EWB Challenge 2014Plan Timor Leste
Sustainable Engineering Practice
South Australian Institute of Business and Technology
Executive Summary
This report provides details on the project that aims at facilitating for the creation of an anaerobic/biogas digester in in Codo town. This is a small town that is situated at Lautern District in East Timor, and it has a population of approximately 500 people. This town lacks a system that can allow them to dispose and manage their waste in an effective manner. They bury their waste underground, and they use burning wood to serve as a means of cooking. The report will suggest various ways that can help to develop Codo by offering them with a system that will allow them to manage their organic waste, as well as an easier and environmentally friendly means of cooking their food.
As a way of preventing pollution and diseases from coming from waste, this report is based on the idea of recycling plastics, waster, and paper among other forms of waste. By focusing on organic waste such as rotten food, manure, feces fruits among others, the report reveals that this form of waste causes harmful effects to people, and often leads to diseases. This report reveals that these kinds of organic materials are essential in terms of helping to produce biogas, which can later be used to address purposes such as heating, cooking, production of electricity, and transport among others.
The report illustrates that Codo is a small town where heating is not a necessity. However, the project will not concentrate on transport, since the area is not well advanced, and production of electricity from the gas would make the project to go beyond its limitations. For these reasons, the project proposes to produce enough gas that can make it possible for the houses in Codo to cook at least one meal in a day.
The major goal of the project will be to help identify various sustainable ways that can help to manage waste as well as improve the health standards of Codo. Others include creating room for safe disposal of feces to as to prevent diseases, to contain as well as process the organic waste that has been created by the inhabitants of Codo as well as their livestock, gain the capacity to produce biogas that can serve approximately 100 households, and make the project resistant to heavy rain as well as the long periods of dryness.
The report will illustrate the manner in which this project will be guided by the challenge of Engineering Without Borders in 2014, which targets helping Codo to develop. The information that has been availed by Engineering Without Borders as well as research has revealed that the implementation of a waste management system would be essential in terms of addressing the current condition at Codo. Once the villagers are provided with the biogas digester, they will be able to cook their food while using the gas, and use the fertilizer that the digester produces. They will also be able to safe a significant amount of time that they waste while gathering food and stockpiling.
Lastly, in order to make the project successful and based on the limitations in skills and knowledge, the project will not address all the possible issues that can be faced during the design and implementation of the project. As a result, project will lay emphasis on the vital aspects that are associated with the system
- Introduction
This report will detail the project for creation of a biogas/anaerobic digester for the town of Codo. The project was inspired by Engineers Without Borders Australia and is made to take part their project Timor Leste. The project aims at the developing of sustainable and affordable life improvement solutions.
- Project Overview
Codo is little town in the Lautem District of East Timor (Timor Leste). With population of about 500 people the town has no system of disposal and management of waste. Currently waste is just buried underground and the method of cooking is through burning wood.
- Project Aims
The primary subject of the project is to contribute to the development of Codo. Our project will help the villagers by providing them with a system of managing organic waste and an easier, more environmentally friendly and sustainable way for cooking food.All aspects of the criteria are given in the Product DevelopmentSpecification sheet, but the most important concern is:
- Cost
- Efficiency
- Modernization
- Improvement on health
- Production continuity
- Problem definition
The ideas that were discussed after deciding to concentrate on waste management went through using different aspects of waste for various purposes. First was considered using different sorts of solid waste for creating means of entertainment such as playgrounds and toys and even building structures, recycling plastic, paper, water etc. was also considered as well as ways to prevent pollution and diseases originating from waste. In the end we got to organic waste such as manure, faeces, rotten food, fruits etc. We found out that this sort of waste has harmful impacts on people’s health and develops deceases. Also what really got to our attention is that organic materials can be used to produce biogas. After discussing the topic and doing research we realised that there are easy ways to make a digester and that the gas can be used for cooking, heating, transport, electricity production and so on. However in the case of Timor Leste heating is not necessary, in the small town of Codo on which the project is concentrated transport is not developed and producing electricity from the gas would extend the project and budget outside its limitations. In this case it was decided that we would find a way to produce enough gas for all houses in Codo to be able to cook at least one meal for the day.
- Project Goals
The initial project goal was to identify sustainable ways to manage waste and improve the health standards of the town. The goals of the final concept however are:
- Safe disposal of faeces to prevent deceases
- Containing and processing organic waste created by the 500 inhabitants of the town and their livestock
- Capability of producing biogas enough for 100 households
- Resistant against the heavy rain and the long dry periods
- Product Development Specification
- Background & Design Brief
The 2014’s Engineering Without Borders challenge aims at Codo in Timor Leste. The information given by the Engineering Without Borders organisation and research has finalised that waste management system implementations would be very appropriate and helpful for Codo’s current situation. Providing the villagers with a biogas digester will allow them to use the gas to cook their food, and use the fertilizer produced by the digester. Providing them with biogas digester will also allow them to save a significant amount of time on stockpiling and wood gathering. Ideally, people have their bowel movement after every meal which is approximately three times a day but in Codo, residents do not have much food source in the village therefore people will only eat a maximum of twice a day. The biogas digester must be able to withstand the weather conditions in Codo and must also be environmentally friendly, low-cost, and easy to maintain. It would be very convenient if the materials that are going to be used in this project can be obtained locally due to expensive transport costs if it is going to be imported.
- Final PDS Sheet Contents
- Project Scope
The project will be dealing with managing disposal of organic material and the production of biogas in the community of Codo. The final concept is to have toilets for the safe disposal of faeces to increase the healthof the community and have a biogas digester system attached to that to provide the community with a modern sustainable method of cooking. The disposal and processing system will be designed according to the goals and criteria set earlier.
- Inclusions and Exclusions
Assumptions need to be made in order to fill in blocks of unclear and inaccessible information. The assumptions made are as follows:
- The people will collect animal manure, will have food wastes and leftover crops such as the famous corn and will maintain the process of digestion
- Temperature does not drop below fifteen degrees Celsius during the night
- Flushing water will be somewhat available during dry season
- Consumption will not exceed the expectations or go below required
- We assume the background of Lautem is district applies somewhat to Codo
These assumptions were made prior to completing the design and calculations.
- Literature Search
- Biogas digestion
- Types
Biogas digesters also called anaerobic digesters use the anaerobic digestion process to produce and contain the flammable gases released from the fermenting of biomasses.There are many different types of digesters for the anaerobic digestion of biomass. One type is the plug flow digester. It usually consists of a dam lined with concrete or an impermeable membrane and covered with a flexible cover gas holder (BioGasAustralia 2014). Ultimately the dimensions of the digester consist of a length greatly bigger than the width and depth. For best performance a biogas booster pump is added, together with a water separator and a biogas purifier. According to the information presented by BioConstruct in their video called ‘How does a biogas plant work?’ published on the YouTube website on the 3rd of April 2008, the large scale biogas plants have an electric powered mixer to pasteurise and mix all biological products which then get heated up through a ‘tubular heat exchanger’ where the hydrolysis process occurs. After that the bio waste goes to the first container or the digester where it is kept at a temperature of 35°C to 55°C to accelerate the formation of methane and is stirred or mixed constantly to avoid the forming of glares of material. After around thirty days the substance goes to a second container sometimes called post-digester or post-fermentator where the biogas formation process is completed in the matter of another thirty days. The final product is the stored in two cement containers before it’s used to enhance soils. The gas is then processed so water vapour and hydrogen sulphate are removed from the gas so it can be then usedin the internal combustion engines of the plant that generate electricity and the fluid used to cool the engines down is used to heat up the bio-waste for its ultimate fermentation.
- Method of digestion
Anaerobic digestion is the natural biological process of organic materials being broken down by bacteria. It is similar to the process of composting but works only in the absence of oxygen. Natural occurring of anaerobic digestion process can be seen in swamps and bogs. The process has four stages
- Hydrolysis - the breaking of chemical bonds by the addition of water. Where a carbohydrate is broken into its component sugar molecules
- Acidogenesis - the biological reaction where simple monomers are converted into volatile fatty acids
- Acetogenesis - the process through which acetate is produced by anaerobic bacteria from a variety of sources of energy (hydrogen) and carbon (carbon dioxide).
- Methanogenesis - the formation of methane by microbes known as methanogens it is the final step in the decomposition of biomass.
These four stages explain why cows have four separate compartments to their stomach (MarchesBiogas 2014). The products dumped intoa digester are called feedstock. Feedstock divides in four main types according to the source:
- Agriculturalresidues, such as livestock slurry and manure;
- Arablecrops, or crops grown and refined for the sole purpose of digestion due to their high consistency of calories;
- Food waste;
- Human faeces
The three types can suffice for digestion on their own but it is preferable to have them mixed up for better results. Slurry is a good feedstock; however it is not the best choice for the production of biogas,because the material has already been digested by an animal. This is why it is recommended to have some fresh undigested feedstock to increase biogas production. Such feedstock are wet energy crops, such as grass silage, whole crop cereals, maize or evenglycerine, found in bio-diesel production,it is also a very valuable co-digestion product. Last but not least important as mentioned before is food waste which is also a good co-digestion product. However food wastes need to processed or pasteurised before they can be used in an anaerobic digester. This however seems to make the production process more complex and expensive.An advantage from using the digesters is the fact that after being digested the materials turn into what is called ‘digestate’. It is rich on nutrients such as Nitrogen, Phosphorous and Potassium. Digestateis basically 90-95% of the feedstock input and can be used as synthetic fertilizers to help grow all different crops. The biogas produced in the process can be used forthe generation of power and heat through a Combined Heat and Power (CHP) unit, or, it can be added to the gas grid or used for transport only after processing and purifying. Processing and purifying the gas can be very costly hence why it is more effectively used for only heating or power (MarchesBiogas 2014).
- Background of Lautem
The town of Codo is situated in the district Lautem is in the easternmost part of Timor and more precisely in the sub-district also called Lautem.
- Geography
The district occupies 1,702.33 km2. Lospalos Township serves as the administrative and economic centre and is conveniently located in the centre of the District. In general, 20-30% of Lautem is corrugated land, 30-35% highland and 35% mountainous. The District has predominantly lowland and fertile soils ideal for cultivation and where traditional agriculture is practiced.
- Climate
The wet season of the district consists of an average of two rainfalls per week during May to July, and the months of November to January have an average of two hours of heavy rain daily. August to October is the dry season with no rainfall. The temperature averages between 23° C - 31°C with peak of 38°C. The rivers Ribeiraraumoco, Ralailaba and the Lake Ira Lalaro are the main sources of water during the dry season. There are three climate zones in the country. The northern zone,that covers the Lautem sub-district where Codo is located, has annual rainfall ranging from 500mm to 1.000mm. The dry season lasts about 8 months. The District is considered to be the wettest area in the whole of East Timor. Heavy rains often result in flash floods that affect households and vital infrastructure such as roads.
- Agriculture
The soil of Lautem is made out of residues, CaC03 and clay. The soil is classified as follows: Litho sol 8% with 45 cm deep layer. Alluvial soil consists of sand 30%, dust 35 %, 35 % light and soft, rego sol and brown forest soil. Average farm holdings are between 1-2 ha per family. Farming is dependent on both irrigation and rainfall. The main food crop is corn, followed by rice. The first crops of corn are grown with the first rainfalls of November/December every year. The second crop is grown in the month of May. The average rice production is 2 -3 ton per ha. Below is a table of the rice plantations area in the different sub-districts:
In the higher areas the paddies are watered by rain only, the lower areas can utilize irrigation techniques during the rainy season. First planting starts in December through to - February, harvesting being 3 - 4 months later depending on the variety, while the second crop is planted between June and August. Other crops grown are different roots and tubers.The second planting season is in the months of April/May. There are no fruit orchards or commercial fruit production in the district, and fruit trees are seen mostly around homes. As with fruit, vegetables are cultivating for home consumption and excess is sold in the local market.Lautem district is one of the most densely forested areas in East Timor, and much of this forest has been registered as a Natural Preservation Area. The forest is a source of resources used by much of the population and the sustainability of the forest's natural resources is just beginning to be studied. Coconut and candle nut trees are the most prolific plantations in Lautem. Unfortunately due to the over planting of these trees, many abandoned plantations can be seen throughout the district and only a limited number of people use the coconut to make oil for home consumption. Lautemcontains over 20,000 ha of grazing land and the district has the potential for commercial livestock activities.Another agricultural initiative that could be commercially successful in the district is that of fresh water fishponds, this could also supplement community food resources.
- Concept Designs and Sketches
Before we finalised the project we first considered three different concept designs. The project started when the ‘plug flow design’ was discussed during lecture six of Sustainable Engineering Practice in SAIBT in march 2014. Then after researching simple home-made designs we created the ‘Alpha design’, then from that we upgraded into what we called the beta design ’Beta Design’. The following sub sections will provide information about each design and will test each design against the most important criteria as described earlier:
- Cost
- Efficiency
- Modernization
- Improvement on health
- Production continuity
- Plug Flow Design
The traditional ‘Plug flow’ design was described in section 5.1. However the design we were considering is a more basic version that is more similar to what people call ‘plastic bag digester;. The design basically involves first the digging of a trench. Then it gets filled up with organic material/ biomass after which it must be covered and sealed with plastic. The plastic is sealed on the edges with soil and has the output lines directly attached to it. The outcome of the project should’ve looked similar to the following:
Figure 1–Kenyan farmers new biogas system by SuSanA Secretariathttp://picturesandbox.com/browse/free-stock-photos/4644386374/Bag-digester-2.html
Figure 2- The Ecofys Plastic Bag Digesterhttp://www.ecofys.com/en/project/ecofys-plastic-bag-digester/
Even though the cheapest possible version of a biogas digester we did not chose this design because it doesn’t provide a modern and safe method of disposal of biomaterials and we also wanted to make something more unique and resistant to harsh weather and a design that will constantly produce gas.
- Alpha Design
The alpha design was the primary design of a simple biogas digester that our team managed to come up with after researching biogas digesters and different sorts of plastic container and cheap solutions offered by other people. Our research allowed us to discover that the ultimate biogas digester should have two separate chambers the first called bio-digester or digester and the second chamber called post-fermentator or post-digester. So we decided we can use two plastic containers connected with PVC pipes to ferment bio-waste. Then we discovered the shown below 1000Liter plastic containers reinforced with a metal cage:
Figure 3 – 1000-Liter-Containerhttp://www.graf-water.com/industry-program/tankscontainers/1000-liter-container.html
The following is a sketch of the design:
- Beta Design
Because we agreed that the Alpha Design doesn’t meet all the main criteria we wanted to cover with our project we decided to extend it and call the new design the Beat Design. We took our concept that involves the two plastic containers and changed to method of bio-waste supply to the system. We decided building toilets can be done at low cost. To reduce cost it was decided that cheap second hand toilet bowls can be found. For the construction of the actual toilet building was decided that concrete will be used as foundation and the method of Straw Bale Construction method will be used to make the structure. This is the ultimate solution because the materials used are of lowest cost and are environmentally friendly (Sustainable Sources 2014). However the details of this method of construction will not be covered in this report.
Calculations
- Temperature
- Input
- Output
- Storage/consumption
Recommendations
Conclusions
References
