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Vacuum toilets and vacuum sewerage

Vacuum toilets and vacuum sewerage

UD toiletsUD toilets

-

StorageStorage

Fertilizing with urine Fertilizing with urine

Soil conditioning with treated excreta and solid biowaste

Soil conditioning with treated excreta and solid biowaste

Anaerobic DigestersAnaerobic Digesters

Composting Composting

Rainwater harvestingRainwater harvesting

Urine processing

Urine processing

Dehydration ToiletDehydration Toilet

Reuse of wastewater e.g. in agriculture, aquaculture

Reuse of wastewater e.g. in agriculture, aquaculture

Gravity Sewerage (conv. or small-bore, central or decentral)Gravity Sewerage (conv. or small-bore, central or decentral)

-

Composting toiletComposting toilet

Wastewater treatment (centralised or decentr.)Wastewater treatment (centralised or decentr.)

Source: based on GTZ-ecosan project Resource Book

Disinfection (if required)

Disinfection (if required)

Reuse: irrigation, cleaning,

toilet flushing

Reuse: irrigation, cleaning,

toilet flushing

Greywater separationGreywater separation

Constructed wetlands,

ponds, trickling filters, septic

tanks, soil filters,…

Constructed wetlands,

ponds, trickling filters, septic

tanks, soil filters,…

Prolonged storageProlonged storage

Waterless urinals, UD toilets

Waterless urinals, UD toilets

Reuse: irrigation,

toilet flushing

Reuse: irrigation,

toilet flushing

UD = urine diversion or urine separation

Important treatment technologies often used as part of ecosan concepts (See Course 2 Units 4-7 for more details on these)

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Process Technical options Reason for popularity in ecosan

Composting Composting plants for secondary treatment

Composting toilet

Suitable for faecal matter and organic solid waste treatment

Produces valuable end product (compost)

Low energy demand

Pathogen destruction (if thermophilic)

Anaerobic treatment

Septic tanks

UASB

Anaerobic ponds

Anaerobic digesters

Suitable for faecal sludge, blackwater, faeces (e.g. together with manure), organic solid waste

Preserves nitrogen (unlike aerobic wastewater treatment)

Produced biogas for cooking, lighting, heating

“Natural systems” (low-rate biological systems)

Constructed wetlands

Aerobic or facultative ponds/lagoons

Waste stabilisation ponds

Suitable for greywater treatment

Low energy use

Cheap if land available

Can have aesthetic and environmental benefits (e.g. increased bird life)

High-rate biological or physical systems

Package plants using attached growth processes

Membrane bioreactor

Trickling filter

Suitable for greywater treatment in urban areas (limited space)

High quality effluent is produced

Alternative sewer systems (See Course 2 Unit 8 for more details on these)

Small-bore shallow sewers for settled or unsettled sewage Vacuum sewer systems:

– Toilets will be described in Part D of this presentation

– Low-diameter vacuum sewer lines (made of PE-HD or PVC) are laid in shallow and narrow trenches

– At the vacuum station the vacuum is generated by vacuum pumps evacuating air from a vacuum tank

– Supplier example: www.roevac.de

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Course 1 Unit 3

Course 1 Unit 3

Part C: Waterless urinals

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For non-native English speakers:Waterless = without water (just like hopeless means without hope!); some people wrongly think that waterless means “less water”

Cheap portable waterless public urinal in use in Amsterdam, the Netherlands

Course 1 Unit 3

Why have waterless urinals for men?

Reduces water consumption (conventional urinals use 4-6 L per flush)

Enables collection of undiluted urine (for reuse as fertiliser) Does not pollute precious drinking water just for transport of urine Can be just as hygienic with same or less odour than conventional

urinals

Mostly used at public places, not usually in private homes (lack of space)

The easiest „first step of ecosan“! (Reuse of sanitised urine as fertiliser would be the second step to close the loop)

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Social acceptability of waterless urinals by men

Generally very high; many men hardly notice the difference Odour should be the same or less than conventional urinals (but

can also be worse) Some do not like it because they perceive it as “not clean”,

since they are not flushed with water Note: Many muslims do not use any open urinals in a row

because they want to wash themselves with water after urination (urinals in separate cubicles would be OK)

• (There are also other men who don’t like to use public urinals – not for religious reasons but just because they prefer to urinate in a private cubicle – I wonder what % of the male population this applies to?)

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Odour control methods for waterless urinals Attention to urinal surface

– Special smooth surface material (e.g. wax coating) to reduce sticking of urine and bacterial biofilm

– Wipe surface of urinal once, twice or several times per day with moist sponge

Block the odour from sewer or urine storage tank with one of the following methods (see photos on following slides):– Mechanical seal, e.g. rubber tube or rubber curtain– Seal with floating oil layer – Old light bulb (see slide after next): “Eco-Lily”– Or: well ventilated area, and live with a small amount of

(harmless) odour

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Course 1 Unit 3

Existing suppliers of waterless urinals

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Using rubber tube or rubber curtain seal:

– Keramag (model Centaurus), Germany (photo 1)

– Addicom, South Africa (photos later in this presentation)

Using floating oil seal:

– Uridan, Denmark (photo 2)

– Ernst, Switzerland (photo 3) (– now changing over to rubber curtain seal from Addicom)

– Suppliers in the US: Waterless Co., Sloan Valve Company, Falcon Waterfree Technologies, Zurn

The fact that there are so many suppliers indicates that this is becoming big business and there is money to be made!

See also detailed discussion on waterless urinals on Ecosanres Discussion Forum in June 2007 At UNESCO-IHE we have now 10 urinals from Uridan (April 2006) and 1 from Keramag (July 2007) –

see separate presentation under Assigned Reading

3

1

2

Cheapest waterless urinal: “Eco Lily”

33At CREPA headquarters in Ouagadougou, Burkina Faso, Oct. 06

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Uridan: in use since April 06 Keramag Centaurus (taken into service: 6 Aug. 07)

This is the view in August 2007 at one of the three male toilet locations at UNESCO-IHE where we have waterless urinals

Note the blocked off pipe just above the urinals where the water pipe for the water-flushed urinals used to be

How does the rubber tube or rubber curtain seal work?

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The black rubber tube is flat at the bottom when not in use (and hence blocks odour from the sewer) but opens up when urine is flowing through

Course 1 Unit 3

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View of urinal with sieve and rubber seal removed (odour from sewer becomes noticeable). Note yellow stains from urine precipitates (under the sieve)

Assembly of sieve and rubber tube (with removal device on left) on 6 August 07 – after only 2 weeks of use

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Above:Close up view of rubber tube (note slit in the middle)

Above:Demonstration of functioning of rubber tube with water

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Demonstration of how water flows through the rubber tube and how the unit could be cleaned (better to separate sieve and rubber tube from each other for cleaning purposes)

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Urine stone scaling after 3 months of use (2 Nov 2007; urinal in UNESCO-IHE building). Rubber piece needs more frequent cleaning. If tube does not close anymore at the bottom, odor from sewer could become noticeable

Example of user feedback from Hamburg, Germany

Posting by Martin Oldenburg on EcosanRes Discussion Forum on 12 Oct 2006:• Regular cleaning also of the rubber seals is important. The city of Hamburg

has installed these type of waterless urinals in public toilets. We have visited them once and discussed with the operation staff. The toilet is used by approx. 1,000 persons per day. They remove the rubber seal once a day and clean it with water and replace it again. The seals are replaced after approx. 6 months. The experience they have is much more positive than with the urinals with the liquid seal. Furthermore until now they don't have any problems with pipe blocking (since 1.5 - 2 years).

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Some more general information about Keramag Centaurus urinal

Information below from phone call with Ronald Herkt from Keramag (27 July 2007):

• Cost brutto list price is € 520 (significant discounts for large clients possible)

• The rubber tube piece as a replacement piece costs € 17 (should last at 4,000 uses – typically 6-12 months); should be cleaned with water once per fortnight

• Numbers sold: On the market since about Jan. 2004; now selling several thousand per year with sales growing by 30-50% per year

• One important client is for example the Hamburg Environmental Authority (installed 1,500 units in Hamburg’s schools)

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Course 1 Unit 3

Further information on the Keramag waterless urinal (model: Centaurus)

• Note: Keramag is a huge sanitary company and it is not so easy to find information about their waterless urinals on their general website (www.keramag.de)

• You can find information by going to their product database and entering as a search term: Centaurus (also provided under Extra Materials)

http://pro.keramag.com/?id=497&s=22

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Low cost waterless urinal for South Africa and beyond

(minimal maintenance required)Supplier: Addicom, see detailed info on next 3 slidesPrice: approx. € 50

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Urinal bowl viewed from underneath

Blue “curtain” made from liquid silicon rubber which opens as urine flows through

The supplier calls this patented piece the EcoSmellStop device (ESS)

Ernst waterless urinal (at a camping park in Switzerland)

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This painted-on fly improves men’s aiming (don’t laugh, it’s true!)

Same EcoSmellStop device as Addicom (previous slide)

Some details from supplier Addicom about plastic waterless urinal (slide 1 of 3)

E-mail from Peter Dahm (4 August 2007): The fabrication process of the urinal bowl dictates, as you call it, a "pronounced

rim" . The urinal is produced in the so called "rotation single skin moulding", process. A cheap and simple process and not too "high - tech".

Should a "rimless" urinal be produced then a double skin mould would be required. We have experienced problems with double skin moulds insofar as they require a considerably higher skills level. If the production process is not closely  monitored then the wall thickness of the urinal will vary considerably

Secondly a double skin urinal will therefore consume double the amount of material and the costs will raise accordingly.

The "one screw" fitting method, a very positive feature of our urinal, would not be possible with a double skin design.

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Supplier contact details:Addicom (Pty) Ltd (Peter Dahm)info@addicom.net - www.addicom.co.za

Johannesburg, South Africa

Some further information on this urinal is provided under Extra Material

Some details from supplier Addicom about plastic waterless urinal (slide 2 of 3)

E-mail from Peter Dahm continued (4 August 2007): The answer against odour is the material of the urinal bowl. Linear low density

polypropylene is among the most inert plastics (non stick surfaces). The hot production process at 180°C guarantees a smooth, non porous, surface, therefore making it virtually impossible for bacteria to gather. We had no problems up to now and use this urinal type since 2004.

The SVR-M bowl is meant to be used in downtown and rural areas, albeit university of the north, Potchefstroom campus is one of our large clients using this bowl.

We want to encourage our 3rd world clients to produce the urinal bowl in their country (we would supply the mould at cost) and only get the EcoSmellstop (ESS) fitting from us. If the urinal bowl is made in the country of destination the transport costs will be negligible.

Our ESS element can be changed completely "touch free" in seconds. We have several hundreds of our units installed in Johannesburg's public

facilities since 2004. Some of the installations are frequented up to 1400 (!) times a day (16 hours). Each ablution block has got an

attendant which pours once in the evening one liter of 10% dialuted HCl down the urinal.

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Course 1 Unit 3

Some details from supplier Addicom about plastic waterless urinal (slide 3 of 3)

E-mail from Peter Dahm continued (4 August 2007): In Feb 2006 we have upgraded all installations to the blue ESS 

and they are still today in operation. The blue ESS element is made out of Liquid Silicon Rubber or

commonly known as LSR. The liquid material of relatively high visvosity is injected (in a

cooled piping system) into a mould permanently heated between 180 - 240°C

LSR consists of two components and once they are mixed the "hardening" process starts. In a cooled environment it will take an eternity and at high temperatures only seconds.

The process is "high tech" and the mixing and injection requires very sophisticated machinery. The moulds are virtually a piece of art!

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Waterless urinals by Uridan

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Cost of one Uridan urinal: Varies depending on model.

The ones we have at UNESCO-IHE were € 700 each (cost would come down if higher numbers are ordered and once demand really picks up)

Course 1 Unit 3

Uridan urinals have a blocking fluid against odour from the sewer

Blocking fluid (“Urilock”): Plant-oil based (200 mL for one urinal) Needs to be replaced once urine

cyrstals or solids have accumulated (see next slide)

This occurs after about 7,000 uses of the urinal (according to supplier)

Cost of Urilock: was € 18 per 200 mL, is now € 4 per 200 mL (February 2007)

Disadvantages: Stagnant urine leads to urine

precipitates and ultimately blockages (slide 9)

Cost for blocking fluids replacements Oil is thought to take up the smell

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• This is what it looks like when the blue blocking fluid needs replacement

• Urine would still drain through it, but slower than normal (building up some head)

• Eventually, the urine would no longer flow through

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Urine precipitates in outlet section of urinal can lead to blockages

5130 August 2006 in UNESCO-IHE building after approx. 5 months of use

Each urinal has two plastic insert pipes, which are removed to replace the blue blocking liquid (this liquid just drains to the sewer)

Advantages and disadvantages of rubber tube/curtain vs. oil based odour control

systems Advantages:

– Quick and easy to clean

– Does not need frequent and costly replacement of blocking fluid

– Can be inspected without losing blocking fluid

– Much less likely to develop hard blockages Disadvantages:

– May need regular manual cleaning (depending on number of users, e.g. Keramag states once per fortnight; Addicom less frequent)

– Rubber tube may loose elasticity over time and need replacement (e.g. Keramag: once or twice per year, but cost is only € 17)

52I don’t want to discredit the Uridan urinals, but I have to say I quite like our new Keramag Centaurus urinal and find it easier to deal with.

Food for thought

So, how about converting the water-flush urinals at your workplace to waterless urinals?

Would the men be happy with waterless urinals? Which supplier would you chose? Can you get a local supplier? Or make your own?

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Course 1 Unit 3