Thai Harvest Initiative: Ban Huay Mii Village Water Filtration System

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 Engr 103 - Spring 2012

Engineering Design Lab III

Lab Section: 024                                        Date Submitted: June, 7, 2012

Group ID: 001

 Advisors: Dr. Moseson, Ken Mallory

Group Members:  Joshua Shore

                       Vito Velinov Milanov

                       Eduardo Gomez Leon

Abstract:

The Village of Ban Huay Mii, Thailand possesses a rudimentary water system which provides them with unsanitary, cloudy, and foul tasting water. In order to address this issue several different types of filtration systems were analyzed to see if they would be sustainable solutions to this issue. The method of activated carbon filtration was chosen. A system to manufacture the activated carbon locally has been developed. This system functions using the process of pyrolization, which is the decomposition of organic material using heat in an oxygen purged environment. This process creates activated carbon which has a large surface area, making it an ideal substance to filter out bacteria, as well as large particulates from water.

Introduction:

Problem Overview:

Most villages in the Bo Klua district of Northern Thailand have very rudimentary and unsanitary water filtration systems. The goal of this project is to design a way to significantly improve the quality of their water by reducing the turbidity and bacterial contaminants to similar levels that were observed in the bottled water tested by the first team who analyzed the village water quality [1]. This project will specifically focus on the village of Ban Huay Mii. Because this village is not wealthy the filtration system must be as inexpensive as possible to manufacture and maintain.

Ban Huay Mii’s Current Water System:

Ban Huay Mii’s current water filtration system is called a “Mountain Water System” [1].  This system basically is a water transportation system which brings fresh water from a small dammed reservoir to their village.  This is a simple and practical system consisting of PVC pipes leading from the dam to a series of settlement tanks. In the storage tanks foreign matter and other particles settle to the bottom of the tank, improving slightly the turbidity of the water. Attached to the water storage tanks are webs of small pipes that terminate at different taps near the villager’s homes [1].  These taps can be found throughout the village allowing the villagers to have instant access to water.

         The village is also located a short distance away from two muddy streams. When the settlement tanks run dry the villagers are then forced to walk all the way to these streams and collect the dirty water by hand. This is by far not an ideal system, but when water is scarce, it is their only available option.

Pre Existing Solutions:

            Water filtration systems are found all over the world, ranging from home water-pitchers, to systems that provide water to hundreds of people. Water filtration devices vary depending on the use that it is needed for. Three water filtration systems that could be applicable to Ban Huay Mii water system are: Slow Sand filter, Ultraviolet Water Purification and Activated Carbon Filtration.

                Slow sand filter involves running water through a compact layer of sand. This will remove many particulates and other small or large objects from the water source. This system also serves as a checkpoint to filter out bacteria contaminating the water.  While this is an excellent, inexpensive method for cleaning water, it requires a lot of maintenance. The bacteria layer which forms on top of the sand, aiding in the filtration of bacteria, must be sifted and cleaned periodically throughout the year [2].

                Ultraviolet water treatment has proven to be an effective way to purify water. This system operates by running clear water through ultraviolet light. This will kill most if not all bacteria living in a contaminated water supply [4]. The system requires power from a solar panel, which if damaged, would be difficult for the villagers to replace.

                Activated carbon is another excellent method to filter out particulates and potentially harmful biological material from water. A filter containing activated carbon would work similarly to a slow sand filter, in relation to the gravity fed system where water is pored over a layer of activated charcoal and filtered out the bottom. Because activated carbon is relatively easy to produce this is a perfect filtration method for the Ban Huay Mii village.

Project Objective:

Rather than ship in a filtration system which will rely on outside aid to maintain, the final design produced is intended to provide a cheap and effective way for the villagers themselves to produce activated carbon which can be used to filter their water supply.  This filtration method will reduce both the turbidity and bacterial levels in their water. Though the process of pyrolization it is possible for the villagers themselves to manufacture all that they need to maintain indefinitely a carbon filtration system operating in tandem with the water system already in place there. By pyrolysing agricultural waste and lumber grown nearby activated carbon can be made.

A fireplace will be constructed from clay bricks, and using a bellow system  similar to those found in pre-industrial local forges (see figure #1), it will be possible to heat up a rotating oil drum to the temperature required to efficiently pyrolyze the wood and agricultural waste (rice husks). The clay bricks and bellows will be necessary in order to make sure that the fire reaches temperatures around 600 to 700 degree Celsius.

Figure #1: Bellows

The oil drum fitted with two one way valves and an airtight hatch will be made from steel as its melting point is roughly 1100 degrees Celsius, far above the required temperature. The rotating oil drum is supported by a shaft connected to two pairs of 2 inch thick steel pipes which holds the oil drum 3 feet above the fireplace. The container itself will be filled with nitrogen gas so that there will be as little Oxygen as possible in the container allowing for the pyrolysis to take place, instead of combustion. A crank handle connected to the shaft allows the oil drum to be rotated by hand (see figure #2).

This is a sustainable solution to the villages water problem since the materials that need to be shipped to them are not fossil fuels, and are relatively inexpensive.

Figure # 2: ACS - Activated Carbon Synthesizer (not drawn to scale).

Technical Activities:

        The first step taken in the process of developing a safe water system for the Ban Huay Mii Village is to evaluate different existing water filtration systems in the context of their applicability to the Ban Huay Mii village.

Table #1: Decision Matrix

        Each filtration systems applicability to the village water system is evaluated on a scale from 1 to 5. Each column represents a constraint that the filter system should satisfy in order that it be applicable to this situation.

Estimated Cost:

Because Ban Huay Mii is a poor village each filter system was evaluated based upon the estimated cost it would require to be implemented. Slow sand filtration is a cheap method because sand is relatively cheap and easy to come by. This is also true with chlorine tap boxes, as well as activated carbon. The foam filter is expensive, and Ultraviolet Purification requires electricity, so these are poorly suite this category.

Maintenance:

        Slow sand filtration and ultraviolet purification require lots of maintenance. Slow sand filters need to be regularly sifted [2], while ultraviolet purification requires working electronic components which will need to be replaced every so often.

        Activated carbon chlorine powder tap boxes, and the foam filters are fairly simple to maintain. The chlorine and activated carbon needs to be replaced every so often, and the foam filter need to be cleaned by hand.

Implementability:

        This category refers to the ease of manufacture and construction. Slow sand, activated carbon, and the foam filter would be fairly simple to integrate into the current system in Ban Huay Mii. Ultraviolet and chlorine filtration perform poorly in this category because they will require parts to be shipped to the village on a regular basis.

Filtration Effectiveness:

        This category analyses the ability of each filter system to improve the turbidity (cloudiness) of the water. Ultraviolet and chlorine powder tab box do not perform well in this section. This is because chlorine does not affect the turbidity of the water, and the UV purification does not work at all unless the water is clear [4].

Purification Effectiveness:

        This category is meant to analyze the ability of each filter to filter out potentially harmful bacterium from the water. All of the filtration systems perform very well in this category except for the foam filter, as that is solely a turbidity filter.

Pre Reqs (Prerequisites):

        This final category assigns applicability values to the filter systems based upon their need to work in tandem with other filtration systems in order to be effective. Activated Carbon and slow sand filtration perform the best in this category.

Final Decision:

        Activated carbon filtration came out to be the best choice (4.19 out of 5) according to the table above. Therefore it was decided that designing an activated carbon filtration system would best benefit the village of Ban Hua Mii.

Producing Activated Carbon:

Through the process of pyrolysis, decomposing organic matter using high heat in an oxygen deprived atmosphere, it is possible to make activated carbon [3]. Activated carbon is a good filter because it has a very large surface area which gives it the ability to filter out very small things, even bacteria, from water [3]. Because activated carbon is fairly easy to produce, and can be made using agricultural waste such as corn husks, an apparatus was designed which would allow the villagers to manufacture their own activated carbon (see figure #2). This system is large enough that it can be used to provide activated carbon to many villages, not just Ban Huay Mii.

Results:

        The final design of the activated carbon synthesizer system will include a 50 Gallon Oil drum, 4 steel pipes and an iron crank with an insulator. The design of the system is very simple. The 50 gallon oil drum will be suspended above a fire by 4 steel pipes, two on each side, welded together forming a V-shaped angle. An iron crank will be welded to the oil drum to allow an operator to rotate the drum about its axis during the heating process. There will be two valves, each a one way valve. One will allow air out of the drum, while one will only allow air into the drum. The valve which allows air into the drum will have a screw cap which will allow it to be sealed during the heating process. The valves will allow the use of nitrogen to purge the tank of oxygen which will improve the quality of the activated carbon. Because the district of Bo Klua has rudimentary welding capabilities it is likely that they have nitrogen gas on hand [1]. The nitrogen tank will be connected to the one way valve, and the other valve will be opened, passing the nitrogen gas into the tank, while the oxygen flows out the other valve.

        If however nitrogen gas is unavailable it is still possible to use this apparatus to make activated carbon. This would require that the drum be heated very slowly, to allow moisture to leave the air in the tank. After the tank is very hot, then it can be sealed and the pyrolysis process can begin [3]. In this situation the one way valve allowing air into the tank would be shut off, while the other valve would be used to relieve the pressure build up caused by the heating of the atmosphere inside the tank.  

The final dimensions of the materials used are as follows: The 50 gallon oil drum has a length of 2.8’ with a diameter of 2’, the steel pipes will be 5’ tall with a diameter of 1 ¼”, and the iron crank has a length of 3’ with a width of 1 ½”. Attached to the handle Silicafelx Tape AB will be used as a grip and insulator.  All of the materials, except for the tape, are commonly found all over the world due to their wide versatile uses.

After the activated carbon has been produced, it is a rather simple process to integrate the carbon filtration system with Ban Huay Mii’s main water filtration system.

Materials Required and Estimated Costs:

1. $68 for a steel close headed drum container. [5]

2. $600 for 300 clay bricks [6]. could be possibly bought or made cheaper locally.

3. $34 for a Thermometer to ensure that required temperature is reached and maintained [7]

4. 42.02 for one 2”x10’ steel pipe [8]

5. Other: Wood to fuel the fire is locally grown, time and labor put into constructing the fireplace.

6. Unown Costs: shipping costs and taxes, Silicafelx Tape AB (requires a quote from the manufacturer), crank handle (estimated to be very low, under $25).

Material Specifications and Dimensions:

1. Oil Drum - Length - 2.87 Feet,  Diameter - 2 Feet

2. Two Steel Pipes - Length 10 Feet  (to be cut in half and welded together as support structure) Diameter - 1 and 1/4 Inch

3.  Iron Crank - Length  3 Feet, Width 1 and 1/2 Feet

Sustainability:

        The underlying theme of this project is designing for sustainability. Below are listed the 4 basic subsections of sustainability, and how our project for the most part satisfies each aspect.

1.  People - The people of Ban Huay Mii have unclean, unsafe drinking water. This system for creating activated carbon will address this issue, and provide sanitary drinking water to the villagers.

2.  Planet - Although no fossil fuels will be consumed during the pyrolysis process, wood and other organic material will be burned releasing carbon dioxide. In a responsible world which replants all wood that is burned, this project would be a 100% sustainable solution. None the less this method will slightly harm the environment.

3.  Prosperity - This system will significantly contribute to the prosperity of the village. It will improve their water quality, keeping the villagers healthy, resulting in increased productivity. Because of the relatively low expense of manufacturing the activated carbon, this system will have little to no noticeable negative economic effect on the village.

4.  Performance - Still to be determined. Due to constraints involving insurance, and chemistry lab availability, the team was unable to get into a lab and test the effectiveness of the method the Activated Carbon Synthesizer uses. Nonetheless it is theorized that this will be a very efficient method of creating activated carbon which should prove to be an excellent filtration system [3].

Future Work:

Scale Model and Tests:

        Do to circumstances out of the team's control, small scale testing was impossible to complete, even though the material that the villagers would use to make the activated carbon was obtained. This would be a necessary step before the full scale model would be produced. Store bought activated carbon would need to be compared to activated carbon made in the lab. They would be tested by running contaminated water through each, and a comparison of the resulting filtered water would need to be done.

Prototype: Full Scale Test

        Assuming the scale model test show successful results a full scale model and similar tests to those written above would be run. It will also be important to write up exact instructions for bringing the temperature up to the required level. After completion the apparatus would be disassembled and shipped to Thailand.

Integration Into the Ban Huay Mii Water System: 

The objective of producing the activated carbon is so that it can be integrated into the Ban Huay Mii water system. More detailed diagrams and information would need to be gathered detailing the exact dimensions of the water storage tanks there. The activated Carbon produced would then be ground by hand into granules, and put into the storage tanks as a layer, or several layers, separated by layers of large rocks or sand (see figure #3). These layers will be surrounded by mesh screens, so the activated carbon does not dissolve in the water.

Figure #3: Activated Carbon Filtration

Refrences:

[1] Moseson, Alexander, “Integrated Development Assessment,Bo Klua, Thailand,Field Assessment” Drexel University, Philadelphia, Pennsylvania, USA. Mar. 2010.

[2] W. Shirt et al., “Biological mechanisms in slow sand filters,” American Water Works Association, vol. 89, pp. 72, Feb. 1997.

[3] Dimitrios Kalderis, Sophia Bethanis, Panagiota Paraskeva, Evan Diamadopoulos, Production of activated carbon from bagasse and rice husk by a single-stage chemical activation method at low retention times, Bioresource Technology, Vol. 99, Issue 15, Oct. 2008.

[4] S. Vilhunen, H. Särkkä, M. Sillanpää, " Ultraviolet light-emitting diodes in water disinfection," Environmental Science and Pollution Research International, Vol. 16, no. 4, 439, Jun 2009e

[5] Best Containers. [Online]. Available: http://www.bestcontainers.com/steel-drums---barrels-un-rated-steel-drums-open-head-drums-with-12-gauge-bolt-type-locking-ring--bol.html

[6] Google Market. [Online]. Available: http://www.google.com/products/catalog?hl=en&rlz=1C1CHFX_enUS484US484&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1600&bih=756&q=prices+of+clay+bricks&um=1&ie=UTF-8&tbm=shop&cid=4057634393968426676&sa=X&ei=uxXFT9ixM6bk0gGdlrWbCg&ved=0CKoBEPMCMAM

[7] Inesun. [Online]. Available: http://www.inesun.com/Non-Contact-IR-Laser-Infrared-Digital-Thermometer-50-700-degree-C--17095.html

[8] Sears [Online] Available: http://www.homedepot.com/Plumbing-Pipes-Fittings-Valves-Galvanized-Pipe-Fittings/h_d1/N-5yc1vZbuu8/h_d2/Navigation?catalogId=10053&Nu=P_PARENT_ID&langId=-1&storeId=10051&currentPLP=true&omni=c_Galvanized%20Pipe%20&%20Fittings&searchNav=true

[9] Filter Fast [Online] Available:  http://www.filtersfast.com/articles/ArticleImages/carbon-adsorption.gif