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faisal
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Posted: 02 July 2012 at 10:27am | IP Logged Quote faisal

GOOD EVENING
am working in sudan , we have a big issue of smell from sludge 
 we made sludge pits at land and we keep sludge thats pits for drying
we having major complain from town peoples of smell how can we solve this problem
 best regard


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cbblackie3
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Posted: 02 July 2012 at 2:07pm | IP Logged Quote cbblackie3

How are you seperating the solids (sludge) from the liquids.

 



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faisal
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Posted: 03 July 2012 at 2:41am | IP Logged Quote faisal

we using aluminium sulphate and poly electrolite then when sludge is settle down and we take out water , then we pass the sludge through centriquipe , and remove remaining water , and sludge gone on land and we keep there for dry , 

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DavidR
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Posted: 03 July 2012 at 10:52am | IP Logged Quote DavidR

Dear Faisal:  You do not so much need a tanner but a very competent detective!  On general principles, however let me make a quick suggestion.  Sulphur in the minus two oxidation state (Sulphide) is really the most toxic form and Nature has tried to make organic sulphides, that is mercaptans, (Skunk "essence", gas-leak warning by smell system, etc. etc.) particularly unplesantly odororipherous.  By using sodium metabisulphite in the delimming operation, depending on how much sulphide was used in the beamhouse (try initially 2% metabisulphite); the oxidation state of sulphur in SO2-gas derived chemicals, such as metabisulphite, etc. is in the plus four state.  A relatively small amount of sulphur plus four chemical will oxidise sulphur minus two compounds to elemental sulphur (cero oxidation state, which is odorless and not toxic in a chemical sence) and hopefully affect favorably your resulting sludge-smell!  There is unfortunatelly also in Mediterreanean influenced cultures great aversion to tanneries, to this day the belief that leather is not Hallal ("pure") enough to enter a Mosque, the house of G-d!  Hence the public is predisposed to mistrust tanneries from a sannitary viewpoint, but please try my suggestion at once and if it does work, get back to me and we will figure out what is the best to do next!

Edited by DavidR on 03 July 2012 at 9:37pm


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cbblackie3
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Posted: 03 July 2012 at 10:54am | IP Logged Quote cbblackie3

You should try aluminum chloride.

What happens ius the sulphate from the aluminum can reverse with time to create H2S, which causes the smell.

If there is anyway you can airate the solids until, then you should have far less problems.



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DavidR
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Posted: 03 July 2012 at 11:04am | IP Logged Quote DavidR

Dear Mr. Black:  I would guess that they are not recovering hair and the presence of keratins will generate lots of sulphur compounds inmany oxidation states any way.  There is so much sulphate present anyway in the combined effluents (that perhaps pre-removing sulphate with lime would be more practical) that under anerobic conditions it will be difficult to avoid sulphur compounds entirely.  The presence of sulphur plus four chemicals, by oxidizing will tell us by solving the odor problem, where we can finally go!

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kallenwe
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Posted: 03 July 2012 at 10:17pm | IP Logged Quote kallenwe

Why would the odor be sulfide and not ammonia?  Would not air catalyzed digestion cure both? 

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DavidR
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Posted: 03 July 2012 at 11:44pm | IP Logged Quote DavidR

The likely "bad odor" are (organic)  mercaptides, that is sulphur in the minus two stage.  There might be very complicated CN- compounds formed by anerobic fermentation when amonium is present.  Some of these smells have been reported to me as similar to those in onions, but distastefull and not like the bewitching aroma of a mediterranean region restaurant frying onions!  The use of plus four sulphur in the way of sodium metabisulphite solved the particular problem including the the change of cyanide to thiocyanide, that is not toxic at all, thus solving the legal problem that was starting to take ugly shape, but fortunatelly was snipped in the bud, very empirically, and I must say ignorantly.  The real chemistry involved is just too complicated to guess at at this stage, but I am sure it will eventually be solved.  There is both sulphite/bisulphite and even thiosulphate generated by hide keratins decomposing, and ever since the foolish sannitary authorities have been suggesting transferring COD from the tannery effluents to landfill effluents, by salvaging and then burring the hair, problems with cyanides have been developing in tanneries because of the lack of thiosulphate then reacting to form thiocyanide which is harmless.  Thiosulphate is even recomended as an injectable intravenous antidote into individuals poisoned by HCN gas!  The complexities involved in anerobic fermentation by microörganisms is much too complex for tanners to cope with, but your personal background in microbiology would make your observations and comments much more more relevant.

Edited by DavidR on 03 July 2012 at 11:48pm


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faisal
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Posted: 04 July 2012 at 3:28pm | IP Logged Quote faisal

Thanks both of u , for given me some suggestion today i made a trail , cover the sludge pit with lime liq , and made a nearly 3 mm layer of lime over it after that am felling there less smell , am also "ll try metabisulphite
 best regard
and best wishes


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DavidR
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Posted: 04 July 2012 at 5:53pm | IP Logged Quote DavidR

Please try the metabisulphite (2%) at the deliming stage, good luck!  DR

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