Blog #5

Today we visited a landfill and co-generation plant in Serdiana. There are six landfills at the site, and the co-generation plant next to it converts the methane gas that is produced from the landfills into energy. They also have some solar panels that harvest energy, and they sell all of the energy from the methane gas and the solar panels to the grid.

I thought it was interesting how the final covers on each landfill differed from each other based on what the underlying layer was. If the landfills were previously covered with soil, the final cover was made of dry grass because all of the water soaks through the soil and into the landfill, so the grass doesn't get much water. However, if the landfill was previously covered with clay, the water does not soak through the landfill, so it stays on top and waters the grass. Therefore, the final cover is made of green grass and flowers. The landfill that was covered with clay was used for hazardous waste, which is ironic because you wouldn't expect the hazardous wasteful landfill to looks nicer than the landfill with regular municipal solid waste. We also noticed that there were trenches around the landfills to catch the runoff water, which is good because the water coming off of the landfill could be contaminated.

We then visited a landfill that has not been closed yet. It is on top of another landfill of municipal solid waste because the previous landfill makes a good solid foundation. We could see a construction vehicle spreading out bottom ash from an incinerator plant. The engineer who was giving us the tour told us that they have an air quality monitoring station and groundwater monitoring wells that they check every 3 months. There were two pools of leachate next to the landfill, and I was surprised at how much leachate there was. Most of the leachate is sent to a waste water treatment plant, but the leachate from the special waste landfill is sent to a different facility.

The engineer in charge of the co-generation plant took us to the plant and showed us the main components of converting the methane gas to energy. The methane gas travels from the landfill to the plant in a pipe that is 2.5 km long, and it enters a container that cools it to remove any water and solids in the gas. We went into the control room and through a window saw the combustion chamber where the gas is converted into energy. The energy is produced at a low voltage, so it needs to go through a transformer before selling it to the grid.

The co-generation plant has a few methods of re-using resources that they have. They have 3 motors, and the water that they use to cool the motors is used in the winter to heat the buildings. Also, since people are trying to move away from landfilling, they would like to get anaerobic digestion to process organic waste. Overall, even though landfilling is the last option for disposing waste, the engineers at this plant are doing the best they can to dispose of waste safely and use it to generate energy.