No short cuts to clean water

I HAVE been asked by many quarters, be it the laymen, media and even fellow academics, regarding the state of river pollution in Malaysia and why isn’t something immediate being done about it.

The most common question is: Why not develop a technology to treat river water? A technology that will remove all pollutants from the water and make it crystal clear again?

While this may seem to be a logical and straightforward course of action, it is not quite that simple.

Rivers flow from upstream to downstream and polluted river stretches are usually located downstream, after receiving input from various pollution sources.

Let’s say a treatment technology was applied downstream, the subsequent reaches may become cleaner, but the location upstream of this point would remain polluted. Fish and other aquatic life will continue to suffer.

The volume of water is also huge (particularly the downstream stretches), hence the corresponding structural costs would be equally monumental.

Rivers in Malaysia have been taunted as being teh tarik (murky) in appearance. This is due to the elevated levels of earth, sand, silt etc; these materials are collectively referred to as “suspended solids”.

On-site removal of these solids via gravitational settling (a very basic form of treatment technology) would have monumental cost implications and there are no obvious immediate economic returns.

In addition, the removed solids still need to be disposed of, which is another cost factor. While physical appearance may improve with the removal of the solids, the water may still be polluted.

It is important to remember that water pollution does not only constitute a murky appearance, but other things as well, such as elevated levels of ammonia, organics and bacteria. These are not visible.

A case in point is the closure of the Cheras Batu 11 and Bukit Tampoi drinking water treatment plants in February due to elevated levels of ammonia.

Besides this, there is always the possibility of increment in pollution load due to future developments.

Engineering wise, this is an important factor, as any treatment system requires a design basis. Without it, variations would be incurred and this would inevitably affect the treatment efficiency.

In other words, if the pollution load were to increase beyond the treatment capability, the system will fail. These factors make treatment of river water (for rehabilitation) impractical; at best it can only serve as a temporary remedial stopgap solution.

Understandably, the previous water rationing has caused many quarters to scour for quick solutions and fixes. In terms of water supply, it may be plausible to use membrane filtration in Drinking Water Treatment Plants (DWTPs) although this is an “end-pipe” solution.

More importantly, pollution sources/load needs to be reduced. Pollution not only affects us but the environment as well.

Reduction in the pollution load is the only sustainable measure to improve the water quality of rivers and other surface water bodies.

As a society, we need to learn to be in harmony with the environment instead of trying to conquer it.

This is not the first time we had to pay for our naivety.

In the past, channelisation (straightening) of urban streams and rivers for flood mitigation had caused the destruction of many aquatic ecosystems. Straight, instead of natural, meandering rivers allow water to drain faster (during rain). Unfortunately, fish and aquatic creatures cannot survive when water is flowing so fast.

The irony of it, while floods may have been mitigated in some areas, other locations actually incur flooding when previously there was none.

This is just one example.

To secure a future for our children, we have to humble ourselves. We need to stop thinking that we can do a better job than what the Almighty has “designed”.

We need to accept this fact and reduce pollution. This is the only way to go.

ASSOC PROF DR ZAKI ZAINUDIN

Faculty of Engineering

International Islamic University Malaysia