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Super small scale to just small scale

I currently have a 10 tray system in my basement, enclosed in a (roughly) 2' x 3' deep by 8' tall enclosure. I want to scale up my production. My plan is to build an insulated room in my outdoor 20' x 30' shed. I'm curious if there is any literature about this scale, maybe a 10' x 15' x 8' tall room - how to ventilate, what type of HVAC system would work best, how to stack the trays for optimal production within a given space (like rolling shelves or racks??), air movement requirements, types of doors that work best to keep the internal temp normalized and pests out, that sort of thing?


  • Hi oskizzle, - In regards to outside air exchange HEPA filters (0.3 micro-meter) keep air contamination to no more than 10,000 particles/cubic meter (maximum 1% contamination). This would be the type of filter a "clean room" uses & you do not need that kind of facility.

    An alternative for outside air exchange is the furnace filter, which keep out 100,000 particles/cubic meter. Am on tablet now & when get chance will try to link way to determine fan size for room size.

    Oxygen O2 diffuses in 25°C air at the rate of 0.205 square cm/sec., normally air is 21% oxygen (by volume.. While in water O2 diffuses 0.000024 square cm/sec. at 25°C, and then too as temperature goes up the amount of dissolved oxygen goes down.

    I think you may be planning on increasing relative humidity (water vapor in gas atmosphere) in the entire room & so suggest you give yourself working access to the air blower of your build in case want to upgrade (air filter access should permit changing too). There are small air flow meters (anemometer) that would allow you to measure local air velocity sold at places lijeceBay. Avoid the dew point where get condensation on bin sides or surface above (develops on whichever surface is relatively cooler).

    Oxygen saturation at any one bin of bugs is going to be a function of partial pressure concentration of gases & local surface to volume ratio (increasing the depth of bin substrate/feed in relation to the width/diameter of bin substrate/feed decreases oxygen diffusion). If loosely lay a top of something impervious on a bin then it's air exchange might be 0.1 times - 1.0 changes/hour; whereas micro-porous coverings can give you 6 air changes/hr.

    Energy synthesis from sugar (glucose) that many insects derive from their feed carbohydrates can be processed into pyruvic acid (pyruvate) without oxygen via (an-aerobic) glyco-lysis; & that pyruvate passed to the "Kreb's" cycle (also known as the tri-carboxylic acid, or TCA cycle). It is in Kreb's process that oxygen is used to "oxidize" intermediate molecules transitorilly made from ingested carbohydrate carbon; which creates metabolic CO2. (((There are small CO2 meters to monitor the air in spots like different bug bins, which are usually cheaper than oxygen meters; you need to do a reverse calculation to estimate air O2 content air with over 400 ppm CO2 will usually have proportionately less than 21% O2. Changing levels of CO2 in the head space above bugs is used to measure how well they are metabolizing different kinds of feeds, since the more CO2 they put out the more carbon feed conversion efficiency was.))

    At the same time, as those Kreb's cycling intermediate carbon based molecules are "oxidized" they donate electrons that get passed in a series of carriers leading to oxygen O2 eventually losing an electron; then as a consequence an O2 that lost an electron ("reduced") can bond with hydrogen to become internal H2O (water). If there is simply too low oxygen this limits Kreb's cycling, pyruvate is broken down (de-carboxyl-ated) & also the bug would generate less internal water ((they can dry up then without external source of moisture since de-carboxy-lated pyruvate can be converted into acetaldehyde which, if itself "reduced", can provide a fermentable molecule that is also dessicating)).

  • Meant to add some other things. The air intake should not be situated low toward the floor. Inside leave a space between the bottom of your bug bins and the floor so you can routinely sanitize the room easier (avoid just stirring up what is on the floor by sweeping). Only bring disinfected feed ingredients into the bug room as one preventative strategy against pathogen related losses.

  • I will need to have higher humidity and temperature, I'm raising mealworms...totally missed putting that in my original post.

  • Hi oskuzzle, - Interior rooms used for different purposes need different rates of air changes per hour. Since rearing insects are concentrated populations actively metabolizing a good guide would be industry practise for poultry & swine houses.

    This is 6 - 10 air exchanges per hour. Your finished 10 x 15 x 8 enclosed space = 1,200 cubic feet (34 cubic meters). For getting an idea of this kind if air supply figure a public waiting room averages 4 air exchanges/hr. & retail shopping stores average 6 -10 air exchanges/hr.

    To get 6 air changes/hr. in that space you suggested you need to bring in outside air at the rate of 120 cubic feet air/min. (7,200 cubic feet/hour); & to get 10 air exchanges/hr. you need to bring in air at the rate of 200 cubic feet air/min. (12,000 cubic feet/hr.) The capacity of some kinds of fans/blowers to move a volume of air are listed by some manufacturers.

    I am skipping converting this into metric system numbers, as well as for any other # of air changes & those corresponding blower/fan capacity; & for that matter any other room area. These can be determined by using the formula I used to generate the above reference points. To determine how much air (cubic feet of air) one needs to move in from outside multiply the total cubic area of the interior space (cubic feet or cubic meters) by the number of air exchanges you want to give that interior space per hour.

    I raise mealworm larvae in racked tiers of grow bags suspended in a plastic under bed style rectangular bin (pictures elsewhere in Forum) when stand in front of the rack I am about 3 feet in total from the wall. Once I remove or install a bin onto a rack I need more depth away from the wall to perform my maneuvering.

    If these were "rolling" shelves I would still need to take up more floor space once am moving & would not have the degree of flexibility to maneuver bug load in tight spaces. Wheeled shelves would need big wheels to roll easily once loaded & reliable frames for those wheels; the wheels (& chassis) would probably be annoying to try & clean.

    My inclination would be to set racks in tiers along your 15 foot wall & on the opposite wall give yourself a work surface, breeding niche, egg/tiny larvae staging area. This way you can pivot from one side to the other & man handle operating bins around, etc.

    As for door, try to have it open outward if not concerned delinquents would pull the hinge pins out. A hermetic sealing door is probably not necessary, afix flexible plastic weather stripping pre- mounted on aluminum strips on edges to keep infiltrator bugs out & narrow adhesive backed roll of home window weather proofing foam where the door seats into it's frame. Those kind of attatchments are commonly available in hardware sections.

  • Great ideas gringojay.

    For the racks/tubs, I had a thought last night - I'm currently wasting space with my existing bins. They are 6" tall, but I'm only using 3" of it for substrate and probably only need an inch to maintain containment of the mealworms/beetles. This means I'm getting less tubs/bins in the space I have available.

    Is there any other option out there, as far as tubs like this, that are shorter but just as cost effective?

    I will explore the bag option in the future (I know there are tons of posts here about it), but for now am sticking with tubs.

  • Again oskizzle, - You may be interested in looking at Forum thread titled "Commercial Insect Farming". The 8th comment down has pictures of my array for mealworms, it uses re-purposed stuff I had laying around so is not maximizing it's utilized space like you intend.

    What I want to direct your attention to is the 6th picture down, which shows mealworms "wandering" up & out of their bran. The Forum search box function can bring up more if input the word "wandering."

    Since you are designing a mealworm project read the 2nd comment in that thread. It has a suggestion you may find worth experimenting with - namely, how to get clean larvae that are done growing just before they pupate & leave those not ready yet more time in their feed (I use wheat bran & spent carrot pulp).

    Most people either saw pictures of hobbyist mealworm bins or commercial operations modular unit stacks; which have smooth sides. The TinyFarm mesh grow bag reveals the last instar mealworm larvae will climb up a textured surface (like the well touted "self-harvesting" black soldier fly larvae).

    As far as whether my 2nd comment suggestion is workable (desirability issue was raised by EntoJesse) in your proposed modular unit stacking of bins I can not say, because have never played with a design that became an experimental set-up. Still, I am making this comment since you are considering investing in different depth bins.

    Square (-ish) bins don't let the mealworm larvae "wander" somewhere. My under bed product bins are not particularly shallower than yours but I think the rectangular shape would be easier for side placement of something (ramp) giving them an incline to blunder into as they wander & leave their bedding (black soldier fly larvae pull themselves up inclines with a mouth part & presumably this is how grow bag raised mealworm larvae haul themselves up on mesh).

  • My wandering black soldier fly go up a 12 inch long ramp that rises 8 inches upward over the course of 9 inches horizontally. For shallower mealworm bins (which affords less amount of total rise possible) you can recreate the angle of incline to fit the course (afford a greater total horizontal distance) by using a longer ramp leading from the feed surface to get out.

    Where the incline ramp ends have someplace for the wandering larvae to go or even drop of the edge (black soldier fly larvae do) & fall into. This probably could be a narrownplastic container with smooth sides hung inside the bin by hooking it over the bin rim; the collection container(s) should be easily removed for dumping out the larvae before the pupate. Alternatively, a few PVC plastic angled elbows could be rigged to catch the larvae coming off the up-ramp & directed to a collection container on the outside of the rearing bin they were in.

    Again, this is conceptual so before anybody builds a project instalation arund it I suggest making an experimental proto-type. For large scale production mesh grow bags are probably too time consuming because, although larvae wander up out of their feed, culling only those is impractical. Issues range from tight access, non-rigidity when handling fabric & tenacious larval hold on mesh (which may mean when design a self-harvesting ramp not using meshed fabric, instead something like "fine" grit sanding paper stuck on rigid length of ramp piece all the way up).

  • Maybe once my business is running smoothly I'll experiment with other ways of sorting. For now, I use a weekly rotation process that results in similar sized worms. Then, I have a 'shake-n-filter' system based on this:

    It very quickly sifts the frass/substrate and leaves the worms. I also use this for the beetle tray when rotating my trays/bins each week. It is very quick, different sized mesh for the various needs (beetles vs mealworms vs frass filtering).

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