* Active flow-circulation induced by air alone; 6.3 gallons/minute
* Efficient gas exchange system for excellent dissolved oxygen maintenance
* Works with or without an extractor bag (extractor unit included)
* Two different ways to configure apparatus
* Translucent barrel promotes the growth of phototrophic microorganisms
* 3.5 CFM diaphragm air pump with 1 year warranty
* Can be dismantled and cleaned in under 40 minutes, including the barrel
* Sturdy parts used in manufacture
* Specially designed machine slotted PVC diffusers
* Operational instruction on DVD included
* Inexpensive; $545.00 USD without barrel
As of 2007, I am taking orders for the 50 Gallon Microbulator compost tea brewer or as I affectionately call it, a microbe extractor and multiplier (bioreactor). One of my largest obstacles in getting to this point was deciding on a price. My goal from the beginning was to provide an affordable, efficient device geared to the small farmer/grower who doesn’t need the fancy looking brewer, just one that works and is easily cleaned. During the end phase of development and testing I discovered that my device would not work in just any shape of tank so be sure you use a 55 gallon (US) barrel of the correct dimensions. I will provide barrel specs with purchase. I have kept my overall mark-up lower than the norm resulting in a price much lower than similar sized commercial brewers. My price is $545.00 USD without barrel. Other similar sized brewers on the market are much more expensive. Compare for yourself. People deciding to provide their own container will need to ensure the correct dimensions. These barrels are easily found in all localities.
The Microbulator 50 works with or without an extractor bag. That decision is the owner’s, based on the planned uses, application method and coarseness of the compost used.
Now, how does this work and what makes it different than other commercial brewers on the market?
My design, unlike other commercial brewers I have seen, does not just blow air into water or into the extractor bag but actively circulates the water while charging it with oxygen. This is done using only an air pump. No water pump is involved. This is accomplished by a diffuser housing fixture I designed and built which incorporates the diffuser inside an 1 ½ inch PVC pipe [1.25 inch industry size]. The whole 50 gallons of water is cycled through this pipe every 8 minutes at a measured flow rate of at least 6.3 gallons per minute. The water is drawn from two opposing sides of the bottom of the tank, pushed past the diffuser, while being injected with O2, up the pipe and through the return nozzle suspended about 2 to 5 inches above the water’s surface, falling back into the liquid, pushing O2 into the water by breaking the surface tension barrier, facilitating the release of CO2 from the tank and the absorption of O2 (gas exchange). This is not unlike the action of a waterfall or flow form. This action pushes the oxygenated water into the body of water further raising the dissolved oxygen content. Because the water intake openings are located at opposing sides at the bottom of the barrel, a current-like flow is created and maintained so any still areas of water are highly unlikely. The release of CO2 is essential to create space in water for the absorption of dissolved oxygen and the only way for CO2 to be released in a CT brewer is through the surface. At the same time a large slotted PVC diffuser is infusing the whole body of water with air. Oxygen is absorbed by the interface of the bubbles created on the way to the surface and the surface tension barrier is broken again by the bubble turbulence, allowing the further release of carbon dioxide and the maintenance of dissolved oxygen. By this means, there are three interfaces where O2 is being injected into the water or compost tea.
This highly efficient yet very simple method is generally able to raise and maintain the dissolved oxygen (DO2) content of fresh well water having a TDS/EC of 21 to 30 PPM and temperature of 18 C to 21 C (65 F – 70 F) at least 3 PPM (parts per million) above the natural DO2. Using the same water within the same temperature range, with; 4% compost/vermicompost, 0.75% black strap molasses, 0.25% kelp meal and 0.063% fish hydrolysate, the DO2 is maintained at 8.8 to 9.8 PPM up to a 48 hour brew time. Please note that these are maximum amounts of compost inputs and not recommended for people brewing without microscopes.
The circulating action, the force of impact with the water’s surface along with the air from diffusers provides sufficient agitation to break the microbes loose from their binding spots in the compost. The continuous flow provides a more homogeneous dispersal of oxygen and microbes, avoiding still water areas where potential undesired microbial life may develop. Once free swimming or bound to smaller particles, the bacteria, archaea, yeast cells and fungal hyphae graze on the feed supplied and multiply or grow.
Maintaining a reasonably high rate of dissolved oxygen in the body of water is essential to the device’s efficiency for extracting and multiplying the beneficial aerobic microbes, consisting of; archaea, bacteria, fungal hyphae, flagellates, amoebae, some ciliates, yeast cells and yeast fungal hyphae. Because of the constant cycling, microbes are fairly evenly distributed throughout the tank. To get a sample, simply hold a container under the return nozzle.
With Extractor Unit;
The Microbulator can be used in free suspension or with mesh extractor bag configurations. A specifically designed diffuser is used in the bag while the internal diffuser continues circulating the water/tea breaking the surface tension. Both configurations are good for multi-purpose compost tea but using the extractor radically reduces particulate matter in the tea and is good to use for foliar disease suppression. The extractor should be used if you are using coarse compost with pieces between 1/2 inch and 1 inch cubed.
The highest microbial numbers are going to be developed using the device configured for the compost placed in free suspension but if one requires the extractor for a reduction in particulate matter this configuration provides a comparative alternative.
On the farm we usually use the Microbulator 50 without the extractor, remove the apparatus once the brew is complete, allowing the particles to settle to the bottom, lower in a submersible pump just above the level of the spent compost/particles and pump out the clearer compost tea. Alternatively one can place the pump in a mesh bag (fly screen size) and drop it in or simply scoop out the compost tea with a pail or watering can. Afterwards dump out the thick leftover slurry onto your soil or compost pile. If you are using vermicompost any worm eggs/capsules/cases remaining will still hatch once in the soil or in a non-hot compost pile.
What did you use and why?
Pump: I settled on the Eco Plus Commercial diaphragm operated air pump. I was first using the Hailea 9730 (rated at 60 LPM) but the air flow was just not strong enough to support 50 gallons of compost tea and it is only warrantied for 6 months. The Eco Plus puts out a whopping 3.4 to 3.6 CFM (<>100 LPM) configured the way we use it. The flow on each pump is tested with our flow meter prior to being shipped. On top of this the pump is warrantied for one year and replacement parts are available if it does quit. It is a little noisier (the price of power) and because it is lighter it wants to vibrate around. To cease the wandering and help with the noise I’ve included a little rubber damper mat with each kit.
IMPORTANT NOTE: I did not use a check valve for the pump because it prohibits air flow so the pump must be placed above or at the same level of the water surface to prevent back flow if there is a power outage or the pump is turned off.
The Air Tubing; The air tubing is heavy duty 7/8 inch braid reinforced clear vinyl. I tried the regular clear stuff but it kinked too much and wore quickly. Each kit includes enough tubing for the device to insert into the barrel plus 6 feet for lead to the pump. You can decide where to place the pump and trim the excess accordingly. Remember the pump must be above or at the same level of the water surface.
Clamps: We have, as of January 2009, started using stainless steel pinch clamps permanently affixed, combined with stainless steel gear clamps.
Air Control Valve; I used a brass plumbing valve to control the air flow between the large diffuser and return flow nozzle. I tried cheaper plastic valves but they didn’t cut it.
Piping; I decided on PVC pipe because it is inexpensive, easy to clean, can be fitted together without glue in low pressure applications like this or can be glued when necessary (as are a few of the pieces). I am using 1 ¼ inch diameter pipe because it is the right size to accommodate the flow needed for the 50 gallon brewer. One small disadvantage is that sometimes when disassembling one must use pliers or vice grips to pull apart a pipe and fitting. NOTE; The industry sizing of the pipe is 1 1/4 inch but the actual diameter is 1 1/2 inches.
Diffusers; As of January 2009, I am using only, machine slotted PVC diffusers which I designed and get cut at a machine shop. Many of you will know that I wanted to stop using the glass bonded stone type diffusers because the muriatic acid used to clean them is not environmentally friendly. Via research over the winter I succeeded, by altering the depth of the slots and lengthening the large diffuser, in improving the PVC diffusers so as to match the dissolved oxygen maintenance of the glass bonded diffusers. The slots are 254 microns in width. There are three of these diffusers included with the brewer.
Brass Fittings: We use brass fittings throughout, where applicable for purposes of longevity and quality. Where the brass must be adhered to PVC we have used a high grade non toxic epoxy.
Barrel: As mentioned previously please check with me for barrel dimensions and potential sources. I use a translucent barrel, as I believe this encourages the growth of phototrophic microorganisms.
Extractor; The extractor bag we are using is 400 microns mesh size, 24 inches long and 7 inches in diameter. There is a stainless steel supportive ring sewn into the top and a rubberized poly cap, with an entry hole for the diffuser. The unit is hung over the PVC pipe with nylon line. Replacement bags will be around twelve bucks. I tested many sizes of mesh prior to choosing 400 microns. I tried 200, 250, 300, 400, 800, 1000 microns mesh sizes.
Bungee Cord; A rubber bungee cord is included which holds the unit in place and prevents floating, as it is filled with air charged water. The hooks are the perfect size to secure the positioning of the control valve and large diffuser. This beats trying to use weights inside the tank.
Ongoing Improvements; As occurred with the slotted diffusers, I will endeavor to apply improvements in structure or function which are discovered. I am planning on getting a custom seamless extractor bag in future.
How about cleaning?
The whole unit can be dismantled and cleaned in under twenty minutes. Add ten minutes if you use the bag and another ten for the barrel. The unit should be removed from the compost tea while still pumping air for best results. This prevents back-flow into the diffusers and into the air tubing. While pumping air, particles and bacteria will have a more difficult time entering the air system. The whole unit then pulls apart and can be cleaned quickly with fresh water, a scrub brush or pad and a bottle/pipe cleaner (available at Wal Mart, etc.) If you clean the unit right after use, generally you can use water alone but occasionally you may wish to use hydrogen peroxide or bleach. It is not advised to use bleach on the extractor bag but you may use it on the pipe and tubing. You should not need to clean the inside of the air tubing if you prevent back-flow. The extractor bag should be flushed under fresh water immediately following use and can be hand washed using a peroxide product like Oxy-clean.
What about brew times?
Brew times are 24 hours using Keep It Simple, custom made Pro Kit for the Microbulator.
I am confident that the Microbulator 50 will match or surpass any other commercial brewer as far as production of numbers and diversity of microbes and DO2 maintenance, given equal parameters of water, temperature, compost, foodstock and time. It is very important to be aware that you need good quality compost/vermicompost and feedstock to get good quality compost tea. Temperature and water quality must also be considered. Really, there can be so many variables and the best way to know at what hour your microbes are at the optimum level is by microscopic examination.