POST TIME: 10 July, 2019 00:00 00 AM
Environment friendly waste management in coal-based power plants
Presently Bangladesh government is giving special attention on coal-based power plant as they feel the need of coal-based electrical supply for maintaining the growing population demand
Polin Kumar Saha

Environment friendly waste management in coal-based power plants

Energy sources for the developing countries such as Bangladesh still require the demand of coal-based thermal power plants. But this type of plant mostly performs in lack of environmental management requirements. As the disposal of the increasing amounts of solid waste is becoming a serious concern to the environmentalists, where such plant produces huge amount of coal ash, 80% of which is very fine in nature and is thus known as fly ash is collected by electrostatic precipitators in stacks. Fly ash is largely responsible for environmental pollution. In developed countries like Germany, 80% of the fly ash generated is being utilized, whereas in Bangladesh most of it is not utilized.  However, if we yet to continue with a demand of energy supply from coal based plants, we should be very careful of the environmental management of solid waste produced by the plant. In principle, we must follow some processes in all of our solid waste management: collection, transportation, disposal or recycling and monitoring of the waste. This term is assigned to the waste material that is produced through human being activities. The material is managed to avoid its adverse effect over human health and environment.

As the organic mixtures of coal combust, adiversity of solid wastes isproduced inside the boiler from unburnt carbon and other inorganic components. These solid wastes are identified as coal combustion products. Ash is the key solid waste come from the coal-based thermal power plant. The waste contains fly ash, bottom ash and boiler slag. Fly ash is a by-product of crushed combustion in thermal power plants, where Fly ash particles are characterized as light, likely to get airborne and contaminate the atmosphere.

On the other hand, depending on the source (type) of coal the emissions from the burned coal contain pollutants such as sulfur dioxide (SO2), sulfur trioxide (SO3), nitrogen oxides (NOx), particulate matter (PM), condensable PM, mercury (Hg), trace metals and radioactive nucleoids. When we inhale contaminated air with those substances; lead, cadmium, chromium, arsenic, silica in coal ash can cause damage to nervous system, lung diseases, kidney disease, high blood pressure, delays in development, swelling of the brain, hemoglobin damage.

Presently Bangladesh government is giving special attention on coal-based power plant as they feel the need of coal-based electrical supply for maintaining the growing population demand. The completed coal-based power plant is Barapukuria power station. But the power plant was shut down after the discovery of Barapukuria coal scam in 22 July 2018, due to acute shortage of coal. But there are several coal based power plants in Bangladesh under construction. Among them notable ones would be Matabari power station (1200MW), Payra thermal power plant (1320MW) and Rampal power plant (1320MW). All these are not only being constructed by government but also involve international, private sectors and stakeholders.

From studying their monitoring reports, it can be inferred that waste management activity is given less/no importance. Unfortunately, coal industries of Bangladesh have not managed fly ash yet in line with the requirement of environmental sustainability. As coal wastes can be recycled or disposed we may adopt some strategies for waste management similar to those taken in developed countries who are already involved in coal-based energy production.  Below are few suggestions as to how they may make use of fly ash so it does not go in waste.

Enactment of appropriate legislation: The problem of fly ash is common to all the industrial nations of the world. But they have successfully tackled the problem of fly ash disposal due to enactment of law. Many countries, including our neighbor India, have executed laws limiting the period of storage of fly ash. This has led the industries to consider utilization of fly ash seriously. As a result, the fly ash utilization rates are progressively increasing in India, increasing from 1 million tons in 1994 to 45 million tons by 2005. Similar trends are observed worldwide. But due to lack of such legislation in Bangladesh, no such alternatives are yet being considered and the dry storage of fly ash is constantly threatening the environment. Appropriate legislation to regulate fly ash emission and utilization should be the top most priority in industrial sector, as it will force the industries to change and recognize this impending threat.

Embankments: Fly over embankments and roads can be potential areas for effective usage of fly ash. As example in India, recent embankment constructions with fly ash has formed an economy over mining and transportation cost saving. Apart from economy, the usage of fly ash in road embankment mayenclose the fly ash into earth, segregating it from rainwater and dismissing the risk of metal leeching. Thus the process of fly ash use in embankments will bedecreasing pollution.

Utilization in concrete and cement: Fly ash, being pozzolanic in nature, is a substitute of cement in concrete. Fly ash reduces the problem exposed by free lime in concrete and sorts the concrete durable. Additionally, it performs as a substitute of cement in concrete, returnable cost and potentialityin concrete greener by cutting down CO2 production. The practice of using fly ash in concrete should be encouraged in Bangladesh without hesitation.

Manufacture of Bricks: Fly ash bricks can demonstrate to be an important addition in environment friendly construction materials. Almost all bricks manufacturing in Bangladesh playwith the conventional method of using clay, which is very harmful in conserving our soil quality. However, Fly ash bricks are beneficial in many forms of conventional bricks in advance with higher strength, lower penetration of water etc. The unburnt carbon of fly ash saves energy cost by delivering fuel for burning.

Interminable supply of power and energy is the prerequisite for the progress of an economy. The importance of energy is even more supplementary in the context of Bangladesh, an emerging economy that has been experiencing rapid economic growth but also has been experiencing prolonged period of energy crisis. Power Crisis has been a long clamor in Bangladesh and this seems to persist for the coming decade or so.

In order to match the accelerated need of country towards a developed country, there is exigency to take the sustainability challenges to adjust the time and cost required to complete a coal based power project. Therefore, any upcoming projects also needs to be environment friendly with proper management of waste so that the project like coal based power plant even would not be a threat to us.

The writer is environment expert