Selection and Adaptation of Microorganisms in Waste Treatment

Abstract

Micro-biological metabolism is the basic mechanism in purification of polluted water and wastes. Purification of such waters by biological treatment processes, i.e., activated sludge, trickling filters, oxidation pond, etc., is not essentially different from natural stream-self-purification. The active members of a particular system are dependent on the organic and inorganic content, and on pH and temperature of the substratum, and have been selected and adapted from the infinite number of microorganisms and microenvironments present in soil, bottom muds, composts, etc. Selection is accomplished by fortuitous matching of potentially competent microorganisms of the habitat and available appropriate waste materials. Further adaptations are achieved by the acquisition of additional enzymes either by activation of latent characteristics or by genetic changes that arise spontaneously or by stimulation from environmental forces. Mutations may produce variants that are either more or less suited to the environment. Only the "more fitted" progeny are likely to survive. The parts played by other genetic changes such as recombination, transformation and transduction in the selection of the microbial biota in waste treatment processes cannot presently be assigned.