From: "Joe Ruocco" <JoeR@ICMINC.com>

To: "Sarah Holman" <Sarah.Holman@erg.com>

Date: 10/16/2006 5:50:38 PM Subject: RE: capacity of Bio-Methanators

All of the above- recycled as backset, evaporated t o syrup and sometimes

sent to anaerobic treatment.

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From: Sarah Holman [mailto:Sarah.Holman@erg.com] Sent: Monday, October 16, 2006 8:03 AM

To: Joe Ruocco Subject: RE: capacity of Bio-Methanators

Thanks, Joe.

My last question then is:

What happens to the stillage from the ethanol proce ss at wet milling facilities? Is it typically recycled or sent somew here other than the anaerobic treatment system?

Thanks,

Sarah

Sarah Holman Chemical Engineer Eastern Research Group, Inc. 703-633-1661 (phone) 703-263-7479 (fax)

>>> "Joe Ruocco" <JoeR@ICMINC.com> 10/15/2006 6:01: 12 PM >>>

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From: Sarah Holman [mailto:Sarah.Holman@erg.com]Sent: Friday, October 13, 2006 6:32 PM

To: Joe Ruocco Subject: RE: capacity of Bio-Methanators

Thanks a lot, Joe, for the wet milling information. Again, very useful.

I do have some questions about the COD loadings:

1. Is the COD loading range (20,000 to 100,000 ppd) for a combined

wastewater stream that is sent to the anerobic trea tment system? yes

2. If so, what wastewaters are included in this com bined stream? Steeping and washing wastewaters only, or stillage from distillation as well? Not stillage, but a lot of wash waters from s eparation and product washing operations

3. In your experience, does COD loading correlate t o ethanol production? So, for example, is the high end of the COD loading range (100,000 ppd COD) likely from the largest wet milling ethanol fa cilities (around 250 MMGY)? Not really- not the way it does in dry mill plants done by the same designer - there is a lot more product diversi ty in a wet mill, therefore a lot of variability in the ww COD loadin g

Thanks,

Sarah

Sarah Holman Chemical Engineer Eastern Research Group, Inc. 703-633-1661 (phone) 703-263-7479 (fax)

>>> "Joe Ruocco" <JoeR@ICMINC.com> 10/9/2006 11:33: 03 AM >>>

Sarah,

Wet mill facilities generate much more wastewater a t much higher COD than dry mill plants. This due to steeping and wash ing operations. Details vary depending on precisely which products the mill is making.They typically use anaerobic systems first (larger than dry mill

systems- much larger), followed by aerobic polishin g systems to either directly discharge to he environment or to a city P OTW.

COD loading can be anywhere from 20,000 ppd to as m uch as 100, 000 ppd depending on the mill.

Joe

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From: Sarah Holman [mailto:Sarah.Holman@erg.com] Sent: Friday, October 06, 2006 10:14 AM

To: Joe Ruocco Subject: Re: capacity of Bio-Methanators

Thank you, Joe,

Yes, this information is quite helpful.

Since you were kind enough to respond, I will bothe r you about one more topic (the last I promise!).

I have found little information about the wastewate r at wet milling facilities. I realize that you do not typically wo rk with wet milling ethanol production facilities, but I thought I woul d try you anyway. These are my questions:

1. My understanding is that wet milling facilities that produce ethanol typically do not process the stillage (distillation bottoms) into co-products like distillers dried grains. I assume this is because at wet milling facilities, the gluten/fiber portion of corn is separated prior to ethanol production. In addition, wet mill ing facilities are large and typically have on-site wastewater treatme nt that can handle treating the large stillage volumes. Is this corre ct?

2. Because the gluten/fiber portion of corn is sepa rated prior to ethanol production at wet milling facilities, is th e COD of the stillage from distillation much less than at dry milling fac ilities?3. Do you know if the amount of stillage from disti llation is much

different at wet milling and dry milling facilities ? For example, would a 100 MMGPY wet milling facility produce more or le ss stillage from distillation than a 100 MMGPY dry milling facility?

4. Do you know if many wet milling facilities recyc le the stillage from

distillation?

Please feel free to call me if you are interested i n discussing anything about ethanol production wastewaters (703-633-1661)

.

Thank you,

Sarah

Sarah Holman Chemical Engineer Eastern Research Group, Inc. 703-633-1661 (phone) 703-263-7479 (fax)

>>> "Joe Ruocco" <JoeR@ICMINC.com> 9/29/2006 12:23: 47 PM >>>

Sarah,

Anaerobic systems are rated in terms of COD total l oading capacity- that is the number of pounds per day of COD fed to the r eactor per day is how we design and discuss all anaerobic systems, includ ing of course high

rate Bio-Methanators such as ours.

Yes, plant capacity dictates the amount of evapora tor condensate produced along with total COD loading. In a typical 50 MMGPY plant flows tend to be 80 to 140 gpm. In a 100 MMGPY plant they tend to be 200 to 275 gpm. Loading ranges from 2000 PPD COD to 16,000 PPD depending on size of the plant and the design- some designs gene rate more COD than

others.

I hope this helps.

Joe