Abstract: A method for removing the oxy-anions of selenium from FGD scrubber purge water. The purge water is contacted with free hydroxyl radicals to effect oxidation of reduced forms of sulfur to sulfate and the destruction of sulfur-nitrogen compounds present in the purge water. The purge water is then subjected to chemical reduction and co-precipitation of selenium with an amount of ferrous ions effective to remove the oxy-anions of selenium in the liquid in less than 30 minutes of reaction time. The resultant ferrous-selenium solids generated are separated and stabilized to elemental selenium in a separate reaction vessel.

Abstract: A method for improved slurry-phase bioremediation treatment of organic sludge and mixtures of organic sludge and organics-contaminated soils by dissolving the contaminants into an aqueous phase and microbially degrading same. A high solids slurry of the sludge and soils is formed with water and an active bioslurry consisting of large populations of acclimated hydrocarbon-utilizing bacteria and small amounts of biodegradation residue. The slurry is passed through a plurality of in-series bioreactors in each of which a low hydraulic shear is maintained to promote the development of a large population of microorganisms that will form flocculent suspensions. The output from the series of bioreactors is flowed continuously or semicontinuously to a liquid-solids separator to partition the mixed liquor bioslurry from the biodegraded waste residue The mixed liquor bioslurry containing small amounts of biodegradation residue is returned to the slurry being processed for recycling.

Abstract: Free cyanide-containing wastewater is treated to destroy the free cyanide content thereof by the step of treating said water with sulfur in the form of polysulfide in an integrated process wherein thiocyanate is also eliminated to produce a non-hazardous wastewater effluent and treating the wastewater in a second step with cultures of bacteria of the genus Thiobacillus in combination with nitrifying bacteria which oxidize ammonia to nitrite to nitrate. The first step is preferably carried out in the presence of a cationic surfactant, preferably a quaternary cationic surfactant, as a catalyst.

Abstract: Free cyanide-containing wastewater is treated to destroy the free cyanide content thereof by the step of treating said water with sulfur in the form of polysulfide in an integrated process wherein thiocyanate is also eliminated to produce a non-hazardous wastewater effluent and treating the wastewater in a second step with cultures of bacteria of the genus Thiobacillus in combination with nitrifying bacteria which oxidize ammonia to nitrite and nitrite to nitrate. The first step is preferably carried out in the presence of added metallic zinc.