The amount of municipal solid waste (MSW), commonly known as garbage, is increasing year by year. If not properly managed, it will cause serious environmental problems such as groundwater and air pollution. For instance, households in Kuala Lumpur generate nearly one million metric tonnes of MSW per year. For Malaysia as a whole, MSW generation is around 10 million metric tonnes per year.
What are the options available to us in managing MSW? Confronted with this question, for most of us who are aware of this issue, there are only two options: sanitary landfill or incinerator.
A sanitary landfill is an excavated site with a protected bottom containing solid waste undergoing slow biodegradation. On the other hand, incinerators are containers for burning solid waste at high temperatures.
Considering land area requirement, for the same amount of waste, a sanitary landfill requires a significantly larger land area compared to that needed for an incinerator. If this is the only factor for our consideration, incinerators are the right choice.
But obviously, there are other factors worth considering. Cost is one of them. Taking cost into consideration, an incinerator would be costly compared to a sanitary landfill. Firstly, for 1,000 metric tonnes per day of MSW treated, the installation cost of an incinerator would easily be in the price range of RM700 million to RM900 million. The cost of a sanitary landfill, on the other hand, is a quarter of that.
Secondly, the tipping fee (paid by the government to waste treatment plant operators) for a sanitary landfill would be about RM50 per metric tonne of MSW. The tipping fee for an incinerator could be four to five times higher than that for a sanitary landfill.
Another factor requiring serious discussion is the composition of MSW. MSW contains about 40% food waste, 20% plastics, 15% papers and 25% other materials including aluminium and glass. The moisture content of local MSW is greater than 60% by weight.
Because of its high moisture content, local MSW adversely affects the performance of incinerators. The high moisture content prolongs the drying process of solids in incinerators. On the other hand, the moisture content of MSW in industrialised countries is lower, less than 40%. Based on this information, it can be said that while incinerators are practical for industrialised countries, they are not so for Malaysia.
There is yet another factor requiring our attention. Of all the factors, the one causing the most worry to residents in the vicinity of an incineration facility is the emission of hazardous pollutants.
Although incinerators with modern flue gas cleaning systems are capable of reducing emissions of heavy metals and toxic chemicals such as dioxins and furans to a very low level, environmental concerns associated with dioxins remain.
From the technical point of view, catalytic systems can remove dioxins of up to 99% but its high investment cost and operating cost limits its use.
Problems arise when incinerators operate at sub-optimal conditions and when the flue gas cleaning system is not well maintained.
In discussing the environmental concern, it is fair to say that dioxins are highly toxic. According to the World Health Organization, dioxins can cause reproductive and developmental problems, damage the immune system, interfere with hormones and also cause cancer.
Based on the above discussion on environmental concerns, it is justified to suggest that there is a need for continuous monitoring of emission of dioxins from incinerators.
There is also another option worth considering: a MSW sorting and biogas plant (MSWSBP). Since this technology is within the reach of local expertise to design and build, why is it not popular in Malaysia?
Compared to incinerators or even sanitary landfills, MSWSBP is cost-effective and environmentally friendly. It is cost-effective because it is revenue generating from the recovery of valuable materials. The organic portion of MSW (about 40% by weight) produces biogas (about 65% methane) and organic fertiliser. Because biogas plants (closed tanks) operate at ambient temperature, it does not give rise to hazardous air pollutants. From this perspective, it is more environmentally friendly compared to the other two options.
For MSWSBP, household waste sorting at the source is not necessary. This saves the trouble of having separate containers for food waste, plastic, aluminium cans, glass and paper.
It is also worth mentioning that MSWSBP fully supports the 4R principle (reduce, reuse, recycle, recover), reduction of greenhouse gases and sustainable development. It also reduces the volume and weight of waste to be land-filled.
In my opinion, MSWSBP is a better option considering that its cost is significantly lower than that of incinerators and its land area requirement is significantly lower than that of sanitary landfills. Furthermore, MSWSBP can be locally developed, and as such, there will be no need for foreign consultants and imported technology.
Nordin Abd Kadir Bakti is a consultant and FMT reader.
The views expressed are those of the author and do not necessarily reflect those of FMT.