The Best Biogas Desulphurisation Solutions for the Potato Processing Industry: A Performance Comparison

10 February 2025

The potato processing industry is growing rapidly across the EU, driving high investments in production capacity. With increasing environmental regulations, reducing water and energy consumption while optimizing biogas production is more critical than ever. Efficient biogas desulphurisation plays a key role in ensuring stable, sustainable operations.

Challenges for the Potato Processing Sector

The potato processing sector is rapidly expanding in the EU, driving high investments in new production capacity. This industry is both water- and energy-intensive and generates large volumes of heavily organic-loaded wastewater.

To meet increasingly stringent EU targets for water conservation and carbon footprint reduction, technologies like anaerobic wastewater treatment, biogas desulphurisation, aerobic polishing, and bio-effluent recycling via reverse osmosis are becoming increasingly important.

Need for performant and flexible biogas desulphurization

Potato processing plants must operate 24/7 under constantly changing conditions, demanding highly flexible and reliable processes. This applies equally to biogas desulphurisation technologies, which must ensure continuous performance and adaptability.

Comparison of 2 biogas desulphurization systems in potato processing sector

Waterleau has extensive experience in the potato sector with both the BIOTIM® scrubber technology and the high pH washing with biological caustic regeneration system provided by third parties.

BIOTIM ® scrubber on potato processing plants like Ecofrost, Clarebout, Mydibel

As H₂S dissolves readily in slightly alkaline water (pH > 7.6), the BIOTIM® scrubber offers a straightforward and efficient solution. Wash water is sourced directly from the aerobic wastewater treatment plant. The multi-stage scrubber achieves very low H₂S and O₂ concentrations in the desulphurised biogas (< 0.2 vol% O₂).

This system requires higher CAPEX and is well-suited for high-capacity applications, making it a good fit for the potato sector.

Key operational benefits:

Simple process requiring minimal operator intervention.
Can handle variable S-loads (10% to 100%) within minutes.
Proven long-term performance under fluctuating feed conditions (e.g., at Ecofrost and Clarebout).
No caustic soda required.
Uptime exceeds 99%. Every 4 months, automatic on-site rinsing and C.I.P. are performed. The system returns to full capacity within 12 hours.

High pH Washing with Biological Regeneration Using Thiotrix Bacteria

This system consists of:

Step 1: High pH (8.5) chemical washing, without oxygen injection. This results in low H₂S and low O₂ concentrations in the biogas.
Step 2: Biological regeneration of the Na₂S solution using Thiotrix bacteria, which convert sulphide into elemental sulphur (S⁰) and regenerate NaOH, which is reused in Step 1.

This system also requires higher CAPEX and is suitable for high-capacity facilities.

Operational insights:

The regeneration step relies on slow-growing Thiotrix bacteria in a narrowly defined redox and oxygen range.
Requires 1 to 1.5 hours/day of operator attention by skilled personnel.
Sensitive to temperature and nutrient levels; performance drops below threshold conditions.
Rapid process imbalance can occur under varying feed conditions—common in potato factories. During imbalance, the system reverts to a standard caustic scrubber, significantly increasing OPEX.
High Na salt concentrations can destabilize redox and conductivity, delaying full recovery (up to 2 weeks).
Requires careful maintenance of sensors and aeration systems.
Overall, under the dynamic conditions of potato processing, this system risks 5–10% downtime.

Conclusion

Both biogas desulphurisation systems have demonstrated technical feasibility in the potato processing sector. However, the BIOTIM® scrubber stands out for its operational robustness, simplicity, and flexibility under highly variable process conditions—hallmarks of the potato industry. With minimal operator involvement, no chemical dosing, and >99% uptime, it offers a low-maintenance and cost-effective solution over the long term.

Discover the best biogas desulphurisation solution for your needs

Are you in search of a durable, adaptable, and user-friendly solution for biogas and extraction gas treatment?
Reach out to us today. We are eager to share our expertise in biogas purification and introduce you to our BIOTIM® scrubber technology.

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