Enviromix Biomix

The plant I currently operate converted to a two stage EBNR process from a traditional activated sludge process. Instead of opting for the standard mechanical mixers in the anaerobic and anoxic zones, the decision was made to use the Enviromix Biomix compressed air system. I wasn’t at the facility at the time so I had no choice in the matter, but I have to say that after operating the system for over two years it really proved to be a good design choice. There are a lot of reasons for that. Traditional mechanical mixers can be a challenging maintenance problem, especially in aeration tanks that often require long shafts to accomplish the mixing. Bearings go bad, motors need to be replaced, and the list goes on and on. The Enviromix Biomix compressed gas system eliminates a lot of those issues. This system uses a compressor to send air to a fixed header near the bottom of the aeration tank. The air flows through nozzles that create large bubbles that mix the anaerobic and anoxic zones. You can adjust the pulses and other settings via the Zombie Valve Module (I have no clue why its named that, but hey, marketing). It also has the capabilities to tie back to a SCADA system to control remotely if you wish. Obviously, since this is the anaerobic and anoxic zones of the process you don’t want this sending so much D.O into the system it hinders the process. I can say that it does not even on the default settings. You can observe how large the bubbles are and how well it mixes in the video below. If you are really concerned about it, using an ORP probe or monitoring the D.O would be an easy process control measure to make sure you’re actually in the ranges you desire.

Since we eliminated motors, bearings, and shafts, what is the biggest maintenance item of the entire system? The compressor. Ours is an Atlas Copco and it has ran pretty much just like any other compressor I’ve ever dealt with. The biggest issue we have had so far is the unit over heating and that was due to us not cleaning the room enough (if you didn’t know, spiders and bugs reallllllly love wastewater plants) and radiator of the compressor itself. Once we cleaned the entire room and the housing of the compressor, it hasn’t overheated since. This unit is on an annual maintenance plan with a company that specializes in compressors and after the first annual maintenance, there was an oil leak. This led to some rather frustrating back and forth with that company (not Atlas Copco or Enviromix), and we finally got every thing resolved. It has been running well since and I don’t foresee many more issues with this compressor. Another area of note for maintenance are the headers in the aeration tanks. The fixed header near the bottom of the tank has nozzles designed to create large bubbles. As of this writing, I’ve never had an issue with them clogging. The pulses look exactly the same as when the system was started over two years ago. Once we drain the tanks a simple inspection is all it takes to see if there is any need to replace the nozzles.

Overall if you’re looking for more control in your mixing then this is definitely an option for you. If you’re looking for less maintenance than traditional mechanical mixers, this solves that as well. There is virtually no maintenance other than the compressor and maybe cleaning the tank that is being mixed. I am overall very impressed with this system and how it can help BNR process. I also believe this could be used in other areas and processes of that plant. Anywhere you need mixing, I think this system could be utilized. Lastly, I sat through a presentation a year or so ago from Enviromix on how they had some data that indicated by modifying the pulsing schedule you can create a fermentation zone in the anaerobic zone itself, potentially eliminating the need for a separate tank like at my facility. Food for thought.