Reducers Break down chemical compounds to more simple species and thereby extract the energy needed for their growth and metabolism Chemotrophs Use chemical energy derived from oxidation-reduction reactions for their energy needs. Phototrophs Utilized light energy from photosynthesis. Autotrophs Use carbon dioxide and ionic carbonates for the C that they require. Heterotrophs Obtain their carbon from other organisms. Incidence of cancer Sediments Water quality, aquatic biota, wildlife Taste, odor, and color Esthetics Chapter 8 Methods to treat waste water Municipal water treatment Treatment of water for industrial use Sewage Treatment Primary treatment Consists of the removal of insoluble matter such as grit, grease, and scum from water.
Process involves screening and solids are scraped off and disposed of.
Grit Removal Practiced to prevent grit accumulation in other parts of the treatment system, to reduce clogging of pipes and other parts, and to protect moving parts from abrasion and wear. Process involves allowing the grit to settle in a tank under conditions of low velocity and then it is scraped mechanically from the bottom of the tank. Primary sedimentation Removes both settleable and floatable solids. Tendency for particles to aggregate, sometimes aided by the addition of chemicals. Secondary treatment Designed to remove BOD, usually by taking advantage of the same kind of biological processes that would other wise consume oxygen in water receiving the wastewater.