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

  • guilherme
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Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)

Hi Dean,

The idea is to really separate black and greywater, and direct greywater straight to the constructed wetlands (a floating wetland with emergent species over a bamboo rack, btw), but this involves a future refurbishment that was not possible to happen, as of yet. In other words, this is a temporary solution.

Best to you all, and thanks for your work and attention!

--
Guilherme Castagna
Fluxus Design Ecológico
Pedra Bela/SP - Brazil

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  • guilherme
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Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)

Dear Bogdan,

The vermifilter I mentioned was built using 1m (diameter) concrete rings. They consist of 2 rings of 0,5m high put one on top of the other, totalling 1m as well. This was my first vermifilter and I thought, based on the studies I had read by then, that it´d be better to get the effluent applied to an area that would be larger than the plastic tanks I had found so far, but not wide enough to create preferential flows since the effluent comes in from a 100m pipe, straight from the toilet + shower.

As I mentioned to Dave, my original plan was to have it receiving blackwater only, a load varying from 5 PE to 20 PE (person equivalent). It now receives usually 1 PE on a day to day basis, and up to 20 in single events. It has already received the volume of up to 20 showers/day in events, whereas today it´s not more than 8/10, as we have been able to build a separate installation for additional showers, which have helped to reduce the load.

Good work out there, best from Brazil!

--
Guilherme Castagna
Fluxus Design Ecológico
Pedra Bela/SP - Brazil

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  • AditiOS1
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Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)

Dear Dean,

We did a pilot based on the inputs provided by you, the results are definitely more encouraging. We are now looking at replicating the same for a slightly bigger scale (10,000 litres per day) , the effluent from the existing septic tank would be taken into the vermifilter using a feed pump and sprayed evenly over the active bed. Trying to work out on the recirculation rates, what percentage of the water should be recirculated and how many passes should we design for to get optimum quality of water. Should the recirculation spray be done alternatively or simultaneously with the raw sewage spray over the bed ? We are also getting yellowish tinge in the water how to reduce the same ???
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  • goeco
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Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)

Hi Aditi
Are you pumping from the outlet of the septic tank up into the inlet of the vermifilter which has an outlet that then drains back into the inlet of your septic tank, or do you have two pumps, one for pumping the effluent from the septic tank into the vermifilter and another to recirculate from a sump below the vermifilter back into the top of the vermifilter? Is your septic tank system baffled with one chamber? How many stages (chambers) are there?
cheers
Dean

Dean Satchell, M For. Sc.
Vermifilter.com
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  • AditiOS1
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Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design)

Dear Dean,

The septic tank has three baffles (4 chambers) and has about 2 days of retention (approx effective volume 20,000 litres). we have put a submersible pump in the last chamber from where we would pump the water on the vermifilter bed. The drainage from the bottom of the vermifilter flows into another holding tank from where we can pump the effluent back for recirculation.

The organic media that we are planning to use is wood chips mixed with humus and earthworms. Sugarcane baggase is also available but I am not sure if such a complex organic matter would be a good choice for treating inlet BOD levels of 80-100 mg/l.

For the inorganic filtration media we are using river bed gravel. However, I am not sure about the long term availability of this material. Can we use construction gravel or fly ash instead ?

You mentioned using fruit crates as the holding tanks, we thought about replicating that on a larger scale to basically cut down on the hassles of changing the media using shovel and hands. What do you think ???

Regards,
Aditi.A
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  • AjitSeshadri
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  • Marine Chief Engineer by profession (1971- present) and at present Senior Faculty in Marine Engg. Deptt. Vels University, Chennai, India. Also proficient in giving Environmental solutions, Prof. Ajit Seshadri, Environment Consultant located at Chennai, India
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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Dr. Aditi.
I am not too friendly in answering in weblinks. If it disappears pl feel free to email .. This email address is being protected from spambots. You need JavaScript enabled to view it. .... For your design you need to take care of HRT say the plant capacity in volume ought to be 7 to 8 times to bring raw sewage mixed with sullage waste water... say inlet BOD to plant may be 400-500ppm..
then you can get < 30ppm( less than). Have it in 3 phases.. Simple anaerobic septic tank with 1 or 3 baffles can be more.. next have stone, pebble& sand fllteration filters .. lastly phyto r use plants for r- remediation.. store the outlet water for settling- curing & maturing .. then this water can be re used for secondary uses viz. landscapes. ponds. fountains. Shallow aquifer recharge.. prudently.. w wshs..
Prof. Ajit Seshadri.
Vels University.
Chennai.

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

Hi Aditi,
okay, so I'm assuming you will have a float switch on your pump so will be pumping the same volume from the septic tank into your vermifilter as your wastewater inflow and it will be dosed.

With only two days residence time you won't be getting a high level of treatment from your septic tank, but you could take advantage of it being multi staged by recirculating (with a constantly operating pump) from the 4th stage through the vermifilter and back into the 3rd stage of your septic. This would take advantage of the capacity in the septic tank by making the 3rd and 4th stage aerobic, which will be more efficient, while also treating the wastewater through the vermifilter. A 10 watt 12v pump does about 10,000 litres per day which is the capacity of those two stages. Maybe aim for two cycles per day, with a 20 watt pump at a 2 m head (2 fruit baskets stacked)?


Brushless 12 v pump. This is $30, 12 watts, 650l per hour with a max head of 3.8m

You could even have two vermifilters operating, one recirculating from and back to the 3rd stage, the other from and back to the 4th stage. Less equipment, lower cost.

Yes, you can feed the output from the septic tank through a vermifilter and recirculate back through this using a holding tank.

Working out recirculation rates, vermifilter capacity and septic tank capacity will be trial and error. Given a set capacity for both septic tank and vermifilter and with a constant hydraulic loading rate (i.e. sewage influent volume per hour or day), recirculation will increase hydraulic retention time. The more volume you recirculate, the higher the hydraulic retention time, therefore the higher the level of treatment. Keep in mind that hydraulic retention time can also be increased by having less porosity in the media, but this entails a higher risk that hydraulic loading could exceed hydraulic retention time. Greater depth of media (or stacked fruit crates) also increases hydraulic retention time but the increased head means more energy is required for the same volume recirculated.

A higher level of treatment is also achieved by increasing capacity of either septic tank or vermifilter. Therefore, to achieve higher level of treatment your options are either increased capacity or increased recirculation or both. Think about costs for each of these and make the right trade off. Pumping has a cost over time whereas capacity is capital outlay. Perhaps fine tune the system by using modular reactors that can be added if required. Stacked fruit crates + recirculation pumps...

Fruit crates make the greatest vermifilters, they can be shifted with forklifts and stacked into towers, several high if necessary. They have been my best kept secret till now... you must promise to open source what you learn! You can use corrugated plastic as the outside covering, screwed on to the crates for easy dismantling.

I'd recommend the woodchips, bagasse might decompose too quickly. Sawdust is good. If you use fruit crates then don't bother with the inorganic layer. Baskets don't need it, they have air underneath.... provided you provide sufficient ventilation around them.

Don't forget to share your findings. We're all learning.

cheers
Dean

Dean Satchell, M For. Sc.
Vermifilter.com
www.vermifilter.com
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  • AditiOS1
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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Dear Dean,

The pumps we use here have a much higher head ~7-8 mtrs, we intend to regulate the flow using float switch and rotometer for the flow per hour and timer for batch operation. As the septic tank is already constructed increasing the capacity of the septic tank would not be possible, however we can definitely look at the size of the vermifilter and the recirculation rate. Due to certain aesthetics at the site, the max height that we can manage is 1.5 mtrs so would be working out the fruit crates according to that, ventilation should not be an issue as there are perforated versions available.
Planning to start with 10 kgs worms, hopefully they would get enough food and like our vermifilter and multiply abundantly.

Would share info and photos as the work progresses.

Edited to add: As we would not be requiring the gravel, should we pack the whole vermifilter with wood chips or the humus/vermicompost should be added as half of the volume ?

Regards,
Aditi
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  • AjitSeshadri
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Re: Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design)

Dear Aditi.
Its good to note that you are onto an intricate project involving vermi action with worms etc..
You would be aware that feed for worms have to be pre-cooked i.e kept in anaerobic state for some time.. and then fed in the vermi beds..
or else you can give a separation between the 1st stage and the 2nd stage wherein the worms are added..
All the best.

Prof.Ajit Seshadri.
Vels University.
Chennai.

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

Hi Aditi,
Although the crates are well ventilated, also make sure your enclosure is well ventilated, both for air flow but also to ensure excessive heat isn't trapped inside. The worms will die if it gets too hot... you might need to shade your vermifilter.

Don't be in any hurry to add the worms. Their purpose is to maintain the porosity of your media (which isn't a problem in the early days of operation) and they "graze" on the excess microorganisms that build up on the surface of the media. The microorganisms do the work and these take a few weeks to build up on your media. Once operational, wait for a month or two before you add the worms... and don't expect miracles straight away.

If you are using fruit crates and recirculating, use just woodchips. They have good porosity so your hydraulic loading can be high. Over time the woodchips will start to decay and the worms will produce humus, so the hydraulic retention time will stabilise and you'd reduce hydraulic loading. 

cheers
Dean

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

Hi Dean!

Look what I have done with the crates!
forum.susana.org/52-shared-toilets-commu...toilet-in-kiev#21516

Regards,
Bo

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

Hello Dean!


Do you think it would be able to run a primary black water vermifilter for a family house with 4-6 inhabitants who come there and live for several days and then may be away for a month, although sometimes 1-2 people in the house, sometimes up to 8? Would a recirculation from secondary tank downstream be an answer meaning that vermifilter is constatly kept wet? However no regular feces input -- I mean very fluctuating. Will the worm population ajust ?

Thanks,
Bogdan

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