Biogas Desulfurization

DUCON® Biogas Purification System

DUCON® is a cost-effective and sustainable biogas purification system that meets your quality requirements. It delivers very high H₂S removal efficiency; ≤ 50 ppm H₂S in the treated gas is routinely achieved whether the inlet concentration is 1 ppm or 2,000 ppm. Thanks to its wide turndown ratio (load flexibility), the system easily handles large fluctuations in gas flow.

Because the process does not add air or oxygen to the biogas, the calorific value is not diluted. The treated gas can be fed directly to a gas engine or boiler. With negligible methane slip, DUCON® is also an ideal solution for projects that upgrade biogas to biomethane / Renewable Natural Gas (RNG).

As a biogas upgrading/gas cleaning system, DUCON® combines high efficiency, proven reliability, and a low total cost of ownership, demonstrated at numerous installations worldwide. It maximizes the value of your biogas while enhancing plant sustainability through biological sulfur recovery.

System Advantages

• High-performance H₂S removal: ≤ 50 ppm in the treated gas (routine).

• Broad load flexibility: Handles large flow variations without issue.

• High uptime and reliability.

• Gas quality preserved: No air addition; calorific value remains intact.

• Low chemical consumption with no hazardous by-products.

• Valuable by-product: Recovered sulfur can be used to produce high-quality organic fertilizer.

• Proven technology: 35+ years of operational experience with continuous innovation.

Broad Applicability

DUCON® can purify virtually any H₂S-containing gas stream, including geothermal gas. It can be integrated with any DUCON® anaerobic wastewater treatment system. Typical applications include pulp & paper, food & beverage, wastewater treatment, landfills, municipal facilities, bioethanol, sludge/solids treatment, and the biofuels industry.

Capacity range:
Biogas flows from 50 Nm³/h up to 5,500+ Nm³/h; typical sulfur loads of approximately 10–50 kg/day.

Process Description

The DUCON® biogas filtration system combines rapid chemical absorption with robust biological sulfur recovery to remove H₂S from (bio)gas. The system consists of an absorber column, a bioreactor, and a sulfur recovery unit.

• Absorption: The H₂S-containing gas is brought into counter-current contact with mildly alkaline wash water; H₂S dissolves readily in this solution.

• Biological regeneration: In the bioreactor, naturally occurring bacteria oxidize dissolved sulfide to elemental sulfur particles, continuously regenerating the wash solution. This allows in-loop reuse of the alkaline solution in the absorber and results in very low operating costs.

• Solid–liquid separation: The produced elemental sulfur is separated and discharged for use in organic fertilizer applications.