How does the SULFURIX™ work?
The system consists of a SULFURIX™ scrubber tower containing a non-clogging inlet distribution system and two layers of non-clogging fixed, modular media.
Within the SULFURIX™ tower, the biogas is “washed” with aerated, sulfide-free wastewater. Typically, “mixed liquor” from the aeration tank of an aerobic treatment system is used as the wash water. Activated sludge is ideal as the washing liquid, due to its typically high pH and associated buffer capacity.
In the “washing” process, sulfides in the biogas are dissolved in the liquid, absorbed by the biomass within the wash water and affixed to the internal media, and partially oxidized, as oxygen (air) is added to the scrubber in very small amounts.
The wash water flow rate is set at that which will facilitate to dissolve all H2S from the biogas, at the prevailing pH and temperature. Any biological treatment that takes place provides a factor of safety to ensure optimal scrubbing.
In general, about 80-95% sulfide removal is obtained in a single- stage SULFURIX™ scrubber. In a single-stage unit, the performance largely depends on the design height of the desulfurization tower. Two-stage scrubbers are also available (two SULFURIX™ units operating in series), which can provide a combined removal efficiency of more than 99% in many cases.
The SULFURIX™ scrubber is typically placed at an elevation higher than the activated sludge aeration basin from whence the washing liquid is obtained, to allow a gravity return of the “spent” scrubbing liquid to the aerobic treatment system. If this is not possible, customized scrubber models with a built-in water reservoir and pumped recirculation loop can be provided.
As pressure loss through the scrubber is minimal, typically no biogas blowers are required. The biogas is usually under sufficient pressure within the anaerobic digester(s) to suit the SULFURIX™ unit.
Scrubbing occurs at a constant rate at all times, for all flows and H2S concentrations. Removal efficiency is consistent throughout the scrubber’s height and width.
The principle of natural dissolving of H2S in water makes the SULFURIX™ scrubber particularly suitable for treating H2S rich biogas (> 1% concentration). Biogas flow and net sulfur load determine the design and cost of the final technology.
As such it is an ideal “roughing” pretreatment before other scrubber systems when high H2S concentrations are present in the raw biogas, and low levels are required for use. The SULFURIX™ can be employed upstream of GWE’s BIO-SULFURIX™ system, which is a closed loop pure biological scrubber system, in order to meet strict H2S limits.
GWE’s SULFURIX™ scrubbers are made entirely out of corrosion-proof materials: anti-static HDPE and polyester. The GWE portfolio contains a series of standard models with heights ranging from 6 to 9-meters (approximately 20-30ft), covering a biogas flow range of 100 to >1000 m3/h (about 60 to >600scfm) at any H2S concentration. Activated sludge (standard conditions of pH 7.3 and 30°C) is assumed as the washing liquid. Design adjustments are then made to suit a client’s specific needs and operating conditions.