Autrotrophic Sulfur Denitrification

[olinf]

I was wondering if anyone has used an ASD device in practice in their tanks? I don't have the guts to try one in one of my reef tanks, but I was considering trying one in my live rock growout tanks. I built a modified version of the device described in the Dec. 2000 FAMA. Rather than the 3 chamber unit described, I used a tall piece of 3"PVC filled at the bottom with 5kg of sugar sized aragonite (I felt this would help increase anaerobic conditions for better calcium dissolution while increasing surface area for sulfur adsorption as compared to the marble chips the author used). Above this is 5 kg of 2.5mm sulfur beads and on top of this is 2 kg of coarse aragonite which seems to be able to release the produced nitrogen gas just fine. It is fed with 7.5 liters/hr of water from the top. So far it is only hooked up in my lab, and I have been testing it's abiity to process water from my water changes. So far it looks good, it quickly lowers nitrates, and it's effluent contains undetectable levels of H2S, calcium at 450-480mg/L and a pH of 8.0-8.2. My primary concern is creation of bacterial exotoxins due to sulfur metabolism and sulfur saturation in the aragonite leading to H2S release into the tank water after time. Any thoughts?
Olin

 

[esmithiii]

What does kg mean? mm? 3"? Man we are confused in this country about measurements!

I would love to hear more about your experiment and how it turns out. What do you have in your LR grow out tanks?

E

 

[olinf]

Well, in my growout tanks are aquacultured live rocks that I use to supplement my research budget. I am trying to create a "plankton-friendly" environment in which veliger larvae from the housekeeping snails will have a chance to settle. This one of the reasons I am interested in the ASD system. Its low flow rate might allow for retention of larvae in the tank, especially if its intake has a large surface area micron screen. I want to create a system with minimal maintenance. The ASD costs much less than a calcium reactor or plenum, plus as a dorky microbiologist it's just fun to play with natural processes.
Olin

 

[danmhippo]

I have been thinking about the ASD and have asked Andy of Myreef to build a prototype for me. (I am not a DIY type of person..) So far......Well........

ANDY, Where the hell are you?????

My concern with your setup is
1. The sulfer particle may have a chance to seep through the lower chamber of aragnite and be released raw into the tank. Media mixing is adviced against in the article as well.

2. If you are using a PVC tube, how do you monitor the usage rate of the sulfer beads?

3. Do you let the effluent of the ASD goes directly to the holding tank, or to the sump. If I were you, I want to have an extra measure to make sure whatever comes out, does not goes directly to the main holding tank.

BTW, Good Job. I've always want to build one.

 

[Veng68]

Just curious....... where did you get the sulfur beads?

Cheers,
Veng68

 

[olinf]

Hippo,
Those are all very good points you brought up.
This unit that I built was just an experiment to see if the principles work, I threw it together out of materials I had on hand when I was bored waiting for another experiment to complete. When I try one in my tanks, I will likely incorporate many of the changes you suggested in a 2 or 3 chamber unit. At the moment, I am not overly concerned with sulfur particles reaching the tank water, given their relatively large size compared with the interstitial spaces in the well packed sugar sized aragonite, but this may be a factor in the future as they are consumed and lose mass. You are right, the rate of dissolution can't be monitored in the current system but the usage is likely very low. IMO, the aragonite would likely lose its capacity to adsorb the sulfides before the sulfur runs out which could be detected in the effluent water (a good reason for a sump). That is my current problem, how to build a sump while maintaining a plankton friendly system. Basically I am using 350 gallon tubs with airstone circulation. I am trying to minimize the use of traumatic pumps. My thoughts so far are that I could either use peristalsic pumps to drive the sump, or build the ASD so it sits on top of a sump which then sits on top of the tanks. The water from the ASD could feed the sump and have an overflow into the tubs? Perhaps fill the sump with live rock and Caulerpa to kind of buffer the water before it reaches the main tank? If nothing else the stuff in the sump would show signs of stress before the stuff in the main system if there was something wrong with the ASD since it would be fed with 100% ASD effluent. Any suggestions would be greatly appreciated.
Oh, by the way, the sulfur I bummed off a biochemist down the hall, but I know it is used in industry to make acid resistant concrete, so an industrial chemical supply house might have some cheap. I also remember seeing some at home depot a long time ago but I don't know what it was for, perhaps gardening?? VWR scientific www.vwrsp.com has reagent grade sulfur powder but it is VERY expensive, something like $36 for 500g and it is likely too fine for use in an ASD device.
Olin