Cheese whey vermifilter treatment

[Георги Николов]

Hey everybody,

I am trying to design a vermifilter system for the treatment of wastewater from cheese manufacturing which is by volume 50 % whey and 50 % washing waters. Total 30 m3/day.

I found an article which traces the performance of such a filter in the pre-Alps - G. Merlin

I have a lot of questions...

How much should the OLR be? Being situated outdoors in a warm moderate climate (seee the graphic) - will the biofilter perform well all year round?

The brine that is used in the manufacturing process - will it cause any troubles and accumulate in the biofilter? DO you know how should the ventilation pipes be spaced in the vermifilter and in general should they be used to ventilate the drainage layer or do they have to aerate the whole mass?

BTW

primary calculations i have made with OLR 1,2 kg COD/ m2 a day have given me size of the biofilter of  700-800 m2  ( the whey is very high in cod 60-100 g/l). 

Hope we have a good discussion! I am available for further questions

[Dean Satchell]

Hi Georgi,

I'm not familiar with wastewater from cheese making, but imagine it will have a high content of dissolved organics contributing to a high biological oxygen demand (BOD). What exactly is the "brine" and what is the salt content of the wastewater? Be aware that higher salt content can become toxic to plants over time and will require a larger land disposal area for the treated wastewater, and that vermifilters don't remove salts and nutrients, but rather they remove BOD, suspended solids and pathogens. Dissolved salts will go through the vermifilter... but keep in mind that if the water is too salty it will kill the worms.

I'd also be interested in the size profile of the solids in the wastewater. This is critically important for design (sizing), because fine suspended solids behave very differently than solids which accumulate on the surface.

I'm also wanting to know what you are trying to achieve? Are you focused on a specific treatment level that allows you to discharge to land, in particular surface irrigation?

I also don't understand why whey would be waste. Whey is rich in protein and surely has value as a by-product?

Cheers

Dean

[Георги Николов]

Hi Dean, 

Thank you for the information and the questions.

I will try to answer the questions and will post an update of the situation in another post.

The whey has approximately 50-60 g lactose per liter;6-9 grams of protein and a around 4 g of fat per liter. These are all valuable byproducts and my opinion is that it is best to be valorized, but the infrastructure that is needed is costly and involves big capital investments in membranes and spray drying equipment. I have been told by people in the field that below 25 cubic meters of whey per day is not worth it - the capital expenditures....

About the fine solids, well - I don't happen to have tests on these, but I think they will be in colloid form. My best guess is there will be very few real suspended solids...

About the treatment level - yes, we are trying to achieve appropriate levels for surface irrigation. We want to discharge the water as surface irrigation. 

The brine is 10 % w/w solution of salt but we have arranged for it to be treated separately.

Sincerely,

Georgi

[Dean Satchell]

Hi Georgi,

I'd suggest building a scaled down prototype, say with a 1 cubic metre capacity, and adjust the quantity of water per day that achieves your required water quality. You could build it with five plastic pallets, one underneath and four walls. You'd use pine bark and a recirculating pump, and a makeshift sump. I'd guess that you'd treat 1 cubic metre of water per day per cubic metre of media capacity, i.e. 30 m3 rather than your 700-800 m3. But your effluent is pretty rich, so testing would provide your answers. Keen to support you in building your prototype.

Cheers

Dean

[Георги Николов]

Hey Dean,

We built a prototype with 1 cubic meter volume. We are setting it up. Last friday we started it, and now it has flies. Your idea with the plastic pallets is good but my patner has these flat panels of polypropylene and it was easier to make one with them. We have put a ventilation pipe in the middle of it that goes through the drainage layer. There is cloth on the pipe where it goes through the gravel and sand layer. 

There is a drainage layer 10-15 cm of big stones, than a shade cloth to hold the gravel layer and on top of them a sand layer. Nex there is the worms with compost and on top there is straw and a little bit of pine bark. 

Right now we have a problem with flies and fermentation( my partner told me that the fermentation is in the retention tank with the runoff)... I will see it in wednesday but I think that we will have to use some additional cover/screen because of the flies. What are your thoughts on the flies?

We can check the COD and pH when we have it running completely good.

Best wishes,

Georgi

[Георги Николов]

I have other pictures but google won't let me publish them, because the message gets too big...

[Георги Николов]

https://drive.google.com/file/d/1ot4KW5-uCUgywApK0_9-mK9a2zs6loF8/view?usp=drive_link

https://drive.google.com/file/d/1oyrIUHNmc2Uyg27Lx-xF2kJ-hvYnwzc4/view?usp=drive_link

https://drive.google.com/file/d/1p42W6Z8xQKXOnaBYuR_kLunOvZpwbWYB/view?usp=drive_link

https://drive.google.com/file/d/1p6lHULLGgJz3Qum9wh6cebKwe6yci6np/view?usp=drive_link

https://drive.google.com/file/d/1pAWJU5H_A-dWlmHJC4e6BKgsgZ5lgrTz/view?usp=drive_link

https://drive.google.com/file/d/1pDZZW5TCcNd4z8MmHRPw5X7hyRAXhV-f/view?usp=drive_link

hope you can see them

[Dean Satchell]

Hi Georgi,

A couple of important points relating to your design. The first is that for an efficient vermifilter you need really good ventilation.

The reason why I use plastic pallets is so that the walls and false floor are well ventilated (with shadecloth attached to the inside surface of the pallet to retain the substrate, and a solid wall attached to the outside surface). The cavity provided by the pallets provides ventilation right around and underneath your media basket. Your solid walls provide no ventilated surface area. Your design is like what Merlin and Cottin reported, a very inefficient design. They also reported that "Effluent dissolved oxygen levels were low and close to 1 mg L−1, showing that anoxic conditions existed within the beds". My fully ventilated design will open you to the real possibilities of vermifiltration. Think about supplying enough air for ten kilograms of worms, and think about how much you weigh and how much air you need. Your ventilation pipe is not enough...I cannot emphasise enough how much ventilation you need right around and underneath your media basket, that was my big breakthrough. You can use cable ties to construct a cube from six pallets. You also need to provide ventilation without allowing flies to have access. Mosquito netting is ideal, attach over holes in the outside wall or between wall sections.

Can you get composted pine bark fines? if not, use woodchips. Don't layer the media, just fill the basket with the fine pine bark or wood chips. 

Recirculation is essential.

Cheers

Dean

[Георги Николов]

Hey Dean,

Sorry for delaying my answer ( funny how google groups notifications are put into spam folder by google... took me a month to see that you have replied...).

I really appreciate your insights and totally agree that ventilation and good recirculation will be paramount. COD tests showed that after 24 hours with 50-60 litres of whey given to the pilot installation we had around 12000 mg/l COD, so around 80 % reduction. A lot of the reduction could be due to sorbtion of the organic loading onto the media or to other factors. 

Since the real installation will be around 320 m2 - it would be hard ( costly) to do the vertical pallets for ventilation and also the foundation with a plastic pallet. I do acknowledge that this design is superb for ventilation. Well it could be that I am wrong and that the design with pallets for ventilation is not that much more expensive... We were thinking of putting a ventilation pipe for every 4-5 m2 of the filter and woodchips or pine bark fines( not composted) as media but the project is on hold for now. Once again I want to thank you for your inputs! 

What are your thoughts on the filter working in winter time?

Sincerely,

Georgi