Have you ever wondered where waste ends up? This post will analyze and discuss the procedure and the limitations of landfills, the recovery center, and the landfill gas treatment facility of Al Qusais landfill, and solutions suggested to prevent the limitations from reoccurring.
Al Qusais Landfill
Al Qusais landfill is one of the largest landfills in Dubai, it is a 3.5 km2 land which is composed of cells that are 2 meters in depth to contain waste. The landfill receives around 7000-7500 tonnes of Municipal Solid Waste delivered by over 1000 trucks daily. The MSW includes waste such as paper, plastic, yard debris from households, institutions, and industrial and agricultural sources.
Once received, the waste is dumped in the cells, compressed, and evened out by using compacting trucks to limit oxygen between the gaps to prevent explosions from occurring. The waste is then covered with 30 meters of sand to prevent odors.
Recovery Facility
Around 5000 tons of waste is brought into the recovery facility each day, only 30% of the waste is recycled.
The first step in the recovery facility starts with the weighing of the trucks that carry the waste, and then weighing it when it leaves again in order to find the difference, thus giving us the weight of the waste. Then, the waste is unloaded and the waste goes through a trammel screen, which separates the waste based on their size, large objects are first and the smaller objects gets separated last. Afterwards, the waste passes through a magnetic separator, which removes ferrous metals. Next, the waste that is still left gets separated manually based on their type. After the separation of waste, it is compacted and is sold to be reused. The operation also recycles micro beads of plastic and then sell them to manufacturers in china.
Landfill Gas Plant
With the help of anaerobic bacteria, the organic waste that is buried in the landfill starts to decompose thus producing landfill gasses. The composition of landfill gasses mainly consists of 40-60 percent of methane, 40 to 60 percent of carbon dioxide. It also contains small amounts of oxygen, nitrogen, sulfides, ammonia, hydrogen, carbon monoxide and nonmethane organic compounds (Agency for Toxic Substances and Disease Registry, 2010).
In Al Qusais landfill, methane contributes to 58% of the total landfill gas that is produced. Methane is 25 times more harmful than carbon dioxide, thus in order to reduce the harmful effects of methane it is burned using two Oxygen atoms to create carbon dioxide. This is done in a process where It is pulled by negative pressure into 20 kilometers of pipe, which are used to collect the gas. Then its transferred through the collection chambers, there is a total of 12 chambers. Afterwards, the pipes cool the gas and the gas moves up in order to be burned. It goes up to a tower that is called the flare, which flares 6000 m3 of methane gas per hour. This process turns methane to carbon dioxide only.
The landfill uses electricity that is generated by the usage of methane, which is used to produce 1 MWh of electricity, this electricity is used to power the landfill and it also helps in reducing the amount of greenhouse gasses. One of the experts has pointed out that if the electricity was connected to the Dubai Electricity and Water Authority grid, it can light up around 20,000 homes. Also, it was mentioned that the plant has managed to reduce 1.4 million tons of carbon dioxide, which is comparable to reducing 90,000 cars in Dubai. However, the Dubai Electricity and Water Authority is not giving them the approval which is a limitation of this part of the landfill.
Limitations
A limitation of this landfill is that the landfill should not have reached a level higher than the surrounding buildings. Despite the fact that high measures of environmental control are taken, the landfill is located in a site where it is surrounded by residential buildings which can pose a serious health risk to the residents. Previously, this was not an issue as the site was isolated from residential areas, it was built decades before the residential buildings around it were built. However, the area became occupied as the population grew.
Another limitation is the abundance of birds and pigeons around the landfill site. This presence of the birds is dangerous for numerous reasons. First, for health and safety reasons. The site contains organic waste which attracts them to the site and this is a limitation because the birds can carry waste or disease-causing pathogens to the residential areas, posing a greater risk to the residents. Moreover, the birds pose a threat to airplanes and can disturb the flight paths as the site is located near the Dubai International Airport.
Suggestions
In order to build advanced sanitary landfills with waste to energy facilities, the information gathered about Al Qusais landfill must be used and the limitations must be prevented. As previously mentioned, the landfill should not be surrounded by residential areas as it can pose health risks to the residents. Also, more attention needs to be payed in regard to the way waste is recovered and recycled from authorities. That is because as mentioned above, landfills have many risks such as air and land pollution to the surrounding areas. Moreover, we all hold responsibility to reduce waste, reuse more and recycle.
Bird Control for Dumps & Landfills. (2018). Retrieved from https://www.birdgard.com/bird-control-for-dumps-landfills
Landfill Gas Primer - An Overview for Environmental Health Professionals. (2010, November 01). Retrieved from https://www.atsdr.cdc.gov/hac/landfill/html/ch2.html
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