ESM 212 Assignment #4
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Stony Brook University *
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Date
Jan 9, 2024
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4
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ESM 212 Introduction to Environmental Engineering
Fall 2023: Assignment #4
Due: 10/16/2023
1. Describe the problems related to Cuyahoga River. How many plants were dumping waste
into the river? (200 words max)
The Cuyahoga river was one of the most polluted waterways in the nation. Due to hundreds of
years of waste being dumped into the river, the Cuyahoga river caught on fire on multiple
occasions during the sixties (1960’s). The main issue with the incident was the versatility of this
river that many used for their own self-indulgence. It was thought of as a sewer, and as such
required cleaning desperately before any use. The Cuyahoga River was flammable and forcibly
resulted in the passage of the Clean Water Act in 1972 by the Environmental Protection Agency
(EPA). Numerous industries, including steel mills, chemical plants, and sewage treatment
facilities dumped most of their waste directly into the river. It was the accumulation of this waste
and lack of treatment that brought forth these fires. The Cuyahoga river is a primitive example
for the purpose of stricter environmental regulations, leading to much needed improvements in
water quality standards and pollution control measures.
2. Listen to Marc Edwards award lecture. Use your own research and try to describe science
behind the problem he identified in water quality issues in Flint. You can use any materials
available. Do not paste and copy, try to rewrite it in your own words. (500 words max).
The water crisis in Flint, Michigan was a result of authorities choosing to switch the maintained
Lake Huron to the Flint river. This decision was based on the financial situation of the area
requiring that they save money using less resources on something that was seen as a natural
‘free’ resource. Although the water in the Flint river was very unsatisfactory for the reason that it
was much more corrosive and caused lead to leak into the already aging pipes. That is how the
water became infected with lead resulting in the vast amount of cases from lead poisoning. The
contamination of lead in the water may have been prevented had the Michigan Department of
Environmental Quality foreshadowed the possibly corrosive water in the Flint river. Not only
that but authorities still underestimated the severity of the issue causing many serious health
issues, especially in children, as a consequence of no action being taken to decontaminate the
water. This Flint river crisis was very significant in the sense that it highlighted a serious issue of
potent environmental injustices nationwide. This is just an example of inadequate governmental
support from authority figures due to a lack of sensitivity for civilians living in the area.
3. Based on the EPA database:
https://geopub.epa.gov/DWWidgetApp/
and
NYC Department of Health Report:
https://www.health.ny.gov/environmental/water/drinking/violations/2021/2021_compliance_repo
rt.htm
Find drinking water quality violations in the area where you live. Briefly describe them
(200 words max).
Within New York State, with the assistance of the EPA database as well as the NYC
Department of Health, there have been multiple violations regarding the maximum contaminant
levels, treatment technique variations, variances and exemptions, and Significant monitoring
violations. Maximum contaminant level violation is the limit that is set by the federal
government as to how many contaminants water is permitted to have. In other words this law is
in place to verify that there is no surpassing of prescribed limits for contamination. However, the
poor filtration system has been inundated with several contaminants (chloroform, bromoform,
bromodichloromethane, chromium, etc.) resulting in a violation of this policy. Treatment
technique variations is more of an engineering issue to demand that all filtration systems are
working properly and maintenance is regularly scheduled. Operation of water treatment
technologies must run smoothly in order to avoid any excess leaks of contaminants in the tap
water. Significant Monitoring violations as the name suggests is a policy mandating the
periodical monitor of water quality. This is to verify that maximum contaminants are not
exceeded. A better way of visualizing this policy amongst the others is as a background check.
Where maximum contaminant level policy is the actual violation, the others provide either
support or additional security for this.
4. An industry discharges 0.8 m3/s of a waste with a 5-day CBOD of 600 mg/L to a river
with a flow of 4 m3/s and a 5-day CBOD of 8 mg/L. Calculate the 5-day CBOD of the river
after mixing with the waste.
??𝑂?
?𝑖???
=
𝑄
?𝑎??? • ??𝑂?
?𝑎??? +
𝑄
?𝑖???
•
??𝑂?
?𝑖???
(
)
/ 𝑄
?𝑎??? +
𝑄
?𝑖??? (
)
flow rate of waste (m^3) = 0.8m^3/s
𝑄
?𝑎??? = = 5 day CBOD of the waste = 600 mg/L
??𝑂?
?𝑎???
= flow rate of the river (m^3/s) = 4m^3/s
𝑄
?𝑖???
= 5 day CBOD of the river (mg/L) = 8 mg/L
??𝑂?
?𝑖???
= 5 day CBOD of the mixed river (mg/L) = ?
??𝑂?
?𝑖???
??𝑂?
?𝑖???
=
0. 8 ?
3
/?
•
600 ??/𝐿
+
4 ?
3
/?
•
8 ??/𝐿
(
)
/
0. 8 ?
3
/?
+
4 ?
3
/?
(
)
??𝑂?
?𝑖???
=
106. 67 ??/𝐿
The 5 day CBOD of the river after mixing with the waste is 106.67 mg per Liter.
5. If the settling velocity of a sphere of gold (density =19.5 kg/m3) is 1.2 m/s in a viscous
liquid (density =1.5 kg/m3), find the settling velocity of a sphere of silver (density =10.5
kg/m3) of the same size in the same liquid.
Density of gold:
ρ
?
=
19. 5 ??/?
3
Setting velocity for liquid:
?
?
=
1. 2 ?/?
Density of viscous liquid
ρ
?
=
1. 5 ??/?
3
Density of silver:
ρ
?
=
10. 5 ??/?
3
Formula for terminal speed:
,
?
=
2??
2
(ρ−ρ
0
)
9η
for gold:
,
?
?
=
2??
2
(ρ
?
−ρ
?
)
9η
1. 2 =
2??
2
(19.5 −1.5)
9η
, 1. 2 =
2??
2
(18.0)
9η
for silver:
,
?
?
=
2??
2
(ρ
?
−ρ
?
)
9η
?
?
=
2??
2
(10.5 −1.5 )
9η
, ?
?
=
2??
2
(9.0)
9η
?
?
1.2
=
2??
2
(9.0)
9η
2??
2
(18.0)
9η
?
?
1.2
=
9
18
=
1
2
?
?
= 1. 2(1/2)
?
?
=
0. 6 ?/?
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A sphere of silver the same size as a sphere of gold entering a viscous liquid at that speed will
return at the given (0.6 m/s) settling velocity.
6. A city has a population of 50,000 people, an average household generated wastewater
flow of 430 L/day-person, and the average BOD5 of the untreated wastewater in population
equivalents is 0.1 kg BOD5/day-person. If the BOD reaction rate coefficient for the
wastestream is 0.4/day, determine the ultimate (L0) BOD of the wastewater.
,
y = 5-day BOD
𝐿
0
=
?
?
1−?
−?
𝐿
?
(
)
?
5
=
𝑇ℎ? ?????? ?? ?𝑎??? ???? (?)
𝑇ℎ? ?𝑎?? ?? ?𝑂?
5
(?)
Need to determine water used by city pop. in 5 days
Volume of water used by the city pop. in 5 days is:
? = 50, 0000 ?????? ? 430 𝐿
?𝑎?−??????
? 5 ?𝑎??
? = 1. 08 ? 10
8
𝐿
The mass of
over 5 days is:
?𝑂?
5
? = 0. 1 ??
?𝑎?−??????
? 50, 000 ?????? ? 5 ?𝑎??
? = 25 ? 10
3 ?𝑂?
5
?
5
=
25 ? 10
3 ?𝑂?
5
1.08 ? 10
8
𝐿
? 1000 ? 1 ?? ? 1000 ?? 1 ?
?
5
=
231 ?? 𝑂
2
𝐿
𝐿
0
=
239 ?? 𝑂
2
𝐿
1−?
−0.4/?𝑎? ? 5 ?𝑎??
𝐿
0
=
269 ?? 𝑂
2
/𝐿