Sewage Processing & Disposal

Question 1

Definition of Sewage

Answer 1

• The waste & wastewater produced by residential & commercial sources that s discharged into sewers.

Question 2

Key components/history of sewage disposal

Answer 2

• The Minoan culture of Creta between 1500 - 1700 B.C.E had an advanced sewage management system.
• Romans constructed a sewage system & aqueducts.

-The Middle Ages were a time of regression for the sanitary disposal of sewage.

** During the 19th century, methods for the treatment of sewage began to improve.

Question 3

Sewage Processing & Disposal:
What is considered sewage?

Answer 3

• Sewage includes wastewater generated by people in homes & businesses, which is conveyed by sewer pipes to sewage treatment plants.

Question 4

Why is sewage treated with bacteria?

Answer 4

• Sewage is treated with chemicals & bacteria to produce clean water, which returns to rivers or ponds.

Question 5

What does modern technology do for sewage processing?

Answer 5

1) Removing solids
2) Deactivating microbes
3) Producing wastewater that can be returned safely to waterways or in some cases can be reused or recycled.

Question 6

What does bacteria do to sewage water?

Answer 6

When bacteria act upon the organic matter in sewage or certain industrial wastes discharged into waterways, large amounts of dissolved oxygen are rapidly used up.

*( Can result in fish death & other alterations in the aquatic environment )

Question 7

How is the amount of organic material measured?

Answer 7

The most used measurement of the amount of organic material polluting water is a parameter referred to as

Biochemical Oxygen Demand (BOD)
*This is an indication of how much putrescible organic material is present.

Question 8

Process of Sewage Treatment: Primary Stage

Answer 8

During this step, ~60-65% of suspended solids are removed & BOD is reduced ~25-40%.

Large materials removed may be composted or shipped to landfills.

Question 9

Process of Sewage Treatment: Secondary Stage

Answer 9

Promotes bacteria digestion of organic material.

**Uses microorganisms naturally present in sewage or other microorganisms (protozoans, nematodes) to enhance organic digestion.

Question 10

Process of Sewage Treatment: Tertiary Stage

Answer 10

Required in situations where substances that can cause water quality problems are still present.
Removes remaining solids & microorganisms from sewage.
Uses filtration through sand & charcoal filters & the deactivation of microorganisms using chlorine, UV, Ozone.

Question 11

Chapter 2-2 (11-7-2023) Page 13

Question 12

Tertiary Treatment:
1 of 9

Answer 12

1) Chemical coagulation-flocculation, by adding polymers (neutralized charge) the aggregation of small particles is induced together into large aggregates. This makes their separation from water and the removal of phosphates easier.

Question 13

Tertiary Treatment
2 of 9

Answer 13

2) Activated carbon,
activates carbon that is generating small/low pores to increase the absorption of particles like synthetic chemicals or bad odors.

Question 14

Tertiary Treatment
3 of 9

Answer 14

3) Nitrifying Towers,
biological oxidation of ammonia or ammonium to nitrite, followed by the oxidation of NITRITE to NITRATE.

Question 15

Tertiary Treatment
4 of 9

Answer 15

4) Air Stripping,
is the transfer of volatile components and ammonia of a liquid into an air stream.

Question 16

Tertiary Treatment
5 of 9

Answer 16

5) Oxidation ponds,
a pond that contains partially treated wastewater which is left to allow the growth of algae & bacteria to decompose the remaining waste.

Question 17

Tertiary Treatment
6 of 9

Answer 17

6) Reverse Osmosis,
water purification using semipermeable membrane to remove ions, molecules, & large particles from the water.

Question 18

Tertiary Treatment
7 of 9

Answer 18

7) Electrodialysis,
uses transport salt ions from one solution through ion-exchange membranes to another solution under the influence of an applied electric potential difference.

Question 19

Tertiary Treatment
8 of 9

Answer 19

8) Foam Separation,
removing a component of a liquid mixture using a chemical process where foam is used to separate components of a solution when they differ in surface activity.
* Later this is absorbed on the precipitates.

Question 20

Tertiary Treatment
9 of 9

Answer 20

9) Land Application,
applying wastewater to land for remediation as a method to recycle nutrient & organic matter as well as preserve water resources.
**It is the most cost-effective way of treating municipal wastewater, particularly in arid regions.

Question 21

What are the processing components involved in sewage (sewage processing system)?
(4)

Answer 21

1. Primary Tank
2. Secondary Processing
3. Aeration
4. Empty Aeration Tank

Question 22

The final factors of the processing & treatment of sewage wastewater:

Answer 22

• Final product may be recycled for watering landscapes or flushing toilets.
• Recycled water from sewage saves millions of gallons of fresh water/per year.
• Some countries used tertiary treated sewage to augment their supply of potable water.

Question 23

U.S. Sewage Requirements
(2)

Answer 23

(1) Most jurisdictions in the U.S. require that wastewater receive at *** least secondary treatment.
(2) Water that has received only primary treatment is not recommended for any use & generally needs secondary or tertiary treatment for common purposes such as landscape irrigation.

Question 24

Other methods of sewage disposal? (1) listed

Answer 24

1) Composting Toilets

-Convert human excrement into a soil-like product
-Uses little water
The composting of waste is generated due to aerobic process generating:
1) Methane Gas, can be used as a source of energy.
2) Composting toilet for application of soil improvement.

Question 25

Septic System

Answer 25

Septic system - a type of underground well which stores human sanitary waste.
Includes; septic tank & fluid distribution system.

A common on-site method for disposal of sewage in rural areas.

*A passive method for waste treatment using aerobic & anaerobic stages.
[ Anaerobic bacteria digest waste material stored in a septic tank ]
[ Effluent from tank direct this material to an absorption field where aerobic organisms treat it]

Question 26

How many years are domestic septic systems designed for?

Answer 26

20 - 30 year life

[ Longer duration is dependent upon selecting the type of waste that is sent through the system ]

Question 27

Animal Wastes:
What waste makes up the vast majority?
(4)

Answer 27

1. Manure
2. Urine
3. Carcass of dead animals
4. Reproductive tissue

Question 28

Components of animal wastes:
(3)

Answer 28

1. Nutrients
2. Organic materials, microorganisms
3. Residues of animal medicines

Question 29

Environmental Hazards:
(3)

Answer 29

1. Buildup of nutrients on the land.
2. Surface contamination
3. Water Pollution

**Workers are exposed to pathogenic microorganisms.

Question 30

PAGE 23

Question 31

Hazards Posed by Animal Wastes:
(3) main components

Answer 31

1. Contamination from nutrients, organic materials, microorganisms, residues of medicines, & potentially toxic gases.
2. Workers in contact with livestock exposed to pathogenic microorganisms.
3. Creation of antibiotic-resistant bacteria that may endanger human health.