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Thanks for the responce.
The sulfide odour not being detected is still a mystery for
us.and yes probably Sulfide odour was not detected physiologically.
The design of the gas collection systemn is such that once the
water levels are down, the reactor becomes partially open to air. Also as a
precautionary measure, we had been pumping approx. 500 -700
m3/hr (Reactor volume 2300 m3) of air in the reactor during the
biomass unloading.
(And still the ammonia smell persisted and no sulfide
smell)
Regards,
Avadhut Bapat
----- Original Message -----
Sent: Thursday, December 13, 2001 1:58
AM
Subject: RE: DIG-L: Ammonia in
Biomethanation !!!!!!
The mystery to me is not the strong ammonia
smell, probably due to the high loading rates CB mentioned earlier, but why no
sulfide odor was detected. Is it possible that the intense ammonia odors
masked the sulfide? Was there any
laboratory analysis of the fumes from the repair effort? Olfactory
fatigue for hydrogen sulfide occurs quickly at high concentrations. OSHA
warns that sulfide levels of 300 ppm or higher cause the olfactory nerve to
lose sensitivity (even higher levels cause death!). Is it possible that
the concentrations of sulfides were such that its' detection was no
longer physiologically possible whereas, ammonia detection was not
inhibited in the same way?
Patrick Griffith, P.E.
Los Angeles County Sanitation
Districts
1955 Workman Mill Road
Whittier, CA 90601
(562)
699-7411 x2117
FAX (562) 692-9690
pgriffith@lacsd.org
Hello & Thanks,
We dont have 4 digestors. We have only 2 !! These
have been designed on a VLR of 15 kg/m3/day. The total volume of the 2
reactors is 4768 m3.The BOD/COD and the TKN values for the other reactor are
the same as these 2 reactors are operated (Fed)thro a single Buffer
Tank.
Thanks!!,
Avadhut
----- Original Message -----
Sent: Friday, December 07, 2001 4:16
PM
Subject: Re: DIG-L: Ammonia in
Biomethanation !!!!!!
Hello again,
my experience with uasb digesters is that they operate at very low BOD
levels which is why they have a high throughput.
From your figures
yours is a very high BOD input; this would explain the ammonia; digestion
is not as complete as it should be and BOD is probably being throughput
too fast.
Perhaps diluting the BOD, or extending the retention time up to 15 - 19
days as opposed 3 - 5 days for a standard uasb.
What are the BOD and
ammonia readings from the other 3 operational digesters that you have
there?
What retention time are you using in your uasb digesters?
Regards
CB
OLEL wrote:
Thanks for an instant
responce !!1.The pH of the Distillery Spentwash is
around 4. But the pH of the Raw effluent is adjusted to 6 to 6.5 before
it enters the UASB system by using the Biocarbonate Alkalinity from the
treated Effluent(Which is recycled in a buffer Tank , where it gets
mixed with the raw Effluent) and an external addition of Lime to the
Buffer Tank.2. We are not using Proprietory Bactria
or Organic Media Cells.3. I didn't understant
what you mean by UASB as a Dilute Process.Would be grateful if you
could explain. The COD of the
Distillery Spentwash is 100000 mg/L. The organic Concentration entering
the reactor after dilution and mixing with the recycled flow is 30000-
40000 mg/L(COD) !!!! Thanks again for the
responce.,Avadhut Bapat.
----- Original Message -----
Sent: Friday, December 07, 2001
10:53 AM
Subject: Re: DIG-L: Ammonia in
Biomethanation !!!!!! Chances are the pH is the
determination factor of the excess ammonia.
Are you using
proprietory bacteria?
Organic media cells for the bacteria?
UASB is a very dilute process and the absence of H2S is not
surprising; but this is dependant on the throughflow rate of your
wastes.
A low pH will deliver excess ammonia residues.
Just my two bobs worth
good luck
Regards
Carmine Bocchino
OLEL wrote:
I operate an anaerobic UASB system for the treatment
of 700m3/day Cane molasses based Distillery Spentwash.This plant has
been in operation for the last 6 years.One of the UASB ractors was
recently opened for the repairs of the feed distribution Network.
Besides many interesting findings , one puzzling observation was
that, throughout the period when the Anaerobic Biomass was being
removed from the reactor(i. e. for about 3 weeks) , a very
strong odour of Ammonia was persistent in the reactor.
Actually H2S smell was expected as the Spentwash contains high
concentrations of sulfates and the Anaerobic Biomass contains
Sulfate Reducing Bacteria. But No H2S smell was encountered.
Can somebody please throw some light on the possible
reasons for the presence of this strong Ammonia smell ??
P.S. 1.No external Nitrogen was being added as the
TKN concentration in the distillery spentwash is in the range
of 1000 to 1500 mg/L. 2. Moderate quantities of yeast may have
accumulated in the reactor(Source: Distillery Spentwash).
Thanks., Avadhut
Bapat
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