FE Exam - Environmental

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facultative pond purpose and depth

- have three zones: aerobic, facultative, and anaerobic - depth = 1-2.5 m - follow the Michigan Rules

What are the Michigan Rules

1. BOD5 loading rate should not exceed 22 kg/ha*d --> prevents pond from becoming anaerobic 2. detention time = 6 months Rules for facultative ponds

Three units of WW pre treatment

1. bar racks 2. grit chambers - velocity controller or aerated 3. equalization basins

Reactor Types and definition and example

1. batch: fill, treat, empty; washing machine, treat industry ww 2. completely mixed flow: continuous flow, stirred; activated sludge unit 3. plug flow: no mixing; natural systems, pipes

three primary exposure pathways for human

1. dermal adsorption 2. inhalation 3. ingestion

three layers of lake stratification from top to bottom

1. epilimnion: warm, aerobic, well mixed 2. thermocline: area where sharp temperature difference occurs 3. hypolimnion: cool, poorly mixed, anaerobic

orders of the biological zones in lakes from top level to bottom

1. euphotic zone 2. light compensation level 3. profundal zone

the 2 groups of coliform

1. human/animal 2. soil

Steps of a conventional activated sludge WW treatment plant

1. rack 2. grit chamber 3. primary settling tank 4. aeration tank 5. secondary settling tank 5a. return sludge line, half returned to aeration basin (RAS), half wasted to the digester (WAS) 6. disinfection

8 steps of conventional surface water treatment

1. screen 2. rapid mix 3. flocculation basin 4. sedimentation basin AKA clarifiers 4a. sludge discharge 5. Filtration - rapid sand filter 6. disinfection 7. storage 8. discharge to distribution system

one mole of gas at standard pressure and temp (760 mm HG and 0C) occupies how many liters?

22.4 L

FEL

Frank Effect Level dose that marks the point where maximum effects are observed with little increase in effect for increasing dose

carbonic acid

H2CO3 When pH < 4.5 Alkalinity = 0 because only H2CO3 or CO2 are present

bicarbonate

HCO3- alk = [HCO3-] when pH = 8.3

Hazard Index equation

HI = (chronic daily intake CDI) / (RfD)

TMDL =

Total Maximum Daily Load max amount of pollutants that can be discharged into a water body without deteriorating its quality

What is a bacteriophage?

a virus that infects bacteria

standard for disinfection

disinfection > 99.99% removal

exact alkalinity =

exact alk = [HCO3-] + 2[CO3 2-] + [OH-] - [H+]

eutrophic lake =

high nutrient levels --> high productivity DO ~ 0 at the bottom turbid; lots of algae does not support fish life well T&O issues

Units of hydraulic detention time, θ

hours

How is the productivity of a lake measured?

it's ability to support a food web, algae is the base of the food web

nephrotoxicity what causes it

kidneys tox heavy metals - lead, mercury, cadmium

standard for lead

lead <0.005 mg/l

LD50

lethal dose 50 dose at which 50% of test animals die

definition of alkalinity

measure of the buffer capacity

ppm =

mg/L

ppb =

micro g/L

What is mixed liquor?

mixture of activated sludge and ww in the aeration basin

ppt =

nano g /L

neurotoxicity

nervous system tox

limiting nutrient in lakes

phosphorus

What unit is used for WW primary treatment? what is it's typical removal efficiency?

primary settling basins (primary clarifier) solids: 50-60% BOD5: 30-35%

The addition of protozoa in WW will....

protozoa consume algae and bacteria in ww

What is the objective of WW secondary treatment? What are the two approaches to accomplish this objective?

remove organic material 1. biological treatment 2. aerobic degradation of organics

purpose of filtration

remove suspended or colloidal solids form water by passage through porous media

Examples of decentralized ww treatment systems

septic tanks mound systems sand filters

littoral zone =

shallow water near shore where rooted water plants grow

LIMNOLOGY

study of the ecology of lakes

What do dissolved substances cause in water?

taste and odor issues

Sequence of oxidation by bacteria in the presence of no oxygen compounds to be oxidized nitrate (NO3- sulfate (SO4-2) dissolved oxygen

the essence of oxygen usage reduced by bacteria is dissolved oxygen, nitrate, then sulfate

filter loading rate definition

the flow rate of water applied per unit area of a filter

Reference dose (RfD) and concentration (RfC)

the safe daily intake that is believed to not cause adverse health affects

Why are carcinogens somewhat unique toxicants?

they do not have any apparent threshold of response at low doses any exposure is assumed to have an associated risk

TLV

threshold limit values concentrations in air that workers could be repeatedly exposed to on a daily basis without adverse health effects

TLV-STEL

threshold limit values - short term exposure limits 15 minute exposure

TLV-TWA

threshold limit values - time weighted average maximum time-weighted average a worker can be exposed to in an 8 hr day

what is the objective of toxicity tests?

to establish dose-response curves

standard for total coliform

total coliform --> positive <5% of 40 samples per month

immunotoxicity

tox of immune system

hematoxicity what causes it

toxicity of the blood benzene, lead, methylene chloride, insecticide, CCL4, mercury, cadnium, CO, H2S

cardiotoxicity

toxicity of the heart

heptatoxicity what causes it

toxicity of the liver hexavalent chromium, arsenic, CCl4, alcohol, hepatitis

pulmonary toxicity

toxicity of the respiratory system

What occurs in the rapid mixing phase?

trivalent cation (Al3+ or Fe3+) coagulant is added to the water and mixed in they react with colloids in the water to eventually form a floc

what do colloidal substances cause in water?

turbidity

standard for turbidity

turbidity < 0.3 NTU @ 95% of samples

Flocculant settling is considered type _____ settling

type II settling

senescent lake =

very old shallow lakes will become marshes

aerobic pond purpose and depth

-aerobic bacteria consumes organic waste -shallow to maintain dissolved oxygen throughout entire depth - highly photosynthetic

mg/L as CaCO3 =

= mg/l as species * (EW CaCO3 / EW species)

How do coagulants effect the water chemistry?

Al3+ and Fe3+ consume alkalinity to form Al(OH)3 and Fe(OH)3 if there is enough alkalinity, the pH stays stable Not enough alkalinity, the pH needs to be adjusted ny adding lime or soda ash

carbonate hardness, CH =

CH = HCO3-

carbonate

CO3 2- alk = 2[CO3 2-] + [OH-] when pH > 12.3

What does the Sludge Volume Index (SVI) equation determine?

How much sludge should be returned

LOAEL

Lowest Observed Adverse Effect Level level at which effects related to the response can first be measured, and are the same effects as those that are observed at the higher doses

LOEL

Lowest Observed Effect Level

MCL

Maximum Contaminant Levels Set standard for drinking water quality

What are membranes, where and why are they used?

Membranes separate contaminants based on physical and chemical properties - help achieve higher water quality standards - ex: micro filtration, RO, non filtration, ultra filtration

MLSS

Mixed Liquor Suspended Solids whole sludge --> organics and inorganics

MLVSS

Mixed Liquor Volatile Suspended Solids Only organic portion of sludge

Non-carbonate hardnes, NCH =

NCH = TH - CH

Anoxic decomposition

NO3- if final e- acceptor

What is NPDES?

National Pollutant Discharge Elimination System permitting system for monitoring discharge into water bodies

NOAEL

No Observed Adverse Effect Level level at which effects related to the response can first be measured

NOEL

No Observed Effect Level

what does activated carbon do?

Placed in filter or mixed directly into raw water used to help with T&O and removes disinfection byproduct precursors (organic matter)

Purpose of sedimentation basin (clarifier)

Provide sufficient time for particles to settle out

total hardness, TH =

TH = Ca2+ + Mg2+

Lake turnover

The epilimnion level cools to 4*C in the fall and becomes more dense than the hypolimnion level, causing the lake to turnover

Anaerobic Decomposition a. end products b. appropriate BOD levels c. how much sludge produced

a. CO2, methane, water, ammonia, hydrogen sulfide b. > 1000 mg/l c. very little sludge, anaerobic can be used to stabilize sludge produced in aerobic and anoxic treatment d. is a smelly process and requires temperatures to be elevated initially

Aerobic Decomposition a. end products b. appropriate BOD levels c. how much sludge produced

a. water, CO2, new cell material b. <500 mg/l (dilute ww) c. produces a lot of sludge

Calculating alkalinity in mg/l as CaCO3

alk = [HCO3-] + [CO3 2-] + [OH-] - [H+]

Flocculation purpose

allow enough time for the particles to come in contact and collide, stick together, and grow to a size that will readily settle

additive effects

applies only when the effects of the component gases occur within the same organs

approximate alkalinity =

approx alk = [HCO3-] + 2[CO3 2-]

mesotrophic lake =

between oligotrophic and eutrophic low DO levels

Definition of activated sludge process

biological ww treatment technique where ww and biological sludge (microorganisms) are mixed together and aerated.

Mass balance for biomass under steady state conditions for completely mixed activated sludge

biomass influent + net biomass growth = biomass effluent + biomass wasted

benthic zone =

bottom sediments of lake -> where things settle after they dies, bacteria decomposes the dead stuff

Oligotrophic lake =

clear low nutrient levels --> low productivity level aeriobic support fish life well

What are the characteristics of colloids that make them difficult to treat?

colloids are very small --> cannot be filtered and do not settle colloids have a negative charge around them --> prevent them from flocking and settling

standard for copper

copper <1.3 mg/l

Units of Solid residence time, θc

days solids residence time = sludge age = mean cell residence time

Anaerobic Decomposition

decomposition in the absence of oxygen and nitrate - primary electron acceptors are sulfate (SO42-), CO2, and organic compounds that can be reduced

Aerobic Decomposition

decomposition of organic material in the presence of oxygen


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