Veolia Water Technologies – Sulfothane™ Biogas Scrubbing
Water and Wastewater Treatment Technologies
About the Company:
Veolia Water Technologies is committed to providing innovative solutions with proven value-added performance.
As demand for milk, cheese, yogurt and other dairy products continues to grow, new technologies are helping to optimize and control major costs for dairies and dairy plants: water usage and energy consumption.
Veolia offers industry leading technologies for the reduction of water use and wastewater treatment improvement while ensuring continuous water supply compliant with state-of-the-art hygienic standards and regulatory requirements.
Their solutions are able to optimize energy usage inside the process and promote green gas production. They also can ensure by-products valorisation (animal feed, fertilizers, bioplastics) and improve some production yields.
About the Solution:
Sulfothane™ a low-maintenance, low operational cost technology that cleans biogas for use while recovering elemental sulfur for reuse.
Biogas is generated by the anaerobic digestion of industrial wastewaters, manure and municipal solids, as well as by covered landfill sites. Before the biogas can be utilized, it is essential to remove odorous sulfur compounds, which are mainly present in the biogas as hydrogen sulfide (H2S). Sulfur can cause severe corrosion in boilers and engines utilizing biogas. Sulfothane is environmentally safe, has minimal power requirements and uses a clog-free scrubber that requires no maintenance. The process operates at ambient temperature and pressure, and requires almost no chemicals since only the chemicals lost in the small sulfur bleed stream have to be replaced. The recovered sulfur can easily be reused as a fertilizer or further purified for sulfuric acid production.
Similar to a chemical scrubber - but with a distinct advantage
Sulfur is an essential nutrient for living organisms and is found in proteins. During the production of biogas, the sulfur is converted biologically to H2S. Fortunately, biological processes can also be used to remove the H2S from the biogas.
The Sulfothane process consists of two steps and resembles a chemical alkaline scrubber for H2S, but with a distinct advantage. The alkaline solution in the Sulfothane process is continuously regenerated in a biological process using aerobic sulfur bacteria.
The first step consists of a scrubber column, in which the H2S present in the biogas is transferred to the slightly alkaline washing liquid and is dissolved as sodium sulfide. In the second step, the sodium sulfide is biologically oxidized to elemental sulfur. In this biological process, the washing liquid is regenerated by producing sodium hydroxide and elemental sulfur.
The scrubber column is operated in counter-current mode, which results in efficient removal of H2S, achieving concentrations less than 10 ppm. With this process, H2S removal efficiencies exceeding 99% can be obtained. This high removal efficiency is achieved without diluting the biogas with air, which preserves its energy value and reduces its corrosiveness to the downstream equipment that puts the biogas to work for you. As an added bonus, the reduced corrosiveness minimizes maintenance and extends the life of your systems.
Standard designs or custom systems
Standard design units are offered for biogas flows ranging from 125 to 1500 SCFM and H2S concentrations of 10,000 to 25,000 ppmV, but custom designs are also available. The units are factory-tested, pre-commissioned and designed for easy transportation, installation and maintenance. Materials of construction are selected for long life and durability. For large capacities, multiple units can be placed in parallel.
Solution Strengths, Weaknesses and Critical Indicators
Anaerobic Digester Associated Technology:
NOTE: There are several technology types that are used as part of an integrated manure management system that includes an anaerobic digester and are not applicable to manure management in other cases. The impact of these technologies on the critical indicators are represented as those of an entire anaerobic digester system.
- Long usable life and can be run reliably
- Creates energy and generates environmental credits
- Requires proper preparation of the feedstock
- Requires other technologies for energy utilization
- Requires other technologies for digestate handling
- Proper feeding & system monitoring is required to avoid system downtime
- Proven technology for odor control, GHG reduction and pathogen reduction
Violia has a long track record of manufacturing reliable water treatment equipment and is currently working with Newtrient to provide additional information on its solutions and installations.
1. OPERATIONAL HISTORY