Scholarly Work - Center for Biofilm Engineering

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Effect of hypochlorite on microbial slimes
(1971-05) Characklis, William G.
Oxygen supply limitations in full scale biological treatment systems
(1972) Matson, J. V.; Characklis, William G.; Busch, A. W.
The effluent refractory assessment concept
(1972) Busch, A. W.; Characklis, William G.
Industrial wastewater treatment
(1972) Characklis, William G.; Busch, A. W.
Mathematical model for biological reactor design incorporating characteristics of cell aggregates
(1973) Matson, J. V.; Characklis, William G.; Rios, R. A.
Attached microbial growths-I. Attachment and growth
(1973-08) Characklis, William G.
Water-soldi interfaces occur universally and are critically important in natural andindustrial processes. Microorganisms accumulate at these interfaces, frequently withbeneficial effects.A trickling filter can be described as a fixed bed reactor supplying a large amountof surface area used for the purification of organic waste of domestic or industrialorigin. Microorganisms attach to the packing material and form a reactive surface forthe adsorption and breakdown of the wastes. The benthos of natural streams carriesout an analogous process although this can be a significant drain on the oxygenresources of the stream.More often, however, microbial attachment is undesirable. Marine fouling isinitiated by the development of slimy films on submerged surfaces. The formation ofsuch primary films is believed to be a necessary precursor of heavy fouling (WOOD,1967) and is, at least in part, the result of microbial activity.
Attached microbial growths-II. Frictional resistance due to microbial slimes
(1973-09) Characklis, William G.
A number of cases have been reported in which water-carrying conduits have suffered from remarkable losses in delivery capacity within relatively short operation periods. In one instance (SEI~RT et al., 1950), the maximum capacity of a 24-in. (nominal diameter), 50 mile long water supply line was reduced to about 55 per cent of its original value within a few years. The loss was due to a thin, slimy layer that consisted largely of organic material imbedded with fine clay particles and was not caused by a substantial decrease in effective internal diameter. The layer was characterized by a "ripple-like" surface having an average height of 0.025 in. The results indicate that this type of roughness could not be explained in terms of equivalent sand roughness common to friction factor relationships.The rippled surface structure seems to be an essential, but not the only, factor involved in the unusual frictional behavior caused by microbial slimes. Experiments using solid surfaces of similar pattern have shown a high frictional resistance, but not nearly as high as those occurring in water mains.
Diffusion and reaction in microbial aggregates
(1974) Characklis, William G.; Pipes, D. M.; Matson, J. V.
Fate of cyanide and related compounds in industrial waste treatment
(1974) Raef, S. F.; Characklis, William G.
Fate of cyanide in aerated microbial systems
(1975) Raef, S. F.; Characklis, William G.; Kessick, M. A.
Maximum utilization of water resources within a planned community
(1975) Characklis, William G.; Gaudet, F. J.
Temporal characteristics of stormwater runoff: an overview
(1975) Zogorski, John S.; Characklis, William G.
Characteristics and management of storm runoff in a planned community
(1975) Characklis, William G.; Zogorski, John S.; Roe, Frank L.
Algal Bioassay:Evaluation of Eutrophication Potential of Stormwater Runoff
(1976) Ward, C. H.; King, J. M.; Characklis, William G.; Roe, Frank L.
Diffusion into microbial aggregates
(1976) Matson, J. V.; Characklis, William G.
Theoretical work in the biological waste treatment field has been directed at modeling substrate removal processes in fluidized and fixed film microbial systems in terms of the basic rate processes. Much of the research has been directed at delineating the rate limiting steps to simplify the problem. Various researchers have shown that the rate limiting step can be mass transfer through the microbial aggregate to the active sites at the cells. Therefore, any mechanistic model that incorporates mass transfer must be sensitive to variations in the reactant diffusion coefficient through floc material. A direct measure of mass flux has been developed to determine the variations in the diffusion coefficients of glucose and oxygen through microbial aggregates grown under various experimental conditions. A factorial analysis indicated significant changes in the molecular diffusion coefficient with variations in sludge age and carbon-nitrogen ratio in the growth media. Oxygen diffusivity varied from 20 to 100% of its value in water, glucose from 30 to 50%. A simple zero order diffusion-reaction kinetic model for spherical floc was constructed. It indicated that oxygen diffusion limitations are possible in the high rate activated sludge processes with large floc particles.
The influence of carbon-nitrogen ration on the chlorination of microbial aggregates
(1976-01) Characklis, William G.; Dydek, S. T.
Experiments were conducted with attached microbial films in a continuous flow reactor to determine the response of the film to hypochlorite treatment as a function of influent substrate concentration, influent carbon-nitrogen ratio (C/N) and shear force at the slime-water interface. Experiments were also conducted in batch systems with suspended organisms grown at varying C/N.Results were obtained regarding the relationship of bactericidal action to slime destruction. Comparison of experiments with HOCI and Hg2+ indicate that bactericidal efficiency does not influence slime destruction. Destructive effects of hypochlorite oxidation were noted by measuring decrease in solids concentration of bacterial cultures.
Modeling urban runoff from a planned community
(1976-04) Diniz, E. V.; Holloway, David; Characklis, William G.
Treatment of wastewater from torpedo refueling facilities
(1977) Kessick, M. A.; Characklis, William G.; Elvey, W.; Metzgar, L. P.
Control of microbial fouling in circular tubes with chlorine
(1977) Norrman, G.; Characklis, William G.; Bryers, James D.
Fate of cyanide and related compounds in aerobic microbial systems-I. Chemical reaction with substrate and physical removal
(1977) Raef, S. F.; Characklis, William G.; Kessick, M. A.; Ward, C. H.
The chemical reaction of cyanide with substrate was investigated in sealed glass ampoules using glucose as substrate and inorganic buffers. The reaction was found to be pseudo-first order and pH dependent, with an optimum pH near 11.0. The cyanide-glucose reaction products were found to be biodegradable by both acclimated and unacclimated heterogeneous cultures in shake flask and BOD bottle systems.Adsorption onto microbial solids was investigated using sealed, stirred glass reactors containing bacteria and potassium cyanide in water buffered at pH 7.0 with inorganic buffers. Very little adsorption occurred on a starved non-flocculating pure culture of Bacillus meqaterium, although up to 15% adsorption occurred in systems containing a stirred flocculent heterogeneous culture.Stripping was investigated from a starved heterogeneous culture in an aerated microfermenter at neutral pH. Hydrogen cyanide and carbon dioxide in the off-gas were trapped in sodium hydroxide solution, separated and analyzed. Stripping removed up to 80% of original cyanide, and tests using K14CN revealed that a small amount of cyanide had been metabolized.