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

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

goeco - 13 Apr 2017 00:01
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
I have to say that I treat the IIT version of Soil Biotechnology (SBT) with some considerable scepticism. I have no issues with the concept and design, it's the patent and proprietary nature of their "additives" that smells like snake oil...Basically a special proprietary culture of soil, earthworms, bacteria and special additives. Starts with a septic tank, then to the bioreactor, with rubble in the bottom as drainage layer, then proprietary rock material, special additives and soil as the filter layers. Plants are grown over the top of the SBT beds on soil bunds and wastewater is trickled on top.

There is nothing proprietary about the SBT apart from specific materials that are used, such as minerals and bacterial cultures. Check out their patent, US Patent No: 6890438 " Process for treatment of organic wastes"
www.google.com/patents/US6890438

The patent is riddled with misinformation about vermifiltration that is then used to support their approach using special proprietary additives. It reads like a comic book... the goal being to disingenuously claim superiority to set up a monopoly.

Their bioreactors use vermifiltration combined with plants to purify primary treated wastewater. I'm okay with that, but am convinced this is not the best approach. By using plants to treat wastewater, you add to maintenance and costs. In my view the best method is to treat the wastewater to a level that is safe to use for irrigating productive crops, while retaining the plant nutrients. That is, treat for the plants rather than treat with the plants.

cheers
Dean
goeco - 13 Apr 2017 00:11
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
Hi Bogdan, vermifiltration has been used for domestic sewage treatment for some time in New Zealand and Australia. I have not heard of any cases where the worms were killed by household disinfectants etc. I would imagine that pouring a fairly large quantity of pure disinfectant down the drain would kill the worms but in common use this would not happen. It appears that standard practices such as washing disinfectant down the sink with water sufficiently dilutes the chemicals to not kill the fauna. I haven't actually tested the limits of this but do use standard household disinfectant and laundry steriliser.

cheers
Dean
BPopov - 13 Apr 2017 07:15
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
Hi Dean !

Thank you! Sounds good again.

I wanted to ask you about the profile of your vermifilter. Do use wood chips all the way down both as bedding and drainage or still have some kind of gravel underneath for drainage? If so what is grain size of the gravel and what its depth? Do you have some kind of collecting perforated pipe underneath?
Regards,
Bogdan
BPopov - 13 Apr 2017 07:24
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
I agree with you Dean in terms of proprietary issues applied to vermifiltration. You can't patent worms, plants, bacteria and water -- it's like trying to patent nature itself. We are to achieve nothing in terms of solving global water and sanitation challenges if resort to this attidude.
goeco - 15 Apr 2017 08:37
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
I wanted to ask you about the profile of your vermifilter.

We probably should be discussing primary treatment and secondary treatment vermifilters separately. In a secondary treatment vermifilter you don't need much space above the media because solids don't really build up over time. This is because only liquid circulates through the secondary treatment module. Depth of media is also important.

On the other hand, primary treatment vermifilters need lots of space above for buildup of solids, they should be wide to allow the solids to spread out rather than build up, and they don't require much depth of media.


DSC02612-1.jpg

Media basket using plastic mesh, shadecloth, polythene pipe and plastic cable ties



DSC02613-1.jpg

Basket installed in 250 litre plastic drum


DSC02615-1.jpg

Coarse pine bark media installed in basket

Because there is air surrounding the media there is no need for a coarser drainage layer at the bottom. I do use a free draining media that doesn't impede percolation and air penetration into the media though. If you use a fine media such as peat or sawdust, you might need a coarse gravel drainage layer at the bottom. Keep in mind that using a basket means that impeded drainage doesn't result in over-saturation/flooding. You can't drown the worms this way and the environment always remains aerobic. Also note that I drill lots of fine holes in the drum to allow ventilation (but not flies). In your case you'd have insulation and a ventilation system to ensure the reactor doesn't freeze.

cheers
Dean
BPopov - 15 Apr 2017 17:12
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
Hello Dean!

Thank you ! The basket idea is great! So this means in the bottom there is even bigger air gap between the drum walls and busket. How do you drain the water from the drum then? A pipe outlet in the drum wall near the bottom?
Is conical basket shape essential? What if the basket will be more or less cylindrical following the shape of the drum? Wouldn't we get more substrate volume this way (and worms population) and therefore more water treated?
goeco - 16 Apr 2017 01:41
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
Hi Bogdan,
the basket is cylindrical (my photo might have been misleading) and all the way to the bottom. There is an outlet at the bottom of the drum.

cheers
Dean
BPopov - 16 Apr 2017 19:49
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
Hi Dean! Thank you and happy Easter!

As far as I understood you shared the secondary treatment vermifilter arrangement. What about the primary vermifilter for black water? Could it also be a basket filled all the way down with wood chips but wider ? In the tiger toilet article that you shared before the layering is quite elaborating consisting of diffrent granular material as well as charcoal.
Also as far I understood you system is of batch type with one chamber resting and one active. What is happenning in the resting chamber when worms eat completely the nutrients? Also is there danger that resting chamber go dry?

Regards
Bogdan
goeco - 17 Apr 2017 01:36
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
Great questions Bogdan!
Okay, now to the primary treatment vermifilter. Here is a diagram of a twin chamber digester:

just_digester1b.jpg


You will see that the two baskets are contained within the one chamber. The worms can migrate from one basket to the other depending on where the best food source is. This allows you rotate the influent from one basket to the other and to dig out humus from the rested basket without fresh poo deposit in the way (say every 5 years).

I use plastic fruit crates for baskets:

palletbox.jpg


They are the right size, durable and hold the weight of 5 years of accumulated solids. They allow air flow below and through the sides. Two of these sit side by side against each other on a concrete sump. The walls/roof are screwed to the crates with a cavity for ventilation. Inside the basket is lined with shadecloth and a 20-30cm layer of coarse bark is provided for the worm refuge.

Now, the other thing is that if you have the fall to design a passive (gravity) system you can stack the crates for primary (top) and secondary treatment (directly below). Greywater and recircultion can go to the secondary crate, which is almost filled with media.

cheers
Dean
JKMakowka - 17 Apr 2017 07:45
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
A bit off topic, but have you thought about doing the primary treatment with Black Soldier Fly larvae to do some resource recovery?
goeco - 17 Apr 2017 08:15
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
Hi Kris, thought about it but possibly am a little too privileged to try and recover protein from my poo! I like the convenience and low maintenance of flush and forget, but would certainly be interested in hearing of any developments and experiences. At times there is an abundance of earthworms which could possibly be harvested?
BPopov - 17 Apr 2017 08:31
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)
Hi Dean! Plastic fruit crates are gifts from saniation Gods! What size do you use
for the primary filter? I have used them as composters and then they can be used directly as grow boxes.

What about mixed flow (grey+black)? Do you think it's possibly to use vermifilter in this case? Maybe it should be some kind of middle way system with more volume ot top but still deep enough with recirculation.?

Regards
Bogdan
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