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Day 1 > Envi > Flashcards

Envi Flashcards

1
Q

A stream flowing with a velocity of 2mph contains no BOD, but has an oxygen deficit of 6 mg/L.

What would be the deficit 35 miles downstream from the original point?

A

1.46 mg/L

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2
Q

Calculate the degree of deprotonation of the side chain of cysteine at pH 7.30, given side chain has pKa =8.2

A

Cysteine x= 0.11
Histidine x=0.86 pka =6.5

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3
Q

If each mol of ATP yields 7.3 kcal of energy upon hydrolysis, how many kilocalories of energy would you get from 1 g of CH3COO-

A

1.5 kcal

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4
Q

If you add 30 g if calcite (CaCO3) to a 1 L volumetric flask and being the final volume to 1L

pKs for calcite = 8.48

A

[Ca2+] = 5.75 x 10-5

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5
Q

30 g of calcite diluted to 1 L of solution having 0.01 M NaCl

A

[Ca2+] = [CO3 2-] = 8.7 x 10-5

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6
Q

A solution initially supersaturated with CO3 2- and Ca2+ such that the concentrations are both 50 mg/L.

A

4.17 x 10-4 M

16.7 mg/L

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7
Q

A solution of HOCl is prepared in water by adding 15 mg HOCl to a volumetric flask, and adding water to 1 L mark.

% dissociation

A

22.4℅

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8
Q

You are working at a site where a leaking underground storage tank has contaminated the soil and groundwater below a gas station

45, 500 ug/l
0.09, 0.01

A

0.36 ug/L
5 ug/L

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9
Q

Cesium-137 was measured in soil at a concentration of 2x10⁴ Bq,/kg soil. How many years will it take before the concentration of Cs reaches background level?

A

t half of Cs-137= 30 years

459 years

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10
Q

2,4,6 chickenwire degrades in water

A

First order reaction

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11
Q

A falling raindrop initially has no dissolved oxygen. The saturation for oxygen in the drop of water is 9.2 mg/L.

A

10.4 s

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12
Q

Commercial sulfuric acid is often purchased as 93 wt ℅

Molarity, Normality

A

M=18.15
N=36.30

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13
Q

The pH of a water is measured to be 7.5m The concentration of bicarbonate was measure to be 1.3 x10-3

A

H2CO3 = 8.2 x 10-5 M
CO3 2- = 1.9 x10-6 M
Ct= 1.4 x 10-3 M

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14
Q

A water contains 100 mg/L CO3 2- and 75 mg/L HCO3- at a pH 10. Calculate exact alkalinity

A

233 mg/L

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15
Q

A soil sample is collected and the soil water is analyzed for the chem compound 1,2-dichloroethane. The concentration is found to be 12.5 ug/L.

Kd= 0.724

A

905 ug/kg

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16
Q

A chemical has a partition coefficient of 12,500 mg/kg mg/L. If the concentration of the chemical in water is found to be 105 ug/L

A

12500*105/10

1312.5

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17
Q

A 1m³ sample of air was found to contain 80 ug/m³. What was the SO2 concentration?

A

0.03 ppm

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18
Q

A solution of acetic acid is prepared in water by adding 11.1 g of sodium acetate to a flask and bringing the volume to 1 L. Final pH is 5.25

What are the conc of acetate and acetic acid

A

Acetate = 0.033
Acetic Acid = 0.102

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19
Q

Rate of respiration can be determined by monitoring the rate of oxygeb consumption or CO2 production

A

k = 0.09, 0.14

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20
Q

Using half reactions given below for oxidation of acetate to CO2 and the reduction of molecular oxygen to water, determine the amount of energy consumed or released per mole of acetate

A

one mole of glucose yields 2881.68 kJ

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21
Q

Awell mixed sewage lagoon is receiving 430 m³/day of untreated sewage. The lagoon has SA of 10 hectares and a depth of 1 m

Find steady state concentration of pollutant in the lagoon effluent

A

Ceffluent = 1.1

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22
Q

Wastewater treatment plant disinfect its effluent before discharging the wastewater to the nearby stream.

Cin = 4.5x10^5
Cout = 2000
k= 0.23/min
v= 0.75 m/s

A

L=1060 m

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23
Q

A contaminated soul is to be excavated and treated… Determine the time to achieve 99℅ reduction in the original concentration

A

92 days

24
Q

A chemical degrades in a flow balanced, steady state CMFR. The upstream conc of chemical is 10 mg/L. The downstream conc is 2 mg/L. Water is being treated at a rate of 29 m³/min. Volume of tank is 580 m³

A

k= 0.2/min

25
Q

In evaluating a possible food poisoning. The family purchased 12 kg of hamburger, 6 kg of chicken, 5 kg of corn, 20 L of pop soda

Energy input
Work in the first 2 hrs

A

0.54 kJ/s

0.044 kW or 44 W

26
Q

A municipal landfill has available space of 16.2 ha at average depth of 10 m. 765 m³ of solid waste is dumped at the aite 5 days a week. Estimate the expected life

A

16.25 or 16 years

27
Q

Liquid hazardous wastes are blended in a CMFR to maintain a minimum energy content before burning them in a hazardous waste incinerator…

How long will it take the effluent from CMFR to reach an energy content of 9 Mj/kg

A

34.5 or 35 s

28
Q

A sewage lagoon gas a surface area of 10 ha and a depth of 1 m is receiving 8640 m³/day of sewage containg 100 mg/L

A

k=0.35/day

29
Q

A water in a biological wastetreatment system must ve heated from 15 to 40 C for the microorganisms to function. If the flowrate if the wastewater is 30 m³/day

A

3.14 GJ/day

30
Q

A cooling water pond is constructed for a power plant that discharger 17.2 m³/s of cooling water. Estimate the surface area

A

175 ha

31
Q

The radiative heat load on 2 surfaces of a horizontal leaf is 1.7 kW/m²

A

27% heat loss by radiation

32
Q

A deer eats 25 kg of herbaceous material per day. The herbaceous matter is 20% dry matter

How many megajoules are converted to body tissue on daily basis

%energy conversion

A

7.5 MJ/day
15℅

33
Q

A farmer has a 7-year rotation of corn, soybeans, and wheat for 4 years of alfafa. Manureee

In year 2, the farmer mentioned plans to plant soybeans. Estimate the remaining Phosphorus and Potassium

A

Version 1: 20000 kg manure per hectare

Version 2 : 77.3 kg P, 48.5 kg K

34
Q

Professor Dexter has made measurements of her solid waste, shown in the table. If the container volume is 0.0757 m³

A

ave density = 58.4 kg/m³

35
Q

A powerplant in a college town is burning coal on a cold, clear winter morning at 8AM with a wind speed of 2.6 m/s.

Calculate the distance downwind

A

5.8 km

36
Q

A landfill that us 12 hectares in are has a liner if thickness 0.9 m. Each year 1700 m³ of leachate is collected.

What is the head?

A

1.04 m

37
Q

Number of roadrunners one five and ten years later

A

1 - 234
5 - 381
10 - 515

38
Q

Lake has a surface area of 2.6x10^6 m². The average depth is 12 m. The lake is fed by a stream having a flow rate of 1.2 m³

A

20 ug/L steady state concentration of Phosphorus

Eutropic state

39
Q

The trees are growung with an r if 0.21. The carrying capacity is 3250. What is the population in 35 years?

A

3247

40
Q

A coal power plant converts about 33% of the coal’s energy into electrical energy. For 800 MW electric output. Estimate volume of ash

A

2.4x10^5 m³/year

41
Q

Estimate the amount of waste rock generated in producing 100 kg of copper from an ore containing 0.05% copper

A

200,000 kg

42
Q

In 2002 international production of iron was 1080 Tg. How long will world reserves last

A

40years

43
Q

A waste is being discharged into a river that has a temperature of 10 C. What fraction of max oxygen consumption has occurred in 4 days… k=.115/day

A

0.12

44
Q

What is the BOD5 of the wastewater sample if DO values of blank and diluted sample after 5 days are 8.7 and 4.2?

A

205 mg/L

45
Q

Theoretical NBOD 30 mg/L as Nitrogen and as Ammonia

A

137 mg/L

113 mg/L

46
Q

Total hardness, carbonate, and non-carbonate hardness with table

A

TH = 332.8
CH = 284.0
NCH = 48.8

47
Q

The design flow and overflow rates for a settling tank are 0.044 m³/s and 20 per day.

Determine length of tank using conventional wisdom

A

190 m³
16 m length
1.7 m depth

48
Q

A house built in 1950s gas 14.86 m² gazed windows. Estimate the heat loss…

A

single gaze 1.86x103 W
double gaze 9.29x102 W

49
Q

Decay constant for metal recovery is 0.0202 cycle -1. What is the percent recovery?

A

98

50
Q

A steam containing no BOD has a DO of 5 mg/L and a flow rate of 8.70 m³/s. The temperature of the stream is 18 C.

Determine rate of reaeration

A

0.632 mg/L day

51
Q

A city of 200 000 people disposes 1.05 m³/s of treated sewage… kd is 0.61 kr is 0.76

a. what is the DO mix and L mix
b. what is the DO 16 km downstream

A

DO mix= 6.85
L mix = 6.75

DO = 5.9 mg/L

52
Q

Seeded problem

A

625 mg/L

53
Q

The initial BOD after mixing of the Belgelmir river is 12 mg/L. Determine critical point and DO

A

2.88 days
7.53 mg/L

54
Q

Sugar beet plant, DO at the critical point to fall to 4 mg/L. What DO will result if the concentration of the waste is reduced by 50℅

A

7.4 mg/L

55
Q

A home water softener has 0.1 m³ of ion exchange resin with an exchange capacity of 62 kg/m³

A

471 L/day

Day 1 (4 decks)

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