Water Treatment Wastewater Treatment APES Types of Treatment

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Water Treatment Wastewater Treatment APES

Water Treatment Wastewater Treatment APES

Types of Treatment • Water Treatment: prepares water for use in homes, businesses (drinking

Types of Treatment • Water Treatment: prepares water for use in homes, businesses (drinking water) • Waste Water Treatment: prepares sewage/wastewater to be returned to the environment

Water Treatment Stages 1. Screening 2. Aeration 3. p. H correction 4. Coagulation and

Water Treatment Stages 1. Screening 2. Aeration 3. p. H correction 4. Coagulation and flocculation 5. Sedimentation 6. Pre-chlorination and dechlorination 7. Filtration 8. Disinfection 9. p. H adjustment isis. csuhayward. edu/alss/Geography/ mlee/geog 4350/4350 c 4 f 01. ppt

Initial Stages • Screening - the removal of any coarse floating objects, weeds, etc.

Initial Stages • Screening - the removal of any coarse floating objects, weeds, etc. from the water. • Aeration - dissolving oxygen into the water to remove smell and taste, promote helpful bacteria to grow, and precipitate nuisance metals like iron and manganese. • p. H correction - preparing for coagulation and to help precipitate metals. isis. csuhayward. edu/alss/Geography/ mlee/geog 4350/4350 c 4 f 01. ppt

Major Clean Up • Coagulation and flocculation - causes the agglomeration and sedimentation of

Major Clean Up • Coagulation and flocculation - causes the agglomeration and sedimentation of suspended solid particles through the addition of a coagulating agent (usually aluminum sulfate and/or iron sulfate) to the raw water along with a polymer to help form a floc. • Sedimentation - Floc settles out and is scraped and vacuumed off the bed of large sedimentation tanks. Clarified water drains out of the top of these tanks in a giant decanting process. • Pre-chlorination and dechlorination - mostly to kill algae that would otherwise grow and clog the water filters. Also kills much of the remaining unprotected bacteria. isis. csuhayward. edu/alss/Geography/ mlee/geog 4350/4350 c 4 f 01. ppt

Coagulation • Rachel Casiday, Greg Noelken, and Regina Frey, Washington University (http: //wunmr. wustl.

Coagulation • Rachel Casiday, Greg Noelken, and Regina Frey, Washington University (http: //wunmr. wustl. edu/Edu. Dev/Lab. Tutorials/Water/Public. Water. Supply. html) isis. csuhayward. edu/alss/Geography/ mlee/geog 4350/4350 c 4 f 01. ppt

Sedimentation • Rachel Casiday, Greg Noelken, and Regina Frey, Washington University (http: //wunmr. wustl.

Sedimentation • Rachel Casiday, Greg Noelken, and Regina Frey, Washington University (http: //wunmr. wustl. edu/Edu. Dev/Lab. Tutorials/Water/Public. Water. Supply. html) isis. csuhayward. edu/alss/Geography/ mlee/geog 4350/4350 c 4 f 01. ppt

Filtration • Rachel Casiday, Greg Noelken, and Regina Frey, Washington University (http: //wunmr. wustl.

Filtration • Rachel Casiday, Greg Noelken, and Regina Frey, Washington University (http: //wunmr. wustl. edu/Edu. Dev/Lab. Tutorials/Water/Public. Water. Supply. html) isis. csuhayward. edu/alss/Geography/ mlee/geog 4350/4350 c 4 f 01. ppt

Final Touches • Disinfection - water completely free of suspended sediment is treated with

Final Touches • Disinfection - water completely free of suspended sediment is treated with a powerful oxidizing agent usually chlorine, chlorine then ammonia (chloramine), or ozone. – A residual disinfectant is left in the water to prevent reinfection. – Chlorine can form harmful byproducts (THMs)and has suspected links to stomach cancer and miscarriages. – Many agencies now residually disinfect with Chloramine to prevent formation of THMs. • p. H adjustment - so that treated water leaves the plant in the desired range of 6. 5 to 8. 5 p. H units. isis. csuhayward. edu/alss/Geography/

Municipal Water Purification Plant

Municipal Water Purification Plant

Wastewater Treatment • Septic Tanks: typically treat small volumes of waste (e. g. ,

Wastewater Treatment • Septic Tanks: typically treat small volumes of waste (e. g. , from a single household, small commercial/industral) • Waste. Water Treatment Plants(WWTP) : typically treat larger volumes of municipal or industrial waste.

Treatment Objectives • Wastewater treatment systems take human and industrial liquid wastes and make

Treatment Objectives • Wastewater treatment systems take human and industrial liquid wastes and make them safe enough (from the public health perspective) to return to the aquatic or terrestrial environment. • In some cases, wastewater can be clean enough for reuse for particular purposes. • Wastewater treatment systems use the same purification process that occurs in a natural aquatic system only faster and in a controlled manner. isis. csuhayward. edu/alss/Geography/ mlee/geog 4350/4350 c 4 f 01. ppt

Septic Tanks • Approx. 22 million systems in operation ( 30% of US population)

Septic Tanks • Approx. 22 million systems in operation ( 30% of US population) • Suitability determined by soil type, depth to water table, depth to bedrock and topography • Commonly fail due to poor soil drainage • Potential contaminants: bacteria, heavy metals, nutrients, synthetic organic chemicals (e. g. benzene)

Sewage or Wastewater Treatment • Sewage or wastewater is composed of sewage or wastewater

Sewage or Wastewater Treatment • Sewage or wastewater is composed of sewage or wastewater from: – Domestic used water and toilet wastes – Rainwater – Industrial effluent (Toxic industrial water is pretreated) – Livestock wastes

Sewage Treatment: Multistep Process 1. Pretreatment: Bar screening large rack with bars to remove

Sewage Treatment: Multistep Process 1. Pretreatment: Bar screening large rack with bars to remove large objects that can damage equipment These objects are sent to landfills

Multi-Step Process (con’t. ) • Primary Treatment: Settling Tanks – Primary Sludge: heavy solids

Multi-Step Process (con’t. ) • Primary Treatment: Settling Tanks – Primary Sludge: heavy solids that sink to the bottom - removed and sent to solids treatment facility – Light grease/oil float to top--skimmed off and sent to solids treatment facility This takes several hours

How are Liquids Treated • Secondary Treatment: Aeration Tank – Biological Treatment – Activated

How are Liquids Treated • Secondary Treatment: Aeration Tank – Biological Treatment – Activated sludge: contains bacteria/protozoa that eat organics in the liquid wastes – Air bubbles pumped in to aid bacteria in digesting

Liquids (con’t. ) • Secondary Treatment: Final Clarifiers – Microbes fall to bottom and

Liquids (con’t. ) • Secondary Treatment: Final Clarifiers – Microbes fall to bottom and most get recycled back into aeration tank to work on more waste – Any excess microbes are removed and sent to solids treatment

Liquids (con’t. ) • Final Treatment: Disinfection – Chlorine: kills disease causing organisms •

Liquids (con’t. ) • Final Treatment: Disinfection – Chlorine: kills disease causing organisms • Can react with organisms to form chlorinated hydrocarbons that can cause cancer – UV light or ozone: can be used instead of chlorine, but more expensive Clean water is then sent to ocean, river, etc.

What Happens to the Solids? • • Mainly anaerobic digestion Large tanks mix and

What Happens to the Solids? • • Mainly anaerobic digestion Large tanks mix and heat solids. Microbes eat solids and produce methane Excess water removed to reduce volume before transport – Remaining solids: some are recycled as fertilizer and some are sent to landfills – Methane: can be energy source for the

Advanced Sewage Treatment Tertiary: Chemical and Physical • Tertiary: Chemical and Physical • Removes

Advanced Sewage Treatment Tertiary: Chemical and Physical • Tertiary: Chemical and Physical • Removes specific nutrients--such as phosphate, nitrate • Expensive! Not used in many systems

Reusing Wastewater • Currently, treated wastewater, no matter how “clean” cannot be directly mixed

Reusing Wastewater • Currently, treated wastewater, no matter how “clean” cannot be directly mixed with treated raw water and supplied as potable (from Latin potare = “to drink”) water (most places) • However, if a dual plumbing system is available, wastewater can be piped into facilities for specific, approved uses for which non-potable water is adequate (process water, irrigation, sanitary use, etc. ) • Dual plumbing systems in America are colored purple to distinguish pipes, valves, taps, etc. from potable ones isis. csuhayward. edu/alss/Geography/ mlee/geog 4350/4350 c 4 f 01. ppt

Indirect Use of Wastewater • Increasingly, treated wastewater is being used in Aquifer Recovery

Indirect Use of Wastewater • Increasingly, treated wastewater is being used in Aquifer Recovery and Storage projects, used to recharge and protect groundwater that will ultimately be used for potable supplies. • In dual systems, the wastewater “gray water” can be used for irrigation • Treated wastewater is frequently used as sources of saline intrusion barrier water. isis. csuhayward. edu/alss/Geography/ mlee/geog 4350/4350 c 4 f 01. ppt