Municipal wastewater treatment

Municipal Wastewater Treatment

GF Piping Systems

Steven Wells / 11/12/2016

Municipal Wastewater Treatment | 11/12/2016 | Steven Wells2

Primary treatment to remove solid material Secondary treatment

• Digest dissolved and suspended organic material • Nutrients nitrogen and phosphorus • Sometimes disinfection to kill pathenogenic bacteria

Tertiary treatment as needed…• Reverse osmosis• Advanced disinfection

Sludge Treatment turns solids into fertilizer or fuel

Basic Processes, Typical Municipal Sewage Treatment


Basics of water treatment process at OCSD

https://www.youtube.com/watch?v=WvZJs69kr1c

Sewage Treatment


Produce effluent that will do as little or no harm to the surrounding environment when released

Various demands depending on type of influent Various demands depending on where the water goes

Closed cycle systems?

Goal of Treatment


YT University Overview


Process Flow: Typical Large-Scale Treatment Plant


Process Flow: Subsurface Flow Constructed Wetlands, requires lots of land


Objects commonly removed include trash, tree limbs, leaves, branches, and other large objects.

Bar Screen to remove all large objects like cans, rags, sticks, plastic packets etc.

Solids are collected and later disposed in a landfill, or incinerated.

Pretreatment (mechanical) removes all materials that can be easily collected


Sewage flows through large tanks aka settling basins, sedimentation tanks or primary clarifiers

Grit Removal by slowing velocity to allow gravity to work FOG removal. Small tank with skimmers to collect fat on the

surface Mechanical scrapers drive sludge towards hopper in the base of

the tank. Sludge pumped to and treated at sludge treatment facilities

Primary Treatment: Sedimentation Phase


Degrade biological content using aerobic biological processes• Bacteria & protozoa do the work• Require oxygen (pumping air in these tanks is biggest consumer

of electricity in the process)• May also use anaerobic sections to

May include secondary clarifier to settle out & separate biological floc

Output still has high mineral content

Secondary Treatment (Biological)


anything more than primary and secondary treatment in order to allow injection into a highly sensitive or fragile ecosystem (estuaries, low-flow rivers, coral reefs,...).

May be disinfected chemically (chlorine, ozone, etc) Physically (by sand filters, lagoons and microfiltration) Reused: for the irrigation of a golf course, green way or park Groundwater replenishment or agricultural purposes if sufficiently

clean

Tertiary Treatment (Chemical)

https://en.wikipedia.org/wiki/Microfiltration


May be considered a type of secondary process or tertiary treatment process

Focused on removal or nitrogen and phosphorus• Note: both of these cause weeds or high algae growth which

leads to low oxygen content in water and dead zones Nitrification is a 2 step aerobic process using different types of

bacteria• Oxidation of ammonia (NH3) to nitrite, (NO2

- ) by 1 bacteria• From nitrite, (NO2

- ) to nitrogen (N2) by another• Which bacteria species is controlled by oxygen content of water

and starting material

Biological Nutrient Removal


Pharmaceuticals Ingredients of household chemicals Methods costly since small amounts Little to no on-line measurement of these parameters

Additional Areas of Concern


Pumps, mechanical movement of solids and liquids Aeration Flow, pH, ORP, oxygen, chlorine, phosphate, nitrate, turbidity, UV,

ozone, etc

Instrumentation & Automation


Groundwater Replenishment Process Steps


Orange County Sanitation District (OCSD.com) Orange County Water District (OCWD.com)

Further information


Questions?

Municipal wastewater treatment

Environment

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