Appropriate technologies for drinking w ater supply in developing - - PowerPoint PPT Presentation

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Appropriate technologies for drinking w ater supply in developing - - PowerPoint PPT Presentation

Dec 02, 2023 29 likes •766 views

Appropriate technologies for drinking w ater supply in developing countries. Caetano C. Dorea Look what 22000 litres of water has done for me! Infectious diseases Caused by: Bacteria; Viruses; Protozoa.

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“Appropriate technologies” for drinking w ater supply in developing countries.

Caetano C. Dorea

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Look what 22000 litres

  • f water has

done for me!

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Infectious diseases

Caused by:

  • Bacteria;
  • Viruses;
  • Protozoa.
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Water-related disease

  • Related to w ater or impurities in the

w ater;

  • Person to person;
  • Animal to person;
  • Does not include illnesses caused by

chemical contaminants.

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Faecal-oral route

“Hardw are”:

  • Water supply;
  • Sanitation;
  • Drainage.

“Softw are”:

  • Hygiene promotion.
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Faecal pollution

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Water-borne diseases

  • Transmission: through ingestion
  • f contaminated w ater;
  • Improvement of supplied w ater

quality;

  • Prevention of the use of

contaminated or unprotected sources.

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Water-w ashed diseases

  • Transmission: depends on w ater

availability and quantity;

  • Personal and domestic hygiene;
  • Increase in w ater coverage,

quantity and continuity.

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Water-w ashed diseases

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Water quality

Best w e can achieve?

  • Industrialised

countries;

  • “High tech”

approach;

  • Precautionary

principle (chronic risks). Worst w e can tolerate?

  • Developing countries;
  • Appropriate

technologies;

  • Acute risks (e.g. w ater-

related disease).

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Appropriate technologies

  • …techniques that can be

implemented/operated by the beneficiary community;

  • Closely tied to “sustainability” or

“maintainability”;

  • Depends on:

– Available skills and resources; – Cultural and environmental settings.

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Developing countries

  • Humanitarian emergencies (Asian

Tsunami, Pakistan Earthquake);

  • Development (Rw anda);
  • Collaborations w ith Oxfam and
  • Univ. of Surrey.
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Development

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Service indicators:

  • 1. Coverage (maximum number of people);
  • 2. Quantity (varies w ith climate and

cultures: 20 to 120 L/head/day);

  • 3. Continuity (days/year and hours/day);
  • 4. Quality;
  • 5. Cost.
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Rw anda

  • 1994 genocide:
  • 800000 victims
  • 100 days of

massacre

  • Mass exodus
  • Mass return in 1996
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Case study: Rw anda

  • Nyabw ishongw ezi
  • 18000 people
  • Water????
  • Iron in groundw ater
  • Little yield from w ells
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Umuvumba River

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  • Reduce particulate loadings to slow sand

filters;

  • Together w ith SSF form multi-stage

filtration systems.

Multi-stage filtration

Up-flow gravel filters in series Slow sand filter

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Improvement: not ideal, but much better!

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Problems though!

  • Low usage →

low income from tarriffs;

  • No community ow nership →

no previous community;

  • High costs of pumping diesel;
  • By 2004 WTP stopped w orking.
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Not as bad as...

Ntoma

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Continuous flow sedimentation basin (w hen operated properly)

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(w hen not operated properly)

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Abandoned pre-filters Unused slow sand filters

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Emergencies

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Microbiological safety: no pathogens

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Water must look and taste nice…

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Queuing time less than 15 min

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Less than 3 min to fill a 20 L vessel

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Maximum distance 500 m

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Or else…

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Quantity vs. Quality?

  • Most diseases due to inadequate

amounts of w ater for hygiene;

  • Priority for sufficient quantities;
  • Large amounts of good quality w ater is

better than…

  • Small amounts of excellent quality

w ater.

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Emergency phases

Immediate (1 st w eeks) Late emergency (1 to 6 months) Post-emergency (> 6 months or years)

1 to 5 L/p/d Survival (drinking and cooking) 10 to 20 L/p/d Stabilisation (Other needs: bathing, laundry, livestock) > 20 to 25 L/p/d Relative stability (search for more durable/sustainable w ater supplies)

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Sanitation Water treatment and supply Hygiene promotion

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The Asian tsunami…

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Oxfam Field Upflow Clarifier Kit

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Outlet Fabric polishing filter

Floc Blanket

Inlet Water level

Flocculator

Drainage

Yield = 10 m 3/h

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FUC run no. 3 - 9640 L/h; alum dose = 40 mg/L

0.1 1 10 100 1000 1 2 3 4 5 6 7

Run time (h) Turbidity (NTU) Raw water Treated water

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Simplified field jar-test.

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Service indicators:

  • 1. Coverage (maximum number of people);
  • 2. Quantity (varies w ith climate and

cultures: 20 to 120 L/head/day);

  • 3. Continuity (days/year and hours/day);
  • 4. Quality;
  • 5. Cost.
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Sustainability/maintainability:

  • Efficient and reliable service at

desired level;

  • Financially and technically feasible

to maintain;

  • Can be used efficiently w ithout

negative effects on the environment.

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Conclusions

  • By-the-book designs only w ork if they are run by-

the-book (skills and resources);

  • Adequate design is needed to maximise donor

funding and public health impact;

  • More advanced processes (e.g. coagulation) can

be “suitable” or “appropriate” in certain circumstances;

  • Main bottleneck is know ledge transfer!
  • Tarrifation (maintenance) must also be

considered.

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So, w hat’s the w ay forw ard?

  • 1. I don’t know … still w orking on it!
  • 2. Community involvement!
  • 3. Capacity building – “softw are”;
  • 4. Current trend: decentralised household

treatment approach;

  • 5. Must consider improvement to livelihoods… not

just health.

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Thanks!!! Any questions???