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Flashcards in Wastewater Deck (12)
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1

What are the 2 goals of the Clean Water Act?

1. To provide fishable/swimmable waters 2. Total elimination of pollutant discharge by 1983

2

Where are CWA permits applicable? CWA standards established conventional and non-conventional pollutants. Name examples from each. (5 + 4)

CWA permits apply to POTW

Conventional: BOD, TSS, pH, oil/grease, fecal coliform

Non-conventional: chemical oxygen demand, total organic carbon, total solids, NH3

3

How is an ambient water quality criterion established? (5 steps)

1. lit review of toxic effects on aquatic life

2. find effect on most sensitive species

3. apply safety factor

4. list safe concentration

5. assume/list excursion frequency used to derive discharge standard

4

What is the difference between a technology-based and water quality-based standard?

Technology-Based: sets limit on concentration discharged; easy to enforce; set by EPA

Water Quality-Based: recognizes variability in quality & use of receiving water; more cost-effective; considers dilution of receiving water; set by states

5

What are 4 considerations in the development of a water quality-based wastewater discharge standard?

1. characteristics of receiving water

2. chemical content of waste, maximum discharge rate, minimum receiving water flow

3. whole effluent toxicity testing

4. sample monthly, report quarterly

6

What are 4 reasons for pre-treatment?

1. Prevent dangerous conditions (eg, explosion)

2. Prevent interference with city system

3. Prevent pass-through of city system

4. Prevent sludge contamination

7

Describe a typical municipal wastewater system.

8

What is primary wastewater treatment?

Removal of solids using screening, filters, grinding

9

What is secondary wastewater treatment?

Primary + Biological Treatment

Microorganisms break down contaminants

If only secondary treatment was used, bacteria would be released along with water.

10

What is tertiary wastewater treatment?

Tertiary treatment uses final sand filtration to further reduce BOD.

11

In nutrient removal, what two nutrients are removed?

What are some techniques for nutrient removal?

Phosphorous & Nitrogen

Techniques:

aerobic activated sludge processing

anaerobic treatment

enhanced biological removal

coagulation/precipitation

12

What are biosolids? Why are they beneficial? What are public health risks?

Biosolids: nutrient-rich organic materials from treatment of domestic sewage

Benefits: recycled for fertilizer and soil ammendment to stimulate plant growth

Risk: may contain low levels of pathogens or toxic chemicals