Pict. 13. A Canadian harbor fouled with sewage
waterways. Examples of treatment processes include sedimentation ba- sins, wetlands, or vortex separators for removing coarse solids.
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Decide whether the following statements are true or false accord- ing to the text.
1. There are three types of sewage: domestic sewage, sanitary sewage, and industrial sewage.
2. Wastewater is treated in the underground pipes.
3. Household wastewater is more than 99.9% dissolved and suspended impurities by weight.
4. Pathogens are disease-causing microbes, bacteria, viruses and para- sitic worms.
5. Grey water is wastewater from kitchen and bathroom sinks, baths, showers, washing machines, dishwashers and laundry which can be recycled for flushing toilets.
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6. Industrial effluent contains specific biological compounds, depend- ing on the nature of the industrial process.
7. Such contaminants as oil and grease can be found in both domestic and storm sewage.
Answer the following questions.
1. What is wastewater?
2. Why does sewage need to be made safe before sending it back into the environment?
3. Where is sewage usually treated?
4. What is the main purpose of sewage treatment?
5. What types of sewage are there? What are the sources of these types of sewage?
6. What substances and impurities does domestic sewage contain?
7. What is the classification of sanitary sewage?
8. What does the nature of chemical compounds in industrial effluent depend on?
9. Why is some level of storm sewage treatment required before storm water is discharged into waterways?
Choose the right variant according to the text.
1. Wastewater is created … . (several answers possible)
A. by residences
B. by industrial enterprises
C. by commercial establishments
D. by pathogens (disease-causing microbes, bacteria and viruses)
2. Household wastewater is also called … .
A. residential or domestic wastewater
B. storm sewage
C. industrial effluent
D. sullage
3. Grey water is … than black water.
A. more dangerous
B. cleaner
C. lesser
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D. a more health risk
4. Grey water is used for watering plants or … for flushing toilets.
A. recirculates
B. reused
C. discharged
D. disposed of
5. Storm water is runoff from … .
A. photofinishing laboratories, dry-cleaning services and printing houses
B. kitchen and bathroom sinks, baths, showers, washing machines, dishwashers, and laundry
C. toilets
D. precipitation
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6. Sanitary sewage may contain … . (several answers possible)
A. putrescible organic materials and plant nutrients
B. pathogens (disease-causing microbes, bacteria and viruses) and parasitic worms
С. human wastes
D. metals, dissolved gases, dirt particles, food fragments, oil and grease, cleaning agents, solvents, paint, pharmaceuticals, and cosmet- ics
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