Covering Slurry lagoons??? Good thing or not???

[O'Reilly]

The sooner you can get it mixed the more you will reduce losses - and it foams a lot! You can get some benefit by mixing in the tanker, but nowhere near the full amount.

So tipping a bucket of acid in the reception pit every day would be better? Provided it didn't eat the concrete before you got it mixed of course!

 

[sjt01]

So tipping a bucket of acid in the reception pit every day would be better? Provided it didn't eat the concrete before you got it mixed of course!

Mix it in, then wait for the foam to subside, then test for pH to see if you have enough. However I would not recommend manual handling of conc H2SO4!

 

[som farmer]

stayed on a farm, b and b, looking round, his lagoon was covered, had a tree growing on, and loads of tall weeds/ shrub etc. for a farm bb I thought it was bloody dangerous!!!!!! thought about putting cover on ours, but stirring, emptying actions, couldn't quite see it. and, of course, if you took the grant, you are telling defra, csf etc the size of your lagoon! which might not be the best of ideas, as a local farmer found out, on an nvz inspection !
I think separators are the way to go

 

[pappuller]

stayed on a farm, b and b, looking round, his lagoon was covered, had a tree growing on, and loads of tall weeds/ shrub etc. for a farm bb I thought it was bloody dangerous!!!!!! thought about putting cover on ours, but stirring, emptying actions, couldn't quite see it. and, of course, if you took the grant, you are telling defra, csf etc the size of your lagoon! which might not be the best of ideas, as a local farmer found out, on an nvz inspection !
I think separators are the way to go

Is separated liquid not still treated as slurry tho ?

 

[jimmer]

I know it's not possible for everyone due to cropping etc
But I'd rather pay for an extra umbilical session or even 2 per year and get better utilisation of slurry, than bugger about with covers and special stirrers and de silting etc

 

[vantage]

I know it's not possible for everyone due to cropping etc
But I'd rather pay for an extra umbilical session or even 2 per year and get better utilisation of slurry, than bugger about with covers and special stirrers and de silting etc

I agree,but unfortunately in Wales we may have a five month closed season for spreading dropped on us by the Welsh gov if rumours come true

 

[jimmer]

I agree,but unfortunately in Wales we may have a five month closed season for spreading dropped on us by the Welsh gov if rumours come true

Another reason not to move to Wales

 

[vantage]

Another reason not to move to Wales

That and Tb,or rather the unwillingness to do anything while it runs rampant especially in Pembs,test yesterday 5 r’s,6 ir,s,all probably to go.

 

[jimmer]

That and Tb,or rather the unwillingness to do anything while it runs rampant especially in Pembs,test yesterday 5 r’s,6 ir,s,all probably to go.

Cuss


Another reason

 

[stirrer]

Depends on the buffering capacity of the slurry or digestate, best to use a pH meter. It should be about 4 kg/m3 for our digestate

you dont need a big stirrer. the mixit will deliver 200hp and is widely used with the big Scottish lagoons.
they also have an extension frame see here http://farmingforum.co.uk/forums/attachment.php?attachmentid=1760&d=1447155950
i will try and find the link to this chap stirring a big lagoon.

 

[stirrer]

you dont need a big stirrer. the mixit will deliver 200hp and is widely used with the big Scottish lagoons.
they also have an extension frame see here http://farmingforum.co.uk/forums/attachment.php?attachmentid=1760&d=1447155950
i will try and find the link to this chap stirring a big lagoon.

i have found the link to the pics plus a few comments.
inthe mixit stirrer any good below

Mixit slurry stirrers any good?

Ah naw the size and diameter of some towers and lagoons take a bit of getting moving.even a 150hp tractor can get warm on a cold day

thefarmingforum.co.uk

 

[stirrer]

I did the same!

Ended up with a 5' crust,circulated it,blew air into it,bugs etc.. nothing worked! Admitted defeat and cut the cover off.

Ideally need a tensioned cover,not sure why they're only available for round stores.

i am a bit puzzled as to why a crust is not considered a cover. ammonia is lighter than air so will escape whatever.
if you leave your slurry unstirred until you wish to spread it then the thickness of crust is not a problem IF you have enough liquid.
anything less than 2/3 liquid is a problem.
I have stirred many tanks with 6ft of crust but usually run out of water.
the Mixit stirrer has a rotating tube and auger so is capable of cutting through the crust to reach the liquid.
the impellers have two sets of blades so there is no problem delivering all your tractor's power to the slurry. up to 200HP!
a video of it working is available on youtube or the website.

 

[Tarw Coch]

Just how does covering a slurry pit help with emissions? Unless the methane is taken off as in a digester surely it’s still there waiting to enter the atmosphere at some point.

 

[stirrer]

Just how does covering a slurry pit help with emissions? Unless the methane is taken off as in a digester surely it’s still there waiting to enter the atmosphere at some point.

the methane is the product of digesting slurry. As far as i know, and i am not an 'expert', no methane comes from an open slurry store.
In fact, little ammonia evaporates until spread. There is a study on spreading which found - the runnier the slurry being spread, the less the ammonia evaporates.
i.e. is runs into the ground.

 

[Tarw Coch]

the methane is the product of digesting slurry. As far as i know, and i am not an 'expert', no methane comes from an open slurry store.
In fact, little ammonia evaporates until spread. There is a study on spreading which found - the runnier the slurry being spread, the less the ammonia evaporates.
i.e. is runs into the ground.

Second point is interest, most people try to keep water out of slurry storage, could it be that adding it would be better for emissions?

 

[sjt01]

the methane is the product of digesting slurry. As far as i know, and i am not an 'expert', no methane comes from an open slurry store.
In fact, little ammonia evaporates until spread. There is a study on spreading which found - the runnier the slurry being spread, the less the ammonia evaporates.
i.e. is runs into the ground.

The rate of loss of methane from a slurry store will depend on the temperature more than anything else. The bugs that produce it perform best at cow body temperature, and produce very little at winter temperatures.
Ammonia is a different story, it is split between ammonia (which readily evaporates) and ammonium ions (which stay in the slurry). The higher the pH, the greater proportion as ammonia, and the same with temperature. As ammonia is lost from solution, more ammonium will be converted into ammonia, but the lower the proportion as ammonia the slower that will be.

Note that the y axis of the graph is a log scale, so going from pH 8 to pH 5.5 is a thousand fold reduction.

I think the best way to reduce ammonia losses is to reduce pH with sulphuric acid (cheaper than buying sulphur as Double Top or ammonium sulphate), rather than covering lagoons. I am part way through developing a system for our AD digestate.

 

[stirrer]

The rate of loss of methane from a slurry store will depend on the temperature more than anything else. The bugs that produce it perform best at cow body temperature, and produce very little at winter temperatures.
Ammonia is a different story, it is split between ammonia (which readily evaporates) and ammonium ions (which stay in the slurry). The higher the pH, the greater proportion as ammonia, and the same with temperature. As ammonia is lost from solution, more ammonium will be converted into ammonia, but the lower the proportion as ammonia the slower that will be.

Note that the y axis of the graph is a log scale, so going from pH 8 to pH 5.5 is a thousand fold reduction.

I think the best way to reduce ammonia losses is to reduce pH with sulphuric acid (cheaper than buying sulphur as Double Top or ammonium sulphate), rather than covering lagoons. I am part way through developing a system for our AD digestate.
View attachment 833288

AHDB have just publish info on slurry cooling etc. it is also featured in this month's Pig Farmer.

 

[O'Reilly]

The rate of loss of methane from a slurry store will depend on the temperature more than anything else. The bugs that produce it perform best at cow body temperature, and produce very little at winter temperatures.
Ammonia is a different story, it is split between ammonia (which readily evaporates) and ammonium ions (which stay in the slurry). The higher the pH, the greater proportion as ammonia, and the same with temperature. As ammonia is lost from solution, more ammonium will be converted into ammonia, but the lower the proportion as ammonia the slower that will be.

Note that the y axis of the graph is a log scale, so going from pH 8 to pH 5.5 is a thousand fold reduction.

I think the best way to reduce ammonia losses is to reduce pH with sulphuric acid (cheaper than buying sulphur as Double Top or ammonium sulphate), rather than covering lagoons. I am part way through developing a system for our AD digestate.
View attachment 833288

Are you then going to patent the system and sell it? Sounds like a lot of people are going to need something like that.

 

[sjt01]

Are you then going to patent the system and sell it? Sounds like a lot of people are going to need something like that.

See how it goes. Unlikely to be patentable, however design registration might cover it, if not may just sell the control system and build plans.

 

[Mr Mackay]

An advisor and buildings planner that I know ,was telling me how in Wales they are getting possessed about ammonia and covers and , ecology reports etc ,and a chap he knew had spent £3000 on reports and planning stuff even before he starts spending the £15000 on a simple earth lagoon , away from anything - that they seem to insist will need to be covered too!! 100 cow size possibly .
Seemed to be driving them both mad