How to deal with a noisy sewerage treatment plant

[Pauljg79]

On 04/11/2018 at 10:20, Roger440 said:

 

A septic tank kind of smell!

 

my understanding is the soil pipe on the house, which, logically has a clear path from tank to stack was all it needed.

 

That said, it a 16 man unit with only 4 people, so it needs turning down. From the blurb, whilst it trumpets the fact you can turn it down, it doesn’t actually tell you how,

 

Ventilation should be the first point of call to look at when it comes to smell. A standard soil stack will draw air out of the plant as long as there is a way for fresh air to come in. People often try and seal off treatment plants to prevent air getting out, but if your soil stack is trying to pull the air out then its good to allow air in too. 

 

I see a lot of pumped outlet treatment plants smelling over gravity outlet plants because of the fact that gravity outlet plants have an open ended pipe allowing fresh air in. 

 

Once you're happy with ventilation, then you have to start to look at treatment quality. You could be right, the plant could be slightly underloaded. How long has it been in and working? It can take a while for bacteria to form, also food waste breaking down in the primary chamber will cause anaerobic respiration which smells quite bad, so make sure no food is going down the sink, Also, dont put any milk down the sink either, that has a huge BOD loading and can cause bad smells. 

[Pauljg79]

On 02/11/2018 at 09:43, joe90 said:

No they don’t! But I cut mine off anyway.  I lined my box with sound absorbing foam and under the pump but still noisier than I would like. I’m with @Roger440 about redesigning it. I like the idea of burying it (eyesore as well) but with high water table I have to be careful, perhaps a drain down to the rumble drain below?. Mass and below ground seem a very good idea. I have much to much to do to finish the build but it’s on my “to do” list for next year.

 

If you plan on burying it i would enclose it in something completely water tight, a drain down to a soakaway opens up risk of water coming back up into the enclosure. Just make sure there's some sort of vent above ground level to allow fresh air in, and good access.

 

 

[Jeremy Harris]

The 19mm bore hose that fits the Secoh JDK 60 we have will easily run for 20m with virtually no flow reduction at all, as it's way oversized for the pump flow rate.  I strongly suspect that this is to do with Secoh having standardised their smaller pump housings, as the pump with double the output of ours still uses a 19mm outlet.

 

If anyone is concerned about flow reduction/head loss over a long run of pipe I can quickly and easily do the calculations, but 90% of the time all they will show is a very, very tiny loss that's not worth worrying about.

 

I did use reinforced spiral wound 19mm bore hose, inside a duct, down to the treatment plant, just to make sure that it didn't get squeezed anywhere.  This then gets reduced down in diameter inside the unit anyway, using the pipe fittings that were originally supplied to adapt the 19mm outlet from the pump when it was living inside the top of the unit.

 

That stone housing has, as mentioned earlier, a gauze filtered air inlet, arranged to minimise noise transmission and keep bugs out.  The lid is also sealed with a neoprene tape gasket.  Another thing I added was a timer to cycle the pump on and off (and disable the under-pressure alarm when off) to reduce the running cost.  Our unit (like a lot of units, I suspect) massively over-aerates the effluent.  A quick calculation showed that even with a maximum BOD effluent input, at maximum daily flow rate, it was still providing around three times more dissolved oxygen than needed.  It's a pity that cheap, rugged and reliable dissolved oxygen sensors aren't available, as it would be nice to be able to run closed-loop control to ensure that the BOD of the discharge was always within limits, yet without having to waste a lot of energy pumping air through the unit that simply isn't needed, accepting that regular high volume air pulsing is required to ensure good circulation of semi-solids in the main treatment section of the unit.

[Roger440]

On 30/11/2018 at 12:05, Pauljg79 said:

 

Ventilation should be the first point of call to look at when it comes to smell. A standard soil stack will draw air out of the plant as long as there is a way for fresh air to come in. People often try and seal off treatment plants to prevent air getting out, but if your soil stack is trying to pull the air out then its good to allow air in too. 

 

I see a lot of pumped outlet treatment plants smelling over gravity outlet plants because of the fact that gravity outlet plants have an open ended pipe allowing fresh air in. 

 

Once you're happy with ventilation, then you have to start to look at treatment quality. You could be right, the plant could be slightly underloaded. How long has it been in and working? It can take a while for bacteria to form, also food waste breaking down in the primary chamber will cause anaerobic respiration which smells quite bad, so make sure no food is going down the sink, Also, dont put any milk down the sink either, that has a huge BOD loading and can cause bad smells. 

 Whe i wrote this, 3 days! Smells have now gone, so i guess its now starting to work.

[Roger440]

On 30/11/2018 at 12:11, Pauljg79 said:

 

If you plan on burying it i would enclose it in something completely water tight, a drain down to a soakaway opens up risk of water coming back up into the enclosure. Just make sure there's some sort of vent above ground level to allow fresh air in, and good access.

 

 

 

 Im going off the "bury it" idea, for exacxtly those resons. Water, ineveitably WILL get in. Shame as i think its the best option from a sound point of view. I think i will do as Jeremey has done. Furtunately for me, im building a retaining wall round the patio so can incorparate a block built structure into it for the compressor. Well, at least thats the current plan!

 

[Roger440]

On 30/11/2018 at 16:45, JSHarris said:

The 19mm bore hose that fits the Secoh JDK 60 we have will easily run for 20m with virtually no flow reduction at all, as it's way oversized for the pump flow rate.  I strongly suspect that this is to do with Secoh having standardised their smaller pump housings, as the pump with double the output of ours still uses a 19mm outlet.

 

If anyone is concerned about flow reduction/head loss over a long run of pipe I can quickly and easily do the calculations, but 90% of the time all they will show is a very, very tiny loss that's not worth worrying about.

 

I did use reinforced spiral wound 19mm bore hose, inside a duct, down to the treatment plant, just to make sure that it didn't get squeezed anywhere.  This then gets reduced down in diameter inside the unit anyway, using the pipe fittings that were originally supplied to adapt the 19mm outlet from the pump when it was living inside the top of the unit.

 

That stone housing has, as mentioned earlier, a gauze filtered air inlet, arranged to minimise noise transmission and keep bugs out.  The lid is also sealed with a neoprene tape gasket.  Another thing I added was a timer to cycle the pump on and off (and disable the under-pressure alarm when off) to reduce the running cost.  Our unit (like a lot of units, I suspect) massively over-aerates the effluent.  A quick calculation showed that even with a maximum BOD effluent input, at maximum daily flow rate, it was still providing around three times more dissolved oxygen than needed.  It's a pity that cheap, rugged and reliable dissolved oxygen sensors aren't available, as it would be nice to be able to run closed-loop control to ensure that the BOD of the discharge was always within limits, yet without having to waste a lot of energy pumping air through the unit that simply isn't needed, accepting that regular high volume air pulsing is required to ensure good circulation of semi-solids in the main treatment section of the unit.

 Jeremy, can you expand on what you did to the intake to minimise noise?

[Jeremy Harris]

42 minutes ago, Roger440 said:

 Jeremy, can you expand on what you did to the intake to minimise noise?

 

Initially I just fitted a length of 40mm solvent weld waste pipe through the wall, fitted with a straight connector plus a screw on access plug, like this: https://www.screwfix.com/p/floplast-abs-access-plugs-white-40mm-5-pack/23322 poking out the front of the box, near the top.  I bored a large hole in the access plug lid, and then screwed it back on with a disc of stainless gauze trapped between the rubber washer and the inside of the lid. 

 

The 40mm pipe just projected about an inch inside the housing, next to the pump, but there was a slight noise coming from it (not much, but we're in a very quiet area).  I added a 90 degree elbow and a short length of pipe inside the housing, so that the open end of the pipe was pointing away from the pump, and this reduced the slight noise from the intake to virtually nothing.

 

I have lined the walls and under the lid of the box with acoustic foam, the egg box stuff, and that tends to help absorb what little noise there is, too.

[Roger440]

Thanks Jeremy. The intake was the thing i hadn't really come to a decision on.

 

So just adding bends really!

 

It was the air intake as well for an underground application that was also an issue. The intake would need to be above ground. Which means it still wouldn't be hidden.

[joe90]

I am going to bury mine next year when I get to do the landscaping but I will drain it into the rumble drain leaving the plant. This will also stop it being a potential eye sore in the middle of the lawn.

[Oblik]

This is an old one I know but if anyone is out there...my neighbours fitted a sewage system when they were building their house.

It is sited near our boundary and runs loudly, in a very quiet neighbourhood, 24/7. The council are involved (again) after 8years of it and I am loosing hope that it will ever change.....I bought the house for its large garden, full of birds and native trees, hedgerows and flowers, but now watching bats in the evening or any sort of time of the day requires earplugs. The neighbours dislike me so any resolution will accelerate the disturbance I experience in other ways. Has anyone sued in court? Any advice would be helpful.

 

[joe90]

Not sure “how loud“ would be considered a nuisance, mine is a lot quieter now it’s buried with soundproofing and rubber mat on top of the air pump box.

 

just found this https://www.gov.uk/guidance/noise-nuisances-how-councils-deal-with-complaints hope it helps!

[Long One]

On 03/12/2018 at 14:04, joe90 said:

I am going to bury mine next year when I get to do the landscaping but I will drain it into the rumble drain leaving the plant. This will also stop it being a potential eye sore in the middle of the lawn.

How did you get on with the burying of your equipment. Bit concerned about heat build up without ventilation.

[joe90]

3 minutes ago, Long One said:

How did you get on with the burying of your equipment. Bit concerned about heat build up without ventilation.

Dead easy, dug a hole next to the plant, extended drainage stone below to the rumble drain to stop flooding the unit, installed 2 vent pipes to cool the unit (as directed by the supplier). Put some Astra turf on top and a couple of large rocks, much quieter 👍

[Long One]

That's great news! I might give this a go but I'm unfamiliar with drainage terms such as rumble drain at the mo. 

Did you include access to raise the pump for maintenance and troubleshooting?

[joe90]

2 hours ago, Long One said:

That's great news! I might give this a go but I'm unfamiliar with drainage terms such as rumble drain at the mo. 

Did you include access to raise the pump for maintenance and troubleshooting?

Right, because I was draining to a ditch that was dry for part of the year a rumble drain was required, this is a perforated pipe laid in drainage stone. The lid of that black box is hinged and the air pump and timer are inside it, very easy to access fir maintenance etc.

[joe90]

You can hear it when close to it but much quieter than it was.

[Long One]

I won't be sleeping by it and you've done a good job by the looks.