The assignment is regarding the environmental engineering. Document Preview: Assignment Environment Engineering for Sustainable Development II 1. If 8000m3/d of wastewater from an industry has a BOD5...

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Assignment Environment Engineering for Sustainable Development II 1. If 8000m3/d of wastewater from an industry has a BOD5 of 190 mg/L and k = 0.17 per day (base 10) a. How much oxygen (kg/day) is required to satisfy the BOD demand of this waste, assuming 1 kg of oxygen is to be supplied per kilogram of the ultimate BOD in the waste b. What is the population equivalent of the waste (based on BOD5) 2. A 5000-m3/day wastewater plant discharges to a river with a minimum drought flow of 137.7 m3/min (immediately upstream from the outfall) a. What total allowable BOD5 (kg/day) could be discharged in the river after initial dilution must not exceed 1 mg/L and no upstream pollution is occurring? b. What degree of treatment (% BOD satisfied) does this represent, assuming the plant influent to have a BOD5 of 250 mg/L 3. During recent winters there has been considerable criticism of the practice of dumping salt-laden snow from the streets into rivers and lakes for disposal. What problems are caused by this? (minimum of 4) Should the practice be prohibited? What alternatives are available? How would they resolve these problems 4. Calculate the surface area and depth of an “ideal” settling tank to remove all 10um spherical particles (SG = 2.65) from 1000 m3 of wastewater per day and provide a detention time of at least 1 Hr 5. From the information given, wastewater is made up of many different constituents, which one in your opinion creates the greatest risks to human habitation? Natural habitation? Which ones are reasonably inert? Is treatment the only way to prevent these elements from entering the wastewater stream? Part II 1. Discuss methods that can allow you personally to reduce water consumption. Does individual consumption rates for a community compare to industrial uses? 2. Desalination seems to be the key to unlocking the vast supply of ocean water for our use. Explain, why it is unlikely that desalination – even if costs can be brought down to...



Answered Same DayDec 22, 2021

Answer To: The assignment is regarding the environmental engineering. Document Preview: Assignment Environment...

Robert answered on Dec 22 2021
140 Votes
ANS 1(a).
BODt = BODu(1-10
-kt) ..........................(1)
Given,
BOD5 =190 mg/L
k = 0.17 per day
Q = 8000m
3
/day = 8x106 litres/day
Using BOD5 and k in equation (1) and using t =5, we get ultimate BOD
BODu = 221.25 mg/l
Now total ultimate
BOD for 1 days wastewater = 221.25x8x106 mg/day =1770kg/day
1kg oxygen to be supplied for 1kg of BOD
Therefore total oxygen to be supplied is also equal to 1770kg/day
ANS 1(b).
Population equivalent or number of people
P.E = [BOD5(mg/l)xQ(million gallons per day)x(8.34lb/gal)]/0.21lb/day
Assuming BOD5 per person = 0.21lb/day
We get P.E = 18566 or 19000 people approx.
ANS2(a).
Total BOD = [QriverxBODriver +QwastewaterxBODwastewater]/[ Qriver+Qwastewater]
Allowable BOD is 1mg/l
Therefore,
1mg/l = [QriverxBODriver +QwastewaterxBODwastewater]/[ Qriver+Qwastewater]
Qriver=197.28x10
6l/day
Qwastewater=5x10
6l/day
BODwastewater=?
Using the equation we get
BODwastewater=40.456mg/l
ANS2(b).
Difference in BOD5 in influent and effluent flows = 250-40.456= 209.544 mg/l
Therefore percentage BOD satisfied = (209.544/250)x100 = 83.82 %
ANS3.
Problems caused by dumping salt laden snow in lakes and rivers
 seeps into our water table and contaminates groundwater
 dehydrates our trees and affects the green belt( chloride prevents water absorption)
 poisons wildlife and aquatic life in the natural habitats of lake and rivers( increase in
chloride level)
 disrupts circulation of oxygen to deeper depths of lakes
 damages sidewalks, infrastructure and vehicles.
The practice shall be prohibited in areas where snowfall is not very heavy. Other alternatives
shall be employed to remove snow from the streets without using salt. But it is a necessary evil
in places like marathon county where snowfall is very heavy and is unmanageable to clear the
streets. Alternatives to salt are being considered given the ecological effects of salt. Organic
compounds are developed that don’t have ecological effects like salt and also have longer
residual effect when sprayed. It also reduces icing point much lower than that created by adding
salt. Snowmelt systems, snow blowers or chemical sprayers are some of the other methods used
to clear ice and snow.
Other alternatives are
Sand- provides traction, inexpensive, harmless, absorbs sunlight and gets warmed and melts
snow.
Ashes- traction, melts ice quickly in sun,
ANS4.
Assuming stokes law for laminar flow
Terminal velocity = (p-)gd
2
18
Where p is particle density
is water density
g is gravitational constant
d is particle diameter
 is kinematic...
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