Wastewater treatmentWastewater treatmentHow humans make use of nature

OutlineOutline

1. What is wastewater?1. What is wastewater?

2. Where does the wastewater go? 2. Where does the wastewater go?

3. What is a wastewater treatment plant? 3. What is a wastewater treatment plant?

4. Wastewater treatment steps 4. Wastewater treatment steps

5. Biological treatment & Bacteria5. Biological treatment & Bacteria

6. Who works at a treatment pant? 6. Who works at a treatment pant?

7. Cincinnati Wastewater Treatment Plants7. Cincinnati Wastewater Treatment Plants

What is Wastewater?What is Wastewater?

• Wastewater is a liquid waste, which consists of animal, vegetable, mineral or chemical matter in solution or in suspension with water

• It comes from residents and businesses who flush different matter + water down their toilets or pour it down their sinks and drains

Where does wastewater go?Where does wastewater go?

• Wastewater drains into a network of pipes maintained by the local sewer service municipalities

• Sewer systems are built to collect and flow wastewater and rainwater using the natural slope of land, generally towards the sea front or to wastewater treatment plants

What is a wastewater treatment plant (WWTP)?

What is a wastewater treatment plant (WWTP)?

• A WWTP is the place where wastewater is treated to prevent contamination and destruction of our waterways, and our natural water resources

• It includes physical, chemical and biological processes to remove physical, chemical and biological contaminants

Water Treatment Water Treatment

1. Screening &

Filtering

2. Sedimentation

3. Filtration

4. Aeration

5. Chlorination

12

3

4

5

Water Treatment Water Treatment

1. Screening

2. Grit Chamber

3. Primary

Sedimentation

4. Aeration Tank

5. Secondary

Sedimentation

12

3

4

5

Wastewater treatment stepsWastewater treatment steps

Tertiary Treatment:

Includes a final treatment to effluent (water) to increase the water quality, before the water is discharged to the natural waterways

Tertiary Treatment:

Includes a final treatment to effluent (water) to increase the water quality, before the water is discharged to the natural waterways

Secondary Treament:

Includes degradation of biological content of the sewage such as are derived from human waste, food waste, soaps and detergent

Secondary Treament:

Includes degradation of biological content of the sewage such as are derived from human waste, food waste, soaps and detergent

Primary treatment:

Includes removal of large objects some solid materials like debris, gravel, sand or liquids like fats, oils and grease from the water

Primary treatment:

Includes removal of large objects some solid materials like debris, gravel, sand or liquids like fats, oils and grease from the water

Step 1Step 1 Step 2Step 2 Step 3Step 3

Biological treatment?Biological treatment?

• In the aeration tanks microorganisms and wastewater are mixed, aerated, and maintained in suspension (activated sludge)

• In the secondary clarifier solids are removed and the activated sludge is returned to the aeration tanks

Biological treatment?Biological treatment?

• The effluent (out-flowing water) from the primary treatment stage is sent to the secondary stage were the water is biologically treated

• Most treatment plants use an aerobic biological process, for which bateria are used

• Some bacteria (unicellular microorganisms) need oxygen and organic matter to live

BacteriaBacteria• Bacteria are simple, colorless, one-

celled organisms that use soluble food and are capable of self-reprodcution without sunlight

• There are two main groups: aerobic and anaerobic. They can be found everywhere in soil, acidic hot springs, water, in animals, plants and in our body. There are one million bacterial cells in one mL of fresh water

• Bacteria are considered decomposers due to their indispensable ecological role of decaying organic matter in nature

• Humans make use of this by using them in secondary treatment stage to decompose organic matter in wastewater

Perfect Water Cycle – Eco-Boulevards

Perfect Water Cycle – Eco-Boulevards

* Source: pruned.blogspot.com

Who works at WWTP?Who works at WWTP?

• Civil engineers plan and design many parts of a WWTP

• Chemical engineers design the primary and secondary stages and they also make sure that the cleaned water has a certain quality before it is discharged

• Microbiolologists make sure that enough bacteria and oxygen is provided

WWTP in CincinnatiWWTP in Cincinnati• There are 10 wastewater

treatment plants in the greater Cincinnati area. They collect 200 million gallons of wastewater every day

• The Sycamore Creek Wastewater Treatment Plant was originally built in 1957 with a design average treatment capacity of 1 million gallons per day (MGD). Since that time, the plant has been expanded three times (1966, 1970 and 1991) to increase treatment to its present capacity of ~20 MGD*

* Source: MSD website

JeopardyJeopardy

1

Why do we need to learn about wastewater?

a) Wastewater is part of the water cycle

b) Wastewater is water that cannot be treated

c) Wastewater has to be treated because it is reused

d) A and C

Answer d Click

JeopardyJeopardy

2

How do we use bacteria in a wastewater treatment plant?

a) Bacteria are not used at all

b) Bacteria are animals that eat organic matter

c) Bacteria need organic matter and oxygen

d) Bacteria need sunlight and CO2

Answer c Click

JeopardyJeopardy

3

How is water cleaned in the secondary treatment stage?

a) With filters and screens

b) With mechanical and physical methods

c) Bacteria and oxygen

d) All of the above

Answer c Click