In many cities, wastewater travels through sewer lines to be processed at a wastewater-treatment plant. the treatment plant uses many methods to break down materials in wastewater and make sure materials are safe before release. which of the methods used during treatment is meant to promote the growth of bacteria so they can break down materials in wastewater?
a. burying of solid waste
b. heating of liquid waste
c. aeration of liquid waste
d. settling out of solid waste