Hi I’ve got the 44kw biolectric plant and I’ve currently got a bit of foam but it’s just enough to cause high H2S which means I go through lots of carbon. I believe the foam stops the H2S fro getting to the net which is where it’s caught so if I get rid of foam I get rid of H2S I think! Anyone know how to get rid of it? Currently using envirosystems anti foam product which is 1 litre/day but isn’t getting the foam down enough and is quite costly.
AD plant foam and H2S solutions?
- Thread starter Chippy
- Start date
wasted years
Member
- Location
- Cumbrian born and bread
Stating the obvious but can't the installer help?
- Location
- Cumbria
Foaming can be, and is, a general problem with AD Plants, in the worst case it could take the roof off (and has done at other plants). In some cases the top has a ' burst open ' panel added for safety. It is usually caused by over-agitation, however some feed-stocks can cause it.
Most modern plants have a anti-foam system (catch tanks - spray systems etc) to deal with this common problem.
Adding more/fresh carbon to the gas flow filter to reduce the H2S is not the solution, you must get rid of the foam and foaming.
Installer has helped as much as they can. We have a thing that pops off before foam takes roof off so that’s ok. I did think it was down to too much stirring but last time we reduced the stirring time a crust formed and took a while to get rid of it. But the beauty of a crust is you have no foam and no H2S. Would you recommend letting a crust form and maybe now and again giving it a good stir before it got too thick ?
The Son
Member
- Location
- Herefordshire
I just put 10l of cooking oil or diesel into the top of the tank, reduces surface tension and therefore foaming, have you got anyway of pouring it into the tank?
This will reduce the immidiate problem, but there is somethingbelse underlying it, for me I have to be careful when putting things like spuds, sugar beet or pomace into the diet, introduce them too quick and i get foaming.
Regarding the stirring do not allow a crust to form, keep the tank well stirred, I like to keep my tank between 9-11% dm with the consistancy of porridge.
This will reduce the immidiate problem, but there is somethingbelse underlying it, for me I have to be careful when putting things like spuds, sugar beet or pomace into the diet, introduce them too quick and i get foaming.
Regarding the stirring do not allow a crust to form, keep the tank well stirred, I like to keep my tank between 9-11% dm with the consistancy of porridge.
The Son
Member
- Location
- Herefordshire
No it will be fine, the bugs are fairly resiliant☺
Digester Man
Member
Cooking oil is the job, but engine oil will also work in an emergency
It will also kill the foam when mixing a tank of slurry and silage effluent
It will also kill the foam when mixing a tank of slurry and silage effluent
- Location
- Essex
I have also heard about using Cooking oil - several plants in Germany using a high volume of sugar beet were putting in 'Rape oil' . Engine oil sounds a bit dirty to me and I would be worried about the impact further down the process.
Actually I would want to be sure that any oil used wont cause issues in filters further down the line. How you could test this I don't know.
There is a story about a plant bringing in waxed citrus peel - the wax was not digestible and caused issues.
Actually I would want to be sure that any oil used wont cause issues in filters further down the line. How you could test this I don't know.
There is a story about a plant bringing in waxed citrus peel - the wax was not digestible and caused issues.
- Location
- Essex
I wonder if you could use old oil from a chippy? Nice smell anyway.
- Location
- Cumbria
It is good practice to allow a small crust to form on the secondary tank with a two stage process. This provides an additional surface area for the bacteria to form to clean out the H2S, however, I cannot comment on a single tank system as I have no experience.
So far I’ve had 2 crusts for months at a time before I’ve got rid of them using bugs but whilst having a crust I had no H2S and no foam and still had good gas. Now that I have no crust, I have H2S at 2000ppm and a bit of foam and I’m going through quite a lot of carbon. I wonder whether it could be a routine thing where by I let a crust develop and once every other month or once a month I drop the level of the plant and hit it with a load of bugs and stir the sh!t out of it and get rid of crust. What are people paying for carbon?
- Location
- Cumbria
No, do not do that.
By lowering the tank level, you increase the OLR, and increase the likely-hood of foaming
- Location
- Cumbria
Loading rate (Organic Loading Rate))