Waterwise Property Plus

Tackling detergents in water bodies

It seemed like a Bollywood movie-set but was a main road next to the Varthur lake. Foam was billowing and floating around and the landscape seemed surreal. Immediately it has made news all across India as citizens are agitated by what they see as the utter destruction of their lakes.

What causes the foaming? In our homes and apartments detergents have made a rapid entry as shampoos, soaps, clothes wash powders, utensil wash soaps and liquids and even toilet cleaners.

Now these detergents need to do many things in a sequence. They have to first remove the dirt, oil and dust from the clothes, keep them from reattaching back and finally wash them away. This will make clothes whitest, hairs shiniest and utensils brightest, meeting our aspirational needs.

Detergents have also to work in all water conditions. As increasingly water becomes hard all over India, the first things that detergents have to do is to make the water soft else it will not lather. So phosphates are added which bond with calcium and magnesium present in the hard water and make it soft.

Then surfactants kick in. Made of alkalis and petrochemical products such as sodium and potassium hydroxides as well as sulphur trioxide and mild sulphuric acid. These surfactants adhere to the dirt stains and oil and remove them and keep them from re-adhering by foaming agents.

On agitation such as in hand-washing or in washing machines these foaming agents and surfactants clean up the stain and dirt. Hot water helps further in the cleaning process. As you can see detergents are complex substances which have to deal with an end result where the original environment is not necessarily known such as the hardness of water, the amount and nature of dirt etc.

After the washing of the hair or the clothes or the utensils the detergent is now in the environment. This water contains phosphates which is a limiting nutrient for many water bodies. Once the phosphates reach a lake or a stagnant water body it can result in an explosion of algal, water hyacinth, water weeds and other growth, thus eutrophying or killing a water body by depleting it of oxygen.

On the other hand the surfactants and foaming agents, when agitated in certain warm atmospheric conditions such as while falling from a waste-weir of a tank or dropping through a sluice valve, can start to foam. This is what we see in the lake at Varthur or Bellandur in Bengaluru or near the Byramangala tank.

So what can be done about the foam and how can it be avoided? The first thing is to realise that the foam is a symptom of a problem. The problem being the excessive presence of detergents in water without them being treated adequately. A well functioning sewage treatment plant followed by a constructed wetland can completely eliminate the phosphates and foam. Each and every one of our lakes should have a small well-functioning waste-water treatment plant followed by a wetland so that the waters stay alive and clean.

At the individual level one can use alternatives to detergents such as soap-nut or soapberry-based products or borax-based products. These will be less harmful on the water environment. One can also think of reusing the washing machine and bath water for plants and the garden if one has one though only certain plants such as the canna or the banana can absorb and deal with detergent water. At an apartment level, well-functioning STPs which reuse the water for flushing and gardening purpose can minimise the negative impact on the environment.

Under the Extended Producer Responsibility principle, manufacturers of detergents can work at improving their products such that they do not kill water bodies. Stringent regulation on the sector will also help.

Eventually we will as a society have to pay the true price of water, which means the price at which it is treated sufficiently to return back to nature at the same condition and quality that it was appropriated.

We will also have to demand from product manufacturers and institutions responsible for treating waste-water that they do their job diligently and with full accountability. Only then will we not see foaming lakes and rivers. That will be water wisdom.

Related Topics
This article is closed for comments.
Please Email the Editor

Printable version | Mar 1, 2021 10:07:33 AM | https://www.thehindu.com/features/homes-and-gardens/tackling-detergents-in-water-bodies/article7161992.ece

Next Story