Biogas | Biogas desulfurization | THIOPAQ®

The THIOPAQ® technology is an effective solution for deep biological removal of hydrogen sulfide (H2S) from biogas in anaerobic wastewater treatment plants. The sodium hydroxide solution in the THIOPAQ® absorbers is continuously regenerated biologically, allowing for efficient H2S sorption under slightly alkaline conditions. The process is based on oxidizing sulfides to elemental sulfur by autotrophic sulfur bacteria, while simultaneously recovering hydroxide ions. The THIOPAQ® system achieves high H2S removal efficiency exceeding 99.5%. The elemental sulfur produced as a byproduct is a valuable product that can be used as fertilizer for plants.

The THIOPAQ® technology was developed by Paques in collaboration with universities, research institutes, and clients. It can be applied to various biogas streams containing hydrogen sulfide and serve as an important component in any existing or planned anaerobic wastewater treatment system, biogas production facility, or in the oil and gas industry. The sodium hydroxide solution in the THIOPAQ® system absorber is continuously and biologically regenerated in the scrubbers. In the scrubber, biogas containing hydrogen sulfide comes into contact with the absorption solution fed countercurrently to the absorber. H2S sorption, conducted under slightly alkaline conditions (pH 8-9), allows for the chemical reaction of hydrogen sulfide with hydroxide ions (OH-). This chemisorption translates to higher process efficiency and performance.

The THIOPAQ® system achieves high H2S removal efficiencies exceeding 99.5%. H2S concentrations in the purified gas below 25 ppm are the standard in the vast majority of applications – whether the inlet concentration is 1000 ppm or 200,000 ppm! THIOPAQ® has a wide range of control and easily handles large fluctuations in gas flow. The small effluent stream generated in the THIOPAQ® system as well as the sulfur produced in it do not contain hydrogen sulfide, making their further utilization not a technical or organizational issue. Furthermore, the elemental sulfur produced by THIOPAQ® can be used as high-quality organic fertilizer.

The calorific value of desulfurized gas remains unchanged because no air or oxygen is added to the biogas in the THIOPAQ® process. This also eliminates the risk of explosive methane-air mixtures. The purified gas is ready for direct use in a gas engine (cogeneration) or heating boiler, or in a blend with natural gas. Due to the minimal loss of methane, this technology is suitable for upgrading biogas to biomethane projects (containing 98 to 99% methane), comparable to natural gas or renewable natural gas (RNG). This allows for injection into the gas grid or use as fuel for methane-powered engines.

The high efficiency, proven reliability, and low total cost of ownership of THIOPAQ® as a biogas upgrading system or gas purification system have been demonstrated in hundreds of plants worldwide. It maximizes the value of biogas and promotes sustainable development by enabling biosulfur recovery.

What to know about THIOPAQ®?

• Proven effectiveness;
• Over 30 years of experience;
• Over 300 operating THIOPAQ® installations worldwide;
• Continuous technology development and improvement;
• In-house production and quality control;
• Deep H2S removal;
• High availability and process reliability;
• Low operating costs;
• No air dosing to biogas;
• Production of high-quality fertilizer.

With the THIOPAQ® gas purification system, almost any gas containing H2S can be cleaned, including biogas, synthesis gas, CO2-rich off-gases, ventilation streams, and geothermal gas. THIOPAQ® can be combined with any anaerobic wastewater treatment or fermentation system. Applications of biogas upgrading systems include the pulp and paper, food and beverage, wastewater treatment, waste management, municipal, bioethanol, sewage/sludge fermentation, and biofuel industries.

Biogas flow rates in THIOPAQ® installations range from 50 Nm3/h to over 50,000 Nm3/h, with daily sulfur loads ranging from 10 kg/d to 50,000 kg/d. Standardized systems, such as this biogas purification system, allow for short project realization timelines, and the experienced team of engineers at Paques and Seen Technologie can tailor the equipment to specific needs.

THIOPAQ® Operation Principle
The THIOPAQ® (bio)gas filtration system combines rapid chemical absorption to remove H2S from (bio)gas and effective biological sulfur recovery. It consists of an absorber column connected with a biological reactor and a sulfur recovery unit. In the absorber, H2S-containing gas comes into contact with wash water through countercurrent exchange, where H2S readily dissolves in the slightly alkaline wash water. In the bioreactor, naturally occurring bacteria oxidize sulfides to elemental sulfur particles, while regenerating the wash solution. This allows for continuous reuse of the alkaline wash solution in the absorber column, leading to very low operational costs. The sulfur produced in the system is separated in a suspension separation process and can be reused as high-quality organic fertilizer.

We are the exclusive, authorized partner and distributor of Paques solutions in Poland, which is a great honor for us. Our strategic cooperation with Paques covers advanced anaerobic technologies, phosphorus recovery, and deammonification. This enables us to offer the most modern and efficient installations and devices in these key areas. We are proud to provide customers with innovative solutions that support energy efficiency, sustainable development, and environmental protection.