Abstract: A process for abating the emission of hydrogen sulfide from a condensate of steam, derived from a sulfide-containing geothermal brine, comprising introducing an oxidizing agent into the condensate in an amount less than that which would be required to directly oxidize all the sulfide to sulfate. The process optionally provides for periodically introducing a biocide into the condensate to control the growth of organism therein.

Abstract: A method is provided for oxidizing arsenic in an arsenic-containing solution. The method comprises contacting the solution containing arsenic in a +3 oxidation state with an amount of a specific type of oxidizing agent, i.e., an agent containing at least one ##STR1## wherein X is a halogen to effect substantially complete oxidation of the arsenic to the +5 oxidation state. The amount of oxidizing agent used is substantially less than that which would theoretically be required. In accordance with a particularly preferred embodiment, the oxidized arsenic is reacted with a metal to form a substantially water-insoluble precipitate, preferably an iron or calcium arsenate.

Abstract: Condensate of steam derived from a geothermal brine is treated to enhance its utility as wash water for a brine filter. The condensate is sprayed into a tank in the presence of air to effect substantial oxidation of oxidizable sulfur species contained therein, and the pH of the condensate is adjusted to be within about 1.0 pH units of the pH of the brine. Such treatment substantially extends the life of the filter media used in the brine filter.

Abstract: A process and apparatus is provided for reducing the concentration of fine, residual solids still remaining suspended in clarified geothermal brine overflow from a primary brine clarification stage in which hot, flashed, silica-rich geothermal brine, containing suspended siliceous material, is gravity separated, comprises flowing the brine overflow from the primary clarification stage into a closed secondary clarifier vessel having an internal reaction well. Capacity of the secondary clarifier vessel provides a brine residence time in the vessel of between about 45 and about 150 minutes, the brine residence time in the reaction well being between about 10 and about 20 minutes. Brine in the vessel is blanketed with steam flashed from the brine to exclude air from the vessel. In the reaction well, the brine is contacted with a flocculating agent, such as a cationic, anionic, or non-ionic polyacrylamide having a molecular weight of at least about 1 million, in an amount of between about 0.

Abstract: A method is provided for producing electric power from hot, pressurized geothermal brine containing dissolved toxic elements without significant precipitation of toxic solids. When sludge produced by the process is washed, non-toxic solids are produced which can be disposed of or utilized in an environmentally acceptable manner. The method includes removing geothermal brine from an underground aquifer, separating non-condensable gases therefrom, and handling the non-condensable gases separately from the processing of the non-condensable gas-free brine to prevent reactions therebetween. An air-free flashed brine handling system is established to prevent contact of air with the flashed brine, and all brine contacted with air is injected into the geothermal brine aquifer through a separate, corrosion-protected injection well. Steam derived from the brine is used to produce electric power, the steam being condensed in the process. The steam condensate is air-cooled, and is used in the steam condensation process.

Abstract: The deposition of metal-containing scale, such as iron silicate scale, from a hot aqueous geothermal brine, or the like, is controlled by blending into the brine sufficient reducing agent effective for reducing trivalent iron and manganese cations in a high temperature brine solution to divalent ions to cause an overall decrease in scale deposition, especially of iron silicate scale. Preferably, from 2 to 7 times the stoichiometric amount of reducing agent is used to effect a 70 to 90 percent reduction in the formation of iron silicate scale.

Abstract: A method is disclosed for controlling the deposition of metal-containing scales, such as iron silicate scale, from a hot, aqueous, geothermal brine or the like, without substantial corrosion of brine handling equipment. The brine is contacted with (1) an amount of an acid sufficient to reduce the pH of the brine between 0.1 and 0.5 unit and (2) a greater than stoichiometric amount of a reducing agent for reducing trivalent iron and manganese cations in a high temperature brine solution to divalent ions. An overall decrease in scale deposition, especially of iron silicate scale, is achieved while a silver-rich scale can be recovered from silver-containing brines.

Abstract: A method is provided for combining a high pH steam condensate with a flow of a acidic geothermal brine from which the steam is extracted so as to inhibit the formation of suspended particulate matter, such as heavy metal sulfides, calcium carbonate and iron hydroxide, by the chemical reacting of such impurities as hydrogen sulfide and ammonia in the condensate with such impurities as heavy metals, iron and calcium in the brine. The method includes acidifying the steam condensate, preferably by hydrochloric acid, to reduce the pH to between about 7 and about 4.5 and then combining the acidified condensate with the brine. In a silica crystallizer stage in which flashed brine is contacted with a silica seed material to cause silica removal from the brine, the treated condensate is combined with the brine in a low pressure crystallizer upstream of brine clarification and reinjection stages.

Abstract: A method is disclosed for controlling the deposition of metal-containing scales, such as iron silicate scale, from a hot, aqueous, geothermal brine or the like, without substantial corrosion of brine handling equipment. The brine is contacted with (1) an amount of an acid sufficient to reduce the pH of the brine between 0.1 and 0.5 unit and (2) a greater than stoichiometric amount of a reducing agent for reducing trivalent iron and manganese cations in a high temperature brine solution to divalent ions. An overall decrease in scale deposition, especially of iron silicate scale, is achieved while a silver-rich scale can be recovered from silver-containing brines.

Abstract: A method is provided for combining a high pH steam condensate with a flow of an acidic geothermal brine from which the steam is extracted so as to inhibit the formation of suspended particulate matter by the chemical combining of impurities in the condensate and brine. The method includes acidifying the steam condensate, preferably by hydrochloric acid, to reduce the pH to between about 7 and about 5.5 and then permitting the acidified condensate to outgas such volatiles as hydrogen sulfide and carbon dioxide before combining the condensate with the brine, formation of such insolubles as heavy metal sulfides and calcium carbonate being thereby inhibited. In a silica crystallizer stage in which flashed brine is contacted with a silica seed material to cause silica removal from the brine, the treated condensate is combined with the brine in a low pressure crystallizer upstream of brine clarification and reinjection stages.

Abstract: A method for inhibiting the precipitation of a scale, such as an iron silicate scale, from a hot aqueous brine solution, such as a geothermal brine, during production and handling of the brine wherein there is injected into the brine a brine-soluble acid in an amount sufficient to lower the pH of the brine from 0.1 to 0.3 pH units.