January 2008 Updates Changed formatting to be consistent with other PowerPoint presentations. Added Slide 3 – Presentation Outline. Added Slides 4 and 5 – Multi-barrier approach Added Slide 7 – Sedimentation introduction Slide 9 – changed picture of ceramic candle filter Added Slide 15 – Disinfection introduction Changed disadvantages to limitations on all slides

Household Water Treatment

Presentation Outline Multi-barrier approach Three steps to water treatment Sedimentation options Filtration options Disinfection options Criteria for evaluation HWT advantages and limitations

Multi-Barrier Approach Best way to reduce the health risk of drinking unsafe water. Putting multiple barriers in place can help to protect our health through improved water quality. Step 1 – Protecting your water source Step 2 – Sedimentation Step 3 – Filtration Step 4 – Disinfection Step 5 – Safely storing your water after treatment

Improved Water Quality

The 3-Step Approach for Water Treatment HWT and community systems use the same water treatment process. The 3-Step Approach Filtration Sedimentation Disinfection

Sedimentation First step to reduce turbidity of water before filtration Different methods include: –Settling –Three pot settling –Coagulants

Sedimentation: Settling Key Features Partially removes turbidity Advantages Low cost other than container Simple, easy, and affordable Limitations Time required is variable, depending on initial and desired water quality Time intensive

Sedimentation: 3 Pot Settling Key Features Water settles for up to 24 hours Advantages Simple, easy to do Limitations Time consuming Labor intensive

Sedimentation: Coagulation Key Features Accelerate the settling of suspended particles. Examples include alum, iron salts, and natural plants such as moringa seeds and cactus Advantages Natural coagulants would be free Simple and easy Used in many parts of the world Limitations Costs are variable depending on coagulant Moringa Seeds Cactus

Filtration Filtration may include one of the following technologies: –Biosand filter* –Kanchan filter* –Ceramic pot filters –Ceramic candle filters –Straining * The Biosand filter and Kanchan filter will be discussed elsewhere in the workshop.

Filtration: Ceramic Pot Filter Key Features Small pores in the ceramic trap contaminants Collodial silver is often added Advantages Removes bacteria, protozoa, helminths and turbidity Effectiveness: 99 to 100% removal of fecal coliform indicators Limitations Some removal of turbidity and iron The flow rate is litres per hour, approx litres of water per day Breakable Turbid water may plug the filter

Filtration: Ceramic Candle Filter Key Features Includes one or more buckets with lids and a spigot Quality control during manufacturing required Advantages Removes bacteria, protozoa, helminths, and turbidity Easy to use and users like the taste Limitations $2-10 US for filter, $7-20 US for system litres per hour, up to approximately 18 litres of water per day Breakable: filter must be replaced every year or two Turbid water may plug the filter Source: Kisii Water Filter

Filtration: Straining Key Features Typically used with a sari cloth Can reduce risk of cholera if the bacteria is attached to large particles or copepods in the water Advantages Low cost if extra saris are available Simple and easy Limitations Requires extra washing of sari after use

Disinfection Final step to remove, deactivate or kill any remaining pathogens Various methods include: –Chemical disinfection –Boiling –Solar disinfection (SODIS) –Pasteurization –Ultraviolet (UV) disinfection Distillation

Disinfection: Chlorine Key Features Destroys the cells of microbiological contaminants Kills bacteria and viruses effectively Advantages Inexpensive: $ 0.40 to 0.80 US per family per month Easy to use at a household level Limitations Not effective at removing protozoa or turbidity Expiration and transportation Requires clear water to be most effective Can take time for user to get used to taste Requires that users purchase chlorine continuously

Disinfection: Aquatabs Key Features Sodium dichloroiscyanurate (NaDCC) tablets Advantages Pharmaceutical standards Unit of purchase (10 tablets for 10 days) more compatible with low- income populations Simpler to use. Easier to transport Product expiry is 5 years (liquid chlorine is one year). Limitations Continuous purchase Available in select countries One standard dose of chlorine Sometimes too much chlorine taste Sometimes too little chlorine – not enough disinfection

Disinfection: PuR Key Features Proctor & Gamble product Disinfectant powder Advantages Coagulant and disinfectant Some removal of microbial, chemical, and physical contaminants Current price of about $US 0.01 per litre of treated water Limitations Requires 20 minute wait time Requires outside supply Education: product demonstration to encourage consumer habit change

Disinfection: Boiling Key Features Kills all microbiological contaminants Recommended time: first bubbling point Advantages Simple and widely accepted Locally available Limitations High costs for fuel Contributes to indoor air pollution and respiratory illness Contributes to environmental degradation such as deforestation

Disinfection: SODIS Key Features Uses solar radiation and temperature Advantages Kills most microbiological contaminants Uses local resources and renewable energy Ideal to treat small quantities of water Costs are minimal, only plastic bottles which can be reused Limitations Does not remove chemical contaminants or turbidity Does not change the taste or odor of the water Requires relatively clear water Requires suitable weather conditions Requires time to move the bottles every day

Disinfection: Pasteurization Key Features Achieves same effect as boiling but at a lower temperature (70-75°C) over longer time Use of a solar box cooker Advantages Kills over 99% bacteria, viruses, helminths, and protozoa Can treat up to 1 litre per hour Limitations Cost is variable, from $0 - $25 US, depending on energy source and unit Requires a temperature indicate (thermometer or indicator) Weather dependant Does not remove chemical contaminants or turbidity

Chulli Pasteurization

Chulli Pasteurization Key Features Uses wasted heat generated in traditional clay ovens (chullis) An aluminium coil is built into the clay chulli, and water is passed through the coil during normal cooking events By adjusting the flow rate, temperature can be kept at approximately 70°C Advantages Water pasteurization at no extra fuel cost Simple to set and operate High quantity of safe water produced All components locally available Principle applicable to other large waste heat generators such as rice mills, brick kilns, etc. Limitations Fairly new technology, more research required

Disinfection: Ultraviolet Key Features Disables DNA of the microorganisms, die and unable to replicate Small scale, energy-efficient, low- maintenance UV water disinfection Advantages Effective kills all pathogens Fast, though variable depending on system (about 5 litres per minute) Limitations No chemical or physical contaminant removal Initial costs: $60-$150 US Operating costs: $10-25 US per year for bulb replacement Requires electricity No effect on taste or odor

Distillation Key Features Evaporates and condenses the salt water for purification Advantages Effective in removing biological, chemical, and physical contaminants (including salts) No operating costs Limitations Units must be replaced every 3-5 years Low flow rate: Each unit produces 1- 2 litres per day Requires sunlight to evaporate the water Not widely used because of high costs and low flow rate

Criteria for Evaluation 1.Quality of water treated 2.Quantity of water treated 3.Robustness of design 4.Local materials and maintenance 5.Obvious importance to users 6. Local demand for technology 7. Opportunity for community participation 8. Ease of technology transfer 9. Economical sustainability 10. Opportunity for financing

HWT Comparison

HWT Advantages and Limitations Advantages Only choice other than treated water Less expensive Quicker to implement More appropriate for treating smaller quantities of water Entry point for sanitation and hygiene education Cost-effective Limitations The need for operation and maintenance knowledge The need to motivate the end users to ensure that maintenance is being done correctly