Sewage treatment is the process of removing contaminants from wastewater and household sewage. it includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants. identify the positive effects of sewage treatment on the environment? a) to provide jobs in america b) protection to the public health from the spread of diseases c) to preserve the natural environment by controlling water pollution d) to preserve the natural environment by controlling water pollution and protection to the public health from the spread of diseases