# Environmental Solved Problems - HELP

11 replies to this topic

### #1 amoderski

amoderski

Intern

• Members
• 13 posts
• Discipline:Water Resources

Posted 16 September 2011 - 01:40 AM

Can someone, anyone, help me identify the equations used for Problem 7 in the Environmental Engineering Solved Problems (Schneiter)??? Find the cross-sectional surface area for the filter (Wastewater/Stormwater Section)???

### #2 Dleg

Dleg

Veteran

• EB Supporting Member
• 14,212 posts
• Gender:Male
• Location:digester
• Discipline:Enviro

Posted 16 September 2011 - 03:02 AM

Nope, I looked at my notes on that problem and all I had was "use equation in Solved Problems". It's been a long time, but it may very well have been one of those problems where I just punted, instead of wasting too much study time trying to figure out where it came from.

In other words, don't get too hung up on the occasional problem in Schneiter that you can't solve using the EnvERM. Try to find the source, but don't waste too much time or worry if you can't. Tab the page so you can reference that equation during the exam, and move on.

### #3 amoderski

amoderski

Intern

• Members
• 13 posts
• Discipline:Water Resources

Posted 16 September 2011 - 03:06 PM

Thanks. Sometimes I have no idea where the formula's come from, so it gets frustrating.

### #4 tmac0329

tmac0329

Intern

• Members
• 3 posts
• Discipline:Enviro

Posted 16 September 2011 - 05:51 PM

My notes say Eq 26.19 in EERM. But looks like I skipped the problem in the end. Way more complicated than what you're likely to see on the exam in my opinion.

### #5 VTEnviro

VTEnviro

I'm Coming Back

• 24,469 posts
• Gender:Male
• Location:Frozen Plains of the North
• Discipline:Sorely Lacking

Posted 16 September 2011 - 06:52 PM

Is this from the 101 solved problems book?

### #6 Dleg

Dleg

Veteran

• EB Supporting Member
• 14,212 posts
• Gender:Male
• Location:digester
• Discipline:Enviro

Posted 17 September 2011 - 04:46 AM

yes.

### #7 ccryalphabetsoup

ccryalphabetsoup

Intern

• Members
• 3 posts
• Gender:Female
• Location:new york, new york
• Interests:learning, camping, hiking, driving, bbq'ing, traveling, photography...the list is endless<br /><br />would like to pass this test so i can get back to life as usual. <br /><br />2nd attempt at Water Resources
• Discipline:Civil

Posted 24 September 2011 - 06:43 PM

In Problem #5 about the industrial WWTP:

Where can I find the the 7.7mg/L DO in water @ Temp=22C and elevation correction factor of 0.88 that they refer to in the solution? Initially I thought it would be App 22D.

Thanks

### #8 ccryalphabetsoup

ccryalphabetsoup

Intern

• Members
• 3 posts
• Gender:Female
• Location:new york, new york
• Interests:learning, camping, hiking, driving, bbq'ing, traveling, photography...the list is endless<br /><br />would like to pass this test so i can get back to life as usual. <br /><br />2nd attempt at Water Resources
• Discipline:Civil

Posted 24 September 2011 - 10:12 PM

also...for problem #12.1 (storage capacity) - how do they get 12,500m3 from the graph? I'd think 14,000.

thanks

### #9 okeng

okeng

P.E.

• Senior Member
• 51 posts
• Gender:Male
• Location:OK
• Discipline:Enviro

Posted 03 October 2011 - 06:55 PM

Any luck with this yet? I looked at EEERM table 36.1 but could not find the same factor...

QUOTE (ccryalphabetsoup @ Sep 24 2011, 01:43 PM) <{POST_SNAPBACK}>
In Problem #5 about the industrial WWTP:

Where can I find the the 7.7mg/L DO in water @ Temp=22C and elevation correction factor of 0.88 that they refer to in the solution? Initially I thought it would be App 22D.

Thanks

### #10 envirotex

envirotex

Veteran

• Supporting Member
• 4,055 posts
• Gender:Not Telling
• Location:The ATX
• Discipline:Enviro

Posted 06 October 2011 - 08:23 PM

QUOTE (okeng @ Oct 3 2011, 01:55 PM) <{POST_SNAPBACK}>
Any luck with this yet? I looked at EEERM table 36.1 but could not find the same factor...

QUOTE (ccryalphabetsoup @ Sep 24 2011, 01:43 PM) <{POST_SNAPBACK}>
In Problem #5 about the industrial WWTP:

Where can I find the the 7.7mg/L DO in water @ Temp=22C and elevation correction factor of 0.88 that they refer to in the solution? Initially I thought it would be App 22D.

Thanks

The saturation of DO in water (in mg/L) at standard atmospheric conditions varies with temperature, for other pressures, the solubilities vary approximately in proportion to the ratios of these pressures to the standard pressures (Pactual/Pstandard).

So...According to App22.D @ 22C the DO content is 8.83 mg/L. I don't have the problem, but I am assuming that the pressure correction factor is given or derived from a simple ratio or the equation given at the bottom of App22.D...Therefore, the actual [DO] in the water would be Csactual = Csstandard (Pcorrection)

Csactual = 8.83 *(0.88)
= 7.77 mg/L DO

### #11 okeng

okeng

P.E.

• Senior Member
• 51 posts
• Gender:Male
• Location:OK
• Discipline:Enviro

Posted 06 October 2011 - 11:27 PM

QUOTE (envirotex @ Oct 6 2011, 03:23 PM) <{POST_SNAPBACK}>
QUOTE (okeng @ Oct 3 2011, 01:55 PM) <{POST_SNAPBACK}>
Any luck with this yet? I looked at EEERM table 36.1 but could not find the same factor...

QUOTE (ccryalphabetsoup @ Sep 24 2011, 01:43 PM) <{POST_SNAPBACK}>
In Problem #5 about the industrial WWTP:

Where can I find the the 7.7mg/L DO in water @ Temp=22C and elevation correction factor of 0.88 that they refer to in the solution? Initially I thought it would be App 22D.

Thanks

The saturation of DO in water (in mg/L) at standard atmospheric conditions varies with temperature, for other pressures, the solubilities vary approximately in proportion to the ratios of these pressures to the standard pressures (Pactual/Pstandard).

So...According to App22.D @ 22C the DO content is 8.83 mg/L. I don't have the problem, but I am assuming that the pressure correction factor is given or derived from a simple ratio or the equation given at the bottom of App22.D...Therefore, the actual [DO] in the water would be Csactual = Csstandard (Pcorrection)

Csactual = 8.83 *(0.88)
= 7.77 mg/L DO

That's it! Thanks! Turns out I misread table 36.1 and it works just as well but now I know why. EngineerBoards.com is awesome!

### #12 envirotex

envirotex

Veteran

• Supporting Member
• 4,055 posts
• Gender:Not Telling
• Location:The ATX
• Discipline:Enviro

Posted 07 October 2011 - 02:33 AM