Multiple choice Why are some microbes used in sewage treatment? They enhance soil fertility. They cause diseases. They are used to degrade the organic wastes present in the medium. They cause spoilage of food. They help to make dough rise. Reveal answer Fill a bubble to check yourself C Correct answer Explanation Such microbes help to degrade the organic wastes present in water, reducing their BOD or polluting potential. This feature is made use of in STP's (sewage treatment plants).