A gas stream is purified by a TSA adsorption scheme including at least two adsorbers following, in an offset manner, a cycle including an adsorption phase, and a subsequently, a regeneration phase. The regeneration phase includes a depressurization step, a pre-regeneration step and a regeneration step. A gas circulator is used to circulate the gas within the adsorber in the pre-regeneration step in a closed loop while the circulating gas is heated with a heater.

A biological desulfurization processing system is provided. The biological desulfurization processing system includes a desulfurization reaction tank and a culture tank of desulfurization bacteria. The culture tank of desulfurization bacteria is used for cultivating desulfurization bacteria and is connected to the desulfurization reaction tank. The desulfurization reaction tank includes a desulfurization reaction zone. The desulfurization reaction zone includes at least one desulfurization layer and at least one supporting layer, and the desulfurization layer and the supporting layer are stacked in a staggered manner. A biological desulfurization processing method is also provided.

The invention relates to water-soluble and/or dispersible ferric hydroxide in a strong base that is suitable for hydrogen sulfide removal in contaminated liquid and gas streams. The water-soluble and/or dispersible ferric hydroxide in a strong base may be introduced into a liquid stream to remove hydrogen sulfide. The water-soluble and/or dispersible ferric hydroxide may be further incorporated into a solid substrate for gas phase hydrogen sulfide removal.

The present invention relates to a novel phase transfer solvent composition for enhanced CO.sub.2 and/or H.sub.2S capture from flue gas and biogas having various gaseous compositions. Further, the present invention provides a process of preparing the phase transfer solvent composition of the present invention.

A method for providing a fuel includes providing a partially purified biogas at a first processing site, where the partially purified biogas is produced by multiple biogas sources and/or from multiple feedstock sources. The partially purified biogas is compressed, fed to a mobile tank, and transported by vehicle to a second processing site. At the second processing site, which may also receive biogas from a plurality of biogas sources, the partially purified biogas is further processed to produce a fuel or fuel intermediate.

The invention is directed to a process to convert a sulphur compound to bisulphide by direct or indirect transfer of electrons from a cathode of a bio-electrochemical cell to the sulphur compound under anaerobic conditions and in the presence of mixed culture comprising methanogens and suitably also a anaerobic or facultative anaerobic bacteria. The sulphur compound may be a thiol like methanethiol or ethanethiol or a polysulphide, like dimethyl disulphide.

A gas separation unit for the separation of a first gas, carbon dioxide, from a mixture, by using an adsorption/desorption process using a loose particulate sorbent material arranged in at least two stacked layers. The primary heat exchange piping is arranged on the two outer edges of the layer within the cavity extending along a longitudinal direction. Further, an essentially parallel array of secondary heat exchange pipes is provided, the secondary heat exchange pipes extending along a transverse direction. The first diameter of the secondary heat exchange pipes is at least twice as large as the second outer diameter of the secondary heat exchange pipes and the secondary heat exchange pipes are in thermal contact with sheets of metal which extend oscillating between pairwise adjacent secondary heat exchange pipes.

A process for producing biomethane by scrubbing a biogas feed stream includes introducing the feed gas stream into a pretreatment unit wherein a CO.sub.2-depleted gas stream is partially separated from a CO.sub.2 stream and an oxygen stream and is compressed to a pressure P1 above 25 bar abs. Subjecting the CO.sub.2-depleted gas stream to cryogenic separation in a distillation column to separate a nitrogen stream and produce a CH.sub.4-enriched stream, the distillation column comprising n plates, n being an integer between 8 and 100. Recovering a pressurized CH.sub.4-enriched stream by pumping the CO.sub.2-depleted gas stream to a pressure P2 above 25 bar absolute.

A method for providing a fuel includes providing a partially purified biogas at a first processing site, where the partially purified biogas is produced by multiple biogas sources and/or from multiple feedstock sources. The partially purified biogas is compressed, fed to a mobile tank, and transported by vehicle to a second processing site. At the second processing site, which may also receive biogas from a plurality of biogas sources, the partially purified biogas is further processed to produce a fuel or fuel intermediate.

A method for separating a raw feed gas stream using a plurality of membrane separation stages includes separating a pressurized feed gas stream into a first nonpermeate stream and a first permeate stream, compressing the first permeate stream to form a compressed first permeate stream, separating the compressed first permeate stream into a second nonpermeate stream and a second permeate stream, separating the second permeate stream into a third nonpermeate stream and a third permeate stream, combining the third nonpermeate stream with a raw feed gas stream to form a combined feed stream, compressing the combined feed stream to form a compressed combined feed stream, and combining the second nonpermeate stream with the compressed combined feed stream to form the pressurized feed gas stream.