A carbon dioxide fixation method includes a step of preparing a calcium-containing substance containing calcium, a step of preparing a calcium extraction substance for extracting calcium ions from the calcium-containing substance by a reaction with the calcium-containing substance to produce a calcium-containing intermediate, a step of producing a gel including the calcium-containing intermediate, by mixing the calcium-containing substance and the calcium extraction substance, a step of supplying a basic substance and carbon dioxide to the gel including the calcium-containing intermediate to precipitate calcium carbonate which is slightly soluble, and a step of removing the precipitated calcium carbonate.

A recombinant microorganism including a genetic modification that increases activity of nitric oxide reductase in the recombinant microorganism, a composition for reducing a concentration of nitric oxide in a sample, the composition including the recombinant microorganism, and a method of reducing a concentration of nitric oxide in a sample, are disclosed.

The present disclosure relates to processes for desulfurizing hydrocarbon feedstocks. The processes may include introducing a feedstock comprising hydrogen sulfide to an absorber comprising a metal chelate to form a reduced metal chelate. The processes may further include introducing the reduced metal chelate to a photobioreactor comprising a phototrophic bacterium. The present disclosure also relates to apparatuses for desulfurizing hydrocarbon feedstock. An apparatus may include and absorber and a photobioreactor fluidly connected to the absorber. The photobioreactor may be an anaerobic vessel with a light source.

The present invention describes a fluid which is suitable for the decontamination of heat engines which can carry out both, at the same time, the catalytic reduction of oxides of nitrogen (NOx) contained in exhaust gases and assist in the regeneration of the particulate filter (PF). The invention also describes several embodiments of said fluid.

The invention is directed to a process and apparatus for removing hydrogen sulfide from a gas stream comprising biogas. In accordance with the invention the gas stream is contacted with an oxidizing agent present in a vessel, whereby said hydrogen sulfide is oxidized into elemental sulfur and said oxidizing agent is reduced, wherein oxygen containing gas is also fed to said vessel, wherein said oxygen oxidizes at least part of said reduced oxidizing agent.

The present invention describes a fluid which is suitable for the decontamination of heat engines which can carry out both, at the same time, the catalytic reduction of oxides of nitrogen (NOx) contained in exhaust gases and assist in the regeneration of the particulate filter (PF). The invention also describes several embodiments of said fluid.

A recombinant microorganism including a genetic modification that increases activity of nitric oxide reductase in the recombinant microorganism, a composition for reducing a concentration of nitric oxide in a sample, the composition including the recombinant microorganism, and a method of reducing a concentration of nitric oxide in a sample, are disclosed.