USP has developed a new iron product (SulFeloxTM) as an alternative to nitrates for controlling H2S in wastewater collection systems. SulFeloxTM has been designed with safety in mind, and carries equivalent material safety characteristics to calcium nitrate with 1/10,000 the acidity of traditional iron salt solutions. As such, it has the benefits of traditional iron solutions (i.e., efficient durational control, natural regeneration and long-term effects in downstream gravity sewers and treatment plant processes) without the downsides (no aquatic toxicity hazard, wastewater pH depression, consumption of alkalinity). SulFeLoxTM can go anywhere nitrates can, and is specifically designed to replace nitrate where it performs the least – in long, slow-moving, sulfide generating sewers. Typical applications for SulFeLox™ can substitute for nitrate on a 1:2 to 1:3 basis, meaning significantly less volume demands at the site (fewer deliveries), and approximately 10-20% less cost. Furthermore (for BNR plants), SulFeLox™ does not result in the removal (uptake) of soluble carbon into heterotrophic biomass as does the use of nitrate, and thus can reduce downstream sulfide production and the need for supplemental carbon at the treatment plant.

SulFeloxTM Benefits:

  • Equal performance at <50% the dose rate of calcium nitrate
  • Lower hazard level than calcium nitrate
  • No matting / scum build-up in wetwells or ‘floating’ of clarifiers due to N2-off-gassing
  • Similar iron content as conventional ferrous iron products
  • Lower impact on pH depression of wastewater (affecting H2S volatilization and FeS binding efficiency) than conventional ferrous iron products
  • Significant cost savings potential over calcium nitrate
  • Can be regenerated for downstream odor control, P-removal and struvite control, or dewatering improvements (PRI-TECH®).

SulFeloxTM Performance Comparison to Calcium Nitrate

As SulFeLoxTM is a ferrous chloride based iron solution, its performance is comparable to that of FeCl2. Several field tests have shown that SulFeLoxTM controls dissolved sulfide and vapor H2S to levels similar to calcium nitrate, but at less than ½ the volumetric feed rate, resulting in significant cost savings.

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SulFeLoxTM can be regenerated and re-used multiple times for downstream odor control in the collection system, primary clarifiers and biosolids, as well as for CEPT, P-removal, struvite / biogas-H2S control, or dewatering improvements when combined with USP’s PRI-TECH® technology.