Automatic Biomass Scrubber

[OzIA]

Fail

Fail

Well... The Bioreactor shut down last night about 2:00 AM. You can see the ORP graph attached.

The process pump circulates a batch of water and a dose of carbon through the reactor by pushing water from the reactor side to the inlet side; back into the reactor through the distribution pipe. My assumption was that I could stir the bioballs and keep that path clear but I failed to consider the distribution pipe. The distribution pipe became so clogged with biomass that the water level on the inlet side increased to the point where it reached the overflow port. This essentially drained the bioreactor below the ORP probe, so it stopped working.

I was able to run a brush through the clean out port, that I added last minute and the water levels quickly returned to start-up levels. However, this is far from "automatic" and for this to be required so soon, just a few weeks after start-up is a major set-back.

 

[OzIA]

Back up and running...

Back up and running...

I have been clearing the blockage every few days; when the water level in the inlet compartment rises about an inch above start-up levels. However, I noticed that the blockage was primarily at the entrance of the distribution pipe. There doesn't appear to be any down the length of the pipe nor in the smaller ¼ inch holes that are spaced throughout the pipe. I also noticed that there is a lot of biomass in the inlet chamber. Since this is where I inject the organic carbon dose, I have decided this may be an issue. I have relocated the injection port directly into the bio-reactor, where I have the ability to stir and hopefully control the buildup better. If I can go a few weeks with no increase in restriction, this problem may have been solved. In any event, I guess the experiment will continue, even if I have to manually clear the pipe once a week.

I have adjusted the stir to once a day and the flush cycle to once a week.

The exact carbon dose is critical. Too little will eventually stall the system, which will stop cycling regularly. Too much and the system will cycle too fast and the ORP will drop out of control. I believe this is what the folks at DyMiCo have figured out as their system self adjusts and takes the guesswork out of my manual, trial and error method.

This system does lower the pH so I am using Kalk in order to try and maintain a higher pH.

 

[OzIA]

Test

Test

As a test, I changed the carbon dose slightly from approx. 1.5ml to approx. 1.8 - 2.0 ml after each batch. The system was cycling pretty consistently at about 70 minutes, prior to the flush cycle, (the dip in the middle of the graph). After the change, the system moved to about 50 minutes per cycle. All the ORP targets (trigger points) remained the same. I am using a 10% vodka, 90% vinegar mix for the carbon dose.

 

[OzIA]

Update and observations 04/15/18

Update and observations 04/15/18

I removed the chaeto from that portion of the system about two weeks ago, primarily to see how well the ABS performs on it's own. Nitrate and phosphate did increase some. Nitrate is usually between 1 and 2 ppm. Phosphate is around 0.12 ppm.

I feel like the system is cycling well when it processes batches about twice an hour.

I was really impressed with how quickly pods populated the remote deep sand bed. I noticed them there within a day of turning the system on and they seemed to have reached a saturation point within a few weeks. I wish I could figure out a way to flush some of them back into the tank on a regular basis.

I went through a roll of felt, somewhat prematurely, because the float switch stuck on for about an hour and a half recently. I added some code to prevent that from happening again but the usage is even faster than I had calculated and would probably have only lasted me about 50 days.

Biomass still builds quickly in the inlet side of the reactor; much more quickly than in the reaction area, much to my dismay. The mass primarily builds near the output of the process pump, where the organic carbon rich water meets the higher oxygen levels. I continue to have to manually clear the inlet area to the distribution pipe a couple of times a week.

 

[OzIA]

Update Sept

Update Sept

The ABS has been running, mostly on it's own for the summer. I try to do as little as possible during the summer. I still have to manually clear the distribution pipe every 7 to 10 days.

The nitrate levels are steady at around 2.0 and phosphate has been around .12 every time I have checked it. Not ideal but it doesn't seem to be running away. I haven't used GFO or a skimmer since starting things up so I guess to some extent, it is working. No water changes.

The bacteria mat isn't forming in or on the bio-balls as much as I had hoped. Mostly, it forms in large chunks on the inlet side of the ABS. I am not sure why this happens. It may be related to flow or oxygen levels. The biomass started building right around the area where the process pump injects water into the DSB inlet side of the system and it continues to build there. Occasionally, chunks will break away and that is what ends up clogging the distribution pipe. If I had known this, I wouldn't have even used the bioballs. I've been thinking how I might change things this winter.

Still, the weekly stir process removes enough to keep the phosphate in check. There is no clogging buildup or dark stains in the remote sand bed.

I haven't used the chaeto refugium section, other than to throw a bag of activated carbon in every few weeks. I've been thinking about restarting that just to see what the impact is.

I use a liter of organic carbon (20% vodka and 80% vinegar) every three weeks. The ABS cycles about every 30 to 40 minutes. ORP bottoms out around 50mV and the system runs another batch of water through when I reach the trigger point at around -200mV.

I've been using kalkwasser instead of the calcium reactor in order to offset the already low pH coming out of the ABS. If I let it run on it's own, the pH will bounce between 7.8 at night and 8.0, during the day. With kalk, I get about 8.05 to 8.25 but I'm really close to the limit. I'm pumping over a gallon of solution per day, which is really close to the evaporation limit of the tank.

I've also been dosing strontium and Red Sea Trace Colors A, B, C and D with a dosing pump.

I'm going to take a water sample in the next few weeks and send it off for analysis soon. I will update once that info comes back.