Systems and methods for separating a biogas or other gaseous material into its constituent parts, including solid methane and carbon dioxide, using liquid nitrogen in a processing chamber. The individual parts may be extracted from the processing chamber. Separation and extraction can be performed on a mobile processing plant.

Methods and systems for removing contaminants, such as water and/or carbon dioxide, from a gas stream, such as a natural gas stream or a flue gas stream. One or more solid-tolerant heat exchangers are employed to chill the gas stream to a temperature at which the contaminants solidify. The solidified contaminants may then be separated and removed from the gas stream. In one or more aspects, the one or more solid-tolerant heat exchangers may include a scraped heat exchanger.

Methods of controlling hydrogen sulfide concentration of a biogas occupying an anaerobic membrane bioreactor (AnMBR) containing a submerged membrane are disclosed herein. Methods of controlling dissolved sulfide concentration of a mixed liquor within the AnMBR are disclosed. The methods include directing wastewater containing sulfur and a chemical oxygen demand (COD) to an AnMBR, withdrawing at least a fraction of the biogas from the AnMBR, directing a pre-determined amount of the withdrawn biogas to a scrubber, directing a remainder of the withdrawn biogas to a gas distributor, and directing the scrubbed biogas to the AnMBR. Systems for treating wastewater having sulfur and COD are disclosed. The systems include an AnMBR, a scouring gas closed loop, a scrubber, and a control mechanism for directing biogas to the scrubber and to a gas distributor. Methods of retrofitting a system for treating wastewater having sulfur and COD are disclosed.

One or more embodiments relate to a method for removing CO.sub.2 from a gaseous stream containing CO.sub.2 having the steps of contacting the gaseous stream containing CO.sub.2 with a solvent at a first temperature and a first pressure to dissolve said CO.sub.2 in said solvent, where the solvent is made up of at least one ester, and where said at least one ester has two or more alkyl-ester functional groups on a central hydrocarbon chain.

A solvent and method for removing carbon dioxide from a gaseous mixture flow with high carbon dioxide partial pressures are disclosed. The solvent includes a secondary or tertiary amine, an amine activator, a physical solvent (e.g., thioalkanol), and a carbonate buffer. The solvent contains less than about 60% by weight of water and is in a single liquid phase.

A subsea fluid processing system which receives a wellstream flow. The subsea fluid processing system includes a pressure control device which regulates a pressure of the wellstream flow, a gas-liquid separator unit which receives the wellstream flow downstream of the pressure control device and which provides a liquid stream and a gas stream, a first membrane separator which receives the gas stream and which provides a retentate stream and a permeate stream, a compressor which receives the permeate stream and which provides a compressed permeate stream, and a discharge cooler which receives the compressed permeate stream and which provides a cooled compressed permeate stream for injection into a subsurface reservoir. A density of the cooled compressed permeate stream is higher than a density of the compressed permeate stream.

The present invention concerns the use, for gas separation, of at least one zeolite adsorbent material comprising at least one FAU zeolite, said adsorbent having an external surface area greater than 20 m.sup.2.Math.g.sup.−1, a non-zeolite phase (PNZ) content such that 0<PNZ≦30%, and an Si/Al atomic ratio of between 1 and 2.5. The invention also concerns a zeolite adsorbent material having an Si/Al ratio such that 1≦Si/Al<2.5, a mesoporous volume of between 0.08 cm.sup.3.Math.g.sup.−1 and 0.25 cm.sup.3.Math.g.sup.−1, a (Vmicro−Vmeso)/Vmicro ratio of between −0.5 and 1.0, non-inclusive, and a non-zeolite phase (PNZ) content such that 0<PNZ≦30%.

In some embodiments, the present disclosure pertains to methods of capturing CO.sub.2 from an environment by hydrating a porous material with water molecules to the extent thereby to define a preselected region of a plurality of hydrated pores and yet to the extent to allow the preselected region of a plurality of pores of the porous material to uptake gas molecules; positioning the porous material within a CO.sub.2 associated environment; and capturing CO.sub.2 by the hydrated porous material. In some embodiments, the pore volume of the hydrated porous material includes between 90% and 20% of the pre-hydrated pore volume to provide unhydrated pore volume within the porous material for enhanced selective uptake of CO.sub.2 in the CO.sub.2 associated environment. In some embodiments, the step of capturing includes forming CO.sub.2-hydrates within the pores of the porous material, where the CO.sub.2.Math.n/H.sub.2O ratio is n<4.

A treatment composition for remediating for remediating H.sub.2S, CO.sub.2 and other contaminant(s) in a fluid mixture of contaminated liquids and gasses comprising: a hydrocarbon based liquid; and at least one hydroxide compound dispersed or dissolved into the hydrocarbon based liquid. The at least one hydroxide compound dispersed or dissolved into the hydrocarbon based liquid constitutes 30-50 wt % of the treatment composition, the at least one hydroxide compound includes at least one of potassium hydroxide and sodium hydroxide, and a pH of the treatment composition is in a range of 13-14.0.

Various illustrative embodiments of a system and process for recovering high-quality biomethane and carbon dioxide product streams from biogas sources and utilizing or sequestering the product streams are provided. The system and process synergistically yield a biomethane product which meets gas pipeline quality specifications and a carbon dioxide product of a quality and form that allows for its transport and sequestration or utilization and reduction in greenhouse gas emissions. The system and process result in improved access to gas pipelines for products, an improvement in the carbon intensity rating of the methane fuel, and improvements in generation of credits related to reductions in emissions of greenhouse gases.