<blockquote><cite>Posted By: billt</cite><blockquote><cite>Posted By: trule</cite>I don't see on their web site anywhere that their claims being made against a septic tank.</blockquote>

Go to http://www.wte-ltd.co.uk/sewage_treatment_costs.html; under costs for a septic tank they state

...snipped strawman arguments...

</blockquote>

I visited the Biorock web site - http://www.biorock-uk.com/biorock_sewage_treatment_plants.html - you can tell me what you think of that if you want and I promise TGAS. I agree the WTE site is making dubious claims.

If it's that good, drink it.

The Biorock PST by any other name is an anaerobic digester, i.e. a septic tank. Instead of discharging effluent to a leach field it directs it to a second stage aerobic biodigester. Emptying times are still critical otherwise solid waste will accumulate reducing resident time and increased risk of solids being transported to this second phase where it will reduce biota area, again by accumulation. A 2800 litre capacity is no great shakes for a family unit (5 person) if all liquid discharge passes through the tank. For three day resident time for 400 l per the tank size should ideally be around 5000 l. Goodness knows what the BBC has to do with it but here's a cite.

http://www.bbc.co.uk/dna/h2g2/A873876

Dickster was told that the bagged mineral wool filter was washed occasionally: is that every 15 years? What tests were carried out to show 15 years successful unattended operation?

What mechanism ensures oxygen throughput in the biodigester? Passive stack? So what drives it? Convection, vacuum?

Finally, Biorock do not publish test results on their website, only their own interpretation. How about putting up all the test results here?

Posted By: wastetech
Every claim made on thehttp://www.biorock-uk.com" >http://www.biorock-uk.comwebsite is true and can be substantiated.

To answer a couple of the 'opinions', the first tank in the BIOROCK system is NOT A SEPTIC TANK, but a Primary Settlement Tank (PST), the same as is inside package sewage treatment plants which are emptied once a year. The reason why the BIOROCK PST has a four yearly emptying interval is that it is much larger than a package plant PST. A package plant PST for 5 persons needs to be only 765 litres, but the PST on the BIOROCK is 2800 litres.

The stone fibre filter media has proved to be self cleaning over the last 15 years and does not block with slime.

The EN 12566-3 2005 test results are published on the BIOROCK website. The 'doubters' should ask other manufacturers for theirs?

I haven't examined the www.biorock.com website thoroughly, but some of the claims on the Wastetech site (www.wte-ltd.co.uk) do not agree with your statements. (The contact address for both sites is identical so it is reasonable to assume that they both represent the views of the company.)

http://www.wte-ltd.co.uk/settlement_tanks.html has links to the "settlement tanks" that you use. If you look at the document you will see a drawing of a two chamber septic tank, labelled "septic 2,800l class 2 shell". If it looks like a septic tank and the makers call it a septic tank it is a septic tank. (In fact http://www.biorock-uk.com/settlement_tanks.html links to the same file.)

FYI BS6297 gives a formula for the calculation of septic tank sizes - V=(P x 180) +2000; V is volume in litres and P is the number of persons served which gives a volume for 5 people of 2,900l. 2,800l is the minimum acceptable size for a septic tank based system.

Claiming a longer emptying interval for your septic tank based system compared to a package plant system may be reasonable, but on your website you claim that a standard septic tank system needs emptying once a year as well. As your recommended septic tank size is the standard septic tank size there is something of an inconsistency here!

The biorock-uk site is slightly more circumspect than your other site so I think that you are being somewhat disingenuous by ignoring the claims made on your more general web site.

FWIW my name is Bill Taylor and as I'm a private individual with an interest in "green" issues and a sewage treatment system in need of improvement, but no commercial interest in any aspect of building, I am not going to publish my contact details in an open forum.

Again, I say, please speak to me rather than 'assume' in a public forum.

There is no inconsistancy. The Conder settlement tank is NOT A SEPTIC TANK, as stated earlier. Conder make them especially for us using the same external mould as their septic tank but the internals are very different (ask Conder) and they are NOT the same. They are not 2 chamber tanks, as with Conder septic tanks, but a single stage horizontal flow primary settlement tank with a settlement tank filter integral in the tank. The tank is not designed to be a septic tank and does not work as such. The reason that we use the Conder septic tank pics is that Conder do not have pdf drawings of the tanks they make for us, but as the dimensions are the same, that is all the installers need. The system has the EN 12566-3, unlike many UK plants, and has been extensively tested.

The BS 6297 - 'Design and installation of small sewage treatment works and cesspools Page 9' - gives a design sizing criteria for Primary horizontal flow settlement tanks (which is what the BIOROCK settlement tank is) as:-

C = 180 x population x 0.85
C = capacity of the settlement tank required in litres
180 is the litres/person/day
Therefore, a 5 person plant requires a primary settlement tank of :-
C = 180 x 5 x 0.85
Capacity required = 765 litres.

Our Primary settlement tank is 2800 litres, hence the 4 year emptying interval.

The BIOROCK has been in production for over 15 years and has PROVED to be self cleaning. The top layer of sacks require inspection annually and hosing off if required.

When Klargester and other UK sewage treatment plant manufacturers publish their full EN test results on their websites, we will publish ours. It will make interesting reading. In the meantime, they are available to 'Mark Time' if he would like them - just ask me.

by e-mail.

For the attention of Maureen Webb.

Thank you for your invitation to contact you from the Green Building Forum for details of the CEN test results for Biorock sewage treatment systems.

I look forward to receiving a copy of accredited results from an independant testing authority.

Best regards

marktime

Disclaimer. I am not associated in any way with any manufacturer or supplier of sewage treatment systems.

I'm going to get a biorock installed.

As with most products/companies, you only really know how good they are when you've parted with your money and in this case, installed the plant deep in the ground. It's then too late to do much about it if it's rubbish. So in my case, having confidence in the product/company plays a large part in the decision making process.

It's good to see a company defending their product on this forum, gives me that little bit more confidence to enable me to make my mind up.

When installed, I really think we've got to have a treated effluent drinks party, and you're all invited!

NB. We live on 60 litres of water per person per day and have no rainwater harvesting as yet.

Ah! glad you asked.

We're the first house at the top of a valley in the new forest, with sea tout, brook lamprey etc all living in the stream at the bottom of the garden. So we take our responsibilities very seriously.

The effluent will then go into a drainage field. Might seem like overkill, but rather have that than kill the little fishes!

Dickster. I applaud your decision to go with a sewage treatment plant and it appears to me that the Biorock, if well maintained, will give you years of excellent service. Have you opted for the exit filter on the anaerobic digester, (let's not get hooked up on semantics) so that the effluent stream to the biodigester is kept free from solids? I would think it's well worth fitting as the extra effort involved in flushing it clean every so often, probably at the same time time as you flush the primary filters of the Biorock would be part of the ongoing maintainance. I like your idea of discharging into a drain field as it will give you a margin of safety if anything should alter the characteristics of the system. That would be my reply to trule: if you are going to fit a septic tank, why not go the extra green mile and fit a secondary purification system so that wherever you discharge, the effluent quality is high.

When I was looking at Biorock many years ago I thought about fitting pipe work to provide a flushing supply of water to clean the plastic alveoli that sit at the level of the air intake in the waist.

Dickster, are you obliged by the Environmental Protection Agency to provide routine test samples to check the quality of the discharge?

Posted By: wastetechOur Primary settlement tank is 2800 litres, hence the 4 year emptying interval.

Has this been field verified?
I use about 500L/day (based on my water softener meter) and have a 3800L tank. I had my first pump-out last week at under 2yrs of usage, as I wanted to get an idea of how frequently it would need pumping. The guy that pumped it said I shouldn't wait any more than 3yrs for my next pumping.

I wonder if people in the UK can get away with less frequent pumping due to warmer ground temperatures (and therefore more active anaerobic bacteria)? Deep ground temperatures here are around 7-8C.

Larger tanks are good not only for pump-out intervals but for longevity of the leech field. Larger tank = longer settling time in the tank = less solids reaching the leech field.

-Ralph

Maureen I've already sent you an e-mail with my details. Nonetheless, I find it hard to grasp why, if your results make you feel proud, and so they should if you achieve 10:10:10, why you aren't publishing them freely. You only have to show the results of CEN 12566-3 Annex B, giving you an edge over your competition and demonstrating independant verification of your claims. Who could ask for more?

When I receive your data you do expect me to publish here, I hope.

Settlement tank, the first chamber of a two chamber septic tank, is for collecting solids such that they do not enter and clog the leach field.

Its 6 of one and half a dozen of the other...

I responded to your invite through the contact e-mail address posted on your website.

I have contacted you again direct to the e-mail address above.

Ms Webb did what she promised and did send me a copy of test results. They lacked details as to what was being tested and although they could loosely be described as being in accordance with EN 12566-3 Annex B they are not in compliance. I was asked to keep them confidential which is surprising seeing that this particular set of results are freely available. (Google is your friend).

The data appear to be for a two stage treatment system tested at a hydraulic loading of 5 x 180 l/day, suggesting that it featured the 2800 l septic tank as a front end. I imagine that the debate over calling it a primary settlement tank (PST) is the brainchild of product differentiation dreamt up by Marketing. It’s true that not all settlement tanks are septic tanks but it’s certainly true that all septic tanks are settlement tanks. Just my POV, not worth arguing about.

Annex B calls for 48 weeks of testing plus a period of initial settlement, a month is usual, giving a performance spectrum over a full year, which is probably what the framers of the directive had in mind. These results cover 31 weeks plus an initial 4 weeks of settling. The directive also calls for specific stress testing with regards to loading, both biological and hydraulic. This data does not indicate the testing laboratory or any other accreditation.

edit: Added this link:

http://biokube.dk/upload/filer/CEN%20Standard%2012566-3.pdf

The biological loading employed, (measured as the biological oxygen demand of bacteria contained in a sealed sample for 5 days, BOD5), on the septic tank was high (av. 294.6 mg/l) compared to the average of 200mg/l for domestic wastewater.

(All data from US EPA Septic on-site systems: “On-Site Wastewater Treatment Manual” except where stated. An outstanding source of lay information).

http://cfpub.epa.gov/owm/septic/septic.cfm?page_id=271

Two periods of reduced hydraulic loading (mimicking holiday periods) were included and during the last two weeks the system was stress tested with a 150% hydraulic overload.

Over the test period the results are exemplary. The average effluent quality from a higher than average wastewater loading (and probably a higher than average hydraulic loading), was BOD5 <10mg/l and Suspended Solids (SS) < 10mg/l.

For comparison: the Royal Commission into Sewage Disposal (1898-1915), set a standard of 20:30, (BOD5 mg/l: SS mg/l). In January 2009, UK EPA prosecuted a polluting pub for discharging wastewater that exceeded 40:60.

“The Court heard that the Mortimer Arms has a consent that allows carefully monitored discharges from the sewage treatment works at the pub to the River Cadnam which should not exceed the level of 40mg/l of Biochemical Oxygen Demand and 60mg/l of suspended solids.”

http://www.environment-agency.gov.uk/news/102917.aspx?month=1&year=2009

The results show treated effluent of high quality but whether Ms Webb would actually drink it is doubtful as it contained substantial faecal coliform contamination and a high level of dissolved salts so I will not hold her to her challenge.

Nitrogen depletion, which generally may come under more environmental scrutiny in the future, was expressed as average effluent NO3 levels of 13.5 mg/l, and for total N, 50%. Such high levels of plant nutrient should inspire caution when planting near the final treatment bed.

Now we have to consider how these test results reflect the real world. Retention time in the new septic tank would have been more than 72 hours, yielding a high quality, solids free effluent. Something to bear in mind when assessing cleaning intervals as 40% of raw sewage remains as sludge and scum and build up is reflected in reduced volumes, reduced retention times and poorer quality effluent. The exit filter, if examined routinely, (and carefully so as not to discharge neutral buoyancy solids into the exit line), can be a mechanism whereby emptying frequency can be judged.

edit: As a nerd I would have liked to see figures detailing the influent to the second stage in order to compare them with the output of an in-service septic tank with av. BOD5 = 93.5 mg/l.

Aerobic bacteria die as accretion builds up around them denying access to oxygen and they slough off, hopefully to be eaten by something else. This something else also dies and creates sludge, often separated out in further settlement tanks or clarifiers. Where this will take place within the Biorock is uncertain. As no information is offered about the long term maintenance that is a prerequisite, (and often mandatory), of all sewage treatment systems, this is something a prospective purchaser should follow up.

Hydraulic loading of 180 l/person/day creates quite a margin of safety, European use is judged to be closer to 100-150 l/d. In my home of two active people, including watering a small patio garden and relying solely on passive water economy, our annualised monthly use is 6 m3, i.e. 100 l /person/day. Our American cousins use more than 200 l/d filling up 24.6 million on-site wastewater treatment systems, the overwhelming majority of which are septic tanks discharging into a sub-surface wastewater infiltration systems i.e. leach fields.

Faecal coliform (the collection of gut bacteria including E.Coli, present in faeces), is reduced through the system but Biorock effluent still contained 10^4-10^5 /100 ml, well above the 10^2 /100 ml recommended as the limit for body contact. However, survival within the hostile environment of a drainage field is limited to a 600-900 mm radius from the point of infiltration so you can massacre the little buggers there.

The air temperature throughout the testing period ranged from –4 to 27 deg C indicative of a typical Northern European climate and average influent temperature was 10.7 deg C whilst effluent temperatures averaged 9.7 deg C. This latter figure is important as both anaerobic and aerobic digestion are temperature dependant and it raises the question of whether this was an above ground test.

If you accept the authenticity and integrity of these results, and remember that by not publishing them they cannot be challenged, the Biorock aerobic digester appears to offer an outstanding second stage treatment plant to enhance even the ropiest of septic tanks. <grin>

Dikster, if you can read French then this will give you confidence in your decision. Some pics of the sacks as well.

http://www.ascomade.org/upload/ouvrage/1151921441.pdf

Bear in mind that the outlet invert is -1750 mm and you will either have to dig deep or pump up.

I hope this thread has been of use to the OP.