SummaryExperimental evidence is presented which indicates t8hat both chemical and autoflocculation of microorganisms occur by the same mechanism. Basically, long chain polymeric species attach themselves between the microbial particles and agglomerate them into flocculant particles of sufficient magnitude to subside from suspension under quiescent conditions. Properties of the polymers which are produced during autoflocculation are investigated and these polymers are shown to be capable of causing the agglutination of inorganic colloids such as alumina. It is hypothesized that these biologically generated flocculating polymers could belong to a class of compounds known as transport enzymes. The experimental data qualitatively agrees with this hypothesis.Biological treatment systems currently are used extensively in the treatment of domestic and industrial wastewaters. Aerobic heterotrophic systems (e.g., activated sludge, trickling filters) are conventionally used for the removal of organic pollutants as are anaerobic heterotrophic systems (e.g., anaerobic digesters, anaerobic lagoons). Autotrophic systems (e.g., algal ponds, lagoons) are utilized for the removal of inorganic pollutants such as nitrogeneous and phosphatic compounds. Combined autotrophic heterotrophic systems (e.g. , oxidation ponds, activated algal systems) have also been successfully employed for the concurrent removal of organic and inorganic impurities from wastewater.The two basic design considerations of any biological wastewater treatment system are: 1) providing environmental conditions satisfactory for the removal of pollutants from the wastewater by the metabolic activities of the microorganisms, and

From previous work it appears that total phosphorus is transported through rivers by a series of storm events. This paper presents a method for calculating the average distance of travel during any given storm event. The method uses the hydrograph, chemograph, and flow characteristics at a point in the river. Comparisons were made between storm events at the same station in a river, between different stations in the same river basin, and between stations in different rivers. Results show the distance of travel is dependent upon the magnitude and duration of the storm event but not on the magnitude of the total phosphorus concentration.

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The effective enzyme activity decay can be decreased by diffusion limitation in the immobilized pellet. Thiele modulus changes and/or poisoning of various enzyme forms are two phenomena which are influenced by diffusion limitation. This article considers these effects on enzyme decay as applied to glucose isomerase.

Simultaneous measurements of the drop size distributions and rate of dispersed-phase mixing were obtained for an agitated liquid-liquid dispersion in a 1.36-L vessel under steady-state, continuous flow conditions. The impeller speed was varied from 160 to 278 rpm, and the dispersed phase fraction from 0.05 to 0.20. A regime was discovered in which the rate of dispersed-phase mixing varied as the impeller speed to about the tenth power, while the mean drop size was little altered. This is interpreted as a competition between drop breakage rate, drop coalescence rate, and drop flow-departure rate, with a very strong dependence of breakage and coalescence rates on agitation and drop size over certain ranges of these variables.Previously (Verhoff et al., 1977), a technique has been described by which a liquid-liquid dispersion may be sampled to obtain simultaneous measurements of the volume and a tracer-dye concentration for each of a large number of drops.