This Man Is Cleaning India's Polluted Rivers With A Clever Solution

It has been reported that 8 million tons of plastics enters the world's oceans every single year. Various sources put the amount of plastics being carried by River Ganga alone anywhere between 115,000 to 600,000 tons per year.

If that doesn't make you think twice about asking for a plastic bag every time you buy groceries, nothing will.

Google earth // Floating Trash Barrier (FTB) deployed in a canal in Thoothukudi (TN) draining into the Bay of Bengal

We must remember that most of the estimates around plastic pollution is an extrapolation of little primary data and there is bound to be large variance in the actual plastic numbers being discarded and finding their way into rivers and waterways. The situation is grim, no doubt.

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It's very easy to get pessimistic about the whole situation, but I like to focus on solutions we can implement and steps we can take to reverse the damage we are causing to nature -- and indirectly to ourselves in the longer run.

Developing an indigenous solution

The solution we developed was a floating trash barrier (FTB) which deployed in Cooum river in Chennai in 2017. This solution caught 22,000 tons of floating trash, of which 10 percent was plastics i.e 2200 tons of plastic in 2018 alone. We were able to catch 100 percent of surface plastics in this river, which was removed from the river and disposed off in an environmentally safe manner. This would have ended up in the sea, if not for the barriers. This exercise costed Rs 85 lakh in to deploy and absolutely nil operational expenditure for 24x7 securing of the full river width at nine locations.

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Once you decide to clean the river, one can be ambitious and arrest trash at zero operating expenditure. After all, you have flowing river water to do 99% of the job. The water-flow will bring the trash and plastics right up to your chosen spot on the riverbank. This chosen spot is usually where the stream crosses a road. You can bring excavators and tipper trucks once in a few days to remove it from the riverbank. No boats, no fuel and the low per ton cost of arresting and removing plastics from the streams is the achievement of using FTBs.

The floating barriers are passive devices guarding the whole river, 24x7 in rain or shine using natural flow of water. Placing boats with conveyors require fuel, work only few meters wide, in daylight without rain or fog. You can even configure to allow boats to cross while arresting the plastics. This solution sieves the solid waste on the surface while allowing the water to flow past. While seemingly a very simple design, this combines the best of hydrostatics and hydrodynamics. Made of steel and aluminium, this approach withstands the test of heavy monsoon currents as well.

This river clean up compares well with other ongoing attempts to clean the ocean plastics, contrary to spending millions of dollars and managing to recover only a few tons of plastics. Extrapolating these figures for 50 such rivers passing through cities and towns across the country before draining into the seas, we are talking of over 100,000 tons of plastics reaching the sea every year, and this excludes major Indian rivers.

The FTB of AlphaMERS deployed in Cooum river in 2017

It helps to look at the issues of streams and drains in three imaginary bins:

1. Solid waste clean up on surface

2. Silt transport at bottom

3. Water quality and liquid effluents

If you deal with solid waste on surface and silt transport at the bottom, the flow will become efficient, even though the water is still dirty and water quality poor. That is half the battle won.

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Improving water quality in flowing waters is a different challenge. Any water treatment takes time to take effect and the water travels meanwhile. It is smarter to control the liquid effluents at source, though today it may seem easier said than done.

2-1-2-3 dimensional journey of plastics.

The plastics leaks out of formal system, often due to apathy of citizens and sometimes due to overstretched municipal SWM infrastructure. These plastics spread on ¡®2 dimensional land¡¯ in roadsides, playgrounds etc, until the first big rain hits and these loose plastics land up in the nearest drain. It now moves in this single dimensional long journey from the drain to the stream, rivulet, and the river, until it reaches the river mouth. It now spreads again to a ¡®2 dimensional sea surface¡¯ until it breaks up into micro plastics and sinks into a 3 dimensional ocean water column.

Opting to arrest the runaway plastics during its single dimensional journey from drain to the river mouth is a ¡®no brainer¡¯.

Cleaning rivers may not have the ¡®oomph value¡¯ of setting out to clean the oceans, but is indisputably the most sensible. Shutting the taps before mopping the floor, it is called in common parlance.

Google earth // The FTB deployed in a city river passing populated localities.

Once you decide to clean the river, one can be ambitious and arrest trash at NIL opex. After all, you have flowing waters to do the job. The waterflow will bring the trash and plastics right up to the riverbank, due to the alignment of the floating barrier. You can bring excavators and tipper trucks once in two weeks to remove it from the riverbank.

Image below shows how the trash barrier is deployed diagonally, trash collects at one spot accessible from riverbank adjacent to a road, easy to collect and dispose. One does not need to place an expensive boat in the stream to pick it up and send it to the river bank once again. Simple configuration allows the boat traffic to cross while arresting the plastics.

The floating barriers are passive devices guarding the whole river, 24 x 7 in rain and fog using natural flow of water. Placing boats with conveyors require fuel, work only few meters wide, in daylight without rain or fog.

Google earth

Floating barrier deployed diagonally brings plastics and trash to riverbank at a location close to a road. It is picked off by excavators once a week from riverbank.

When in rivers and streams, let the flowing waters bring plastics to where you want to collect it, don¡¯t spend a penny on it.

Having said that, there is some basic design needs of such a device. A simple concept of drag force makes any solid impermeable curtains, a very irrational and poor choice. This application needs a ¡®sieve¡¯ which traps the macro plastics and lets the water flow past. That is why efforts using cheaper oil spill boom using impermeable coated fabric like PVC, Neoprene or Hypalon curtains fail in flowing waters. The last attempt in Mumbai in 2018 is a good example of this. The key differentiator here is the drag forces on a sieve versus the solid hanging curtain.

The excavator scooping up weed and trash trapped by the FTB to load on tipper trucks for disposal.

It brings media interest to make artefacts with recovered plastics. But when you recover thousands of tons of plastics, you need industrial customers. A smarter approach is to handover the recovery to the municipal solid waste management system who have a working system.

These efforts are good candidates for corporates to support with CSR funds and showcase the results in removing plastic waste from water bodies.

The FTB across a stretch of Adyar river in Chennai having trapped a lot of weed.

Ocean Cleanup

The expanse of the seas, the seasonal rough weather, the logistics cost in financial and carbon footprint terms, use of renewables, all these dots have to be connected very well to step into the sea for clean up.

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Any station in deep sea must be of a minimum size to survive and function. Costs to maintain such a station is enormous. We cannot process plastics on land to scale, leave along process it in situ at sea.

The distances are very large at sea. Removing macro plastics at sea does not justify taking large fuel guzzling vessels across thousands of miles unless the harvest of plastics is in thousands of tons.

A model using ocean renewables to move through the water and the ocean currents taking it to its unloading destination is the right way, but a wish list today. A very smart thinking is necessary that makes use of every ounce of ocean energy that can be squeezed out of the sea, be it tidal energy, wind energy or wave energy.

Trash coming from a stream from upper part of image trapped when joining a larger river

This 100% indigenous river cleanup technology was developed by us in 2014, saw commercial traction in 2017 and there has been no looking back since. We have deployed this solution in eight Indian cities out of which four have come in the ¡®Covid¡¯ year of 2020.

We will deploy this solution in two more rivers in the next few months. We have developed and deployed solutions for lakes, storm water drains and related issues in water bodies. We seriously believe we can be enjoying the perks of clean water bodies around us in the next five years. We believe, thousands of people will find their own way to make a difference. We are confident, many like us will develop technologies that are simple, yet are very effective. After all, India is a country of a billion plus thriving minds. Intellectual capabilities are per capita resources, better distributed around the world than oil resources.

And we are eagerly awaiting the day when our floating trash barriers are not required anymore, because the populace have learnt to take ownership of the water streams and have learnt not to throw trash in them!

Sekhar DC

About the author: Capt. D.C. Sekhar is an ex merchant Navy captain and alumni of IIM Bangalore. He is founder of AlphaMERS, a bootstrapped and profit making SME. He has developed solutions for river clean up, harvesting ocean wave energy, maritime perimeter security systems, besides robots for crude oil industry in a separate start up.