Agua, saneamiento y salud (ASS)

Manejo del agua en la vivienda: beneficios acelerados para la salud derivados del abastecimiento de agua mejorado


Chemical methods of water treatment (inglés)


Coagulant Community/Household Use Advantages Disadvantages Cost* Comments
Alum (aluminum sulfate, etc.), alum potash Yes/rare-moderate Community use common; simple technology Difficult to optimize without training and equipment Moderate? Proper use requires skill
Iron salts (ferric chloride or sulfate) Yes/rare Same as Alum Same as Alum Moderate? Proper use requires skill
Lime (Ca(OH2)), lime+soda ash (Na2CO3), caustic soda (NaOH) Yes/rare-moderate Same as Alum Same as Alum; pH control and neutralization a problem; hazardous chemicals Moderate to high? Softeners; not applicable to many waters
Soluble synthetic organic polymers Yes/no-rare Improve coagulation with alum and iron salts Same as Alum; hard to dose; need training & equipment; hazardous chemicals High Use with other coagulants; limited availability
Natural polymers (carbohydrates) from seeds, nuts, beans, etc. Rare/Yes
(in some developing countries) Effective, available and culturally accepted in some places Source plant required; training and skill required; cultural acceptability; may be toxic Low Traditional use based on historical practices

Adsorbent Community/Household Use Advantages Disadvantages Cost* Comments
Clays Rare/rare-moderate Some efficiently adsorb microbes; adaptable to many treatment formats Some adsorb microbes poorly; availability limited Low to moderate Use as an adsorbent or coagulant
Charcoal (C), Activated Carbon (AC) Moderate/Moderate; (AC more in developed world; C more in developing world) Adaptable to many treatment formats; charcoal often readily available Poor microbe adsorption; can degrade microbial quality Moderate (C ) to high (AC) Used as adsorbents or coagulants; use varies regionally; C use based on traditional practice
Crushed organic matter: seeds, rice, etc. No-very rare/Rare-moderate in some countries Ditto charcoal and carbon Poor microbe adsorption; can degrade microbial quality Low Used as adsorbent or coagulant

Exchange Resin Community/Household Use Advantages- Disadvantages Cost* Comments
Softening resins Yes/Yes Easy to use Do not inactivate microbes; spent resin replacement and disposal required; unavailable in some parts of the world High Lack of microbial reduction makes them unsuitable for microbial reductions in household water treatment
Deionizing Resins Yes/Yes Inactivate microbes; easy to use Not recommended for drinking water; spent resin replacement and disposal required; unavailable in some parts of the world High The effects on long-term consumption of deionised water on health are not fully understood.
Iodine Disinfection (tri-iodide and penta-iodide) No/Yes Inactivates microbes; easy to use Risk of soluble iodine leaching into water; spent resin replacement and disposal required; unavailable in some parts of the world High Difficult to determine useable life without added technology; impractical and limited availability in developing world
Adsorbent and scavenging resins No/Yes Easy to use Not likely to inactivate microbes; microbial colonization and release a concern; not available in some parts of the world High Difficult to determine useable life without added technology; impractical and limited availability in many parts of the world

Disinfectant Community/Household Use Advantages Disadvantages Cost* Comments
Free chlorine (NaOCl, Ca(OCl)2 Yes/Yes (worldwide, but not in some regions) Easy to use; effective against most pathogens; stable residual Not available worldwide; some users object to taste and odor Low The most widely used drinking water disinfectant; proven technology
Electro-chemically generated oxidant from NaCl Yes/Yes (limited distribution) Easy to use; effective against most pathogens; stable residual Not available worldwide; some users object to taste and odor (mostly chlorine) Low Practical for worldwide use; can generate on site by electrolysis of NaCl; proven technology
Chloramines (monochloramine) Yes/Rare (less widely used than free chlorine; must react free chlorine with ammonia Stable residual Less effective microbiocide than free chlorine; requires skill and equipment to generate on-site; household use impractical Moderate More difficult to use than free chlorine; potentially available where free chlorine is used but requires ammonia source
Ozone Yes/Rare(less widely than free chlorine; mostly in Europe) Highly micro-biocidal; No residual; Generate onsite; hard to use; need special facilities and trained personnel; hazardous High Not practical for household use in many regions and countries
Chlorine Dioxide Yes/Rare (much less use than free chlorine; for individual use by acidifying chlorite or chlorate) Highly micro-biocidal; Poor residual; generate on-site; some technologies require special facilities, trained personnel and are hazardous; toxicologic concerns High Can be generated on-site by reacting chlorate or chlorite salts with acids; reactants may not be available and some are hazardous
Acids (especially lime juice and mineral acids) and hydroxide (caustic) Limited/Limited (in community systems mineral acid and base for pH control; lime (CaO) and soda ash for chemical softening; in household Treatment lime juice for inactivation of V. cholerae Acids inactivate V. cholerae & some other bacteria; limes and chemicals widely available Limited microbiocidal activity; CaO use requires special facilities and trained personnel and is hazardous; CaO process difficult to control High for CaO; low-moderate for lime juice Lime juice has been reported to be effective for cholera control at the household level; Chemical acids and lime precipitation not practical for household use
Combined chlorina-tion, coag-ulation-flocculation-filtration systems Yes/Yes As sequential processes in community systems and as combined processes in household systems Highly effective for microbe reductions Availability now limited; requires some training and skill; efficacy varies with water quality; High Limited availability and higher cost (compared to chlorine) are barriers to household use in some countries and regions
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