charcoal water filter for western africa by bryce kuhn adam delauder tim haggerty and andrew osheka n.
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Motivation

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  1. Charcoal Water Filter for Western AfricaBy Bryce Kuhn, Adam Delauder, Tim Haggerty, and Andrew Osheka Evaluation and Function of Charcoal Filter Design How to use bleach to kill bacteria and not have high retention times: High retention times are eliminated by high bleach concentrations. To prevent bleach levels from getting too high, we must remove excess hypochlorite from solution through a process called adsorption. This is used by the popular Brita®filter. Unfortunately, our target population does not have access to activated charcoal. They do have access to regular charcoal this is not as porous as activated charcoal, but it still has plenty of active sites where hypochlorite can adsorb out of solution. Assuming the conditions of the Langmuir isotherm and that hypochlorite is the only species adsorbing to the surface of the charcoal, we calculated the life span of a 10 lb. charcoal filter to average 53 daysbefore all the site are completely adsorbed. However, in reality, the design of the filter has to take into account the fact that the charcoal is going to be replaced a lot more frequently. Ideal filter design: Our group’s ideal filter design consists of a 3-stage system. The bleach is mixed before the contaminated water enters the filter. As seen to the right, the first stage contains small pebbles and rocks to sift out the large particles in the contaminated water. The second stage is composed of small-granulated sand that will separate out the smallest contaminants. Finally, the third stage is composed of the ground charcoal that will adsorb any excess hypochlorite and other contaminants present in the water. These three stages offer the best separation of particles from the water, the best neutralization of bacteria from the water, and the best extraction of hypochlorite from the water before it canbe consumed. Dirty water Motivation Every day over 4,000 children are dying of water-related diseases such as cholera and typhoid that are easily preventable. Many more are suffering sickness, diarrhea and acute stomach pains – illnesses that stop children going to school and growing up into healthy adults. The World Health Organization found that 1.1 billion people worldwide do not have access to clean water. Our group’s mission was to develop a water-filtration system that would consistently provide clean water to residents of Midwestern Africa, one of the hardest-hit regions suffering from inadequate sanitary water access. After a semester of research, our team has developed a cost-effective, durable, and practical water treatment system for any water supply. Our device employs a three-stage filtration system usingcommon household bleach, sand, and charcoalto purify water using cheap, readily available materials. Bleach Pebbles Cost Analysis • Targeted Micro-organisms • Diarrhea: caused by a variety of micro-organisms including viruses, bacteria and protozoans. About 4 billion cases of diarrhea per year cause 1.8 million deaths, over 90 percent of them among children under five. • Cholera: an acute bacterial infection of the intestinal tract. In 2002, over 120,000 cholera cases were reported. • Guinea worm disease: In 2002 there were 50,000 cases reported in 13 countries in Africa. • HIV/AIDS: AIDS-affected people are more susceptible to water-related diseases than healthy individuals. Clean water prevents opportunistic infections associated with HIV/AIDS • Intestinal worms: Infect about 10 per cent of the population in the developing About 400 million school-age children are infected by roundworm, whipworm and/or hookworm. • Schistosomiasis: A disease caused by parasitic worms. About 200 million people are infected. Studies have found that adequate water supply could reduce infection rates by 77 per cent. • Trachoma: An eye infection spread mainly through poor hygiene caused by lack of adequate water supplies and unsafe environmental sanitation conditions. About 6 million people are blind today because of trachoma. • Typhoid: A bacterial infection caused by ingesting contaminated food or water. About 12 million people are affected by typhoid every year. Fine sand Charcoal This is a plot of the various starting pH levels of the water to be purified. On the left axis there is milligrams per liter (mg/L) vs. time (s). On the right axis is the initial amount of bleach in ounces (oz) vs. time (s). The 5 mg/L line drawn on the graph is representative of the maximum amount of chlorine allowed in potable water by the World Health Organization. • Future Plans/Research • Water Quality Testing • Purchase a 32-point water quality test from Stevens Ecology, send with next group to Benin • Tests for bacteria, pH, hardness, cations/anions, and trace metals • Hope to use test results to purify their water more effectively • Redesigning to Beninianfeedback • The current filter is a redesign of last year’s filter, which had horrible taste problems due to excess bleach • Draft a bill of materials and an instructions manual to send within the next month • Listen to Benin feedback concerning pros and cons of the filter, redesign accordingly • Hope to continue a partnership with Beninian people far into the future to continue to meet their changing needs • Spread awareness of our filter to gather more input on improvements • Other chemical treatment methods • Other chemicals besides bleach can be used for water sanitation • Iodine, potassium permanganate, sodium chlorite, etc. • Plan to research these chemicals to see if any would be cheaper/more effective than chlorine Method of Operation How to effectively kill bacteria while being cost efficient: Our research indicates that bleach would be a cost effective means to sanitizing the African water. This can be accomplished by utilizing the 3.667% by mass hypochlorite ions (ClO-) in household bleach. This anion neutralizes the contaminants by destroying the cell membranes in the pathogens. How much bleach is needed for how long to neutralize the bacteria: Depending on the level of contamination of the water, certain retention times are needed to neutralize pathogens. These times are proportional to the amount of bleach added to the contaminated water. Case 1: High Contamination or Low Bleach Concentration  High Retention Times Case 2: Low Contamination or High Bleach Concentration  Low Retention Times This can create high chlorine content within the water, however, resulting in a bad taste and potentially unsafe concentrations of bleach. Clean Water