What is a sewage treatment plant???

[Big Neil]

Now then. I know better than many, how to take a curry in one end and put it out the other. I can perform a similar trick albeit from a different waste transfer process, with Erdinger.

Also i understand the words sewage, treatment and plant. Don't really understand how they all work together though, in either the absence of or in compliment to, other words like soil stack, mains sewer and so on.

 

For example; in my house currently, after i have a heavy night down the Bilash Balti House, I take a seat and see how things go. Thereafter i flush a nice shiny handle and if she's unlucky enough to be near a pipe outside my missus knows what's happening. We rest safe in the knowledge that my kids have taken a nice long trip down a very well buried waterslide to the pool, joined by the blankets i wrapped them in before they left.

 

What now happens, when the man from the depot, drops off my nice shiney new treatment plant? how does the whole process change?

[joe90]

A good place to start (i have one  of these). https://www.wte-ltd.co.uk/vortex_sewage_treatment_plant.html

[Big Neil]

thanks @joe90

 

just  read that first page and want to undestand a few things.

 

1. Does all waste from the house flow here, so all bath water, washing up water, human waste, bits of last nights rice pudding washed down the sink. All of it?

 

2. Is the 'clear effluent' that flows through the 'scum baffle' basically all the water with bits removed?

 

3. What happens with all the stuff like toilet paper etc, which gets put throuhg there. Does it have to be emptied periodically.

 

4. Does it not fill up after a time such that it has to be emptied?

[joe90]

1/ yes

2/ yes or bits digested

3/ most things are digested but some emptying will be needed say worst annually, hopefully every other year.

4/it overflows as it fills (input = output) see 3 above 

 

I have had to educate SWMBO about putting bleach down the loo, very small amounts are ok but too much will kill the bacteria that digests your poo.

?

Edited January 11, 2019 by joe90

[Ed Davies]

16 minutes ago, Big Neil said:

1. Does all waste from the house flow here, so all bath water, washing up water, human waste, bits of last nights rice pudding washed down the sink. All of it?

 

For the avoidance of doubt, as the lawyers say, rainwater from the roof doesn't go into the plant.

[Big Neil]

rigggghhhhttt. All sort of makes sense then. So assuming you have a ditch/reed bed or whatever else to discharge into, and it's suitably sized, you don't have to connect your house to the mains sewer. And in respect of stuff like shower gel. toothpaste, dishwasher detergent etc etc, does this have the same effect as bleach as you mentioned above @joe90? Is the solution if SWMBO goes mad cleaning one day to simply have a massive takeaway or invite the neighbours over for a dump party one night, and top the bacteria up so to speak?

[scottishjohn]

if you have the option of mains drains --take it

your own septic tank or sewage treatment plant needs REGULAR maintainance and emptying from time to time --all cost money 

so main drains if possible

soakway drainage fields block as can reed beds 

[Ed Davies]

Here's my understanding, corrections welcome:

 

1) Septic tank: does anaerobic digestion. Produces output which needs to go to a reed bed, leach field or whatever for final treatment. Discouraged in this day and age; you can keep an existing one but likely can't put in a new one.

 

2) Treatment plant: does aerobic digestion so needs some means to get oxygen to the wee beasties doing the digestion which can be a pump blowing air into the soup or some other method. Output should be clean enough that it can in theory be discharged straight into a watercourse but SEPA, at least, want something else in between to do a bit more treatment if something goes wrong.

[nod]

28 minutes ago, scottishjohn said:

if you have the option of mains drains --take it

your own septic tank or sewage treatment plant needs REGULAR maintainance and emptying from time to time --all cost money 

so main drains if possible

soakway drainage fields block as can reed beds 

We had no choice

But it was to install 

We’ve told to check after three years Empty Three to five years (£150)

and don’t add any bacteria like what’s been sold on eBay 

Good reduction on water rates 

 

Though I would have gone for mains had it been an option

[joe90]

I believe (but willing to be proved wrong) that if you have the option to use a mains sewer you have to connect to it. As per @Ed Davies above, no new septic tanks are allowed. If you are lucky enough to have a watercourse or ditch (can be dry fir a few months of the year) you can discharge to that. If not you need a soakaway but it will not block up like a leach field to a septic tank as there is no biological action taking place in the soil.

[Big Neil]

Fair play. So now i know how they work which rocks. If anyone knows about the Having to connect to the sewer thing though that would be good. 

Quick question though @scottishjohn, even if it turns out one doesn't HAVE to connect to an available sewer, why would you choose to INSTEAD of having a treatment plant installed?

[ProDave]

Just to add, I think you would be mad now to install a septic tank.  I don't think it will be long before they are no longer allowed.  You really should install a treatment plant if you are going self contained.  And in any event discharge to a watercourse will only be allowed for a treatment plant.

 

It can be a complex process designing a system. It all hinges on where the liquid output will go.  If you have a watercourse that is a damned good option, though as I found, it is not so easy to get permission for that in Scotland.  Otherwise you have to have some form of soakaway system installed, and that can consume quite a large area of land. That all hinges on the percolation test which is a measure of how quick the land drains that will allow you to calculate the requred area.

 

When you also factor in building regs limits on how far the various elements must be from buildings and boundaries,  it can often be hard or even impossible to actually fit a treatment system onto your land.

 

A common solution to that if you are in the countryside is to negotiate with an adjacent land owner to have the soakaway under their land.

 

And a last resort of the ground has issues like a high water table is an above ground filter mound.

[Ian]

1 hour ago, Ed Davies said:

 

1) Septic tank: does anaerobic digestion. Produces output which needs to go to a reed bed, leach field or whatever for final treatment. Discouraged in this day and age; you can keep an existing one but likely can't put in a new one.

 

 

New septic tanks are still allowed, at least they are in England & Wales

 

Extract attached below is from the current Welsh building regs which are very similar to the English ones:

Edited January 11, 2019 by Ian

[jamieled]

In Scotland SEPA still allow you to register a new septic tank.

[joe90]

I stand corrected ?, but I would not install a septic tank in a new build.

[Ian]

5 minutes ago, joe90 said:

I stand corrected ?, but I would not install a septic tank in a new build.

Agreed...I had the choice on my build and decided to install a sewage treatment plant rather than a septic tank despite it costing extra. The ground worker thought I was mad..

Edited January 11, 2019 by Ian

[ProDave]

18 minutes ago, jamieled said:

In Scotland SEPA still allow you to register a new septic tank.

Only if it has say an infiltration feild. They will not allow one discharging to a watercourse, and I believe from next year, existing ones discharging to a watercourse will need to be updated (several people around here are in for a shock)

[billt]

Why not, if you have the land for an adequate leach field/

 

They don't use power, they don't make any noise, the effluent is arguably better treated than any packaged plant.

 

Running costs are very low if the system is designed and installed properly. Ours was rebuilt 10 years ago and was emptied for the first time last year and was less than 2/3 full, so would have lasted a few more years before emptying. £190 over 10 years isn't much. (The system is over sized for 2 people.) And, yes it is working properly and not bypassed.

[Big Neil]

I am quite interested in why one has to choose mains even if one wants to go off grid. For example what about collection and treatment of water for personal consumption? Is that not allowed if you are near a mains water pipe? One is allowed to go off grid for electricity is one not? Why is that not governed in the same way?

 

All questions of practicality aside, is it not one less headache for a local authority and utilities company if they haven't got to deal with extra load on the system? What should it matter to them? I could take a dump in an ice cream tub and put it in my shed, no one would have a clue.

 

I'm not militant about storing my own faeces by the way, i JUST DON'T GET IT

[Big Neil]

bloody good practical example @billt, sort of why I want to know.

[billt]

Pollution. If you have an accessible mains drain there should be better control of effluent release to the environment.

[Ed Davies]

1 hour ago, ProDave said:

Only if it has say an infiltration feild.

 

Ah, that's probably where I got the idea that septic tanks aren't allowed - it was in discussions of sites that don't percolate (like mine).

[Jeremy Harris]

The reason that legislation is being tightened to try and reduce the use of septic tanks is because the vast majority of them that are over 10 years old will have leach fields that are anaerobic, and so septic, as a consequence of biofilm build up.  The owners will be blissfully unaware of the pollution they are creating, because unless the leach field catastrophically fails, by becoming waterlogged, there will be no external indication that anything is wrong.

 

The easy way to check is to dig down adjacent to a a leach field land drain and look at the colour of the soil (although the stench will usually give the game away).  If the soil looks discoloured and dark, maybe even black, then it's fouled and anaerobic and doing nothing at all in terms of tertiary aerobic effluent treatment.

 

Most of the important effluent treatment with a septic tank isn't done in the tank, that only settles out the solids, with some assistance from anaerobic bacteria in reducing the organic solids content.  The real treatment takes place in the leach field, where aerobic bacteria act on the effluent to both detoxify it, and more importantly, reduce its biological oxygen demand (BOD).  It is the latter that causes major harm to watercourses, when a high BOD effluent discharge quickly reduces the dissolved oxygen content of the water so that other organisms die from lack of oxygen.

 

An aerobic treatment plant removes any need for tertiary treatment, by performing the essential aerobic digestion in the tank itself. 

[jamieled]

1 hour ago, Ed Davies said:

 

Ah, that's probably where I got the idea that septic tanks aren't allowed - it was in discussions of sites that don't percolate (like mine).

I have seen a couple where the effluent gets treated in a reed bed instead of a leach field.  Clearly to do it without pumping requires a certain topography.

[Big Neil]

1 hour ago, JSHarris said:

An aerobic treatment plant removes any need for tertiary treatment, by performing the essential aerobic digestion in the tank itself.

So if a sewage treatment plant  dos this and doesn't cause pollution. Why on earth would it not be allowed? strikes me as very odd