Waste water treatment

Question 1

Define the term coliform and explain the coliform test. Why is the coliform test used to assess the purity of drinking water?

Answer 1

Coliforms are a group of microorganisms that are rod shaped, facultative aerobes and are gram negative
They are used to test the purity of water as coliforms are found in the intestines of warm blooded animals meaning if there are coliforms in the water, feces is present too

Question 2

Describe a method used to detect coliforms.

Answer 2

IDEXX it uses proprietary substrates.
Samples with no coliforms are clear
Samples with coliforms turn media yellow
E.coli turns media blue

Question 3

What are the steps of wastewater treatment

Answer 3

Primary uses physical separation to separate solid and particulate organic and inorganic materials from wastewater
Secondary uses a series of digestive and fermentative reactions carried out by microbes under anoxic conditions
Wastewater forms flocs which are removed
Effluent is then chlorinated

Question 4

There are two different types of secondary treatment for water based on the presence
or absence of oxygen. Describe the difference between these two methods of
treatment.

Answer 4

Anoxic: In bioreactors a series of digestive and fermentative reactions are carried out by various microbes under anoxic conditions

Aerobic: Digestive reactions carried out by microbes in aerobic conditions to treat wastewater with low levels of organic material. Can be done by activated sludge or trickling filter

Question 5

What is the tertiary treatment?

Answer 5

It is a biological process using bioreactors, filtration or chlorination for purifying water and reducing levels of inorganic material. Isn’t often done as its expensive

Question 6

List the steps of purification

Answer 6

1) purification: removing particles
2) Coagulation and flocculation: form clumps of sediment which settle out
3) Filtration
4) Disinfection: Done by chlorine or UV

Question 7

What are some common sources of waterborne infection

Answer 7

Improperly treated potable water
Low quality recreational water

Question 8

Giardiasis and cyptosporidiosis remain significant public health problems even in
areas with stringent water-quality standards. Explain why this might be the case

Answer 8

The two most common ways to disinfect water is chlorine and UV radiation.
Giardiasis is resistant to chlorine and cryptosporidiosis is resistant to UV radiation