R

ecently much attention has been given toward the foul odor coming from the Sentiong River, better known as Kali Item, in Jakarta. The unwanted attention is due to the river’s proximity to the Asian Games venues and lodging houses for athletes.

Contaminated rivers such as the Sentiong are known as “black-odor rivers”, which turn black and produce an unpleasant odor. These rivers are becoming more and more ubiquitous in urban areas, mainly blamed on increasing urbanization rates followed by inadequate infrastructure and public education.

The foul odor from Kali Item and other black-odor rivers comes from a combination of organic and inorganic substances such as ammonia-nitrogen and total phosphorus.

It is difficult to pinpoint a single substance as the culprit of the smell and color. In fact, previous research mentions an apparent synergistic interaction between the polluting substances, chemical oxygen demand and biological oxygen demand in polluted waterways that worsens the smell.

The bulk of pollutants in the Sentiong River allegedly comes from the tempeh industry.

To mitigate the problem, several actions have been taken by the municipality. One action is the use of biotechnology, in this case the use of microbes, to remove the foul odor from the river.

The use of microbes to clean up polluted rivers has been given much attention during the past decade, from cleaning up rivers contaminated with organic material (such as Kali Item) to cleaning up waterways contaminated with oil spills.

Different microbes have different abilities in degrading pollutants, attributed to their metabolism, mainly the enzymes they produce.

In the case of Kali Item, microbes such as the white rot fungi and Lactobacillus were used to good effect. White rot fungi produces the enzyme laccase, which can break down phenol rings, the main compound in many coloring dyes.

Meanwhile Lactobacillus is known as a probiotic with many health benefits besides its well-known ability to produce lactase, the enzyme responsible for converting milk into yoghurt.

The bacteria also produce proteases, peptidases and other enzymes that can help degrade pollutants in the waterways. After several days, the foul odor from Kali Item reportedly somewhat faded.

This is not the first time microbial technology has been used for cleaning up rivers. Another example is Chengnan River in China, also a black-odor river. An even more complicated mixture of microbes was used to successfully return the color of the river close to its original state.

Despite its potential, many have questioned the safety of this technology. Is it safe to release large amount of microbes into the waterways? This is actually a difficult question to answer.

But three things can be pondered upon: 1) The microbes released into the waterways are non-pathogenic (they are not known to cause any diseases); 2) Microbes depend on the media in which they live. As soon as their food depletes, they will also deplete and automatically become in balance with the ecosystem; 3) In clean waterways, the microbe diversity is relatively high, and man-made pollution causes that diversity to deplete, which in turn causes the waterways to lose their ability to self-remediate.

Thus, generally speaking, the release of these microbes might even improve the quality of the environment.

The publicity received for the remediation of Kali Item using microbial technology is good news for biotech research-based innovation in Indonesia. Such efforts have had a lack of exposure in the past.

Hopefully the current events will trigger more use of research-based innovations in other aspects in Indonesia.

So can we trust microbes to clean up our mess? There is definitely big potential for it.

In fact, they might be of help in cleaning the colorful waterways near batik production facilities in Cirebon and Pekalongan in Central Java, or help normalize the terrible smell of waterways near leather processing industries in the otherwise pretty landscape of Garut in West Java.