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Wastewater treatment works


silver pigeon69
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They are building a new one in a village near to me. Apparently "new technology/procedures" etc means that they do not smell or only very rarely. It will be a small one? being fed by 120 houses.

I remember years ago passing the "Beddington farm lane, Croydon" plant on a daily basis. The smell was so bad you tried to hold your breath driving passed!

Is there any one in the know? Who would like to give an honest answer (not the textbook Water authority answer!) on whether NEW works/plants smell?

Thanks,

SP

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Yes they smell, but there are many thing that will influence how pervasive that smell is.

A wastewater treatment plant will handle both household brown waste that is flushed into the sewer system and also surface water that runs down drains, etc.

The important ratio is the mix of solids to liquids and also the types of solid.  Treatment works have sedimentation ponds or tanks where rag and inorganic solids are separated out leaving organic waste suspended in water which is then typically passed through a centrifuge or belt press to get rid of the liquid and also treated with lime to kill the pathogens.  If the liquid to organics solid ratio is right, about 3%, then the process is very effective, the solids come out dry (cake) and reasonably unstinky and this is shipped away, but it if it is too wet then the solids turn into slurry which is mega stinky.

New plants do smell less than old ones, bigger plants smell more than little ones.

Ultimately sewage is stinky stuff and you cannot avoid that.

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Depends on the type - even at that scale the plant could be completely underground. SAF (submerged aerated filter) tanks go up to 600 population and most of them are modular so they can be extended. They will still wiff a bit, but only in very close proximity to the tank (10m or so). The tanks sometimes have active carbon scrubbing and blower systems for the vents so you could be standing right next to one and not know.

If above ground then while things have improved there will still be a bit of a smell from the settlement tanks. Its all based on the mix of solid/liquid. Too much liquid leads to very bad smells.    

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2 hours ago, Lord v said:

Depends on the type - even at that scale the plant could be completely underground. SAF (submerged aerated filter) tanks go up to 600 population and most of them are modular so they can be extended. They will still wiff a bit, but only in very close proximity to the tank (10m or so). The tanks sometimes have active carbon scrubbing and blower systems for the vents so you could be standing right next to one and not know.

If above ground then while things have improved there will still be a bit of a smell from the settlement tanks. Its all based on the mix of solid/liquid. Too much liquid leads to very bad smells.    

viewDocument?file=dv_pl_files%5CRR_2014_

This is the plan. Are they SAF?

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I can see the plan fine, but if I click on it to zoom that it becomes unreadable as the colours invert.

Same on both laptop and phone.

Edit to add, it does look as though it is a subterranean installation and a pumping station and not a treatment works.

Edited by grrclark
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I know a fair bit about about wastewater treatment as I work on them quite a lot.

A works smelling bad or not is determined by many factors. There are many different types of treatment, for starters. What effluent comes into a works has a bearing on treatment and how well the treatment method workss on it. How well the plant is maintained/run will also have an effect on smell and final effluent quality. It is wrong to say that big works will smell worse than small ones. In my experience, it simply isn't the case.

Some works are completely enclosed. All the plant and tanks at Cromer Stw are indoors. I suppose this is to avoid smells at the nearby coastal areas.

I personally would not be at all worried about a new treatment centre being built close by.

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2 hours ago, grrclark said:

I can see the plan fine, but if I click on it to zoom that it becomes unreadable as the colours invert.

Same on both laptop and phone.

Edit to add, it does look as though it is a subterranean installation and a pumping station and not a treatment works.

I get the same on my phone. Haven’t  tried laptop

this is the plan for the WWT plant. The pumping station is a separate plan at a different location. 

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Yup. 

That looks to be largely underground or enclosed at a high level. The only bit that may not be are the humus (soil) tanks, they shouldn't smell much at all though. 

So what happens there is a small pumping station is lifting the sewage to a higher level to avoid burying anything too deep. It's then being separated by sceptic tanks, then via filter before being separated into sludge, humus and discharge. Discharge goes straight to the river and is essentially clean, could drink it if you were so inclined. Sludge will smell, but there won't be much and is collected in a burried chamber. Humus is basically soil like and should be dry and relatively smell free if done properly. 

It also seems the filter tanks have blowers, that usually refers to fans to direct any odour. 

I don't think you will smell much of anything from that. 

Sizeable install for 120 units though. Who's doing it? If it's your water company I would be aware of further development in the area. 

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7 minutes ago, Lord v said:

Yup. 

That looks to be largely underground or enclosed at a high level. The only bit that may not be are the humus (soil) tanks, they shouldn't smell much at all though. 

So what happens there is a small pumping station is lifting the sewage to a higher level to avoid burying anything too deep. It's then being separated by sceptic tanks, then via filter before being separated into sludge, humus and discharge. Discharge goes straight to the river and is essentially clean, could drink it if you were so inclined. Sludge will smell, but there won't be much and is collected in a burried chamber. Humus is basically soil like and should be dry and relatively smell free if done properly. 

It also seems the filter tanks have blowers, that usually refers to fans to direct any odour. 

I don't think you will smell much of anything from that. 

Sizeable install for 120 units though. Who's doing it? If it's your water company I would be aware of further development in the area. 

Thanks for the info.

It is the water company, Southern Water. how many propertys do you think it would service? The Local council wanted it done and were refused by Southern Water on two occasions since 1995 then took it up with the EA? who said it needed doing. There's no plans for large developements, that i'm aware of? Is it possible the water company has had some "insider info"?

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Without tank sizes it's hard to say, but all the kit is modular these days so it's pretty straight forward to expand an installation like that. 

They will definitely know about future development coming. Not only are they a statutory consultee at planning they are consulted pre app by consultants very frequently - that's the kinda thing I do, taking large sites through planning to construction on the roads/drainage side.  

In theory under current rules (due to change April though) they cant forward fund development, even though they often do. Bit of a legal mine field this though when considering allocated development and the statutory maintenance periods. Don't forget, every house connected to that system is income for them so they would be mental not to upsize it a bit or make it easily expandable.

I imagine this got approved as the current WWTW was overspilling untreated sewage too frequently or they were otherwise breaching their discharge liscence which upset the EA. They then have powers to force Southern to fix it or be fined untill they did. That gets a reaction! 

Search your councils website for something called the local plan. This will show sites the local authority have allocated (or will allocate) for development. 

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37 minutes ago, Lord v said:

Without tank sizes it's hard to say, but all the kit is modular these days so it's pretty straight forward to expand an installation like that. 

They will definitely know about future development coming. Not only are they a statutory consultee at planning they are consulted pre app by consultants very frequently - that's the kinda thing I do, taking large sites through planning to construction on the roads/drainage side.  

In theory under current rules (due to change April though) they cant forward fund development, even though they often do. Bit of a legal mine field this though when considering allocated development and the statutory maintenance periods. Don't forget, every house connected to that system is income for them so they would be mental not to upsize it a bit or make it easily expandable.

I imagine this got approved as the current WWTW was overspilling untreated sewage too frequently or they were otherwise breaching their discharge liscence which upset the EA. They then have powers to force Southern to fix it or be fined untill they did. That gets a reaction! 

Search your councils website for something called the local plan. This will show sites the local authority have allocated (or will allocate) for development. 

I think this is new, no existing system.

All the houses are on septic tanks/cespits. In their report they said that many of these were not up to spec and were leaking.

Apparently a lot of people haven't sighned up for the free connection as they think the annual rates would be higher than their current costs(emptying tank etc)

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20 hours ago, silver pigeon69 said:

They are building a new one in a village near to me. Apparently "new technology/procedures" etc means that they do not smell or only very rarely. It will be a small one? being fed by 120 houses.

I remember years ago passing the "Beddington farm lane, Croydon" plant on a daily basis. The smell was so bad you tried to hold your breath driving passed!

Is there any one in the know? Who would like to give an honest answer (not the textbook Water authority answer!) on whether NEW works/plants smell?

Thanks,

SP

Beddington Lane is still the same today, I drive past there  regularly and it still stinks. Same as the Chertsey stretch near the M3 junction on the M25  and the M4  out towards Windsor

Sewage works were built in areas of low population that subsequently filled out

Edited by Vince Green
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