Testing unique organisms sulfide oxidizer + heterotrophic growth using nitrate/nitrite

At Aster Bio we have been bench testing several new organisms with the goal of converting sulfides and H2S into harmless oxidized forms at non-acidic pH. While many Thiobacillus cultures exist that oxidize reduced sulfur, they tend to thrive at pH levels below 5 which is outside the range of many other organisms. So, we started looking for other sulfur oxidizing cultures that worked at higher pH.

After screening a number of candidates, we found some unique microbes with excellent applicability to waste treatment. The first is a Paracoccus denitrificans. This unusual bacterium has a number of key metabolic pathways that are useful in control of both sulfides and malodorous short-chain volatile fatty acids. An additional benefit, is the P. denitrificans can utilize nitrate/nitrate when growing on the short-chain volatile fatty acids. So what does all this mean for waste treatment?

• Help remove H2S & sulfides in collection systems & wastewater at neutral pH
  
  
• Odors from short-chain volatile fatty acids (acetic, propionic, butyric) can be controlled under aerobic and anoxic conditions
  
  
• Nitrate/nitrite reduction – even under aerobic conditions the organisms utilize nitrate for respiration. The P. denitrificans is among the most active denitrifying microbes we have screened
  
  

So what Aster Bio going to do with the P. denitrificans? Our current work is on optimizing industrial scale growth of the microbe in aseptic reactors with downstream stabilization. Once we finish that task – it is not easy – we will work to develop techniques to introduce the P. denitrificans into working systems so that the organisms can work to exploit its ecological niche and improve wastewater quality without odor masking chemicals or oxidants. I will keep you posted on field trial results.

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