*Household and neibourghood Sanitation Infrastructures: Excreta, wastewater disposal in developing countriesDoulaye Kon Eawag/Sandec

*Objectives of a sanitation systems

What are we talking about? Wastewater sources and their characteristicsPathways of domestic wastewaterHousehold sanitation management infrastructuresRealistic holistic sanitation systemsStructure of the presentation

*Tasks of sanitation systemsPrevent disease guarantee effective barriers against sanitation related diseasesProtect the environment prevent pollution, return nutrients to the soil, and conserve water. Be simple - operation of the system must be feasible using locally available resources (human and material). Where technical skills are limited, simple technologies should be preferred.Be affordable total costs (incl. capital, operation, maintenance costs) must be within the users ability to pay.Be culturally acceptable it should fit local customs, beliefs, and desires.Work for everyone it should address the needs of children and adults, of women and men.

*Blackwatertoilet wastewater(faeces and urine with or without flushing water)What are we talking about?Greywaterdomestic wastewater form kitchen, bath, shower (excluding faeces and urine)Brownwater Blackwater without urineYellowwater UrineFaecal sludge Sludge accumulating in "on-site sanitation systems" (Latrines, Septic tanks, etc.)

*sewered sanitation(black and greywater)Septic tanksWastewater treatment plant (WWTP)on-site sanitation(excreta, black and greywater)FS treatmentPlant (FSTP) SeptageEffluent to soakageor drainsLiquid to dischargeinto receiving waters or to co-treatment in WWTPEffluent to agricultural use or discharged into receiving waters~ 2 billion (2004)~ 3 billion (2025)Small-bore sewerage for effluent of interceptor or septic tanksEawag / Sandec 2004The human waste system

*Characteristics of the different wastewater sources* healthy people** can be as high as 50%, depending on washing and dish-washing powder used

TotalGreywaterUrineFaecesVolume [l/cap*a]25000 -10000025000-10000050050NutrientsNitrogen2-4 kg/cap*a5%85%10%Phosphorous0.3-0.8 kg/cap*a10%**60%30%Potassium1-4-2.0 kg/cap*a34%54%12%COD30kg/cap*a41%12%47%Faecal coliforms-104-106 /100ml0*107-109 /100ml

*regulations and standards (including enforcement)costs for construction, O&Mwillingness to pay (initial and monthly payments)self-help potential and initiative of local people and organizationslocal entrepreneurs, consultants, construction companies, ...Existing system!Economic, institutional and other aspectsCriteria influencing the selection of sanitation systems

*Classification of Excreta and wastewater management technologies

*Partially sewered citiesBusiness centre of large cities with high water consumption rateLack of treatment sites and wastewater treatment plantsDischarge of wastewater into natural water bodies and open canals

*Cities without sewersRepresent more than 90% of cities in developing countriesAre very heterogeneous in urban infrastructureOften lack financial and human resources for sanitation development and upgrading

*Decentralised sanitation systems are often more suitable why?Existing systems are decentralised (e.g. latrines)Treatment and reuse can be tailored to the specific waste stream (e.g. urine, faeces, greywater etc.)Decentralised systems are easier to plan and implement (different independent areas with specific needs and characteristics)Capital investments are generally less than for centralised systems (reduced investments for trunk sewers and pumping stations, lower O&M costs)Capacity expansion and thus capital requirements can track demand much more closely (incremental approach)No reason to impose a one size fits all approachDifferent strategies can be employed in various parts of the service area.

*sewered sanitation(black and greywater)Septic tanksWastewater treatment plant (WWTP)on-site sanitation(excreta, black and greywater)FS treatmentPlant (FSTP) SeptageEffluent to soakageor drainsLiquid to dischargeinto receiving waters or to co-treatment in WWTPEffluent to agricultural use or discharged into receiving waters~ 2 billion (2004)~ 3 billion (2025)Small-bore sewerage for effluent of interceptor or septic tanksEawag / Sandec 2004The human waste system

*Simple pit latrine2 m or more in depth covered by latrine slabwith or without superstructurepercolation of liquids into soilpartial anaerobic decomposition of solids

+cheap, easily understood

-unstable soils ( lining)-not good with high water table- hazardous and difficult emptying (depth > 2 m)- odor problems, fly breathingOn-site dry systems

*On-site dry systems

*VIP latrine (ventilated improved pit latrine)Naturally induced ventilation with screened ventilation piperemoves odor prevents escape of flies

+bad smell and flies reduced-difficult to construct properly- more expensive than simple pit latrine

On-site dry systems

*Groundwater contamination

If contamination potential is high --> raised pits or vaults completely over ground> 2m above highest groundwater levelless --> at least 20 m to next well. But: main risk of contamination is via dug wellOn-site dry systems

*Double pit systems and raised pit (vault) systemsPermanent pitsFilling - consolidation -emptyingdehydration and hygienisation --> reusecan be an option with urine separation

+ treatment included+more hygienic emptying

-O&M more complicated-/+ costs

On-site dry systems

*Pour flush pitsFlushing of excreta with 2-3 litersPermanent pits or vaultsCan be combined with double vaults

+ reduced smell problem with water seal - water must be availableOn-site systems

*SiteDistance and position relative to housing: depending on cultural habitsat least 20 m from surface water sourceseasily accessible for all users (children, women, old people, disabled)

Construction materialslocal availabilitystable and durableesthetic considerations

Superstructure designdepending on cultural habits (open or closed)protect from rain, stormwater runoff, ...superstructure = important factor influencing the use (essential that users are involved in design)Designing latrines

*Designing latrines

*Slabsconcrete, wood, fero-cement or plastic (local manufacturers?)keyhole shape most suitablesquat hole covers (not for VIP)

Ventilation pipes15-20 cm diameterlength of VIP pipe = 0.5m higher than superstructureorientation

Pit excavation and liningtop 0.5 m usually lined (pre-cast concrete, bricks, cement blocks, etc.)

No movable parts!

Designing latrines (cont.)

*Designing latrines (cont.)Round pits are more suitable to distribute evenly earth pressure (natural arching effect)Hand-washing facilities must be provided!

*Pit sizing

V: pit Volume (m3) N: no. of usersS: sludge accumulation rate (litres/cap year)D: design life (years) 2-3 years for single pits (where emptying required)1-2 years for double pits0.5 -1 year for double pits with urine separation

F: Infiltration area (m2); (water depth = F / pit circumference)W: Amount of water used for flushing (liters/cap day)I:Infiltration rates (liters/m2 day)Sand 40Sandy loam25Silt loam20Clay loam8Clayunsuitable

Designing latrines (cont.)V = N x S x D / 1000and F = N x W / I

*Sludge accumulation ratesDesigning latrines (cont.)In emergency situations (rapid accumulation) these rates have to be multiplied by 150-200%

Wastes deposited and conditions

Sludge accumulation rate "S"

(litres per capita per year)

Wastes retained in water where degradable anal cleaning materials are used

40

Wastes retained in water where non-degradable anal cleaning materials are used

60

Wastes retained in dry conditions where degradable anal cleaning materials are used

60

Wastes retained in dry conditions where non-degradable anal cleaning materials are used

90

*

*Faeces and urine are separated before they come into contactUrine is collected in tanks and is reused as liquid fertilizerFaeces are dehydrated in the chambers and used as soil conditioner

+ reduced stench problems+ easier handling of dried material+ reduced chamber volume+ no waste, but fertilizer- special squatting pan- 2 separate fractionsUrine diversion latrines

*2 chambers, 0.5-1 m3 each2 doors, access normally from outside1 urine pipe with jerry can, normally outsideSquatting pan with coverUrine diversion latrines

*Urine diversion latrinesOperation:Addition of ash: to increase pH and to reduce moisture In addition: lime, sawdust, dry soil,...Toilet paper separation: Toilet paper will not decompose in the chamber (only dehydration process) separate collection in a bucket.If the toilets are well operated and maintained, no smell problems will occur.Vent pipe and window ensure a sufficient aeration

*Urine diversion latrinesAlways 2 chambersAbove ground level, sealedAccess to the chambers should be possible from outside the houseVolume according to accumulation rate and number of users;

guide value: 100-150 l/year/user and chamberProcessing chambers:

*Emptying urine divertion toilet

*most frequent on-site treatment unit worldwidesedimentation tank settled sludge partially stabilised by anaerobic digestion1-3 compartments Almost no removal of dissolved and suspended matterSeptic tankHousehold / neighbourhood treatment systems+ simple, little space required (underground)+ high institutional acceptance- low treatment efficiency (COD removal approx. 50%)- O&M often neglected (desludging) or unkown!! look for national design standards!

*V=V1 + V2 + V3V3: scum layerF: surface of the tankh: height of the scum layerV3=F*hh=20-30cmV1 and V3 can also be estimated based on existing figures:Septic tank design

*Improved septic tank2 to 3 chambers in series (up to 5) Intensive contact between resident sludge and fresh influentTreatment efficiency: 65 to 90% COD removalHRT = 2-3 days

+simple, high treatment efficiency, hardly any blockages+high removal efficiencies, also for suspended and dissolved solids-construction and maintenance more complicated than conventional septic tankAnaerobic baffled reactor (baffled septic tank)Household / neighbourhood treatment systems

*Septic systems

*Anaerobic filterUsed for pre-settled domestic wastewater with low SS concentrations (e.g. greywater)

Principle: close contact of wastewater with active bacterial mass on filter media

filter material surface: 90 to 300m2 per m3 Treatment efficiency: 70 to 90% COD removalVolume: 0.5-1.0 m3/cap for domestic wastewater

+ simple and durable if well constructed and wastewater properly pre-treated; high treatment efficiency; little space requirements - high construction costs (filter media); blockage of filter possible - maintenance costly and difficultHousehold / neighbourhood treatment systems

*2-2.5 billion urban dwellers on on-site sanitation !Number and share growing !Faecal sludge underestimated problem

Chart2

65

78

98

85

85

50

Percent on-site sanitation

Percent of population served byon-site sanitation

Sheet1

LocationPercent on-site sanitation

Bangkok65

Manila78

Philippines98

Ghana85

Tanzania85

Latin America50

Sheet1

0

0

0

0

0

0

Percent on-site sanitation

Sheet2

Sheet3

*Types of faecal sludge

***The first question of course is:

Why do we need any sanitation facility, be it a latrine, a flush toilet, a septic tank or whatever?What conditions must be fulfilled by any sanitation system?

Sanitation system must...*Domestic wastewater consists of different fractions, with very specific characteristics

*Main differences are in terms of quantities, nutrient content, and level of pathogenic contamination:

Urine:Contains almost all the nitrogen and large parts of the potassium and phosphorous excreted by humans.N:P:K = 10:1:2Urine is usually sterile (exceptions known by urinary tract infections). Contamination with pathogens occurs only if urine is exposed to faeces.Easily applicable, diluted or not, depending on the crop and crop stage.

Faeces:Mainly undigested organic matter made up of carbon.Faeces contain almost all pathogens:bacteria (e.g. faecal coliforms, vibro cholerae)viruses (e.g. rota virus)protozoa (e.g. amoeba hystolitica)helminths (e.g. Ascaris eggs)

Low nutrient content, but good characteristics as soil conditioner:increase the organic matter content,improve the water holding capacity.

Greywater: Greywater is defined as household wastewater without input of human excreta It includes used water from baths, showers, hand basins, washing machines, dishwashers, laundries and kitchen sinksBig quantities with relatively low nutrient contents.Big reuse potential:Irrigation: Agriculture, landscape, aquacultureMunicipal uses: Fire protection, street cleaning, car washing, cooling, road construction operation, ...Non-potable domestic uses: Toilet flushing, laundry, floor cleaningMain issue: Toxic substances (organic compounds, metals, chlorine etc.), fats from kitchen, can affect natural treatment and disposal systems source control very important component of greywater management system

*....

Of course there are many more aspects!comprehensive list doesnt existstrongly depends on local settings

list of criteria has to be developed on-spot, in close collaboration with local people,organisations and institutions

*That means that we have a whole series of sanitation concepts (all with certain strengths and limitations) which require a whole series of technological modules.

Decentralised and centralised options

In DC, also in urban areas, most common systems are decentralised systems. Of course historically grown, but as explained by Roland yesterday, decentralised sanitation not only because centralised systems not affordable, has its advantages:*Lets come back to normal situations in urban and peri-urban areas.

Quite theoretical material, cannot go too much into detail, many source books.Interesting would be to hear from you: expertise, experiences etc.***Alternative to single pit: double pit

**Now look closer to design of latrines, if interesting for you.****Volume depends on number of usersdesign life/emptying frequencysludge accumulation role of pit as infiltration pit (e.g. greywater disposal)

If infiltration required: provide infiltration area at the top, in order to guarantee that when full still infiltration possible*S depends on biodegradability of anal cleaning material (paper, stones, leaves, corncob, water)environment in which material is stored (moisture content)**Now to a very specific case of dry sanitation: UDVery in at the momentMany projects in China, Africa (South Africa, Uganda, Kenia, ...), Latin America (Mexico, Guatemala)Mainly in peri-urban areas, where urban agriculture still dominant role********