First Full Scale Biogas Power Plant from Organic Fraction of Municipal Solid Waste in Thailand 

This is the first full scale and largest biogas power plant using organic fraction from municipal solid waste or MSW in Thailand as of 2019. This factory was constructed by Bankai Papop Joint Venture. The project started in 2018 and was completed in 2019. The factory is located in the Integrated MSW Management Center in Rayong Province and operated by Rayong Provincial Administration Office or PAO in Rayong Province of Thailand. 

This project has a capacity of 225 tons per day and is designed to receive the feed stock from the nearby MSW sorting plant. The feedstock undergo cleaning and shredding to produce 150 tons a day of clean organic fraction of MSW which can go to the biogas plant. 

The project has 3 main processes consisting of: 

  1. Cleaning and shredding process; 
  1. Biogas production process (CSTR); and 
  1. Electricity generation process. 

The cleaning and shredding process started from the wheel loader taking the raw feedstock into the walking floor. This machine feed the waste slowly to the downstream units so that it can be clean and shredded effectively. 

To remove metals from the waste stream, a magnetic separator is applied. Metals are non-biodegradable and can cause clogging in the pipes and downstream processes, so they must be taken out. 

The waste then enters the disc screen which has 25 mm opening. The waste with size larger than 25 mm will be carried forward and then out to waste bunker before disposal in the landfill. 

The waste with the size less than 25 mm will fall from the disc screen. Now it is ready for the extensive shredding using the ball mill machine. Waste will be slammed and shredded with the weight of numerous metal balls while this machine is continuously turning. 

The result is the slurry at the outlet. However, we still have some impurity in the waste, so it needs another screening step using a vibrating screen. This machine has an opening of 6 mm. The larger parts will be sent out and disposed in a landfill. Afterwards, the smaller parts will be delivered to the sand and grit removal tank. 

This purpose of this process is to remove sand, grit and smaller particles from the waste slurry. This is done by slowly turning the waste while keeping the organic content in suspension, but sands and grits can settle at the bottom. 

The slurry will then go to the anaerobic digestion process which consists of 1 acid tank and 2 anaerobic digestor tanks. Acid bacteria converts large molecular organic matters to smaller molecules which are suitable for the following digestion step. The acid tank is installed with a single layer membrane roof to control odor.  

In the anaerobic digestion tanks, methanogens covert organic matters to biogas which composes mainly of methane and carbon dioxide gases. 

The digestion tanks are constructed of reinforced concrete for the longer life time. At the top, the double membrane roof are installed. At the side, there are 4 mixers. This process is designed as a Continuous Stirred Tank Reactor or CSTR. This kind of configuration is suitable for high solid content feed stock such as organic fraction from MSW. 

This whole plant is designed to produce 15,000 Nm3/d of biogas. Before the biogas is sent to the electricity generation process, it has to go through biogas H2S scrubber. This is to remove harmful H2S gas. Afterwards, moisture will be removed with the help of biogas dryer.  

The analysis showed that methane is around 65%, carbon dioxide is around 32.5% Oxygen is 0.5% and hydrogen sulfide is 0 ppm. This biogas is ready to go to the biogas generator set. 

Around 12,000 Nm3/d will be delivered to the biogas genset here. It has a capacity of around 1,000 kW per hour and can produce around 7.13 million kWh per year or enough to power 1 village. 

The rest of the biogas around 3,000 Nm3/d is delivered to the nearby factory for compost drying. 

All instrument and equipment are controlled by PLC and SCADA system. It is very simple to control the operation and see the historical data. The SCADA is system is written by Papop engineers to suit each project site. 

The benefits of this project are as follows: 

  1. This is an alternative and sustainable approach for MSW disposal. It helps to minimize the open dumping which is the most applied MSW disposal method in South East Asia. It also minimizes the disturbing odor from the waste as the process is a fully closed system. 
  1. It can produce electricity as a byproduct from the digestion. This is a clean and renewable energy which helps to decrease dependent of fossil fuel energy. 
  1. It also reduces greenhouse gases up to 46,000 ton CO2 equivalent per year when considering only methane capture. 

If you are interested in applying biogas from OFMSW to your town or cities, please contact us and our staff will be in touch with you in due course.