Abstract: Cyanide (free or as a metal complex) dissolved in an aqueous solution such as waste waters is substantially completely removed by the addition of ferrous bisulfite which forms insoluble Prussian blue and other non-toxic reaction products.

Abstract: Process for the treatment of decontamination effluents, more particularly the components of nuclear reactors, of the type containing in solution permanganate, phosphate and sulphate ions and active manganese, chrome and cobalt ions, wherein it comprises the successive stages of reducing the permanganate ions by adding hydrogen peroxide, alkalization to a pH equal to or above 12, separation of the precipitate formed and final acidification of the residual liquid phase to bring its pH to a value compatible with discharge into the environment.The invention also relates to an apparatus for performing the above process.

Abstract: Method and apparatus for removing heavy metals as sulfides from aqueous liquids. The aqueous liquid is introduced into a circulating liquid loop wherein there are established a mixing zone, a controlled precipitation initiating zone, a crystal growing zone and a crystal settling zone. The aqueous feed liquid containing H.sub.2 S dissolved therein and at a pH below that at which the sulfide is precipitated is mixed in the loop with a pH-adjusting liquid; and the degree of supersaturation with respect to the metal sulfide is maintained within the controlled precipitation initiating and crystal growing zones in the metastable condition so that the growth rate of the metal sulfide crystals remains greater than under uncontrolled conditions vis-a-vis the nucleation rate to effect the production of metal sulfide crystals of a character which makes it possible to separate them through clarification and filtration.

Abstract: Processes for treating the waste water, particularly waste water containing certain unsaturated compounds, from acrolein and acrylic acid production plants to reduce the chemical oxygen demand (COD), which processes comprise polymerizing the unsaturated compounds, desirably with peroxygen compounds; neutralizing the waste water with a reagent forming polyvalent metal ions to provide salts of the polymerized compounds; and separating the salts so formed.

Abstract: Solid and/or dissolved contaminants are separated from a polar liquid such as water by providing in the contaminated liquid medium a galvanically charged particulate dispersion of defined size, concentration, density and free surface energy, and then flowing such loaded medium through successive treatment zones of an electrically insulated apparatus at a rate defined by dimensionless parameters such as Reynolds Numbers so as to prevent phase separation. Gaseous oxygen adheres to particle surfaces and oxidation is further promoted by bringing medium to pH 2.0 to 2.5 as with sulfur dioxide gas, plus exposure to action of heavy-metal ions such as ferrous/ferric. After air blowing, medium is neutralized and brought to pH 10-11 with continuous aeration of suspended flocculant, then treated with soda ash and optionally additional particulate (recycled sludge), and the contaminant matter then allowed to precipitate with concurrant galvanic grounding of the medium.