Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hi Bogdan,
definitely. I remember a discussion here in NZ, animal activists were saying it was cruelty to animals (worms) because the population could starve if the food runs out (such as holiday homes). Yes true! However, there is always eggs and more will grow, they adjust to the food source. I've found that if there is toilet paper being used the pile becomes like a reserve food source. No toilet paper and the worms can keep up with the incoming poo and thus have less reserve.

I've found one of the strengths of vermifiltration is that influent can vary without the system failing. Make sure that ventilation isn't excessive and the pile will not dry out too much for a month or more, so no need for recirculation, unless you want better treatment or you are incorporating greywater. Also make sure that your digester is well insulated in your cold climate so that worms are not killed unnecessarily.

cheers
Dean

Dean Satchell, M For. Sc.
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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Thanks Dean! This sounds promising. I will suggest a black water vermilter for my freind"s part time occupeid house. Mybe help them to build one this year
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Bogdan

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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hi Dean!
Can you think of the minimal volume for the primary vermidigester? Something like 100 l will be enough?
Best,
Bogdan

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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hi Bogdan, 100 litres will be nowhere near enough. Depends on number of users, but bigger is better, especially in a cold climate where it would be good to have surplus capacity. Twin digesters with 300 litre capacity might need to rotate every 5 months, whereas with 600 litres capacity each they would not need rotating for at least 5 years. The "pile" needs to be able to spread outwards freely, so a diameter of at least 1m is best, and you don't want the pile building upwards too much in cold season and blocking the entry.
cheers
Dean

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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hi Dean! Thank you !

But what if we go for more often switch say 1 month or even less and have more than two digesters? What I am interested in is what in general the minimal volume for the biological process of vermidigestion to happen. I know that 100 l is enough volume for composting to happen (though not so fast as in a bigger pile). Or it possible on condtition that you add there enough worms right from the start?

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Bogdan

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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hi. Researchers & Developers. It is great to note the deliberations on vermi filter. In certain of our sites in India we use say 20% by volume -
partly cured excreta from cattle. A lot of benefits and if bio mass is available use them also. All this is required to keep e - worms healthy and well at their work. As saying goes if worms are good both in quantity and quality then the filter will be very fine... w wshs from Prof Ajit Seshadri. Vels University.Chennai.India.

Prof. Ajit Seshadri, Senior Faculty in Marine Engg. Deptt. Vels University, and
Environment Consultant (Water shed Mngmnt, WWT, WASH, others) Chennai, India
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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hi Bogdan,
Wet composting seems to work differently than ordinary composting. With wet composting the heap degrades from the outside-in compared to inside-out with ordinary composting. I trialled 70 litre baskets a few years ago and didn't have very good results, degradation was slow so the baskets filled rapidly. I attribute that partly to lack of time for a stable population of worms to develop (the baskets filled too quickly) but more importantly, in smaller baskets surface area to volume is reduced.


(I'm discussing primary digesters here where toilet paper is used. A heap is inevitable.)

Pretty rough drawing, but the area highlighted in orange is the area that the worms work. They don't venture into the core because it doesn't have enough oxygen, so they work from the outside. See how the small basket has a very large core and a small outer area for the worms to work?

With lots of area for the heap to expand outwards, it tends to "flatten" as it spreads. This ensures fast degradation.

Helpful? What is your cunning plan?

cheers!
Dean

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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hello Dean!

Yes, it is very helpful. Thank you very much! I see what you mean from this pictures. It should be a basin rather than bucket. I thought about making a small demo model from 120 l low and wide barrels available but now understood that it wouldn't work for digester. For the vemifilter it will robably be ok though . By the way did you practise rotation of the vemifilters cells as well or kind of make them working in shifts to recoverbetween cycles?

Best,
Bogdan

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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hello Dean!

Could you tell please, how well these fountain pumps you use for the recirculation tolerate particles in the vermidigester/vermifilter leachate? Did you have any problems with pump clogging?
Best,
Bogdan

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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hi Bogdan,
I originally had the small baskets working in series, it was a long plastic tube made out of 40 gallon drums and I pushed the next empty basket in from one end under the inlet, which pushed all the baskets toward the other end. Was just an experiment... which failed because the composting process was too slow and the tube needed to be too long with too many baskets for my liking. What I learned was that working in shifts is the best option because the worm population builds up. You just need a way for the worms to migrate from one basket to the other... with enough capacity for your rotation length.
cheers
Dean

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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hi Bogdan, yes blockage of these small cheap pumps has always been a concern. Indeed they can block with silt building up in the inlet. The pump itself doesn't block, but the buildup of fine particles can stop the water from flowing into the pump which can burn them out. How I've got around that is to use a series of sedimentation drums between the primary and secondary vermifilters. These remove most of the suspended solids. Also, the intake for the pump is below the surface but not too far below. The solids themselves are never big enough to block the pump, with reliability being the key concern.

I'm sure there would be a thousand different ways to design the system... if there were fall then the secondary filter could be directly under the primary filter and thus avoid any need for settling and recirculation. That is not always possible, however. I'm also interested in hearing others solutions to the problem!

With this system, every 5 years (when I rotate primary vermidigesters) I pump the sediment from the settling drums back into the primary vermidigester. Depending on how well your primary vermifilter removes suspended solids, the buildup of sediment should be quite slow. I don't try and achieve high levels of removal at the primary stage, and with settling drums the secondary vermifilter is not primarily for removing suspended solids, but more to aerate the wastewater and remove BOD, pathogens and smell for subsequent surface discharge.

cheers
Dean

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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Hi Dean!

Thank you! This very valuable that you are willing to share your experince here including trials record. It is only through these experiments we can develop new systems "out of septic box")))).

Now I understand much more about your design and why did you put several setlling tanks after the primary digester. This really makes sense. I wonder if there are any very small low wattage small flow sludge pumps produced capable of passing bigger partickles. and run on 12 volts. I haven't seen any here less than 500 watts so far.
Some cartridge type rough filter serviced from outside like septic tank effluent filter is what what comes to my mind when I think of the ways to make things working with the pump. Probably also control system that warns of level raise in the sump when the filter got clogged.

Best,
Bogdan

Bogdan

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