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Chem 321 > Chem Quiz 4 > Flashcards

Chem Quiz 4 Flashcards

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1
Q

After being treated, waste water should not contain….

A

Dangerous levels of toxic chemicals/organisms

Excessive quantities of oxidizable organic compounds (BOD)

Contains sources of nutrients (that would induced eutrophication)

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2
Q

What are the typical properties of wastewater ?

A

◦ BOD : 250mg/L (greasiest concern for aquatic life)
◦ Suspended solids : 220mg/L
◦ Total phosphorous : 8 mg/L
◦ Total Nitrogen : 40 mg/L
◦ PH : 6.8

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3
Q

What are the levels of waste treatment?

A

Primary, secondary, tertiary

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4
Q

What is the primary level of waste treatment?

A

physical or chemically enhanced settling of suspended particles

	‣ physical screening, removal of substances (plastic bags, toilet paper, todays, and enhanced settling of suspended particles)  
	‣ The primary treatment process involves removal of grit, sand and coarse suspended material through a screening process, followed by settling of suspended solids
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5
Q

What is the secondary level of waste water treatment?

A

‣ biological process to convert organic matter into CO2 to substantially reduce BOD (by 90%)
‣ biological wastewater treatment) is the removal of biodegradable organic matter (in solution or suspension) from sewage or similar kinds of wastewater.[1]: 11  The aim is to achieve a certain degree of effluent quality in a sewage treatment plant suitable for the intended disposal or reuse option

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6
Q

What is the tertiary level of wastewater treatment?

A

— a variety of advanced processes to remove specific contaminants or for disinfection of the water

advanced chemical steps to remove specific contaminants

‣ Ammonia stripping or use of nitrifying bacteria to convert NH4 to NO3 and then use denitrifying bacteria to convert NO3 to N2

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7
Q

What are the typical BOD concentrations in the different levels of the waste water treatment process?

A

• Primary — 175 mg/L
• Secondary (biological) — 15 mg/L
• Secondary (chemically assisted) — 10 mg/L

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8
Q

What are the typical total phosphorous concentrations in the different levels of the waste water treatment process

A

• Primary — 7 mg/L
• Secondary (biological) —6 mg/L
• Secondary (chemically assisted) — 0.1 - 1 mg/L

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9
Q

What is the usual method for sewage sludge disposal ?

A

‣ Historically, disposal is done at sea, in landfills by incineration, and by soil amendment (as it contains toxins as well as its nutrients)

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10
Q

What are rotating biocontactors?

A

support microbial growth and promote the removal of pollutants from wastewater.
* A rotating biological contactor or RBC is a biological fixed-film treatment process used in the secondary treatment of wastewater following primary treatment.
* A rotating biological contactor is a type of secondary (biological) treatment process. It consists of a series of closely spaced, parallel discs mounted on a rotating shaft which is supported just above the surface of the wastewater. Microorganisms grow on the surface of the discs where biological degradation of the wastewater pollutants takes place.

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11
Q

How is drinking water regulated?

A

• Regulated by the Clean Water Act (CWA, 1972), and the Safe Drinking Water Act (SDWA, 1974)
• Regulated by the EPA
• Disinfection must remove/ inactivate 99% of Giardia and 99% of viruses
◦ Giardia Lambia and Cryptosporidium

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12
Q

What are common disinfectants?

A

Cl2, O3, CLO2, Hypoclorous acid

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13
Q

What is the oldest form of disinfection?

A

• The oldest form of disinfection is done by the earth itself through deep rock aquifers, where water is already pathogen free. This is why we use wells

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14
Q

Why is HCIO used for disinfectants?

A

can be easily reduced to Cl-, used in bleaches, diffuses through the cell wall and oxidizes vital molecules

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15
Q

How does Cl2 act as a controversial disinfectant?

A

◦ effective, inexpensive
◦ Controversial — can introduce HOCl into the water, a chlorinating agent . Attacks the hydroxobenezenes in industrial wastes and humic acids
◦ This reaction produces chloroform, a carcinoge

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16
Q

How do nitrates (inorganic contaminants) affect us?

A

‣ Fertilizers can increase the level of nitrate in groundwater
‣ excessive nitrate injection causes Blue Baby Syndrome: conduction of respiratory failure in babies
‣ Nitrate is produced in stomach can react with amines from diet to produce N-nitrosamines (carcinogen)

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17
Q

Why is water disinfectant important?

A

• Used to inactive pathogens and provide safe drinking water
• Involve the removal of pathogens, turbidity, colour, taste, odour, organic matter, and other contaminants: safe for human consumption

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18
Q

What are the water sources for dinking water?

A

‣ Freshwater (conventional treatment)
• surface waters — rivers, lakes
• Groundwater —wells
‣ alternative sources of water (advanced treatment)
• Ocean/saline waters
• Waste water effluents

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19
Q

What are the alternative sources of drinking water?

A

• Ocean/saline waters
‣ Limited access to freshwater
‣ Close to the ocean or ground water with high salt content
‣ Desalination is energy-intensive, therefore, very expensive
• Waste water effluents
‣ Various degrees of reuse-agriculture, potable water, industrial
‣ Public acceptance is a big issue
‣ Wastewater reuse is also an option to desalination (Disneyland and Singapore use this)
‣ Wastewater reuse is practice in places that are in-land

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20
Q

What are the steps in a conventional drinking water treatment process?

A

Screening
Flocculation/coagulation
Sedimentation
Filtration
Disinfection
Distribution

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21
Q

What is screening?

A

‣ Keep out fish, mussels, and large particles from coming into the facility

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22
Q

What is flocculation/coagulation?

A

‣ Coagulants (+) are died which bind and neutralize articles and organic matter (-) to create “flocs”
‣ Coagulants may be polymers and aluminum or iron based chemicals: aluminum sulfate, ferric chloride
‣ Particles are entirely charged and attract positive ions around it (Stern layer) which will then surround itself by negatively charged ions (double layer)

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23
Q

What is sedimentation?

A

‣ Large flocs are allowed to settle at the bottom of the tanks
‣ Clear water is collected at the top of the tank

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24
Q

What is filtration?

A

‣ Small particles and pathogens are filtered out
‣ Filter media can be sad, anthracite, or activated carbon
‣ Filters need to be cleaned every 60 hours of operation

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25
Q

What is disinfection?

A

‣ Chemical disinfectants and UV light are applied to water to inactive pathogens (bacteria, viruses, Protozoa)
◦ UV light can disinfect water
‣ After chemical disinfectants are added, water is sent to a storage rank to allow disinfectants to react and inactivate pathogens
‣ Pathogen inactivation is dependant on disinfectant concentration

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26
Q

What is distribution?

A

‣ Water may travel through the distribution system up to 5 days
‣ North America: typical disinfectant are chlorine or combined chlorine ~ 1-4 mg/L as Cl2 is known as chlorine residual
‣ Chlorine residual and sustained water pressure protects treated water against decontamination in the distribution system
‣ Flint Michigan’s issue with lead was primarily due to changes in their water chemistry and lead-containing pipes

27
Q

How do you inactivate a pathogen?

A

• Disinfectant + pathogens —> inactivated pathogen
• Inactivation goal: 99.9% Protozoa and 99.9% viruse

28
Q

What is activated carbon?

A

• Activated carbon absorbs organic compounds and are typically red o remove organic matter and trace contaminants (pesticides, taste and odour compounds)
• Can be used as filter media (instead of anthracite) or as a finishing step after filtration
• Used in Britain filters

29
Q

What awe disinfection by-products (DBPs)? What are the Canadian guidelines?

A

• Are always in your drinking water, and usually at ug/L levels
• Canadian guidelines for DBPs:
‣ Chlorine: 80-100ug/L
‣ Ozone: 10ug/L
‣ Chlorite: 1mg/L
‣ Combined chlorine: 40ng/L

30
Q

Why are unregulated DBPs of concern?

A

• An epidemiological study relating the consumption of chlorinated surface water and cancer suggest: increased risk in the incidence of bladder cancer and DBP expose
• Association between DBPs and adverse reproductive outcomes including: low brith eight and preterm delivery

31
Q

what are the treatment steps to treat ocean/saline water?

A

• Desalination process:
• Screens
• Micro filtration
◦ Membrane technology
• Reverse osmosis
• Disinfection
• Distribution

32
Q

What is membrane technology?

A

• Water can be purified by passing or forcing it through a membrane with small pores (individual holes) uniform and microscopic size
• Components that are reheated go into the waste stream
• Permeable components ( which pass through the membrane) go to the product stream (water an other components)
• Membranes need significant amount of pressure (and therefore, energy) to drive the water acros the membrane (which is expensive)

33
Q

What is defacto wastewater reuse?

A

• Source waters have a percent volumes that is composed from treated wastewater effluents
• Defacto wastewater reuse is the unintentional use of treated wastewater found in rivers and lakes for drinking water

34
Q

What are the treatment steps used to treat waste water effluents?

A

Micro filtration
Reverse osmosis
Advanced oxidation

35
Q

What are the most common disinfectants?

A

• Chlorine (HOCl)
‣ An acid (pKa=7.5)
‣ Stronger oxidant than OCl-, however ineffective agains Protozoa
‣ Chlorine is not stable at high concentration so it has to be produced on site by Cl2 + H2O
• Combined chlorine (ammonia +chlorine = NH2Cl & NHCL2)
• Chlorine dioxide (ClO2)
• Ozone (O3)

36
Q

What are disinfection by products?

A

Canadian drinking water guidelines for DBPs:

  • Cl: 80-100 ug/L
    -O3: 10ug/L
    -chlorite: 1mg/L
    -combined chlorine: 20ng/L
37
Q

Why are unregulated DBPs of concern?

A

• An epidemiological study relating the consumption of chlorinated surface water and cancer suggest: increased risk in the incidence of bladder cancer and DBP expose

• Association between DBPs and adverse reproductive outcomes including: low brith eight and preterm delivery

38
Q

What are the treatment steps in treating saline water?

A

• Desalination process:
• Screens
• Micro filtration
◦ Membrane technology
• Reverse osmosis
• Disinfection
• Distribution

39
Q

What is membrane technology?

A

• Water can be purified by passing or forcing it through a membrane with small pores (individual holes) uniform and microscopic size
• Components that are reheated go into the waste stream
• Permeable components ( which pass through the membrane) go to the product stream (water an other components)
• Membranes need significant amount of pressure (and therefore, energy) to drive the water acros the membrane (which is expensive)

40
Q

What is defacto water waste reuse?

A

• Source waters have a percent volumes that is composed from treated wastewater effluents
• Defacto wastewater reuse is the unintentional use of treated wastewater found in rivers and lakes for drinking water

41
Q

What are the steps to treat waste water effluents?

A

Microfiltration

Reverse osmosis

Advanced oxidation

42
Q

What is toxicology?

A

The study of harmul interactions between chemicals and biological systems

43
Q

What are the types of toxic substances?

A

Drugs
Food additives
Industrial chemicals
Environmental pollutants
Natural toxins
Household poisons

44
Q

What makes drugs a toxic substance?

A

‣ Highly portent in biological systems
‣ Potentially toxic
‣ Toxicity (overdoses)
‣ Ex. Roxarsone
◦ 1940’s, it acts as a growth promoter in chicken and egg production
◦ Used in 70% of the 9 billion broiler chicken
◦ Converts to arsenic within 10 days
◦ Chicken litter leaked into the groundwater
Average person ingests 5-31 ug arsenic per day

45
Q

What makes food additives toxic substances?

A

‣ Changes colour, flavour, spoilage prevention, causes change in the nature of foodstuff
‣ Potentially toxic substances occur in food (ex. Puffer fish)

46
Q

What makes industrial chemicals toxic substances?

A

‣ Hazard ar workplaces where it is manufactured, used, formulated
‣ Exposure often regulated by law

47
Q

What makes environmental pollutants toxic substances?

A

‣ Sources: industrial processes and improper dumping
‣ Presto died
‣ Shooting ranges (lead in ammunition into the environment)

48
Q

What makes natural toxins toxic substances?

A

‣ Plants/ animals producing toxins for defence purposes
‣ Contamination of food/accidental ingestion/stinging

49
Q

What makes household poisons toxic substances?

A

‣ Pesticide, drugs, solvents/cleaning products
‣ Paraquat:
◦ Herbicide kills by interfering with photosynthesis
◦ Serious lung/kidney damage if not fatal
◦ Structurally similar to diamines, accumulates in lungs

50
Q

What are the types of exposure to toxins?

A

Acute
Chronic
Accidental poisoning
Intentional poinsioning
Environmental exposure

51
Q

What does acute exposure entail?

A

Short contact with the chemical

52
Q

What does chronic exposure entail?

A

Long term expire with the chemical

53
Q

How does accidental poisoning occur?

A

Usually drugs, pericides, household products/ poisons involved

Inhalation for fumes

54
Q

What are the 4 phases in which a toxic compound is moved through the body after exposure?

A

Absorption

Distribution

Metabolism/biotranformtion

Excretion

55
Q

What are the types of toxic responses?

A
  1. Direct toxic action: tissue lesions
    ◦ necrosis, apoptosis
  2. Biochemical lesions
    ◦ interference with vital function
  3. Pharmacological/physiological effects
    ◦ toxins that affect a particular body function (ex drugs effecting blood pressure)
  4. immunotoxicty
    ◦ involving the amount system (ex. Allergic reactions)
  5. teratogenicity
    ◦ The development of the embryo is affected
  6. genetic toxicity
    ◦ Mutations that react form interaction between a chemical and the genetic material
  7. carcinogenicity
    ◦ Chemical that produce a malignant tumour
56
Q

How are toxic compounds absorbed by the body?

A

◦ Involves the passage across the cell membranes
◦ Before substances can enter a toxic effect, they must be absorbed.

57
Q

How are toxic compounds distributed throughout the body?

A

Distributed in the body via blood

Compounds can bind to the plasma proteins

58
Q

How does metabolism/biotransformation occur within the body as a response to toxic compounds?

A

chemicals are converted in the body by enzymatic reactions to products that are more hydrophilic (water-soluble).

Important consequences for toxic potential, the imposition in the body and the excretion

◦ Leads to more polar metabolite, leading to a possible increase in MW, leading to facilitated excretion

◦ Phase 1 and phase 2 reactions (glutathione conjugation and oxidation

59
Q

What is selective toxicity?

A

◦ There are differences in susceptibility to toxic effects between different species of animals and different types of cells. This is due to:
• Differences in absorption , distribution, excretion, metabolism, and biochemical receptors (or lack thereof)
• Ex. Penicillin — interferons with biosynthesis of bacterial cell wall —> selective toxin

60
Q

What is LD50

A

Lethal dose 50, the amount of an ingested substance that kills 50% of the test sample.

61
Q

What is the dose-response relationship ?

A

Describes the magnitude of teh response of an organisms as a function of exposure to a stimulus after a certain exposure time

Can be an:
— all or nothing response (ex. Death)
— graded response (ex. lesions)

62
Q

What is minimata disease?

A

Causes the progressive numbness of the extremities, blindness, deafness

Effected people in minamata

Caused by cisso (neighbouring city) dumping HgCl2 into their bay, bioaccumulating in fish, and affecting thousands of people

63
Q

What are some common sources of mercury?

A
  • insecticides
    -fungicides
    -pesticides
    -mildew inhibitors
    -wood preservatives
  • PVC catalysis
  • fluorescent and neon lights
  • electrical switches
    -medicine
    -shooting grounds

Chem 321 (6 decks)

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