Black spots inside Sulfur Denitrator?

[Exus]

I noticed that there are a couple of black spots on the sulfur pellets. I'm guessing that it's a bad thing, maybe deadspots? Is it a concern if it's just a few spots? No egg smell from the affluent.

I'm using a Georeef sulfur denitrator, it has a recirculating pump.

This reactor has been running for maybe 5-6 months now. My versa doser is running at 100ml/min. My nitrates are stable at 10-11ppm.

The affluent coming out of the reactor tested at 2.0ppm Nitrate today. About 2 months ago when I last tested, it was at 0.3ppm Nitrate.

 

[Randy Holmes-Farley Verified Community Expert]

You may have gotten some detritus into that area which is lowering ORP locally, driving some formation of hydrogen peroxide and subsequent precipitation of black metal sulfides.

It may not be an issue if it stays that localized.