Water Quality and Treatment - Lecture

Water Quality Standards

• How safe is our drinking water?

  • over 90 contaminants by EPA

• How contaminants are measured

  • ppm: parts per million

  • ppb: parts per billion

  • ppt: parts per trillion

• 1974 Safe Drinking Water Act

  • MCLs: maximum contaminant levels

    • highest level of a contaminant that is allowed in drinking water

  • MCCGs: maximum contaminant level goals

    • maximum level at which a particular contaminant is not expected to risk health

• Major health threats

  • 1. Coliform bacteria

    • indicates that water might be contaminated by harmful disease-causing organisms

  • 2. Nitrates

    • threat to young children

Water Treatment

• Drinking water is chemically treated, filtered, and disinfected

• Wastewater

  • includes water that carries sewage from households, manufacturing and storm runoff

    • rural areas use septic tanks

Wastewater Treatment

• Urban and suburb areas

• Sewer systems carry wastewater to treatment centers: inlfuent

• A. Primary Treatment

  • physically removes contaminants in settling tanks

• B. Secondary Treatment

  • water is stimed and aerated

    • aerobic bacteria degrade organic pollutants

• C. Anaerobic Digester

  • sludge (solids) sent here where anaerobic bacteria break it down into bio solids

    • used as fertilizer by farmers

• D. Sanitation

  • water is treated with chlorine and/or UV light to kill pathogens

• E. Effluent

  • final water released back into rivers or oceans

In Class:

• Influent: water coming in

• Effluent: treated waste water (still not safe to drink)

• Pharmaceuticals, microplastics, …, are not safe to drink and difficult to remove from water