Hand powered grinder for homebiogas setup?

I just got a homebiogas setup and I heard that the more surface area that the stuff you are putting in has the easier it is on the bacteria? (and the more gas they produce)
I was looking for something that was hand cranked and had an opening big enough that I could just dump stuff in there and crank it directly into the tank?
A meat grinder was the first thing that came to mind but the opening is a bit small and I spent half my time trying to stuff the scraps into it so that wasn't working.
I am hoping there is *something* out there that can be hand powered, coarsely (or fine but course is ok) grind up table scraps, grass clippings, weeds etc, wont rust too badly, etc etc etc
ideas? please!

heya Reid,

I wanted a home blender without buying  a huge solar system to support the blender motor and this is the solution I found:

fairly clear instructions for a bicycle powered blender

here's another made from an exercise bike

I have this idea you can put the blender for the biogas digester under the kitchen sink counter with a 4" to 6" lid on it which feeds the blender from the top of the kitchen sink counter.

This would give you a pedal powered garbage disposal unit which feeds directly into your biogas digester.

 What I haven't figured out is the gears and pulleys needed to attach to the pedal power machine which I would want to store after running the blender.

Post pics if you actually build one!

How about something like this?

Reid O'landers wrote:I was looking for something that was hand cranked

We tried the grinder direct to the feed input with an Insinkerator on our Solar Cities style digester.  It worked well but it was difficult to get the mixtures right.  Ended up over feeding the digester and it went acidic a few times.

In the end we went back to feed-stock prep into a bucket first.  I redesigned our Insinkerator to circulate the feedstock through a bucket hopper for multiple grinds before it is drained into another bucket for feeding.   That is very accurate and works well for us.


I gave our first IBC digester to the extended family.  I also gave them a vintage salad shredder I had gathering dust on the shelf.  I've attached a photo.  

These are pretty common.  There are a few listings on ebay as we speak.

They attached it to a funnel that feeds a bucket.  Then added a longer crank arm and a 10 lb weight as a flywheel.


Hope this helps.

I can see making an upsized DIY version of that salad shredder.
A stainless steel bain marie perforated with a drill or angle grinder could be mated to a small rear bicycle wheel.
Add weight to the wheel by casting cement inbetween the spokes.
Drive the wheels cogset with a chain connected to a crankset.
A sheet metal lined plywood chute would feed the  matter into the grinding drum.

Hi Thanks All, the feedback is really appreciated.
I found this https://www.thingiverse.com/thing:356580/comments which seems to be the closest to what i was looking for, I am really paranoid about over feeding my biodigester so might get back to you all about that.
I might try ordering the 3d setup with metal gears (instead of the plastic ones in the origonal design) and a hopper with a flywheel crank and see how that does.
About doing it directly into the digestor, the homebiogas folks say about 1.5 kg/3lbs per day is the max, my family actually doesnt produce much compost on a daily basis but we have some fruit trees and i was thinking about weeds as well, so slightly separate question, as we have more fruit than we can ever use (eat/can/juice) does it make sense to say just fill a barrel up with rotten fruit/weeds that we get in one part of the year and slowly feed those into the digestor along with the food scraps? or is partially rotten stuff going to be not worth it?

Reid O'landers wrote:my family actually doesnt produce much compost on a daily basis but we have some fruit trees and i was thinking about weeds as well, so slightly separate question, as we have more fruit than we can ever use (eat/can/juice) does it make sense to say just fill a barrel up with rotten fruit/weeds that we get in one part of the year and slowly feed those into the digestor along with the food scraps? or is partially rotten stuff going to be not worth it?

That looks like a good grinder.  

We have a "pre-soak" drum that we stage our feedstocks in.  It can get kinda smelly and attracts mosquito's, bugs, and especially ants.  Design accordingly.    That being said fermenting before grinding/feeding only helps in our experience.

However .........  

We tried grass/weed/garden waste.  That stuff produces a lot of gas and fertilizer.  But it floats and plugs things up.  It also does not easily digest and will, over the course of time, fill up the digester.  

We ended up adopting a nutrient leeching technique to allow us to use our cellulose/lignin heavy waste resources.  Here is a link to the original paper.

https://universe.bits-pilani.ac.in/uploads/PSG%20Handouts/VFA.pdf

If you are interested I can share what we have done with digesting this material.


Hope this helps.

Mark,  that process seems really interesting.
Was the acid bath/de-ionizing water/filter paper cleaning of the plant material part of of the process in your set up?
It seems very resource intensive.

William Bronson wrote:Was the acid bath/de-ionizing water/filter paper cleaning of the plant material part of of the process in your set up?

No.  I interpreted that to be part of the lab process to minimize variability in the testing environment.