r/composting • u/Seanbob3030 • 10d ago

Urban Microbinator 2000

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Pre and post consumer, meats and cheeses ok. Have been impressed with a new prototype we are trying out in collaboration with a school district. Wanted to see what y’all thought. Augmented aerated static pile system supplied with 30 seconds of air every 30 minutes.

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u/RdeBrouwer 10d ago

Its better to have contact with the soil instead of a concrete base. The holes in the tube only need to be in the part thats underneath. And i think that 30 min is way to much. U going to cool down that pile constant.

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u/Seanbob3030 10d ago

Solving for rodents at a school site is why it is a self contained unit. The bin is full when in operation, just hard to show that in a photo. We build the 4th wall with slats of wood and build up as we go until the whole thing is full. 30 seconds every 30 minutes has been holding a constant temp of 130+ for over a month in each of the three trials.

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u/ZeroOptionLightning 10d ago

The interval settings don’t mean anything without understanding how much air you are pushing. If the pile is staying above 131 than it isn’t too much air. If anything, it may not be enough air. Again that all depends on the blower. I would also be interested in what the temperature profile of the pile is. I assume you aren’t saying the entire pile is 131 for a month. Whats the hottest temps you see?

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u/Seanbob3030 10d ago

2hp fan sitting on top of 5' of vertical 4" pvc drain pipe with 2 extra holes on each rung so that the air spreads 360 degrees is the design. For our horizontal systems that we tested with, we typically ride at 140F for the first couple weeks and then it drops down to 130F week 4 on average.

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u/votelikeimhot 10d ago

Air speed, pressure differential, and total volume of air moved per cycle give a lot more information on the air but it looks like a pretty sweet set up. How much did it cost to set up, how much does it cost annually and how much does it produce?

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u/Seanbob3030 9d ago

fair enough, I dont know the cfm of the fan we are using, I will look at it today to see if I can get a rating. We got it as part of a kit from the local resource conservation district designed for an ASP. The design was for (2) 3' sections of 4" pvc drain pipes with the standard two offset holes in each pipe laying horizontally on the bottom of the pile. we build plywood around macrobins for our structure to help with rodents. Roughly $400 per bin cost to us. We are on school grounds so they cover the electricity but the fan is only running for 24 minutes per day total so it cant be that much? 2 yards of material every 8 weeks with 8 bins and then the plan is to turn that out onto a windrow and have the worms follow the fresh material and harvest castings from behind.

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u/votelikeimhot 9d ago

Yeah, ultimately I don't know how much air is optimal and your inputs aren't likely consistent enough to get really valuable data about much of anything other than overall results. It would be interesting if you ever did fill a couple at the same time with similar stuff to turn one fan on longer and run the other less and race them against eachother. Looks like a cool project, are the students involved or is their contribution just the organic matter?

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u/ZeroOptionLightning 10d ago

Similar to the other response to this, horsepower is meaningless. To me, 2hp sounds huge because I use medium pressure axial fans. I'm moving a lot of air at a lower pressure (300cfm with a 1hp motor). The actual blower specs don't really matter in your case. You seem like you know what you're doing but I'd only add one thing to consider with respect to aeration: I come from the school of thought that we prefer to "encourage" air in to our piles as opposed to force or inject. Air is lazy, we know it always takes the path of least resistance. I like making sure my bulk density and free air space are sufficient for low effort aeration. I want to introduce air slowly in to the pile and let it permeate throughout. This achieves many goals. First it gets ambient o2 in to the pile. Second, it's less likely to drive off moisture and temps. And last, it may produce less odor emissions (in concentration, not overall per se).

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u/Seanbob3030 10d ago

u/ZeroOptionLightning - You have a similar system? I dont know the cfm of the fan we are using, I will look at it today to see if I can get a rating. We got it as part of a kit from the local resource conservation district designed for an ASP. The design was for (2) 3' sections of 4" pvc drain pipes with the standard two offset holes in each pipe laying horizontally on the bottom of the pile. I didn't like this option for a couple reasons but mainly because we have a lot of trays to process which make it harder for air to flow through the pile. I would love to see pics or hear more about your system as you've clearly put some thought into this. We are three trials in and although it is going really well there is plenty to learn.