A method for removing hydrogen sulfide from a biogas, wherein the hydrogen sulfide is absorbed in an aqueous liquid to produce a cleaned gas having a reduced amount of hydrogen sulfide relative to the biogas. The aqueous liquid is subsequently treated by contacting with a sulfur dye or sulfurized vat dye in the presence of an oxidizer such as oxygen gas, to convert the sulfides in the aqueous liquid to a non-toxic, water-soluble, product.

Methods for utilizing waste products of the steel industry are provided that utilize spent pickle liquor to recover valuable alkaline earth metals from low value wastes with significant calcium content in the form of insoluble oxide, hydroxides, and/or salts are provided, as well as methods for generating a ferric oxide hydroxide composite from steel slag. Suitable raw materials include slag from steel manufacturing and ash from various operations. Ferric oxide hydroxide composite materials described herein can be used for removal of sulfur and metals from contaminated materials. Accordingly, compositions and methods of the inventive concept introduce considerable value to low value waste materials that would otherwise be discarded. In addition, compositions and methods of the inventive concept serve to reduce waste streams from industrial processes.

Methods for utilizing waste products of the steel industry are provided that utilize spent pickle liquor to recover valuable alkaline earth metals from low value wastes with significant calcium content in the form of insoluble oxide, hydroxides, and/or salts are provided, as well as methods for generating a ferric oxide hydroxide composite from steel slag. Suitable raw materials include slag from steel manufacturing and ash from various operations. Ferric oxide hydroxide composite materials described herein can be used for removal of sulfur and metals from contaminated materials. Accordingly, compositions and methods of the inventive concept introduce considerable value to low value waste materials that would otherwise be discarded. In addition, compositions and methods of the inventive concept serve to reduce waste streams from industrial processes.

A biogas cleaning method for purifying a biogas waste stream to form a combustible clean biofuel uses a biogas cleaning system that includes a gas control system, a deoxidizer catalyst bed, a hydrosulfurization catalyst bed, a hydrogen sulfide adsorption bed and a thermal sensor controller. The biogas cleaning method includes using a biogas source to introduce a biogas waste stream into the biogas cleaning system, blending hydrogen with the biogas waste stream, combusting the blended hydrogen and biogas stream to remove oxygen, hydrogenating the heated biogas waste stream to convert sulfur species to hydrogen sulfide and adsorbing the hydrogen sulfide from the biogas stream. In some embodiments, a biogas cleaning system also includes a sulfur polisher adsorption bed, a chlorine removal adsorption bed, a siloxane removal adsorption bed, a heat exchanger loop and a biogas precooler. Some embodiments of a biogas cleaning method can also include precooling the biogas waste stream, adsorbing siloxanes from the biogas waste stream and adsorbing hydrogen chloride from the biogas stream.

Disclosed are processes for purifying feed streams containing hydrogen sulfide and sulfur-containing impurities by removing sulfur-containing impurities, such as elemental sulfur and polysulfanes, using solid catalytic sorbents. Also disclosed are processes for producing hydrogen sulfide.

Configurations and related processing schemes of direct or indirect (or both) inter-plants heating systems synthesized for grassroots medium grade crude oil semi-conversion refineries to increase energy efficiency from specific portions of low grade waste heat sources are described. Configurations and related processing schemes of direct or indirect (or both) inter-plants heating systems synthesized for integrated medium grade crude oil semi-conversion refineries and aromatics complex for increasing energy efficiency from specific portions of low grade waste sources are also described.

Configurations and related processing schemes of direct or indirect (or both) inter-plants heating systems synthesized for grassroots medium grade crude oil semi-conversion refineries to increase energy efficiency from specific portions of low grade waste heat sources are described. Configurations and related processing schemes of direct or indirect (or both) inter-plants heating systems synthesized for integrated medium grade crude oil semi-conversion refineries and aromatics complex for increasing energy efficiency from specific portions of low grade waste sources are also described.

The invention relates to a method for preparing a solid comprising a step of mixing a set of compounds comprising at least two Cu.sub.2(OH).sub.2CO.sub.3 powders of different particle sizes and at least one binder and the use of the solid prepared by means of this method.

The invention relates to a method for preparing a solid comprising a step of mixing a set of compounds comprising at least two Cu.sub.2(OH).sub.2CO.sub.3 powders of different particle sizes and at least one binder and the use of the solid prepared by means of this method.

Sorbent compositions containing calcium and iodine are added to coal to mitigate the release of mercury and/or other harmful elements into the environment during combustion of coal containing natural levels of mercury.