Salt in vermifilter

[Kimi Ishikawa]

Does anyone have any idea if salt levels in household wastewater pose a problem for the worms or resulting effluent?

I am aware that Anna Ebey (sp?) purposely used conventional cleaning  fluids in her 1990s vermifilter and had no problems, but her site is no longer online and I don't know what kind of info she has on salts.

I am also aware that the remedy for salinized soils in planting areas is to flush with water, and maybe there will be enough water through the system to mitigate the salts.

We are installing a household vermifilter septic system and will be planting in the drainfield.

Our main salt loads (other than that found in our normal diet) are that I do a lot of lacto-fermentation (although I can recycle brine more than in the past), and my husband wants a dishwasher. Other than the dishwasher we do not plan to use any sodium-based detergents, all of our other soaps are greywater-friendly. 

We probably won't be up and running until fall at the earliest, and will post any results when we get them, but I figured I would ask if anyone has any info on salts from household wastewater impacting the vermifilter or resulting effluent?

An added complication is that we will have a greywater infiltration bed for laundry, and some of our bath/shower water may also be reused as greywater, which would cut down on the water diluting our blackwater into the vermifilter.

[Dean Satchell]

Hi Kimi, I recommend greywater going into the same waste stream as blackwater, explained in vermifilter.com. The dishwasher won't be increasing your salt levels noticeably. I'd suggest you calculate the quantity of salt from your lacto-fermentation and the total quantity of wastewater you produce per unit of time and come back to us with those quantities.

Cheers

Dean

[Kimi Ishikawa]

Thank you for this, Dean.

If I had gotten our vermifilter permit earlier I would not have bothered dual plumbing for greywater,  but the permit took over a year and the plumbing couldn't wait... So as it stands, our laundry greywater line goes out back to one infiltration bed, and everything else (including laundry switchable to go down the blackwater lines) goes out front. So if we have enough water to support both planting beds, the laundry will water that back bed. Otherwise we will skip planting a bed out back that requires supplemental water, and will send everything down the black lines.

Is there a place on your site that explains why you suggest sending everything through the vermifilter? I searched the site for "grey" and "greywater" and found a definition in the glossary and one line that said both grey and black can be handled by the vermifilter,  but I didn't see reasoning why or even mention that it is preferable to combine grey and black...? Of course it would have saved the considerable bother of dual plumbing, but since we already did that, I don't know why it would be preferable to combine.

I am thinking that for us it will just be a matter of volume... if it seems like we are overloading our filter we can split off the greywater. On the other hand, if our water quality is suffering, maybe diluting with greywater would help... but that is just my inexperienced guess.

I would be interested in learning more about why you recommend combining grey and black, if you can point me to the right place on the website...

Thanks again!

Kimi

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[Dean Satchell]

Hi Kimi,

The primary reason for combining greywater and blackwater (especially before the secondary vermifilter) is for simplicity - one dosage system or pump, one surface irrigation field. Sounds like you have fixed infiltration beds with subsurface drains? The rationale for secondary treatment and surface irrigation is that the irrigation lines can be moved so that nutrients, salts and water aren't concentrated in one spot.

Cheers

Dean

[Vermifiltros Ecuador]

Hi Kimi and everyone.

the systems that we build, in small scale we always separate  grey and blackwater , because in our set up grey water goes to grease trap and then join with treated water from  vermifilter  in a constructed wetland. this is precautionary because sometimes overloading the vermifilter with laundry water and bathtub water can result in too much flooding and once the humus is fine this will result in earthworm drawning. If you put 250 l/m2 of waste water per day on the vermifilter its a good loading rate. If you dont have too much grey water its ok to mix, but be carefull.

[Kimi Ishikawa]

Yes, thank you, I agree! 

We (pre-house, pre-plumbing) currently haul all of our water and only use ~1000 liters per MONTH. Our normal use may possibly get as high as 250 liters on some days but right now that sounds like unimaginable luxury...

If we have too much we will make use of our greywater beds.

[Dean Satchell]

Hi Miguel,

Grease doesn't decompose in a grease trap, it just gets trapped, builds up... and turns into a stinky mess that needs removing at regular intervals. Grease traps are not good. Its simple to build a vermifilter for kitchen, laundry and bathroom greywater, one that copes with high water loadings and that decomposes the grease and solids.

A good vermifilter always has a cavity between the media basket and the drum. Here is a photo of a greywater vermifilter. The "basket" is smaller diameter than the 40 gallon plastic drum, so there is a cavity right around the basket. This has about 50 litres of media, with more than a cubic metre of water flow every day... and the worms can't drown. The red arrow shows the surge capacity:

The basket itself acts as a filter for hair, grease and solids. You'll see a thin layer of "sludge" and solids on the surface of the media that does impede drainage but importantly those solids have been removed from the flow and feeds the worms (lots of tomato seedlings also!). In this case the vermifilter has been operating for several years without any maintenance, from the kitchen, laundry and bathroom greywater.

This is just a primary vermifilter that filters out the solids and digests them. I can't emphasise enough that a drum filled with media isn't a good vermifilter, its a worm torture chamber. There must be a cavity between the media basket and the drum for both keeping the media aerated and also for good drainage even with high water flows.

Cheers

Dean