[labnetwork] Fwd: Requesting expertise/ experience with Scrubber by-products in Fab.

[Robert Pollina]

Struggling with Scrubber equipment and sending e-mails!  Hope you saw this
e-mail Michael and Jeff.

---------- Forwarded message ----------
From: Robert Pollina <rpollina at umich.edu>
Date: Mon, Nov 26, 2012 at 7:50 AM
Subject: Re: [labnetwork] Requesting expertise/ experience with Scrubber
by-products in Fab.
To: Rizik <rizik at intengr.com>


Michael,
Thanks for the reply.
I will provide some details of our operation.
  The five gallons of by-product I mentioned refers to a yellow-brown skin
of Fusarium fungus and Negative Rod bacteria that forms on the surface of
the recirculating tank.  This material forms, grows and clogs the spray
heads and pumps in the system.  This material is removed by hand each day.
  The ph of the water in the recirculating tank is maintained between 7.5
and 9.5.  The ph is controlled with a ph sensor in the tank and an
automated Sodium Hydroxide (50% solution) feed pump system.  A constant
flow of fresh "city provided" water is maintained at 1/2 gallon per minute
to make up for evaporation.
  We use this Scrubber system to scrub the acidic fume hood exhaust air
from our labs.
  A conductivity sensor helps to maintain a solution that can efficiently
deliver the desired result.
  A manual "blow-down" valve adds fresh water to the system while ejecting
old tank water to the drain to assist in maintaining a conductivity reading
below 5000u.
The Scrubber tank is completely drained and refilled each week as total
dissolved solids always exceeds the ability for a quick blow-down to lower
conductivity to a good level after 5-7 days of lab operation.
An in-line strainer  collects the same material and is cleaned daily.
  I hope this furthers your understanding of our equipment (Harrington
Scrubber)  and procedures.   Looking forward to hearing from you, let me
know if more info is needed
-Robert.


On Sun, Nov 25, 2012 at 9:44 AM, Rizik <rizik at intengr.com> wrote:

> Please try to answer the following questions before we provide our
> recommendation:****
>
> ** **
>
> **1.      **Daily removal of 5-gallons of concentrated solution - Do you
> mean caustic solution? If yes, what is the concentration?****
>
> **2.      **Is NaOH injection to the recirculating water stream being
> controlled by a pH Controller to maintained a predetermined pH level?****
>
> **3.      **What are you trying to scrub?****
>
> **4.      **What is the makeup water flow rate?****
>
> **5.      **Doe you control Total Dissolved Solids in the recirculating
> water? If yes, is it controlled by a TDS sensor & controller?****
>
> **6.      **Does the recirc water go through a periodic purge cycle or
> does it continue to circulate and water is replenished only when water
> level in the basin drops?****
>
> ** **
>
> ** **
>
> ** **
>
> Rizik Michael, PE****
>
> Principal****
>
> Integrated Engineering Services****
>
> Office: +408 261 3500, Ext. 201****
>
> Cell:      +408 718 0927****
>
> ** **
>
> ** **
>
> *From:* labnetwork-bounces at mtl.mit.edu [mailto:
> labnetwork-bounces at mtl.mit.edu] *On Behalf Of *Robert Pollina
> *Sent:* Wednesday, November 21, 2012 5:32 AM
> *To:* labnetwork at mtl.mit.edu
> *Subject:* [labnetwork] Requesting expertise/ experience with Scrubber
> by-products in Fab.****
>
> ** **
>
> Good morning,****
>
> ** **
>
>   I maintain the exhaust Scrubbers serving our wet-benches and fumehoods
> here at the Nanofabrication Lab at the University of Michigan.****
>
> Exhaust air passes through our Harrington Scrubber where Sodium Hydroxide
> solution is sprayed over a "whiffle-ball-like" material, and a favorable PH
> is reached before the air is vented to atmosphere.  The NaOH solution is
> collected in a lower tank and recirculated to the spray heads. PH sensors
> and Conductivity sensors call for more NaOH and city supplied fresh water
> as needed.****
>
> ** **
>
>   Problem: Large amounts of Fusarium , Negative rod and Rototurula
> bacterias and fungi are created in the tank and must be removed to keep the
> Scrubber operating properly. This by-product is removed almost daily, often
> exceeding five gallons of concentrated solution.****
>
> ** **
>
>   I'm hoping someone has experience with this same equipment and unwanted
> Fusarium growth.****
>
> How do we better control production of this by-product?   What are the
> proper safety procedures for maintenance staff?****
>
> Are there other issues I am not aware of concerning this equipment,  its
> operation, maintenance and safety? ****
>
> ** **
>
>   Any assistance in this matter would be greatly appreciated.****
>
> ** **
>
> Robert Pollina****
>
> University of Michigan****
>
> Electrical Engineering and Computer Science****
>
> Nanofabrication lab****
>
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