MIT OpenCourseWare http ocw mit edu 11 479J 1 851J Water and Sanitation Infrastructure in Developing Countries Spring 2007 For information about citing these materials or our Terms of Use visit http ocw mit edu terms Household Water Treatment and Safe Storage Technologies Susan Murcott Week 7 11 479J 1 851J March 20 2007 MIT Master of Engineering Teams in Brazil 1999 2000 For more than a decade during the late 80s and 1990s I worked with Prof Emeritus Donald Harleman on innovative and low cost wastewater treatment for the developing world In 1998 I was an invited guest speaker to the 2nd International Women and Water Conference Kathmandu Nepal I learned about the need for safe and accessible water from these Nepali village women Since 1998 about 20 MIT student teams have done engineering thesis and MBA projects on household drinking water treatment and safe storage HWTS Our Group Put group photo here We call this initiative H2O 1B Clean Water for 1 Billion People Student s work is primarily field based engineering research We have worked with NGOs municipal governments research labs and development organizations We have been leaders and innovators and in a new area of research and development Engineering Design for Developing Countries especially Household Water Treatment and Safe Storage HWTS We have produced a body of material on household water treatment and safe storage Theses group reports term papers PowerPoint presentations videos articles peer reviewed publications and a Web Site http web mit edu watsan Do HWTS Technologies Detract from Ultimate Goal of Universal Piped Water Provision Multiple Barrier Approach A Watershed Systems based Approach to Water Safety Securing the microbial safety of drinking water supplies is based on the use of multiple barriers from catchment to consumer to prevent the contamination of drinking water and to reduce contamination to levels not injurious to health Safety is increased if multiple barriers are in place including protection of water resources proper selection and operation of a series of treatment steps and management of distribution systems piped or otherwise WHO GDWQ 2004 Multiple barriers to protect drinking water are applied in various locations Watershed Source Protection Treatment centralized and decentralized Piped Distribution safe distribution to the public standpipe or home compound Non piped Community and Household Distribution safe transport from the source to the point of use Storage reservoirs community and home storage HWTS Technologies Examples of Household Safe Storage and Water Treatment Processes and Systems I Safe Storage 1 Plastic or modified clay pot safe storage containers II Disinfection 2 Boiling 3 Household chlorination 4 SODIS and UV disinfection III Particle Removal Technologies 5 Cloth Filtration 6 Ceramic Filters Candle Filters Pot Filters 7 Biosand Filters 8 Coagulation Precipitation Only IV Membrane Reverse Osmosis 9 Membrane Reverse Osmosis Ultrafiltration Nanofiltration V Combined Systems 10 Coagulation Precipitation Chlorine Disinfection e g PUR 11 Filtration Disinfection Aesthetics Hindustan Lever Pure it VI Chemical Removal Systems not covered in this presentation CDC Safe Storage Vessel Characteristics Standardized volume 10 30 liters with handles shaped to facilitate transport and use Durable easy to clean material Inlet diameter between 6 and 9 cm Durable spout or spigot allowing a discharge rate of 1 liter per 15 seconds at outlet Instructions for use cleaning container and disinfecting its contents permanently attached to vessel Disinfection Household Chlorination Household Chlorination using locally produced and distributed chlorine solution Safe Water Storage in plastic containers with narrow mouths secure lids and dispensing spigots to prevent recontamination Education Influence hygiene behaviors and increase awareness about the dangers of contaminated water and waterborne disease The Safe Water System Approach Safe Water System Products Pros and Cons of Household Chlorination Safe Water System Approach PROS Applied properly and with a water that is not excessively turbid this provides a safe disinfected water supply Residual chlorine is simply measured Clinically proven Inexpensive CONS Chlorine taste and smell Some customers only use it sporadically like medicine or just for their young children Must wait 30 minutes before drinking treated water Chlorine availability Storage issues Cost about 7 to 10 per family per year Image removed due to copyright restrictions Solar Disinfection SODIS What is SODIS PET plastic bottles exposed to solar radiation for 1 2 days to disinfect drinking water Variations Exposure time Clear black or reflective surface SODIS SODIS was invented by Prof A Acra et al of American University of Beirut Lebanon in 1982 Researchers at the Swiss Federal Institute of Environmental Science and Technology ETH EAWAG SANDEC took up extensive studies of SODIS beginning in 1991 MIT students have investigated SODIS in Nepal and Haiti since 1999 Pros and Cons of Solar Disinfection PROS Scientifically proven Highly effective against a wide range of microbial contaminants PET plastic bottles widely available CONS User acceptance and sustained behavior change Weather dependency Must expose bottles 1 day for safe water Users in hot climates may reject hot water Cost about 1 per family per year Photographs removed due to copyright restrictions UV Lamp Disinfection Filters Cloth Filtration for Guinea Worm or Cholera Removal Pros and Cons of Cloth Filters PROS Effective at removal of guinea worm Simple and readily available CONS Must be kept clean so as not to be a source of other microbial contamination Does not address other possible contaminants of concern Cost 0 10 1 00 Ceramic Filters Ceramic Water Filter Types Disk Candle Filter System Filter Media Element Pot Pros and Cons of Ceramic Filters PROS About 90 99 removal of bacteria Can be constructed of local materials clay sand concrete plastic by local producers and create local jobs CONS Requires regular cleaning once filter becomes clogged Flow rates are slow and may not provide sufficient water quantity Ceramics can break if handled improperly Cost about 5 40 Biosand Filters Biosand Filter Lid Dirty Water In Metal Diffuser Box Water Clean Water Out Fine Sand Coarse Sand Gravel Bacteria Removal Unit Pros and Cons of Biosand Filters PROS About 90 99 removal of bacteria Can be constructed of local materials clay sand concrete
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