question_answer 28)

  Which one of the following impurities is easiest to remove from wastewater? (a) Bacteria                         (b) Colloid                           (c) Dissolved solids          (d) Suspended solids

Answer:

                  Three types of impurities are found in waste water, suspended particles (solids). Colloidal impurities and dissolved material (inorganic and organic) like calcium, ammonia, toxic material, phosphate, sodium, calcium and nitrate. Out of then-, suspended solids like sand silt and clay impurities are easily removed, in sewage treatment plants.