here are plenty of options before landfills, which can be tried. Even though other options are also practiced often in our country, those are not satisfactory and are done on a very small scale
Wastes are a crucial part of our life. As long as there are lives, waste will be generated. What are wastes, actually? In general, we might say waste is something dirty, odorous that we always dump out.
But the scientific definition of waste is quite interesting. According to the European Waste Framework Directive, "waste" means any substance or object which the holder discards or intends or is required to discard.
For example, I have a pen and it becomes a waste from the moment I intend not to have it. It does not matter whether the ink is finished or not. However, if someone takes it from me then it is no longer something discarded. And so, it would not be a waste anymore.
Once a substance or object has become waste, it will remain a waste until it has been fully recovered and no longer poses a potential threat to the environment or human health. So, once waste is managed, it ceases to be waste.
Now, let us have a look at the waste management scenario in Bangladesh. The most practiced form of waste disposal here is "landfill". A landfill site can be defined as an area where waste materials are intentionally and systematically disposed of either on or under the land.
For instance, wastes of Dhaka city usually end in two landfills – one in Matuail and another in Aminbazar. Maybe, when we ordinary people talk about waste management in our country we also have a general perception: just take the waste and discard or bury it somewhere isolated. But the question is why always or directly to landfills?
The question arises from a concept called "Waste Hierarchy". In simple words, waste hierarchy consists of step by step options for waste management. If we fail in the first step then let's try the second one and then so on.
The best structure of the waste hierarchy is provided by the European Union. It is – prevention/waste minimization ˃ reuse ˃ recycle ˃ energy recovery ˃ disposal (landfills).
So, it is evident that there are plenty of options before landfills which can be tried. Even though other options are also practiced often in our country, those are not satisfactory and are done on a very small scale.
Residents of city or municipality areas usually discard waste in a dustbin. Then, waste-carrying trucks collect the waste and finally take them to landfills. In rural areas, dumping is often not environment-friendly.
Therefore, our first target should be preventing the generation of wastes. How can we do that? An example is provided here. Single use disposable glass/plates are popular in our country for picnics or parties, as there is no hassle to wash them. But once we use them they have to be discarded, and therefore they turn into waste immediately. And, often we do not discard them in a proper way. We can see those things sometimes creating clots in drains or being smashed beneath our feet on the road. These materials are harmful to the environment. If we avoid using them and use glass or melamine plates instead, that would surely prevent the generation of these wastes. This would also save the money required to buy or treat them.
If we fail to prevent or minimise waste the next option is "reuse". Whenever we use something, we can try to reuse them as some different products afterwards.
Let us think about a yogurt pot. After yogurt is finished, the pot can be used as a flower tub. This is something related to creativity. We often see our young girls doing these things at home, creating designs from eggshells or doing crafts from waste. We should inspire them more and more.
This is not only a waste treatment option but also an opportunity for employment or entrepreneurship.
The next option "recycling" is also some sort of reusing, but it is mainly converting things to raw materials or the same product again. Take for example a glass bottle of soft drink Coca Cola. After we drink, we give the bottle back to the shop. However, nowadays, we prefer mostly plastic bottles for comfort. This is adding a great amount of waste to the environment. For our little comfort today, we might have to pay a huge price in future.
The step that comes after recycling is "energy recovery" or "waste to energy". Wastes can be converted to energy in many ways, mainly by biological and thermal treatment methods.
Biological treatment methods include anaerobic and aerobic digestion. Anaerobic digestion (AD) is a very popular method for waste management all around the world. We can get biogas by the microbial degradation of bio wastes. In our country it is practiced in the rural areas. But due to a lack of proper scientific knowledge, the output is not satisfactory. Developed countries take source-separated kitchen wastes and many other biological wastes to commercial plants. A substantial amount of electricity can be produced from biogas and be injected to the national grid.
Landfill is also a sort of anaerobic digestion technology, as wastes get degraded below the ground in absence of air. Solid residues or digestate from AD is used for agriculture, which can serve our agriculture well.
Aerobic treatment includes composting. We do it at our rural level as well. Compost as well as heat energy can be extracted from it. But, as wastes mix up ultimately with soil, composting is often thought of as a recycling step. Composting should be practiced more in the urban areas, especially on the rooftop for gardening. This will help to retrieve the green nature of the city and reduce carbon emissions.
Thermal treatment includes incineration, gasification and pyrolysis; where bio-oil, synthesis gas, ash or heat energy can be produced.
Energy from waste is now a very popular concept. Because of our big population, biological waste generation is high in the country. This is really a great opportunity for us. The prime energy source for Bangladesh is still natural gas, 60% of the electricity is generated from it. But, gas might get depleted by 2031, according to experts. Bio-energy could be an alternative in the future to tackle the energy crisis.
To sum up, landfill is undoubtedly a very good scientific option for waste management. There are lots of hazardous wastes for which this is the only option. But, other types of wastes should be treated differently as there are more options. This will reduce the cost, create employment, produce energy and make the environment cleaner.
Moreover, pressure on the landfills will also be reduced. The Aminbazaar landfill is already having functioning problems with questionable performance. Hence, the government should ponder on the issue and take necessary steps in this regard. The people also should learn more about sustainable waste management. Thus, we will be able to protect the green nature of our country.
The author is a lecturer of environmental science and disaster management, Daffodil International University. Email: [email protected]