BioFilter Treatment Questions

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davidg
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BioFilter Treatment Questions

Postby davidg » Wed May 09, 2007 6:34 pm

1. Where is the water taken from in the last stage?

2. Is it worth installing a protein skimmer component?

3. Since I'm having trouble finding the geo-fabric you show in the system
could I instead use 4-6mm washed river stones?

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Postby Bob » Fri May 11, 2007 11:53 am

1. Where is the water taken from in the last stage?

I have a pump with float switch mounted near the top of the tank. Note the two callouts on the drawing that say "Pump (Not Shown) On" and "Pump Off". (These added details & more will be included in forthcoming book...)

2. Is it worth installing a protein skimmer component?

That is an open question. I suppose it depends on both the quality and characteristics of the water entering the unit, and the desired quality of the effluent. What I learned from experimentation is that inserting an airline to a fine bubble diffuser in the downtube of the third module initially caused a lot of foam to bubble out of the top of it, giving me the idea that it could easily by captured and drained off. However, after initial startup -- after the bacterial populations stabilized, I assume -- it no longer produces the foam that it did at the beginning. But then again, I assume that is a function of what is in the influent.

3. Since I'm having trouble finding the geo-fabric you show in the system could I instead use 4-6mm washed river stones?

I suppose you could, but I don't think it would be a very good substitute. It would be much heavier, provide a lot less surface area/volume, and be harder to maintain/clean. Better to just roll up more furnace filter material -- or I could probably help you locate some sources for the geofabric. It is commonly available here, widely used in roadbuilding & construction industry.

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Areobic chamber

Postby davidg » Sat May 12, 2007 3:45 am

So the water is taken from between these lines near the top of the tank.

I suppose you could, but I don't think it would be a very good substitute. It would be much heavier, provide a lot less surface area/volume, and be harder to maintain/clean. Better to just roll up more furnace filter material -- or I could probably help you locate some sources for the geofabric. It is commonly available here, widely used in roadbuilding & construction industry.


How often does the aerobic chamber(20 litre bucket) need cleaning typically?

In Melbourne, Australia this is not inside a building it just does not get that cold ever, and nearly all houses do not have a basement at all, even in a cold year we might get frost on some mornings but only in early hours of some mornings and only sometimes.

I had a number of 500 Litre "buckets" I have adapted these in place of the drums you suggested as I already had these. This is approx 110 imperial gallons when full to the brim.

I'll send you some pictures of my configuration, when I have finished.
I have modified your layout slightly where the pipes connect into these tanks. so that I can remove the lids still with exception of the geyser pump that goes to the aerobic "bucket" as taking it though the lid was the only way for it to work properly.

Should the 20 litre aerobic bucket be air tight? with the exception of the pipes into and out of it the 20l bucket is currently air tight

I have quite a bit aquarium wool it is similar to furnace filter/air conditioner filter material, I assume this would be suitable for the job it is quite similar. It's cheap here too.

Thanks for the call the other day. I notified the Alasken ISP that some of the IP addresses in there IP ranges are listed on some of the anti-spam black lists. I have also put some exceptions into my mail server to hopefully allow you to send email.

Regards David :D

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Postby Bob » Mon May 14, 2007 10:02 am

How often does the aerobic chamber(20 litre bucket) need cleaning typically?

This particular incarnation has been in operation since September 2006. I haven't cleaned it yet, and it is still working well. I'm going to guess maybe once/year?

I'll send you some pictures of my configuration, when I have finished.
Please do. I look forward to seeing them, and, with your permission, posting them here.

Should the 20 litre aerobic bucket be air tight? with the exception of the pipes into and out of it the 20l bucket is currently air tight

No. I have a loose fitting lid on mine, which only prevents spatter when the geyser pump spits. In general, though, I would think the more fresh air to it, the better.

I have quite a bit aquarium wool it is similar to furnace filter/air conditioner filter material, I assume this would be suitable for the job it is quite similar. It's cheap here too.

Sounds perfect. There are any number of materials that could be used, and what I'd love to see here is feedback from others on what has worked for them, or ideas for other things to try. -- to collectively improve & refine the design

Thanks for the call the other day. I notified the Alaskan ISP that some of the IP addresses in there IP ranges are listed on some of the anti-spam black lists. I have also put some exceptions into my mail server to hopefully allow you to send email.

Thanks. Hopefully that'll solve the problem. Spammers!!!

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Biofilter startup

Postby davidg » Tue May 15, 2007 7:31 am

I have started pumping grey-water into the system it appears to running well enough, of course, I have to wait for the Bio part of the system to ramp up.

Question about the "20L" drum weir in the anerobic drum/chamber, I currently have the water about half way up the holes is this ok, or must it flow of the edge of the holes?

I can adjust this if required this is just where it started of at

While the system is not upto to full speed yet there is no question that the water that goes in as against the water that comes out is different, it is cleaner with a much reduced odor, just got to wait the approx 30 days.

How much "sludge" should be left in the system when it is being cleaned out?

A bit of background about these tanks.

Because of what the tanks (water storage) were being used for in the past I have 2" drain valve system in the bottom of all the tanks, which I should be able to use for clean-out when it is required, will be in the photos when I send them to you. The entire tank system is raised above the ground approx 1 metre again because of what they were being used for in the past.

Now starting to build a small wetland system.

Regards David

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Postby Bob » Tue May 15, 2007 8:28 am

Question about the "20L" drum weir in the anerobic drum/chamber, I currently have the water about half way up the holes is this ok, or must it flow of the edge of the holes?

The intent is to make a 'notched weir'. The idea is to distribute the overflow to multiple points, so that velocity through any one "notch" is reduced.

How much "sludge" should be left in the system when it is being cleaned out?

I started mine by seeding the middle drum with maybe 50-60 L of sludge taken from another treatment unit -- the one that I replaced with this one.

That earlier one was 150 Gallon capacity, and I never removed sludge from it in 12 years -- though I should have. The problem with it -- and one of the primary reasons I went with three smaller drums on the new design was that it was too big and too heavy to deal with easily. I could go a longer time without maintenance, but then when I did need to do maintenance it was much harder to do, so I found it easier to put it off. And of course the longer I put it off, the bigger and nastier chore it was to do when I finally had to do it.

Here's a picture of the earlier one. It was a single 150 gallon tank, performing all the functions of this 3-drum design, but in a single larger (and more expensive and complicated) tank.

Image

another treatment unit

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Postby Bob » Tue May 15, 2007 10:44 am

I've been experimenting with learning how to include video on my website. Here is a link to a short (and unedited) video clip showing routine maintenance.

http://biorealis.com/wordpress

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System Ramp up progress

Postby davidg » Sun May 27, 2007 1:58 am

I was inspecting the progress of our bio-filter system and its operational progress today.

I have noted the following things, because I had no "active sludge layer" at all to start off with in the anaerobic (2)tank the water passed a lot of "ultra fine solids" to the aerobic tank in the beginning, this is now dropping off slowly.

The result was that a lot of "junk" passed in to the aerobic tank in the beginning. It is starting to improve now.

Because the aerobic tank received a lot of micro fine solids in it that should have been caught by the anaerobic tank, I was wondering if I should clean the aerobic tank (not the 20L bit) out and let the aerobic tank semi start-up again. I would not do this for a least another couple of weeks?

There is a lot of sludge in the aerobic tank that I assume would not normally be there if the anaerobic tank was "running" properly.

The anaerobic tank had a "scum" layer in it, I was inspecting other parts and disturbed the scum layer very slightly it slowly sank to the bottom of the (2)tank. I assume that this will be added to the "active sludge blanket" at the bottom of the (2)tank.

I guess what I'm asking is should I clean out the aerobic tank in the near future. What I was considering doing was to drain out the (3)tank and remove the sludge from it, just to get the aerobic tank a bit more of a jump start.

I have a clean-out/drain-out system built-in so it is very easy for me to do.

As mentioned previously our house is a "retro-fit" from traditional water supply and sewer systems. We have some time up our sleeves to get this working properly before using it full on.

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Postby Bob » Tue May 29, 2007 8:32 am

Good questions, David.

I think I'd be inclined to just let it keep going as is for a while longer, and wait to see if it clears up as the sludge blanket grows and biological populations mature. Assuming that the solids in the 3rd tank are settleable -- i.e. not in colloidal suspension, I would think that over time, the surge pump in the 3rd tank should return them to the bottom of the 2nd tank. What kind of flow rate are you getting from the bottom of the 3rd tank to the trickle filter? Would it be possible to increase this? i.e. by turning up the airflow to the pump?

From your description, it sounds like the scum layer in the 2nd tank is comprised of settleable solids that are heavier than water, but that had been floated to the surface with rising bubbles (of biogas?). I'd be curious to know what the pH is.

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Postby Bob » Tue May 29, 2007 9:57 am

An afterthought.

Going back to the page where I describe the biofilter, I note that I did not show ribbon media that I added to the system later. I put it in the downtube in the settling tank (2nd drum).

It is commonly available from aquarium or pond supply sources. I'm not sure it is necessarily the best type of media, but I chose it for this because it has pretty good surface area/volume, and, even more importantly, is relatively easy to clean and maintain -- as seen in this maintenance video. Googling "ribbon media", I find a couple of useful sites, including this discussion, about the advantages and disadvantages of different types of media ...
The most desirable media for a filter meets some, or all, of the following qualifications: provides ample surface area for bacteria to grow on, resists clogging, channeling and compression, maintains loft, is easy to clean, durable, affordable, nontoxic, low density, easy to apply, and readily available. . . . . Below are commonly available filter medias their advantages and disadvantages.

and this interesting page describing how to make your own. (I have had similar ideas, while just cleaning up the waste from cutting & drilling plastic pipe...)

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System Start-up going slowly but progressing.

Postby davidg » Wed May 30, 2007 1:34 am

Bob wrote:Good questions, David.

I think I'd be inclined to just let it keep going as is for a while longer, and wait to see if it clears up as the sludge blanket grows and biological populations mature.


Yes figured as much.

Assuming that the solids in the 3rd tank are settleable -- i.e. not in colloidal suspension, I would think that over time, the surge pump in the 3rd tank should return them to the bottom of the 2nd tank.


I don't think that will happen as the 20L trickle filter contains "aquarium wool" which is catching the larger suspended solids in solution, I suspect I'll have to clean it soon the rate of water flow through it has slowed quite a bit, I now have a continuous puddle on the surface all time now.

What kind of flow rate are you getting from the bottom of the 3rd tank to the trickle filter? Would it be possible to increase this? i.e. by turning up the airflow to the pump?


Um, no the geyser/big bubble pump is flowing about 3-4 litres a minute, I slowed down the surge tank pump slightly as it was really pushing the water through quite quickly reduced it back to an average of approx 120 litres per hour. it was running much faster than that about 4 litres per minute.

From your description, it sounds like the scum layer in the 2nd tank is comprised of settleable solids that are heavier than water, but that had been floated to the surface with rising bubbles (of biogas?). I'd be curious to know what the pH is.


possible. Also, a lot of bacteria as well I suspect, the scum is just under the surface, oh and clings to the sides and anything else it can as it would :), of the (2)tank.

The (3)tank also has similar but to lesser extent and less in solution solids as well. Again I suspect as a result of "start-up" and having no active sludge layer at all to start off with.

We don't use "poisonous" cleaning products anymore and haven't for sometime, all our cleaning, shampoo, soap, etc products are labelled as being "eco or grey-water friendly" and are supposed to be derived from natural renewable materials. Pity I can't say the same for the containers :( .They are mostly plastic at least they are capable of being recycled.

The PH I have not tested it yet.

I should say though that water that exits the system is considerably cleaner than it started in the surge tank so from that point of view it is working OK.

A slight odor is still present after the water exists the (3)tank but it is only about 5% of what it was in the surge tank and the water is fairly clear about 80% compared to what it is in the surge tank. So from that point of view it's working :), I suspect time will help to improve this further.

I'm running the water that exits through another small tank which I'm using to see what "settles out" at the moment. There are micro solids still settling out so this shows that things still need to progress further still.
=========================================

The tanks I used are about twice the size of the ones you used. At the current water levels in them they each hold about 400 Litres of water the surge tank can get to just under 500 litres of water at a pinch. When I was testing things, I found that the surge tank pump at the current setting for the air flow it averages 120-130 litres per hour provided of course there is water to move.

That of course works out at lots (1000's) of litres per day. not required but it can :) which is kind or cool.

With the tanks that I used the cost would be a bit more, about AU$600-$700. This is still fairly inexpensive really.

I have a few people here that have suddenly become interested in my version of this and have expressed an interest in doing something similar, once mine is finished, particularly for some the rural areas where I know a few people, time will tell how these will go.

By the way, the current air pump I use consumes more power than the one you mentioned/used, what I could not figure out is how much air yours pumped in litres per minute or similar, that would have helped a lot.

The air pump, I'm using is able to pump 85 litres of air p/m. I'm using long 4mm black flexible tube used water dripper systems costs about 1/3 of the clear tube UV stabilised as well, each tube is approx 8 metres long, the air pump is inside out if the weather, one spin-off benefit of having long tubes is that the air pulsing has been smoothed out into the pumps the long tubes take the pulsing out which makes the system quite a bit quieter.

Regards David

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Postby Bob » Wed May 30, 2007 10:00 am

...as the 20L trickle filter contains "aquarium wool" which is catching the larger suspended solids in solution, I suspect I'll have to clean it soon the rate of water flow through it has slowed quite a bit, I now have a continuous puddle on the surface all time now.

It sounds like you might want to try experimenting with a different kind of media, something that still has a lot of surface area, but that allows sluffed solids to fall through it without clogging it up.

The air pump, I'm using is able to pump 85 litres of air p/m.

Wow. That is far more than mine. This is an area that could use a lot more experimentation and testing to optimize. Do you have pump curves for that pump that show air flow against head? 85 lpm at what pressure? And what is the wattage?

I've been experimenting with various different air pumps, trying to come up with an optimum airflow/energy use combination. At first, I was using multiple (3) single-outlet Rena 301's, one for each pump and one for aeration in tank3. The only specs I have on it say max 325 LPH, but I haven't actually measured airflows at different depths. It draws 6 watts. I love these pumps. I've had some of them running continuously for 10 years without a failure.

More recently, I've been experimenting with larger cheaper pumps made in China -- connecting a single pump to a manifold. The example shown in the pictures draws 25 watts and produces about 8 LPM at 3 PSI (the V201 in the chart). What I don't know yet about these pumps is their reliability. (6 months so far, without a problem...) Also, 25W running 24hr/day is higher than would be ideal for most off-grid people.

Image

Another downside of using a single pump with manifold is that one of the three airflows (i.e. the pump in the surge tank) will vary widely depending on depth of water over the diffuser. This affects the output of the other two, which I would prefer to remain constant.

The ideal pump -- what I'd like to find -- would be a low wattage, inexpensive, high reliability DC pump with three independent outlets. Independent so that variable resistance on one outlet doesn't affect the output of the others.

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A few more questions

Postby blimpyway » Sun Jul 15, 2007 2:32 pm

Hi again Bob,

what is the role of pvc ribbons (those you clean on the video)?
Wouldnt the dissolved oxigen flowing out of trickle filter be consumed anyway in the sludge at the bottom of the 2nd tank? Hopefully the bottom sludge will develop a small aerobic colony, without needing pvc ribbons on the input vertical tube.

Another question - do you have any figures regading daily BOD / amonia load on your biofilter system?

What is the surface area of the media in trickle filter and how much volume/area would need a biofilter for treatment all sewage (toilet flush also) from two persons, at a total water flow rate of 80 galons/day

Thanks for your patience,
cezar

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Postby Bob » Mon Jul 16, 2007 10:55 am

what is the role of pvc ribbons (those you clean on the video)?
Wouldnt the dissolved oxigen flowing out of trickle filter be consumed anyway in the sludge at the bottom of the 2nd tank?

Good questions, cezar, and not ones I'm sure I have a good answer to. The added media was a bit of an afterthought, something I thought I'd just try, to see how or if it changed the performance. My thinking was that it would add just that much more 'habitat' for colonization, adding to solids retention time, and insuring that the sludge that reaches the bottom is anaerobic by the time it gets there. (But lacking money for lab testing and a control to compare it to, I don't have a clear answer to performance. I suspect the difference in performance is minor -- maybe not worth the additional cost or maintenance it requires.)

Hopefully the bottom sludge will develop a small aerobic colony

Why?

Another question - do you have any figures regading daily BOD / amonia load on your biofilter system?

No. But compared to sewage it is quite low. The design is based on the basic idea that it is much harder and more complicated to try to separate all the constituents of sewage from each other after they have been mixed together than it is to avoid combining them in the first place and treating each separately. (Which also follows logically from the 2nd Law of Thermodynamics)

By itself, urine is easily dealt with. It is sterile, nutrient rich and solids-free (i.e. does not clog small pumps or pipes). It is a valuable soil amendment. It's highest and best use is to dilute it and apply to plant roots (subsurface) immediately before the nitrogen is lost to the atmosphere. Compared to what it takes to remove it from combined sewage this is trivially easy to do. The majority of pharmaceuticals, antibiotics, pesticides and synthetic hormones (mutagens) that we consume is also excreted in urine. These are things that pass through conventional sewage treatment plants and into the food chain.

Human feces (combined with kitchen scraps) is easily composted aerobically -- far more easily than if combined with urine, which adds salts (which kill earthworms), extra nitrogen load (which creates suboptimal C/N ratio, ammonia and odors), and excess liquid (which makes it harder to keep the pile aerobic, requires energy for evaporation and/or drainage, both of which add cost and complication).

This water treatment system is designed for, and sized to handle gray water without either urine or feces in it -- which allows it to be smaller, simpler and less expensive than one that must handle raw sewage.

What is the surface area of the media in trickle filter

I don't know. But, just on visual appearance, I will argue that it is very high for it's volume -- and cost. (I would love to be able to perform -- or see someone else perform some rigorous controlled experiments comparing different media -- especially inexpensive "home made" media. Any volunteers?)

...and how much volume/area would need a biofilter for treatment all sewage (toilet flush also) from two persons, at a total water flow rate of 80 galons/day

As noted above, I intentionally avoid mixing feces and urine with used wash water, thus drastically reducing the loading (both hydraulic and organic), enabling the design to be smaller, simpler and less expensive.

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Postby blimpyway » Wed Jul 18, 2007 6:46 am

Bob,
is true that your waste-management design decisions might be very good, but what is a natural step for an ecological-conscious person might be a too large leap for humankind, or at least for most people in my country :wink:

That's why I'm trying to figure out is what parameters needs to have a DIY household biofilter for all sewage treatment. Knowing these parameters then trying to figure if, and at what costs (investment + recurring energy & maintenance) it can be acomplished.

I'm searching for something more ecological than a septic tank or pit latrine, yet cheaper and using less energy than a household activated sludge aerobic plant.

And an open design that can be shared and implemented by anybody.
cezar

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Postby Bob » Wed Jul 18, 2007 9:57 am

what is a natural step for an ecological-conscious person might be a too large leap for humankind, or at least for most people in my country

Yes, very true. We in the west have such a long history of putting our shit in our drinking water that it is now taken as a given. To suggest that if we just stop doing that, everything becomes much simpler and cheaper ignores the psychological and cultural obstacles and the vast existing supporting infrastructure (e.g. water flush toilets, piped sewers, conventional treatment methods, academia, regulatory agencies, etc.) that support the current insanity. Like the QWERTY keyboard, it is locked in.

That said, if your goal is to reclaim water for reuse, this system, with some minor modifications, could be used to treat septic tank effluent (rather than gray water) to advanced water quality. A few years ago I developed a similar system just for that purpose. Here is an excerpt of a proposal I submitted to the US EPA that describes the basic concept. (They declined to fund it).

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Postby blimpyway » Thu Jul 19, 2007 7:41 am

Yes, I'm interested in water recovery, to the level of making it acceptable for watering the garden. What "acceptable" means - food that is supposed to be cooked.

Dominant in country side here are outhouses/pit latrines in old houses and open-bottom "septic" tanks for newer ones. Since we joined EU, this situation is legally unacceptable yet, except for new houses, litle hope to change soon.

thank you,
cezar

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Postby Bob » Thu Jul 19, 2007 8:18 am

Does the system described in the document I pointed to look like a feasible possibility?

Users would have to install regular (closed) septic tanks, then pump settled effluent from them into this unit for further treatment and reuse.

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Postby blimpyway » Thu Jul 19, 2007 9:04 am

Bob wrote:Does the system described in the document I pointed to look like a feasible possibility?


I dont know, mabe. I think we use an average 180l (~50 gal) / day /person, yet the norms specify a minimum of 300 liter.

I also know the cheapest aerated active sludge residential plant can be purchased for a bit under $2500, for 5 persons. It uses 60 watts power, but I could not find wether this is continuos or not - there is a batch program that provides for anaerobic stage and a settling one, during these I suppose the power use is minimised.

An 1100l (300gal) plastic septic tank can be purchased for ~$1500.

These prices do not include the drainage field, although aerobic active sludge manufacturers claim the effluent can be used for subsurface irrigation.

Users would have to install regular (closed) septic tanks, then pump settled effluent from them into this unit for further treatment and reuse.


I noticed that's how many (if not all) secondary treatment solutions work.

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Postby Bob » Sat Jul 21, 2007 8:47 am

I think we use an average 180l (~50 gal) / day /person, yet the norms specify a minimum of 300 liter.

That sounds pretty typical. The need to design for worst case and safety factor is discussed in the proposal. If a full backup system is in place (a drain field), then the reclamation system doesn't need to be designed for worst case and can be smaller and less expensive.


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