Abstract: A biological process is described for caustic waste streams containing inorganic sulfides to effect neutralization of the caustic and, oxidation of sulfides to sulfate. The process is based on the contact of these caustic streams with mixed, fiocculated cultures of a sulfide-oxidizing bacterium from the genus Thiobacillus and various heterotrophs. The process may also degrade any organic components present in the waste stream.

Abstract: A biological process is described involving the conversion of SO.sub.2 to H.sub.2 S using sulfate reducing bacteria in co-culture with facultatively anaerobic heterotrophs under anaerobic conditions in a maintenance medium which includes a substrate fermentable by the facultatively anaerobic heterotrophs to produce an end product which acts as the carbon and energy source for the sulfate reducing bacteria. Glucose and sewage sludge are the two fermentable substrates described. The process is described as being used in conjunction with a process for removing SO.sub.2 from a flue gas and then converting the SO.sub.2 to H.sub.2 S. The H.sub.2 S may be reacted with some remaining SO.sub.2 in a Claus reactor to produce elemental sulfur or the H.sub.2 S may be used as a reducing gas to regenerate the sorbent being used to remove the SO.sub.2 from the flue gas.

Abstract: Methanotropics are grown in a bioreactor containing a solid support. They decompose halogenated aliphatic hydrocarbons found in ground water. The growth of the bacteria and the methane concentrations in the biomass reactor are controlled to significantly enhance the degradation of the hydrocarbons.

Abstract: Disclosed is a process by which a gas containing nitric oxide is contacted with an anaerobic microbial culture of denitrifying bacteria to effect the chemical reduction of the nitric oxide to elemental nitrogen. The process is particularly suited to the removal of nitric oxide from flue gas streams and gas streams from nitric acid plants. Thiobacillus dentrificians as well as other bacteria are disclosed for use in the process.

Abstract: A process is disclosed for treating water or solids contaminated with a nitro- or nitroso- substituted compound comprising reducing a nitro- or nitroso- substituted compound in the presence of an effective catalytic amount of at least one of a corrin- or porphyrin- metal complex. The present invention is particularly useful in treating waste water or soil contaminated with nitro- or nitroso- substituted compounds.

Abstract: A process for treating water or solids contaminated with at least one chlorinated phenol which comprises oxidizing the at least one chlorinated phenol in the presence of an effective catalytic amount of a corrin- or porphyrin-metal complex. A preferred catalyst is a complex of Fe.sup.3+ ion with protoporphyrin known as hematin. Chlorinated phenols which may be oxidized include those found in hazardous wastes such as chlorophenols, dichlorophenols, trichlorophenols, tetrachlorinated phenols, and pentachlorinated phenols.