An article contributed by Capt. D. C. Sekhar [email protected]

a. Is the water moving like a stream or river? Yes ? Then do not spend a drop of fuel to arrest the floating debris. The water will bring the solid waste to where you want to remove it. Use passive floating barrier near a road / crossing.

b. Stationary waters like a lake ? Install floating barriers in the lake inlets. Most lakes are fed from inlets from SWDs and there is always a little water movement here. Stopping the debris here requires no fuel. Removing it is convenient, unlike when this debris enters the lake and spreads all over.

c. Once you have stopped solid waste entering the lake, surface looks clean. But if the waters are polluted with untreated black and grey waters, you will have weed growing all over the lake. Sweep the floating weed to one side of lake where you have land based gear to remove it. Do not lift these floating matter into the boat and again empty it. It is waste of energy (fuel).

d. Usually such floatsam lies to one edge of the lake. You need low draft (depth) boats that can move in low available lake depths, along the edge of the lake and its propulsion is not fouled by the plants. A ‘Tandem Sweeping System’ with two boats and a boom between them, clears 10 meter wide patch in one sweep. A single operator version saves you one operator for this ‘Tandem Sweeping’.

e. A floating curtain is handy to guide the polluted waters from the inlets, towards an area where you have wetlands to treat it. This is necessary until functioning STPs come into existence.

f. Aerating lakes to improve BOD/ DO as a reaction to treat polluted water is a thankless job, due to the sheer volume of water and the fuel and opex associated with it. Upstream STPs are the only practical answer.

g. Fountains are great cosmetically, but are not very energy efficient to aerate the lake.