How is wastewater from coal washing, containing approximately 3% suspended solids like clay, slate, and stone, treated to remove solid particles?

Explanation

Wastewater from coal washing that contains about 3% suspended solids such as clay, slate, and stone is typically treated in sedimentation tanks equipped with mechanical scrapers. These tanks allow the solids to settle while the scrapers continuously remove the settled particles, making option B the correct method. Other methods like chemical coagulation, vacuum filtration, or clarifiers are not as effective for this specific concentration and type of solids.