M. Tsezos

Comparison of the biosorption and desorption of hazardous organic pollutants by live and dead biomass

The adsorption and desorption of lindane, diazinon, pentachlorophenol and 2-chlorobiphenyl by living and dead cells of the fungus R. arrhizus and activated sludge was studied. A generalization concerning the relative magnitude of biosorptive uptake between live and dead biomass cannot be made using the experimental data. Uptakes by live and dead cells are similarly correlated to the octanol/water partition coefficient of the organic pollutants. The desorption of the organic pollutants is not always complete. A part of the observed biosorptive uptake can be attributed to the cell walls of the microbial biomass.

The adsorption of chloroethanes by microbial biomass

Abstract The adsorption isotherms of halogenated aliphatic hydrocarbons by various selected types of inactive microbial biomass were determined. The isotherms were shown to be independent of the initial organic solution concentration and could be described by a modified Freundlich adsorption equation. Biosorptive uptake capacities varied among the biomass species. The water solubility and the octanol/water partition coefficient of the tested organics affected the biomass uptake capacity. In general, the least water soluble component showed the greatest tendency to be accumulated by the microbial biomass. The results also suggest that structural differences among the various microbial biomass types and possibly the fragmentation of the microbial cells, also affect the biomass uptake capacity for both single and mixed-solute systems.

Significance of biosorption for the hazardous organics removal efficiency of a biological reactor

Abstract Pilot plant data on the removal of lindane and pentachlorophenol by a conventional activated sludge pilot plant reported in the literature were combined with lindane and pentachlorophenol biosorption equilibrium data in order to calculate the pollutant concentrations in the pilot plant effluent and the biological sludge. The result showed that biosorption is a significant mechanism that affects the fate of non-degradable organic pollutants in biological waste water treatment plants.

The selectivity of biosorption of hazardous organics by microbial biomass

Four hazardous organic compounds (lindane, pentachlorophenol, diazinon and melathion) were selected and their biosorption isotherms by two types of microbial biomass (activated sludge and R. arrhizus) were determined from multisolute solutions. The selectivity of biosorption was subsequently quantified through the use of bioconcentration factors. It was shown that, for the compounds that are biosorbed (lindane, pentachlorophenol and diazinon) and within the range of the pollutant concentrations found in wastewater treatment plants, the competition effects are usually minimal. Analysis of the competitive biosorption data, assuming a surface filling mechanism, suggests that hazardous organics biosorption cannot be described successfully by a simple adsorption hypothesis.

A method for the calculation of biological film volume in a fluidized bed biological reactor

Abstract In a fluidized biological reactor, knowledge of the volume of the biological film surrounding each growth support particle is critical to the proper engineering of such reactors. A system of equations has been developed to correlate fluidized bed height with biological film volume. The predictions of the developed correlation have been compared to experimentally measured values. The comparison indicates good agreement when growth is fully developed in the reactor.

A mechanistic study on the fate of malathion following interaction with microbial biomass

The fate of malathion following interaction with live and dead microbial biomass was studied. The experimental results from equilibrium, kinetic and carbon-14 studies suggested that malathion is adsorbed and then chemically decomposed by the microbial biomass into water soluble products. This chemical transformation that was effected by the microbial biomass is not an active metabolic process as it is also exhibited by dead cells and isolated microbial cell walls.

The Pilot Plant Testing of the Continuous Extraction of Radionuclides Using Immobilized Biomass

Microbial biomass has been shown to be able to sequester a variety of metal ions from aquatic solutions. The selective extraction of metal ions from dilute complex solutions by microbial biomass has been termed biosorption. The biosorption of metals is characterized by high selectivity for certain metal ions which is exhibited equally well by live and dead cells. This high selectivity is also exhibited in very complex ionic matrices as for example in acid mine drainage or biological leachate solutions (1,2).