The traditional 'Three R's' that form the cornerstone of waste management and help us conserve natural resources for the long term are:

Which of the following is the safest and most standard industrial method for disposing of toxic dust?

Arrange the following statements in the correct order to indicate the processes involved in a wastewater treatment plant. (A) Sludge is scraped out and a skimmer removes the floating grease. (B) Large objects like plastic bags are removed by passing wastewater through bar screens. (C) Water is made to settle in a large tank with a slope in the middle. (D) Sand, grit, and pebbles are made to settle by decreasing the speed of incoming wastewater. (E) Wastewater enters a grit and sand removal tank.