Printech Archive, November, 1999: Re: Insufficient COD reduction, Is sludge hazardous?

Re: Insufficient COD reduction, Is sludge hazardous?

Deb Jacobson (
Wed, 24 Nov 1999 15:01:25 -0600

Date: Wed, 24 Nov 1999 15:01:25 -0600 
To: Patricia Bastos <>
From: Deb Jacobson <>
Subject: Re: Insufficient COD reduction, Is sludge hazardous?

Patricia -
I am sending you my response, however I plan to confer with Doreen
and may have additional comments afterword. I assisted a U.S. company with
testing, design, and installation of a flexo waste water treatment system.
The waste water sounds very similar. See below comment in red.

At 04:46 PM 11/24/99 -0200, you wrote:
> > In reference to the physical/chemical waste treatment:
> > The wastewater is introduced in the system with COD = 25,000 mg O2/l.
> > The treatment is carried out with NaOH and Al2(SO4)3 as a
flocculent. An
> >anionic polymer is also used before solid being settled..
> > The mixture is "hand made".
In laboratory testing conducted in our lab with water based flexo (high
solids) rinse water the best flocculent was an electrolyte solution (CaCl,
NaCl, or HCl). The Calcium Chloride and Hydrogen Chloride cause the solids
to coagulate much faster than the sodium chloride. Add 5% by weight.
> > The detention time is about 12 hours.
Good, but you may want to consider adding a mixer (air or electric powered)
for the first hour of batch processing to facilitate chemical bonding. I
trust you are decanting the liquid and then drumming up the solid residue.
This can be put through a filter press or other processing for de-watering.
> > The treatment is carried out in batch, with an amount of 1000 liters
> each 2
> >days.
> > No filters are used.
Consider adding 3 to 5 stages of filtration which includes spiral wound
filters with 100 down to 5 micron filters. You can also add a carbon filter
at the end for polishing, but that is optional. I can provide additional
information if needed.
> >
> > Regarding all of those characteristics, which treatment would be more
> >appropriate?
Before you completely change your treatment system or spend a lot more money
consider my above comments.
> >The efluent, using the our current treatment comes out with 3000 mg
> (the
> >limit according to our legal requirements is 150 mgO2/liter). We are
> planning to
> >deliver a test using UV treatment trying to reduce that amout. Do you think
> that
> >would be a good option? Is this kind of treatment usual in the US and
> Canada?
What do you expect to accomplish with the UV treatment? It will not remove
the suspended solids which is contributing to the high BOD. The UV treatment
is common for water disinfection, particularly for drinking water. I am not
aware of it being used for industrial waste water treatment for effluent such
as what you are describing.

What is the chemical characteristics of the cleaning products you are adding
to the water? Is it a detergent alkaline based material?

Have you considered re-using the filtered water vs. discharging it?
> >
> > I look forward for hearing from you.
If you have photographs of your system that you could send me I may be able
to assist more effectively. Particularly if you need assistance with
design/retrofit for filter cartridges.

Best regards,

Deb Jacobson (my address, etc. at end of e-mail)
> >
> > Best regards
> >
> > Patricia
> >
Debra Jacobson (formerly Kramer)
E-mail Address (Revised 9/99)
IL Waste Management & Research Center / IL Dept of Natural Resources
1010 Jorie Boulevard, Suite 12
Oakbrook, IL 60523
630/472-5023 Fax



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