1) Which of the following are natural filters which are used for treatment of sewage waste?
1) Sand
2) Gravel
3) Plants
a. 1, 3
b. 1, 2
c. 3
d. All of the above
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Answer
Explanation
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ANSWER: All of the above
Explanation:
- India and the European Union have developed a cost-effective technology for treatment of sewage waste for irrigation, especially in rural areas, using natural filters like sand and plants.
- The project involves collecting the sewage waste before it reaches the water bodies and then treat it using natural filters like sand, gravel, pebbles and plants to remove the impurities.
- Under the project, many wetland plant species, such as Canna indica, lemon grass, napier, para grass, typha, water hyacinth, water lettuce and a weed species Agaratum conyzoides, have been identified for purifying the wastewater.
- They are helpful in reducing the nutrient load in the free-water-surface and sub-surface constructed wetlands. The project has been undertaken in Karnataka,Maharashtra, Telangana, Uttar Pradesh and Madhya Pradesh.
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