FRESNEL LENS TO STERILIzE MUSHROOM SUBSTRATE

I need to create heat. Purpose is to sterilize mushroom substrate. Requirement is 90'c - 195'f for 5 hours.

Quantity - around 2 cubic meters. Bigger if it makes sense.

Current solution involves a 55 gal steel drum, require burning wood for a LONG time which must be constantly supervised, and uses steam. I feel that is unacceptable.

A low tech solution please - welding skills are not good enough to make an autoclave / pressure cooker.

I was wondering about some concentrating solar solution??? Some Fresnel lens video's are straight out scary.

Any ideas come to mind??

What is the substrate ?

I'm not sure where you are, but it would take a lot of solar reflector area to gather that much heat. Check out solar cooking ovens. Personally, I would think about something more similar to a rocket stove, pottery kiln, or charcoal retort ran at much lower temps.

Substrate is the media in which the mushroom mycellia grow and expand. Mushies are classified according to the substrate they grow on. Lignim (wood) or cellulose (plant).

I'm in THAILAND. Rice straw is used for cellulose, it is bulky and freely obtainable. In fact it is BURNED as a perceived problem causing some of the pollution that right now - as I type - limits visibility to about 800 meters. It is my choice of substrate - I'm surrounded by it, might as well do something with it. Grow food and reduce pollution in one go - AND make compost from the spent substrate. Some experimentation has revealed ANY organic matter is good for some mushroom species - bamboo leaves - very think on the ground under groves, corn cobs insides after the corn kernels have been removed. Lots of waste stream sources.

In effect heating at least 200 litres of water is required. Possibly up to 400 litres depending on quantity of substrate to be processed.

BURNING as explained in the OP is what I don't want to do. However i may be forced to .... I can pre-heat just in a simple glass encased black poly tube up to 50c ... from there to 90c will take more energy perhaps from charcoal as suggested. 5 hours is untenable with an open burn - tending a fire that long is not on. However insulating and using electricity on a thermostat may be viable to maintain the temperature.

I did have an interest in using Fresnel lens as concentrator - and accept that it would need to be repositioned every half hour to maximise effectiveness. Perhaps it could be a supplemental heat source using just a little electricity to top up and keep constant.

Your ideas are welcome.

If pollution is your only objection to burning, you can use gas from some source such as syngas or other biogas or more obviously natural gas or propane or just burn wood or straw or even manure. If you have dry wood or other stuff, it is possible just with basic materials to make a stove that is essentially pollution free except for carbon dioxide.

It doesn't sound like what you are looking for, but one could also make a biochar retort using the heat for your purposes and then keep the charcoal for cooking or biochar soil applications.

For solar, you are going to need a really large reflector oven of some sort and plenty of sunshine. There just aren't that many BTUs in a given area of sunlight to heat that much material without a LOT of batches or a really large system.

I haven't done the math, but I'm thinking even with a system the size of the side of a house, it would probably take more batches than most people would want to do.

To produce steam in a solar system (DONT DO THIS, STEAM IS TRULY DANGEROUS), you would need something like a long trough reflector with a copper pipe in the middle. It would need to be able to change focus with the seasons, but wouldn't necessarily have to be on tracking throughout the day. A fresnel lens can certainly get very hot, but would cost a lot more and requires fairly precise tracking throughout the day, and you would almost certainly want an array of lenses.

I like the purpose of your post and the idea. I would think that this would be a perfect candidate for the Jean Pain, heat by compost method of pasterization at 160 to 185 for an hour. Surely it's already hot there, getting to that temp shouldn't be hard, and you often get a steady heat that could work that way. Whaddya think?
John S
PDX OR

Do you really need 90'c - 195'f for 5 hours?

This PDF has a much shorter, lower temperature recommendation.

"... heating water to 60°C in a volume approximately equal to the volume of dry field waste-substrate to be pasteurized.
When the temperature is reached, the dry field waste-substrate is added to the water. It is desirable to have the
field waste-substrate in a wire or fabric mesh container, so that the water may easily mix with the substrate when
it is put into the hot water and can be easily drained when the pasteurization is completed (Figure 2). The substrate
is held in the water for 30 to 60 min, while the water is maintained at 60 ± 3°C. Then the substrate is drained
and allowed to cool slowly for 16 to 20 h."

Great article and great post. I never suggested that hot. I have used the traditional 160 to 180 F for one hour for pasteurization. This is even a lower temp. It seems to be about 140 F. I often use a slow cool down procedure like they talked about here, and I figure the Jean Pain method would work well for that. With a compost heap, you can control how hot it gets by how you're adding the green stuff to the brown stuff. You can also use a thermometer.
John S
PDX OR

Milo thank you VERY much. I was ignorant of the difference between pasteurization and sterilization - well I know my vasectomy was not pasteurization !! And a great many other things this article makes clear. This is a great article. If you able to offer more assistance in this regard I would really appreciate it.

As you'd be aware there are STERILIZATION needs. The agar containing bottles - here in Thailand we use flat (hip flask style) whisky and brandy bottles (hic!) I have been taught that these do need sterilizing and I was planning to use a regular autoclave (as used by my teacher) for this. My education to this point has suggested autoclaving, but I am open to other suggestions including alcohol rinse, ammonia, even holding over a bunsen burner, or using some other system. The autoclave is a bit of capital expense - and since labour here is inexpensive, some form of human delivered sterilization is possible.

We have other needs - casing material - if used needs to be bug controlled - not sure about sterilised - and not sure if pasteurization is enough. Also we use grain - sorghum - for spawning and it needs to be treated. My education has been that this needs autoclaving.

My objective is to reduce the use of heat as much as possible - or supply it from re-usable means. I have thought about using a bio-digester to turn the spent substrate into methane for use in the process. I'm guessing that might not be the best use of some pretty good material which otherwise I was planning to amend, bag it and sell it. Low demand here, but not NO demand.

I'd be very happy to correspond privately, with you or others who might be interested - not sure about the rules for giving email addresses here so will leave it to you to contact me privately.