Ecosan - sandec

8/11/2019 Ecosan - sandec

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ECOLOGICAL SANITATION(ECOSAN)


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What is EcoSan?

Not a technology but a strategic sanitation

approach.

Comprehensive approach trying to integrate

all aspects of sanitation: human waste, solidwaste, greywater, drainage.

Approach linking sanitation with agriculture.

Approach for both North and South.


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Objective of EcoSan

The objective of EcoSan is not to

promote any particular technology, but

to bring forward a new philosophy of

dealing with what in the past has beenregarded as waste and wastewater.

Move away from a linear to a circularflow of nutrients.


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Criteria for EcoSan systems

affordability

acceptability

return of

nutrients

Environmental

protection

Disease

prevention

simplicity

Ecosan


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Disadvantages of conventional

approach End of pipe technology:

Pipe it first away, thenthink about what comes

next.

High drinking waterconsumption as

transport media.

Discharge of preciousnutrients (N, P, K) in

water bodies, leading to

eutrophication.


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Disadvantages of conventional

approach (cont.) High costs for

construction, operationand maintenance.

Expertise for O&M

required. Combining all kinds of

wastewater and

occasionally stormwater makes removal o

pollutants very difficult.


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Ecosan approach - advantages Barrier against the

spread of diseasescaused by pathogens in

human excreta.

Nutrient recovery (N, P,K) in agriculture.

Eutrophication of water

bodies reduced. Drinking water

consumption reduced.


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EcoSan approach advantages

(cont.) Possibility to produce

energy (biogas).

Lower costs for

construction, operation

and maintenance. Aspects of solid waste

management can be

integrated(comprehensive

approach)


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Working principles

Waste is a resource

Nutrient loops must be closed

(nutrient recycling)

Healthy living conditions must be

promoted

Water consumption must beminimized


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What is really new? The speciality of the

new approach is to view

urine, faeces and

greywater separately as

components with

different characteristicsin term of pathogens,

nutrient content and

benefits to soil andplants.

Waste waste!!!

FaecesGrey-

water

Urine

Waste-water


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Characteristics of the different

components of human waste

47%12%41%30kg/cap*aCSB

0*

54%

50%

87%

500

Urine

107-109

/100ml

104-106

/100ml-

Faecal

coliforms

12%34%1.8kg/cap*aPotassium

40%10%0.75kg/cap*aPhosphorous

10%3%4.5kg/cap*aNutrients

Nitrogen

5025000-

100000

25000-

100000

Volume

[l/cap*a]

FaecesGreywaterTotal


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0*

54%

50%

87%

500

Urine

107-109

/100ml

104-106

/100ml-

Faecal

coliforms




Nitrogen

5025000-

100000

25000-

100000

Volume

[l/cap*a]



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Urine the perfect fertiliser

Contains almost all the nitrogen and big parts of the

potassium and phosphorous excreted by humans. N:P:K = 10:1:2

Nutrients are in ideal forms for uptake by plants: nitrogen i

form of urea, phosphorus in form of superphosphate and

potassium as an ion.

Heavy metal concentrations are much lower than those of

most chemical fertilisers.

Urine is usually sterile (exceptions known by urinary tractinfections). Contamination with pathogens occurs only if

urine is exposed to faeces.

Easily applicable, diluted or not, depending on the crop and

crop stage.


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Microorganisms in urine

Urine is sterile in the bladder.

Freshly excreted urine contains < 10000 bacteria/ml. In some cases urine contains protozoa and viruses, which

are the most persistent.

Faecal contamination constitutes the main risk.

After a storage time of 6 months, urine can be used without

restrictions for fertilising purposes (from a microbiological

point of view).

Higher temperature, lower dilution and low or high pHaccelerate inactivation.

Other possibilities to minimise the risks: personal

protection, appropriate fertilising techniques, choice of

crop.


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0*

54%

50%

87%

500

Urine

107-109

/100ml

104-106

/100ml-

Faecal

coliforms




Nitrogen

5025000-

100000

25000-

100000

Volume

[l/cap*a]



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Faeces soil conditioner

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, tapeworm eggs)

Applied to the soil, processed faeces can:

increase the organic matter content,

improve the water holding capacity, increase the availability of nutrients.

help maintaining a healthy population of beneficial organisms.

Attention! Faeces are hygienically precarious and must be

treated before reused in agriculture!


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Greywater quantitative proble

Greywater = Any water that has been used in the

home, except water from toilets. Hygienically not very precarious.

Big quantities with low nutrient content.

Easily treatable (mostly with soil filters).

Main issues: Fats from kitchen wastewater, soap,

chemicals etc.

Main reuse purpose: irrigation


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Ecosan - How to do?

Dont mix!

Keep the volume of dangerous material small bydiverting the urine and not adding flushing water.

Prevent the disposal of material containing

pathogens by storing it in some kind of securedevice until safe for recycling.

Reduce the volume and weight of pathogenic

material by dehydration and/or decomposition tofacilitate storage, transport and further treatment.

Greywater: water conservation, attention to soaps,

cleansers and other household chemicals.

Fl h 1 d i


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Treatment

Flow scheme 1: dont mix; treat greywater

and faeces

Treatment

Greywater Fac

es

Urine

Reuse


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Flow scheme 2: mix and treat everything

Treatment Treatment

Greywater

Blackwater

Reuse


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Urine diversion yes or no?

Special toilet seats diverturine from faeces.

Urine and faeces are

stored in different

containers or vaults.

Urine and faeces arecollected and treated

together in the toilet

vault.

Greywater is collected

and treated separately.

Principle:

DehydrationAerobic (composting) or

anaerobic (e.g. biogas)

Treatment

process offaeces:

Dont mixMix


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easier to avoid excesshumidity

reduced cross-

contamination

urine as fertiliser, faece

as soil conditioner

no (or small) odour

problemsDifferent and

appropriate treatment of

faeces and urine

no special design of theseat-riser required

cultural acceptance

higher

toilet seat and squatting

pan usually cheaper

Advantages:

Dont mixMix


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special toilet seat orsquatting pan, usually

more expensive

2 different fractions to

deal with (urine and

faeces)

liquids arecontaminated with

pathogens and must be

treated before reused as

fertilizer

loss of sterile fertiliser

(urine)

often odour problemstreatment of faecal

sludge more problematic

Drawbacks:

Dont mixMix


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Urine separation toilet how

does it work?

Seat riser orsquatting pan are

constructed in such

a way that urine isseparated before

any contact with

faeces occurs.

[Esrey et al, 1998]


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Diverting toilets exampleDouble-vault

dehydrating toilet

squatting slab with urine

diversion

pot for collecting urine one drop hole not in use is

closed (with mortar or stone)

bucket with ash to support

the dehydration process inthe processing chambers

Dehydrating toilet, Vietnam (Montagero,1999)


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Diverting toilets exampleDouble-vault

dehydrating toilet

2 processing chambers, only

one in use

When one chamber is full(approx. after 6 months

design criteria!), it is closed

and the second one opened

The faeces in the closedchamber are treated by

dehydration

The chambers are

completely above ground

[Esrey et al, 1998]


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2

Diverting toilets example

The processed material is

taken out of the vault after 6

months and is safe to handle

Double-vault

dehydrating toilet

[Strauss, 1987]


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Diverting toilets example

The processed material is

taken out of the vault after 6

months and is safe to handle

The material looks and

smells like mulch and can be

reused as soil conditioner in

agriculture Urine is collected in a jerry

can or a bucket and

periodically brought to the

fields or to the garden

Double-vault

dehydrating toilet

[Strauss, 1987]


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Design criteria urine diversionSeat or squatting

pan?

Mostly depending on cultural

settings!

China, Uganda, Vietnam :

squatting pans

Squatting pan in Uganda

[Schattauer, 2000]


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pan?


settings!

China, Uganda, Vietnam :

squatting pans

Squatting pan in China

[Anderson, 2001]


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pan?


settings!

Mexico, Guatemala,

Zimbabwe, Europe ...: seat

riser

Seat riser in Simbabwe

[Andersson, 2001]


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Design criteria urine diversion

Processing chambers

Always 2 chambers

Above ground level, sealed

Access to the chambers should be possible from

outside the house

Volume according to accumulation rate and numberof users;

guide value:

100 l/user and chamber

(there is only a small volume reduction due to

addition of ash and anaerobic process)


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Processing chambers (cont.)

Retention time: 6 to 12 months

Why so long? Required retention time is based onthe inactivation of pathogens in the faeces. The goal

is to have a safe material to handle with.

Critical factor are especially the Ascaris eggs, with avery high resistance and a very slow inactivation.

Inactivation of Ascaris eggs (experiments done in

China in 2000):30 days 3.5% 120 days 94%

60 days 50% 180 days 98.5%

90 days 90% 360 days 99.9%


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Processing chambers (cont.)

Inactivation rate of pathogens depends on:

pH: high pH high inactivation

A pH higher than 9 is detrimental to all microbial growth.

Measure: Addition of ash

Moisture: low moisture high inactivation

Moisture


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Aeration: Make sure

the chambers aresufficiently aerated!

vent pipe

window

Other criteria

[Chinese Academy of PreventiveMedicine, 2000]


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Urine pipe:

blockages mayoccur due to

precipitation in the

pipe

cheap plastic pipe not too long

Other criteria

[Andersson, 2001]


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Other criteria

Urine tank: odour

problems couldoccur, transport

must be easy

closed jerry cans

not too big[Chinese Academy of PreventiveMedicine, 2000]


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O&M of urine diversion toilets

Addition of ash: to increase pH and to reduce

moisture cover the fresh faeces with same amoun

of ash

In addition: lime, sawdust, husks, dry soil,...

Toilet paper separation: Toilet paper will not

disintegrate in the chamber (only dehydration

process) separate collection in a bucket

Attention! Men have to sit when urinating!

If the toilets are well operated and maintained, no

odour problems will occur since odours arise from

moisture and the contact between urine and faeces.


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Urine how to apply?

Urine is usually sterile, but if possible:

store it as long as possible (inactivation ofpathogens)

dilution or not for application: not clear yet, but

diluted is safer application: best time just before planting, mixed int

the soil (otherwise ammonium would transform to

ammonia and evaporate) some plants prefer ammonia, some prefer nitrate; 2

weeks after application, all ammonia has normally

been transformed to nitrate.

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