What is the plan for managing nitrates without the sulfur denitrator? I saw a build a while back that incorporated a methanol bio-denitrator which seemed pretty cool. It was a large tank which contained surfaces covered in thick bacterial film/goo that would be automatically taken offline and fed methanol for a number of hours and then off-gassed and flushed back into the system automatically once all of the NO3 in the tank had been consumed. I could see such a system being helpful both as a source of bacteria and a means to control NO3.
When Bob Goemans first talked about NNR (natural nitrate reduction) in the late 1960; his book, “Live Sand Secrets, claimed that facultative bacteria were 100 fold more effective at reducing nitrate to nitrogen gas than anarobic. I have the same waste water certification. I am certified to train people to stir S.H.I.T. (Detritus)
Your description of a sulfur denitrator corresponds to a “anaerobic digester”. While the quote below does not address the “100 fold more efficient” comment but it qualifies how facultative bacteria consume both nitrate & phosphate and also converts nitrate to nitrogen gas while sulfur denitrator converts only nitrate to nitrogen gas and produces carbon dioxide and methane gas.
Facultative bacteria vs. Anaerobic Bacteria
[I am a supervisor of a wastewater plant. We use
nitrification,
denitrification in aerobic systems and use anaerobic systems for the destruction of organics.
Phosphate and Nitrate is consumed by facultative bacteria not anaerobic bacteria. Facultative bacteria can switch for a simple explanation to the use of Oxygen from NO3 and PO3 (Nitrate Phosphate) when the
Oxygen supply is low starting at usually less than 0.5 mg/L. Ideally less than 0.5 and greater than 0.1. This is called an anoxic zone. Give you an idea of how low this is gold fish need a minimum of 3.0
mg/L Oxygen.
Within the same floc (a clumping growth of bacteria either free floating or growing on a surface) there can be all three bacteria. The outer layer exposed to higher levels of Oxygen allow for the Nitrifiers (Ammonia to Nitrite to Nitrate) The Nitrate reducers live deeper in the floc or rock or sand where there is less Oxygen. We use the same bacterial floc in differing levels of Oxygen to achieve this.
Anaerobic bacteria live in zero Oxygen. They convert organics to water,
Carbon Dioxide, and Methane mostly. Hydrogen Sulfide is also a product. You do not want your reef to have anaerobic conditions anywhere. The sulfur dead spots that some people refer to are anaerobic. This happens when a filter media or in this case a sand bed become impacted and diffusion of gas does not take place. Especially true under rocks sitting on sand or worse buried in the sand. A plenum helps moderate the diffusion of gasses through the sand by the osmotic pressure of the levels of dissolved gasses on each side of the sand or filter. (Water under the sand and the water on top of the sand)]
Laissez les bonne temps roulee,
Patrick
