You are probably correct for whole fish meal. But, processors in Alaska
have been trying to solve the stickwater/salt problem for over 10
years. About 20% of the solids in stickwater (in Alaska shore plants)
is salt. The plants process the heads, skins and offal from other
seafood operations and the fish meal is a by-product. The fish absorb
the salt water from RSW storage and transfer, especially in the skins
and this can not be avoided. The salt is carried to the meal process
where most goes into the stickwater. Most meal plants in Alaska already
have evaporators installed to concentrate the stickwater and add it back
to meal, but only about 15% of the stickwater can be added back before
the salt content of the meal reaches an "unacceptable" level. Everyone
is aware of the origin of the salt, the problem is the removal.
The discharge of stickwater is permitted by EPA and state environmental
regulators. Total maximum daily load analysis has been done for the
effect of stickwater and other BOD loads on a site by site basis. Your
blanket statement "the environmental load for discharged stickwater
should not be tolerated", is not supported by the data. Over ten years
of data and analysis on many Alaska meal plant discharges has
demonstrated that there is no statistically significant impact resulting
from the discharge of stickwater. It depends on the assimilative
capacity of the receiving water. I'm sure in some instances, it could
have a huge detrimental impact. But, in others, there will be no
impact.
Regardless, it would be nice to recover that additional protein so if
anyone has any ideas on a large scale cost effective method to separate
the salt from soluble protein, it would very useful. Methods tried or
under investigation include dissolved air floatation, flocculents,
ultrafiltration, and others.
Greg Peters
"Anthony P. Bimbo" wrote:
> The salt doesn't come from the stickwater since this is the water
> within the fish. It normally comes from ocean water used for
> refrigeration if that comes in with the fish or in the case of So.
> America from the pumpwater used to unload the fish. Almost all
> fishmeal is wholemeal, that is, contains all the concentrated solubles
> added back. The quality of the meal depends on the quality of the
> fish and the quality of the stickwater, if it is allowed to decompose
> then it will reduce the quality of the fishmeal. If salt is the only
> issue then it is a matter of looking at the process to see where the
> salt is coming from. For example, some plants receive only trimmings
> and sometimes included with the trimmings are spoiled salted fish. In
> any event, it is, in your case (Alaska), most likely due to adding
> Pacific Ocean water. One also has to weigh the eventual cost of
> treating stickwater if it is discharged or being fined vs the cost of
> adding the evaporation equipment and getting something back. Not sure
> what a sewer system would charge to receive stickwater in a treatment
> plant. One has to assume that sooner or later the discharge overboard
> is going to be stopped. Anyway, that is my opinion.Regards Tony Bimbo
>
> ----- Original Message -----
> From: Greg Peters
> To: Anthony P. Bimbo ; seafood@ucdavis.edu
> Sent: Tuesday, August 13, 2002 6:15 PM
> Subject: Re: Stickwater, COD, BOD
> Sorry,
>
> But you're not exactly correct. The value of meal produced
> from stickwater is not as good as traditional meal. The
> salt content is too high so either additional capital
> expense needs to be added for salt removal or the meal is
> sold at a decreased value. Either way, the payback is
> substantially longer than a year and that is if you have the
> capital to invest in the first place.
>
> BOD for stickwater is usually between 30,000 and 50,000 mg/l
>
> COD is usually 70,000 to 115,000 mg/l
> TSS is usually 20,000 to 30,000 mg/l
>
> Greg Peters
> Alyeska Seafoods, Inc.
>
> "Anthony P. Bimbo" wrote:
>
> > <?color><?param 0100,0100,0100> Mauricio: Try the link
> > below. The EU has been working on this for some time and
> > fish processing is part of the work. Using BOD and COD
> > for stickwater is a non-starter since the solids content
> > is around 8% and when converted to fishmeal is an enormous
> > amount of yield to lose. With prices where they are now,
> > a stickwater plant pays for itself in about a year. The
> > environmental load from discharged stickwater should not
> > be tolerated and the cost to treat the BOD and COD could
> > be equivalent to a medium to large city. Hope this helps.
> > You can read and download the BREF from the website,
> > either via the "Utilities and members workspace" page by
> > clicking on "Direct Access to
> > Public Area" or via the "Activities" page.
> >
> > The address of the website is http://eippcb.jrc.es.
> >
> >
> > ----- Original Message -----
> > From: Mauricio Gonzalez
> > To: seafood@ucdavis.edu
> > Sent: Tuesday, August 13, 2002 4:19 PM
> > Subject: Stickwater, COD, BOD
> > Hello Everyone,
> >
> > Does anybody have information about suspended
> > solids in stickwater v/s COD and BOD (herring
> > and shrimp fishmeal processing plants)?
> >
> > Thanks in advance,
> >
> > Mauricio
> >
> >
> > ==========================================================
> > MAURICIO GONZALEZ
> > Ph.D. Engineering Sciences
> > Docteur en Sciences de l'Ingénierie
> > Doctor en Ciencias de la Ingeniería
> >
> > Marine Products Research and Development Center Inc
> > Centre de Recherche et de Développement des Produits Marins Inc
> > Centro de Investigación y Desarrollo de Productos Marinos Inc
> >
> > 218 J.D.Gauthier Boulevard, 5th floor
> > 218, boulevard J.-D.-Gauthier, 5e étage
> > 218, bulevar J.-D.-Gauthier, 5to piso
> > E8S 1P6, Shippagan
> > New Brunswick, Canada
> > ==========================================================
> >
> >
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