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Makerere upgrades the technology of recycling diesel from plastics

The new technology of recycling biodiesel from plastics

In March 2016, Makerere University Department of Agricultural and Bio systems engineering in partnership with University of Kentucky USA   came up with a new technology of converting plastics into bio-diesel.

Although the innovation was the first of its kind in the country, researchers in the two universities have been in the laboratory experimenting better means of processing the fuel.

The  new process was demonstrated at the agricultural engineering workshop at the Makerere University Agricultural Research Institute Kabanyoro.

Makerere University Principal investigator Prof. Noble Banadda said together with his American counterparts have improved from a batch system to an improved technology of continuous loading and production of the bio-diesel.

The reactor loaded with plastics. This loading can be done continously

The Makerere University team is made of Prof. Noble Banadda as the Principal Investigator (PI) and Co PIs namely Dr. Nicholas Kiggundu and Dr. Ahamada Zziwa. These are working with a team of 7 Masters Students. The partners from University of Kentucky USA are Assoc. Prof. Jeffrey Seay and a team of  5 Masters students.

“Last time we were talking about converting plastics into bio-diesel, we were using a batch system. A batch system means, you open the reactor, load the plastic, close, heat and convert. Every time you want to make a new process, you had to open and close, you lose a lot of time, it was tedious and sometimes frustrating. And, remember we were heating at a temperature of between 400 – 420 Degrees celcius which means  you have to wait for it to cool”,  Prof. Banadda went on to explain the advantage of the new process:

“The beauty of this new process is that you can continuously load the plastics and continuously produce the bio-diesel. We can even make a bigger container where plastics can be fed in to produce more diesel”.

The student lowers the reactor after lighting the fire

Prof. Banadda said the batch system was far away from reality given the fact that volumes of plastic wastes are continuously produced every day.

The PI explained that the process of continuous loading and production of the  bio-diesel, has  many aspects to consider. It has an environment aspect of cleaning plastics from the environment. Secondly, the bio-diesel can be used to run vehicles and tractors on farm operations and boilers in steel industries. With this process, he said, one can also begin a business and employ others.

The American counterpart Assoc. Prof. Jeffrey Seay University of Kentucky said this process begins with a racket stove. A racket stove is a very efficient cook stove that was developed 30 years ago to reduce indoor air pollution. The idea of the indoor stove is that it is cleaner and reduces indoor pollution for people cooking.

The clean burning racket stove system

“So what we decided to do is use the concept of clean burning racket stove to provide energy to dry chemical processes. The chemistry of converting waste plastics to diesel requires heat. So what we have done, is to built a racket stove insulated to conserve the heat”, said Assoc. Prof. Jeffrey Seay.

Prof. Jeffery explained that they discovered that other researchers around the world were looking into turning waste plastics into fuel. And therefore conducted laboratory experiments to figure out this chemistry in the real world where actual people with no background in engineering and chemistry can be able to carry out this process.

“So together with colleagues at Makerere University designed this process to improve and modify the process and eventually what we want to see is people in the community to be able to have this process, collect waste plastics and produce fuel for themselves,” he said.

Assoc. Prof. Jeffrey Seay speaking to the journalist during the demonstration at Kabanyoro

The American Professor clarified that not all plastics can be used to produce the bio-diesel in this process. Prof. Jeffrey pointed out that there are seven types of plastics.

“The types we cannot use are No. 1 clear plastics bottles, No.3 plastics (PVC water pipes) and No. 7 plastics. The types we can use are No. 4, 5, and 6. These include plastics like serving utensils, yoghurt cups, coffee plastic cups, jerry cans, buckets. The three types are classified as polyethylene, polystyrene and polypropylene.  The chemistry perspective is that they contain molecules of hydrogen and carbon that is what we want in our fuel”, he explained.

Prof. Jeffrey also said that the fuel that comes out of plastics is very clean on reason that in this processor, it is melted, decomposes and leaves the processor as vapour. So even if the plastic is dirty, the dirt remains behind and fuel vapour is collected and condenses in the bucket of water. So fuel does not need to be farther treated but only ensure water it is not mixed with water by filtration.

The student showing the biodiesel fuel floating on water

“Most governments have regulations that govern what they can use in motor vehicles including the US. And so we will have this fuel tested to be legal to use on the road but for the farmers’ equipment like tractors and irrigation, we do not need to test at least in the US.  But, I have tested this fuel in my laboratory and found it meets the required standards.” He confirmed.

 The previous batch process according to Prof. Jeffery was slow and inefficient and this was the reason why they we went back to America with the input from Makerere University and redesigned a new process that can run continuously once it is started because the top of the reactor is open.

“One of the things we are going to do is to continue modifying the design to make it sufficient to utilize as little energy as possible. We are taking wood energy and converting it into liquid fuel. Wood is a valuable resource and we are concerned with deforestation. So, we want to be sure that we are absolutely efficient and not to waste this resource”, Prof. Jeffrey said.

The first step, students loading firewood into the reactor

Plastic is a real problem world over. Prof. Jeffrey said, once plastic is thrown, it does not decompose and can stay in the soil for hundreds of years. He however noted that plastic is useful in some aspects for example for preserving food, transporting products and making some materials but it has some negatives especially to the environment.

Assoc. Prof. Jeffrey Seay showing journalist studies indicating the problem of palstics a world wide concern

“So we want to come up with ways we can eliminate the negatives by giving plastics a value. Particularly from the agricultural point of view, small scale farmers can be involved in the process of making fuel and use it for farm tractors and irrigation pumps,” Prof. Jeffrey stated.

Prof. Jeffrey said in the following two weeks, students will be doing precise measures of how much fuel wood is used against the bio-diesel produced so that they can do a cost benefit analysis.

Inside the the racket stove after lighting the fire

“For everyone kilogram of plastics, we get one litre of fuel. 85% of the plastics is converted into fuel but 15% is small lost through gases. We shall be able to know how much wood energy costs and diesel fuel produced and compute the profit. We want to assure people   that they can be able to make money”, he asserted.

Prof. Jeffrey advised that for someone to build this process, he or she requires drums and all is steel. He cautioned that the fuel is flammable and uses open fire. As such, safety precautions must be taken because there is a possibility of fire accidents. He reassured people that this bio-fuel is significantly cleaner than the fuel from a petrol station. The biggest concern with diesel fuel according to ProfessorJeffrey, is Sulphur. He said, this bio–diesel fuel because it is made from plastics, has no Sulphur.

Report compiled by:

Jane Anyango.

Communication Officer, CAES

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