Chapter 13 Water Pollution Water pollution Degradation of

Chapter 13: Water Pollution

Water pollution Degradation of water quality biological l chemical l physical l

Pollutants nutrients l l phosphorous nitrogen (blue baby syndrome) oil toxic substances l l l hazardous chemicals heavy metals radioactive material sediment thermal

Pollutants Biochemical oxygen demand mg/l of O 2 consumed over 5 days at 20°C l agricultural runoff - nutrient l sewage l pathogenic organisms human disease - cholera and typhoid l Fecal coliform bacteria l l threshold 200 cells/100 ml water

pollutant migration source route target

Pollution source point l non-point l state dissolved l not dissolved l sediment borne l release - long term vs single event

Surface water pollution routes direct l washed in l seepage from banks l fate deposited l diluted l consumed l evaporate l

Surface water pollution effected targets water supplies l fisheries l ecosystems l remediation eliminate source l excavate sediment l treat water l

Groundwater pollution route seepage l leaching l fate dissolves and disperses l LNAPLS - floats l DNAPLES - sinks l vaporizes l attaches to earth materials l

Groundwater pollution effected targets wells l surface water l remediation process site characterization l risk assessment l corrective action l

Groundwater pollution: treatment remove source clean (impossible? ) GW extraction - smearing wells/trenches l vapor extraction l sparging l bioremediation l treatment beds l

Saltwater intrusion near coast fresh water floats on saltwater rises drought l withdrawal of fresh water l desalinization (expensive)

water quality standards set by government basis science l economics l ethics l politics l

Wastewater treatment dilute & disperse large-scale treatment septic tank alternatives