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The most significant and differentiating factor of any Fe-based additive is its Reactive Iron Ion Content (RIIC; Higher = Better). RIIC is a metric, introduced and used by SwissBiogas.com, to reliably project the potential of additives to bind sulfur and to support the growth of methanogens. Based on the RIICs of its respective iron compounds, the RIIC of any additive can be calculated as follows:

• RIIC(FeO) = 0.7773 → RIIC(FeO additive) = Content FeO [%] x 0.7773
• RIIC(Fe₂O₃) = 0.6994 → RIIC(Fe₂O₃ additive) = Content Fe₂O₃ [%] x 0.6994
• RIIC(Fe₃O₄) = 0.7236 → RIIC(Fe₃O₄ additive) = Content Fe₃O₄ [%] x 0.7236
• RIIC(FeCl₂) = 0.4406 → RIIC(FeCl₂ additive) = Content FeCl₂ [%] x 0.4406
• RIIC(FeCl₃) = 0.3443 → RIIC(FeCl₃ additive) = Content FeCl₃ [%] x 0.3443
• RIIC(FeO(OH)) = 0.6285 → RIIC(FeO(OH) additive) = Content FeO(OH) [%] x 0.6285
• RIIC(Fe(OH)₂) = 0.6215 → RIIC(Fe(OH)₂ additive) = Content Fe(OH)₂ [%] x 0.6215
• RIIC(Fe(OH)₃) = 0.5226 → RIIC(Fe(OH)₃ additive) = Content Fe(OH)₃ [%] x 0.5226
• RIIC(Fe₂O₃·3H₂O) = 0.5226 → RIIC(Fe₂O₃·3H₂O additive) = Content Fe₂O₃·3H₂O [%] x 0.5226

Examples:

1. Additive X: 60% FeO → RIIC(Additive X) = 60% x 0.7773 = 46.6%
2. Additive Y: 40% FeCl₃ → RIIC(Additive Y) = 40% x 0.3443 = 13.8%
3. Additive Z: 10% FeO + 20% Fe₂O₃ + 45% FeO(OH) → RIIC(Additive Z) = 10% x 0.7773 + 20% x 0.6994 + 45% x 0.6285 = 50.0%

Remark: RIIC(SBGx) > 60%  (Analysis March 2023)

To perform your own RIIC Calculation, daily Additive Dosage Calculation or Additive Dosage And Cost Comparison in general, download our Excel document RIIC_calculator_web from the Resources - Download Area.