Inclusion of Greywater

[Burton & Cherstin Sparks]

Including greywater adds more surges.  What is the max Hydraulic Loading Rate (HLR=InfluentRate/SurfaceArea) you would recommend for a Primary Vermifilter?  This article seems to suggest keeping it well below 2.34m^3/m^2/day to reduce the risk of clogging, which if translated to short term flow doesn't equate to much of a surge (0.5gal/min).

Burton

[Burton & Cherstin Sparks]

I should have mentioned that the  0.5gal/min assumes a 1m^2 surface area.  If I were to guess, it seems like the more porous bark may not clog as readily as vermifilter media used in the scientific papers.  At some point though I wonder if the flow might impede the worms and/or start pushing organic solids through.  The reason I'm asking the question is because it could help determine the required surface area of the primary Vermifilter.

[Dean Satchell]

Hi Burton,

unfortunately the literature has not caught up with innovation. A vermifilter comprising a basket with a cavity between that basket and the wall of the vault does not clog. 

Example of basket with cavity

If infiltration through the media is less than hydraulic loading then rather than overflowing, resulting in solids entering the next stage, the wastewater simply flows through the basket wall, which filters and retains the solids. Basket walls do clog lower down with sediment, soap scum and grease etc, so if flow is high then put less media in so the basket walls are higher, to ensure overflow never occurs.

Blackwater shouldn't cause surges, there isn't enough volume from a toilet flush. Greywater includes showers, washing machines etc, so volume is much higher than blackwater. But remember, surge does not occur in the vermifilter. Surge only occurs in the sumps, causing the water to back up from the sump into the vermifilter. That's quite different than what you describe, which isn't surge at all. To reduce hydraulic retention time for a higher hydraulic loading rate, the media in the primary digester should be coarse and shallow (unlike the designs in the literature). The primary digester's purpose is only to retain and digest the solids and let the liquid effluent through. It doesn't need to treat the effluent, that occurs in the secondary stage, so media depth is not required.

If the surface area of the primary digester is insufficient, the solids will build up on the surface and impede infiltration. In practical terms just make it as wide as you can. I'm waiting for your design.

Cheers

Dean

[Burton & Cherstin Sparks]

Dean,

Thanks for your patience, and ensuring I'm using the right terminology.  Here's the functional diagram (yes, I need to move the recirculating pumps below water level).  I hope to have an updated construction plan rendering this week.  All vermifilters will be made of 4ft x 8ft (x maybe 1/2in thick) sheets of HDPE cut to size and lined with drainage cells.  The vermifilters are set on cement drainage skirts that run the output through a pipe to the respective sump to keep everything vermin and bug proof.

Winters can freeze the ground a couple feet down and I have separate greywater (2in) and blackwater (3in) pipes currently about 2.5ft underground near the site where I'm hoping to build an underground treatment room below a shed.  Current plan is twin bin 5ft square x 4ft tall primary vermifilters (handling 8-10 full-time residents with toilet paper).  To handle greywater with the blackwater I can go larger, e.g. 6ft square or maybe even 8ft square, but then the underground room starts to get bigger than I'd want with twin bin.  Is it better to go with a single (non-twin) 6ft square or even 8ft square primary vermifilter instead of twin bin?

[Dean Satchell]

Hi Burton,

The problem with a single primary digester is that in ten or fifteen years when you want to dig out the humus, it will have fresh stuff on top. Resting the contents for digging out mature humus is advised for that reason, which requires two chambers. The other important consideration is that when you first get the system going, the worms will not keep up with the quantity of solids coming in. Having two primary digesters allows you to rotate them regularly while the worm population is building. For 8-10 full time residents I'd suggest the surface area of your primary digesters is quite small. My rule of thumb is 1 square metre x 2 per four residents.

[Burton & Cherstin Sparks]

Dean,

I hadn't thought about ramp-up of the initial worm population.  That makes a lot of sense, thanks!

Sorry for the confusion.  Saying 5 foot square (vs 5 square feet) is perhaps only a local way of saying a square that is 5ft on each side.  In other words, the above plan represents primary twin bins that each have a surface area of 5ft x 5ft = 25ft^2 = 2.3m^2.  If I understand you correctly, that should handle at least 9 residents: 2.3m^2 * (4residents/1m^2).

Burton

[Burton & Cherstin Sparks]

Ronald,

I'll add the rest of the team to the email for broader support. What are the related code requirements in your area?

Burton

On Sat, Feb 8, 2025, 7:39 AM Ronald Ruben <ronaldbe...@gmail.com> wrote:

Hie team

I wanted to do an onsite wastewater treatment using a vermifilter system. The area has limited space, and I want to treat both blackwater and greywater.  May you assists me with how i can go about it and the steps i should follow to achieve the project. The effluent from the treatment system may be used for various household tasks such as toilet flushing and landscape irrigation. Thank you.

regards,

Ronald

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From: vermifilter-...@googlegroups.com <vermifilter-...@googlegroups.com> on behalf of Burton & Cherstin Sparks <burton...@gmail.com>
Sent: Sunday, November 10, 2024 04:17
To: Vermifilter knowledge hub <vermifilter-...@googlegroups.com>
Subject: Re: Inclusion of Greywater

 

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[Dean Satchell]

Hi Burton, please get Ronald to join the hub so he can pose his question to the group.

Cheers

Dean

[Burton & Cherstin Sparks]

Ronald,

If you can join the Vermifilter Knowledge Hub (https://groups.google.com/g/vermifilter-knowledge-hub?pli=1) you'll be able to get support from Dean (owner of vermifilter.com) who has much more experience than myself.  I'm working up to building my first system this coming summer.  When you use that forum, others, including myself, can participate and share their experience with you as well.  Others can also benefit from any questions and answers provided there.  Dean has helped me tremendously, and will be a great resource for you as well.  At the top of the page linked above there should be a "Join Group" button.  Then you can click the "New Conversation" button at the upper left of the page to start a conversation specific to your circumstances.  I look forward to hearing from you in the group!

Burton

On Thu, Feb 13, 2025 at 2:26 AM Ronald Ruben <ronaldbe...@gmail.com> wrote:

Thank you for the prompt response.

Regarding the code requirements, I'll look into the local regulations for onsite wastewater treatment systems, including the standards for effluent reuse for toilet flushing and landscape irrigation. In Zimbabwe, guidelines are influenced by environmental and public health authorities, and they are similar to those used by WHO.

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From: Burton & Cherstin Sparks <burton...@gmail.com>
Sent: Wednesday, February 12, 2025 03:08
To: Ronald Ruben <ronaldbe...@gmail.com>
Cc: Vermifilter knowledge hub <vermifilter-...@googlegroups.com>