Getting Use Out of Waste
Tejaswini Eregowda says, if treated right, waste can turn into energy, rare minerals, and more.
Population. Over-population. Pollution. The story we now know better than the fairy tales of childhood. Human numbers are beyond 7 billion and climbing. Our resource consumption is shooting up like skyscrapers. But something lurks behind these skyscrapers, hidden in trenches and dumps, swirling in the seas, always pushed out of sight… The silently rising garbage piles that might soon take over the skylines — and fill the oceans. We have to face the problem. What can be done?
Tejaswini Eregowda is a PhD fellow at IHE Delft Institute for Water Education in Delft, the Netherlands. Her research deals with this very problem. “If the population were about a billion,” she explains, “we could let the waste flow unchecked into the lakes and rivers. And let nature deal with it in its own time.” Since that isn’t an option (sans an apocalypse), waste treatment is indispensable.
“An industrial plant without a waste treatment unit is like a house without drainage. The waste has to go somewhere!”
It is an expensive process, however, and one that might not find many investors. “When you have to treat waste, you always have to put in resources for it — you have to build the facility, supply electricity. I wouldn’t want to put money there, because it’s a dead investment. But if there is something coming out of it that is valuable, then it can be economical. That is what our research is focussed on: what you can recover from waste.”
Waste to energy
How is it done? Tejaswini gives an example from her specialty — the paper industry. “To make paper out of wood pulp, you need to separate the fibres that make up the paper, from a gummy substance called lignin. In this process, a lot of methanol is produced, which, if extracted, could be used as a fuel.”
A similar example, already in practice, is seen in the “gobar” gas plants of India. Cow dung (gobar) is used to produce biogas, which then serves as a cooking fuel for over 2 million households in India. Considering the low cost involved and its ubiquity, the positive impacts on the rural economy and employment have been huge. There is more yet to find in the waste, and researchers are exploring.
Resource recovery from waste
In her work, Tejaswini often finds that two problems can solve each other, if they can be put together.
Case in point is selenium, a rare mineral mainly used in the production of glass. The exploration and mining of this mineral are cumbersome and expensive (“tons of earth to get a few grams”). Paradoxically, the selenium in the waste streams of the glass industry is unwanted, even toxic in excess. If this selenium could be extracted profitably, the benefits would be twofold.
A similar case can be made for the phosphates used to make fertilizers. “To be honest, we are running out of phosphates,” Tejaswini worries. “There are very few places to get them from. And on the other hand, in the canals of Delft, excess phosphates cause algal blooms, which are harmful for water life.” She continues to search for effective ways to resolve these paradoxes.
French fries and pigs
The idea of letting two problems solve each other can be used in waste treatment as well. Often, the process requires the presence of substances that the waste stream is deficient in. A stream from making French Fries, for instance, would be deficient in nitrogen. Enter pigs and chicken.
“The waste from poultry and pig farms (basically the poop) is rich in nitrogen. It is deficient, however, in carbon.” What has carbon? Right, French Fries. “If these two steams are combined, both have what they need.”
The big picture
So why aren’t these waste treatment options a big thing already? Again, the trouble lies in the investments needed. Tejaswini is firm:
“The problem is only in the short term. If you setup a biogas plant, for example, the payback time is about 5–6 years. You get your investment back in that time.”
A big-picture perspective is required. “It’s unfortunate that the world we live in today defines ‘benefit’ only in monetary terms.The real benefits come indirectly — in the form of a cleaner environment, more hygienic surroundings — the welfare of earth, air, and water.”
We are cornered.
If the resources run out, “we can’t go to Mars,” she finishes.
Watch a short video on waste-to-energy:
Meet the scientist
Dr. Tejaswini Eregowda is an expert on resource recovery from waste. This interview was conducted on October 21, 2018 when Dr. Eregowda was a PhD fellow at IHE Delft Institute for Water Education in Delft, the Netherlands. She has, since, obtained her doctorate, and currently works as Research Scientist at Karnataka State Pollution Control Board Bangalore, India.
Read more of her research here: Dr. Tejaswini Eregowda
