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1 hour ago, swiss_democracy_for_all said:

If the sewer is cooled by removing heat from it, won’t Mr Pin be busy with even more fatbergs as any oil or fat will solidify even more?

There is also the question as to how important is the heat to a bioreactor.  Perhaps as soon as you remove the heat they stop working.  I've no idea if it is or not -- just that it is a question I have.

 

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1 hour ago, Hopeful said:

Respiration/metabolism produces a lot of heat

Dung heaps can be devised to supply a constant supply of hot water for stables if you bury a water tank in them, need to move it occasionally as decay ends and areas go cold.

Yes. You can heat a greenhouse using nothing but a pile of dung or new compost shoved in a hole. It works for a few weeks. 

If I recall, the heat inside the huge pile at commercial compost makers gets as high as 300 C in the centre. Or something like that. 

Edited by spunko
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53 minutes ago, dgul said:

There is also the question as to how important is the heat to a bioreactor.  Perhaps as soon as you remove the heat they stop working.  I've no idea if it is or not -- just that it is a question I have.

One of my responsbilities in a previously life was to keep an eye on an activated sludge plant (treating organic chemical plant waste); if the load was particularly high, and the weather was warm the aeration basin could get upto around 40C, if the load was low in the winter it could be as low as 20C.

The performance of the plant was good enough at both extremes, from this we can conclude that for some treatment plants (maybe most ?) it would be possible to remove a reasonable amount of heat and recycle it for another use. The issue is that by definition it is very low grade heat, this is expensive to extract and not a great deal of use unless you happen to be fortunate enough to have a low grade heat customer very close to the plant.

Most large effluent plants are not located close to areas with a lot of people about (for obvious reasons) so I would imagine it is just not that practical to implement these schemes very frequently.

Now if the plant were to be an anaerobic treatment plant, then the product is biogas which can be either burned in an engine to produce electricity and heat, or just burned in a boiler to produce heat; in these circumstances then it is possible to make an effluent plant make you some cash as renewable heat and electricity has a subsidy value.

Hope this helps.

Edited by Bornagain
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2 hours ago, swiss_democracy_for_all said:

If the sewer is cooled by removing heat from it, won’t Mr Pin be busy with even more fatbergs as any oil or fat will solidify even more?

Yes I did used to work on big poo processing plants.

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12 minutes ago, Bornagain said:

One of my responsbilities in a previously life was to keep an eye on an activated sludge plant (treating organic chemical plant waste); if the load was particularly high, and the weather was warm the aeration basin could get upto around 40C, if the load was low in the winter it could be as low as 20C.

The performance of the plant was good enough at both extremes, from this we can conclude that for some treatment plants (maybe most ?) it would be possible to remove a reasonable amount of heat and recycle it for another use. The issue is that by definition it is very low grade heat, this is expensive to extract and not a great deal of use unless you happen to be fortunate enough to have a low grade heat customer very close to the plant.

Most large effluent plants are not located close to areas with a lot of people about (for obvious reasons) so I would imagine it is just not that practical to implement these schemes very frequently.

Now if the plant were to be an anaerobic treatment plant, then the product is biogas which can be either burned in an engine to produce electricity and heat, or just burned in a boiler to produce heat; in these circumstances then it is possible to make an effluent plant make you some cash as renewable heat and electricity has a subsidy value.

Hope this helps.

They've just built a new biogas plant at Bran Sands STW  in Redcar.

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38 minutes ago, Bornagain said:

One of my responsbilities in a previously life was to keep an eye on an activated sludge plant (treating organic chemical plant waste); if the load was particularly high, and the weather was warm the aeration basin could get upto around 40C, if the load was low in the winter it could be as low as 20C.

The performance of the plant was good enough at both extremes, from this we can conclude that for some treatment plants (maybe most ?) it would be possible to remove a reasonable amount of heat and recycle it for another use. The issue is that by definition it is very low grade heat, this is expensive to extract and not a great deal of use unless you happen to be fortunate enough to have a low grade heat customer very close to the plant.

Most large effluent plants are not located close to areas with a lot of people about (for obvious reasons) so I would imagine it is just not that practical to implement these schemes very frequently.

Now if the plant were to be an anaerobic treatment plant, then the product is biogas which can be either burned in an engine to produce electricity and heat, or just burned in a boiler to produce heat; in these circumstances then it is possible to make an effluent plant make you some cash as renewable heat and electricity has a subsidy value.

Hope this helps.

Useful.

The question I'd then have is 'what is the temperature dependency?'.

So, I had a quick look at bacterial proteases (can't be bothered to look at others).  It appears that there's a mild temperature dependency from 20c to 40c, with peaking around 45-55c or so, depending on the protease.

But, below 20c there's a rapid decrease in protease activity.

So, in winter, when you'd actually be able to do something useful with low grade heat, as you extract energy from the sewage the temperature will go down and have a material effect on how quickly the sewage is degraded.  This then would require a longer time period for the sewage to decompose.

I really don't know if that actually would make any difference* -- but it suggests that it isn't a free lunch** and that any heat extraction system would have to be carefully designed to ensure continued throughput of decomposition.

[* eg, slurry tanks on farms store the poo over winter and generally won't spread until late spring -- so perhaps slowing things down a bit over winter wouldn't make any difference.  OTOH, a sewage plant is generally about throughput, and there might be little scope for slowing things down over the winter period.]

[** difficult to get away with the term 'free lunch' in a discussion about poo]

 

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Ex basketball player in the US, been running a food collective in a run down fairly high latitude US city, aquaponics, greenhouse growing but uses compost piles to heat the grow houses, extends growing season by something like 2 months IIRC, uses some space but free otherwise.

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4 hours ago, swiss_democracy_for_all said:

If the sewer is cooled by removing heat from it, won’t Mr Pin be busy with even more fatbergs as any oil or fat will solidify even more?

It's actually the waste water that comes away at some point. The guy who looked at it had seen a steaming stream and followed it to its source.

Elsewhere it says;
Lower Wick, Worcester.

Heated using spare methane from the sewage works next door to the point where it's as warm as a bath,

 

It was always a really warm pool but much better than Sansome walk pool which was like ice, and better than our school pool which mostly had polar bears in.

 

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2 hours ago, Bornagain said:

One of my responsbilities in a previously life was to keep an eye on an activated sludge plant (treating organic chemical plant waste); if the load was particularly high, and the weather was warm the aeration basin could get upto around 40C, if the load was low in the winter it could be as low as 20C.

The performance of the plant was good enough at both extremes, from this we can conclude that for some treatment plants (maybe most ?) it would be possible to remove a reasonable amount of heat and recycle it for another use. The issue is that by definition it is very low grade heat, this is expensive to extract and not a great deal of use unless you happen to be fortunate enough to have a low grade heat customer very close to the plant.

Most large effluent plants are not located close to areas with a lot of people about (for obvious reasons) so I would imagine it is just not that practical to implement these schemes very frequently.

Now if the plant were to be an anaerobic treatment plant, then the product is biogas which can be either burned in an engine to produce electricity and heat, or just burned in a boiler to produce heat; in these circumstances then it is possible to make an effluent plant make you some cash as renewable heat and electricity has a subsidy value.

Hope this helps.

Do they even bother doing something with the waste heat off power gen plants, nuclear and gas. I'm assuming that's a much higher grade and consistent heat. They used to in Russia and and New York back in the day, don't know if they still do. But if they can't be bothered to use power gen waste heat, what's the point in pissing about with compost. 

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Just now, sarahbell said:

It's actually the waste water that comes away at some point. The guy who looked at it had seen a steaming stream and followed it to its source.

Elsewhere it says;
Lower Wick, Worcester.

Heated using spare methane from the sewage works next door to the point where it's as warm as a bath,

 

It was always a really warm pool but much better than Sansome walk pool which was like ice, and better than our school pool which mostly had polar bears in.

 

I'm in favour of one cold pool in every town, the health benefits of swimming in the cold are much greater. 

A nice big warm pool for all the feeble types, and an outdoor one (but with warm changing rooms and a covered perspex passage leading to the pool) kept at 15C or lower for the people that want to be healthy and fit - open all year round. 

If governments want to encourage people to be fit and healthy, having some infrastructure for them to do that would help a lot.

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1 hour ago, onlyme said:

Ex basketball player in the US, been running a food collective in a run down fairly high latitude US city, aquaponics, greenhouse growing but uses compost piles to heat the grow houses, extends growing season by something like 2 months IIRC, uses some space but free otherwise.

I used to do some maintenance for a British soils plant many years ago which makes most of it`s soils from compost the heat coming from the composting bays always surprised me  it almost had it`s own little micro climate in the winter 

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2 hours ago, Long time lurking said:

I would have thought that`s just a plant burning biomass AKA as trees they have been building them all over the country for the last ten years ,bio mass and incinerator plants (heat from waste ) 

https://www.bbc.co.uk/news/uk-england-tyne-32688831#:~:text=A North East water company,Bran Sands at Tees Port.

"Northumbrian Water firm turns sewage into gas. A North East water company will soon start producing gas from sewage to feed into the grid. Northumbrian Water already generates electricity from waste through advanced anaerobic digestion (AAD) at Howdon in Tyneside and Bran Sands at Tees Port"

The article is from 2015 but they built more/modified it last year.

Edited by ILikeCake
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7 minutes ago, swiss_democracy_for_all said:

kept at 15C or lower for the people that want to be healthy and fit - open all year round. 

I got all excited with the warm weather we had a the beginning of April ,i knew the sea is at it`s coldest around then ,but thought i would have a dip anyway with no wet suit involved ,feck it was cold icecream headache cold looked at the local surf forecast 9c 

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5 minutes ago, Long time lurking said:

I got all excited with the warm weather we had a the beginning of April ,i knew the sea is at it`s coldest around then ,but thought i would have a dip anyway with no wet suit involved ,feck it was cold icecream headache cold looked at the local surf forecast 9c 

Yeah - I don't know what the optimum temp for geting the health benefits of cool/coldwater swimming is but I'd guess higher than the UK seas in April! I'd guess that a 20-30 minute swim in 12-15C is probably about right, not everyone can be Wim Hof. 

Problem in Geneva is that the cool period for the lake is short in spring and autumn - the water temp often goes from 7C in April to over 20C by the end of May. So no good for year-round coolwater stuff.

Edited by swiss_democracy_for_all
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