Sewage Processing & Disposal Flashcards
Definition of Sewage
- The waste & wastewater produced by residential & commercial sources that s discharged into sewers.
Key components/history of sewage disposal
- 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.
Sewage Processing & Disposal:
What is considered sewage?
- Sewage includes wastewater generated by people in homes & businesses, which is conveyed by sewer pipes to sewage treatment plants.
Why is sewage treated with bacteria?
- Sewage is treated with chemicals & bacteria to produce clean water, which returns to rivers or ponds.
What does modern technology do for sewage processing?
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.
What does bacteria do to sewage water?
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 )
How is the amount of organic material measured?
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.
Process of Sewage Treatment: Primary Stage
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.
Process of Sewage Treatment: Secondary Stage
Promotes bacteria digestion of organic material.
**Uses microorganisms naturally present in sewage or other microorganisms (protozoans, nematodes) to enhance organic digestion.
Process of Sewage Treatment: Tertiary Stage
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.
Chapter 2-2 (11-7-2023) Page 13
Tertiary Treatment:
1 of 9
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.
Tertiary Treatment
2 of 9
2) Activated carbon,
activates carbon that is generating small/low pores to increase the absorption of particles like synthetic chemicals or bad odors.
Tertiary Treatment
3 of 9
3) Nitrifying Towers,
biological oxidation of ammonia or ammonium to nitrite, followed by the oxidation of NITRITE to NITRATE.
Tertiary Treatment
4 of 9
4) Air Stripping,
is the transfer of volatile components and ammonia of a liquid into an air stream.
Tertiary Treatment
5 of 9
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.
Tertiary Treatment
6 of 9
6) Reverse Osmosis,
water purification using semipermeable membrane to remove ions, molecules, & large particles from the water.
Tertiary Treatment
7 of 9
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.
Tertiary Treatment
8 of 9
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.
Tertiary Treatment
9 of 9
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.
What are the processing components involved in sewage (sewage processing system)?
(4)
- Primary Tank
- Secondary Processing
- Aeration
- Empty Aeration Tank
The final factors of the processing & treatment of sewage wastewater:
- 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.
U.S. Sewage Requirements
(2)
(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.
Other methods of sewage disposal? (1) listed
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.
