Thesis (M. Sc.)--University of Adelaide, Dept. of Botany, 1996? / Includes bibliographical references.

The purpose of this investigation was to explore how geosmin, an odorous compound produced by certain algae and actinomycetes, may affect the growth of a selected, odor producing actinomycete of the genus Streptomyces.

No description available.

The purpose of this study was to determine the effect of varying concentrations of geosmin on the growth of Bacillus cereus.

Water is a vital natural resource. To develop more sustainable water systems, we must focus efforts on the removal of persistent contaminants. Aqueous organic contaminants include azo dyes, halogenated organics (e.g. pesticides), and algal and bacterial metabolites. The latter are common to surface waters and freshwater aquaculture systems and can cause taste and odor problems. Two of the principal organoleptic compounds are geosmin and 2-methylisoborneol (MIB). Traditional oxidation treatment methods, utilizing chlorine, hydrogen peroxide, and potassium permanganate, have been employed with varying levels of efficacy for removal of these and other organic contaminants. Advanced Oxidation Processes (AOPs) have greater potential for the removal of persistent contaminants than traditional methods due to their higher pollutant removal rates, their ability to degrade a variety of organic material, and their ability to completely mineralize compounds [1]. An emerging AOP technology is the use of titania based photocatalysts for water treatment. Titanium dioxide (TiO2) is an effective, inexpensive, and stable photocatalyst used for the decomposition of aqueous organics. Titania is primarily activated by the ultraviolet portion of the spectrum due to its energy band gap of 3.0-3.2 eV (depending upon crystalline structure). Photocatalytic efficiency can be enhanced or tuned through the use of semiconductor dopants and the variance of titania crystal structure (i.e. anatase to rutile ratios). Metal oxides, like indium vanadate (InVO4), may enhance reaction rates through new interfacial reaction sites and electron scavenging, transport, and storage. InVO4 has been shown to have four sub-bandgap transitions, of which three are in the visible range [2]. In this work, the synthesis of InVO4-TiO2 composite semiconductors is examined to shift photo-initiation into the visible portion of the spectrum. Parametric studies of the visible spectrum photodegradation of methyl orange, an azo dye, and 2-chlorophenol provide a basis for analysis. Methyl orange was utilized to ascertain the effect of pure and mixed phase titania in the semiconductor composites. The TiO2 photodegradation of geosmin and MIB has been previously demonstrated in small-scale batch slurry reactions. Slurry systems require the downstream separation of catalyst from the liquid. Laboratory trials use centrifugation or micro-filtration. Alternatively, immobilization of the photocatalyst could allow scale-up of the process. Here, titania was immobilized on glass plate substrates using an ethanol spray technique. Finally, naturally tainted waters may contain a number of constituents in addition to the target compounds. In recirculating aquaculture systems, the water contains natural organic matter (NOM), ammonia, nitrite/ nitrate, and carbonate species. These constituents may block light penetration, block reaction sites, scavenge hydroxyl radicals, or affect the surface chemistry of the catalyst. Further, geosmin and MIB concentrations are extremely low, in the ppt range. Naturally tainted waters from MOTE Marine Laboratory Aquaculture Research Park are treated in the laboratory and in situ to demonstrate TiO2 degradation efficiency for trace concentration geosmin and MIB degradation in a complex water matrix.

Iodine number, BET surface area, taste and odour compound isotherms, and trace capacity number tests were used to rank five different granular activated carbons according to thermodynamic adsorption performance. These tests were compared to expected activated carbon service life and loading results of rapid small-scale column tests (RSSCTs) run with water from two lake sources spiked with geosmin and 2-methylisoborneol (MIB). Trace capacity number, used to specifically identify high adsorption energy sites on activated carbon, was hypothesized to be correlated to geosmin/MIB breakthrough and loading performance of different activated carbons. This study found no such clear correlation. However, when only bituminous coal activated carbons were considered, correlations to MIB breakthrough were strengthened. Natural organic matter (NOM) adversely affected adsorption, resulting in decreased RSSCT throughput to breakthrough in surface water with higher total organic carbon (TOC). Methods for improving characterization tests and RSSCTs when NOM is present are discussed.

Iodine number, BET surface area, taste and odour compound isotherms, and trace capacity number tests were used to rank five different granular activated carbons according to thermodynamic adsorption performance. These tests were compared to expected activated carbon service life and loading results of rapid small-scale column tests (RSSCTs) run with water from two lake sources spiked with geosmin and 2-methylisoborneol (MIB). Trace capacity number, used to specifically identify high adsorption energy sites on activated carbon, was hypothesized to be correlated to geosmin/MIB breakthrough and loading performance of different activated carbons. This study found no such clear correlation. However, when only bituminous coal activated carbons were considered, correlations to MIB breakthrough were strengthened. Natural organic matter (NOM) adversely affected adsorption, resulting in decreased RSSCT throughput to breakthrough in surface water with higher total organic carbon (TOC). Methods for improving characterization tests and RSSCTs when NOM is present are discussed.

This thesis outlines results of a series of studies investigating the removal of two common taste and odour compounds, 2-methylisoborneol (MIB) and geosmin, from drinking water using biologically active sand filtration. A combination of full-, pilot- and laboratory-scale studies were carried out. A review of long term water quality data from a South Australian water treatment plant indicated that the conventional plant was capable of removing MIB and geosmin to below detection limit without the need for additional treatment. A series of laboratory studies were carried out, validating the theory that the geosmin removal was occurring through biological activity in the rapid gravity filters of the water treatment plant. Microorganisms capable of geosmin removal were found to be present in the settled water of two South Australian water treatment plants, Morgan and Happy Valley. Laboratory sand column experiments were conducted with these waters and a range of sand media, investigating the effect of biofilm development on MIB and geosmin biodegradation. It was found that the process could produce effective removals, however long start-up periods were often required. A laboratory-scale column utilising new sand fed with Happy Valley settled water took in excess of 300 days before it was capable of removing MIB and geosmin by greater than 80%. Studies on sands with inactivated pre-existing biofilms required much shorter biofilm development periods, from 30 to 40 days. The results of the column studies indicated that a method to encourage sand filters to operate biologically for MIB and geosmin removal would be advantageous. Two methods were studied: preozonation and bacterial inoculation. Pre-ozonation was carried out at a pilot plant, constructed at the Happy Valley water treatment plant. Additional factors investigated during this study were the length of the biofilm development period and the impact of empty bed contact time (EBCT). Preozonation is often used in tandem with biological filtration to increase the fraction of biodegradable organic matter and in turn increase the biomass activity of the filter. The pilot plant consisted of two sand filters; one fed with settled water and one fed with preozonated settled water. Pre-ozonation did not enhance the biodegradation of MIB or geosmin. The pre-ozonated column was run for 550 days. Removals of MIB and geosmin were inconsistent throughout the trial. The maximum removal obtained during the study was 80% for MIB and geosmin, at an EBCT of 45 minutes, after 380 days of operation. The settled water column was run for over 650 days. By day 560, the column was able to remove 60% of the influent geosmin and 40% of the influent MIB at an EBCT of 10 minutes, which is close to that used in full-scale plants. Significant effects of empty bed contact time were not noted in the range of 10 to 30 minutes. Bacterial inoculation studies were carried out at laboratory-scale. The inoculum comprised of a geosmin-degrading consortium of three Gram-negative bacteria previously isolated from the biofilm of the Morgan water treatment plant filter sand. A sand column with a pre-existing biofilm was inoculated with the organisms, achieving 70% removal of geosmin. Inoculation of columns without biofilms gave lower geosmin removals, with an average of 41% removal. These were preliminary studies only, and further work is required. A biomass activity assay, based on the concentration of adenosine triphosphate (ATP), was developed over the course of the project. This assay was particularly helpful when studying the attachment of the inoculum in the laboratory columns. Other methods to study biomass were flow cytometry to enumerate the water-borne and biofilm associated bacteria, and scanning electron microscopy to obtain a visual observation of the biofilms on various sands. This work demonstrated the potential of biological sand filtration for MIB and geosmin control. It was shown that long biofilm development periods are evident before effective removal of the compounds can occur. The potential to minimise these long biofilm development periods by inoculation of filters with geosmin degrading organisms was demonstrated. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1340100 / Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2008

Indiana University-Purdue University Indianapolis (IUPUI) / The accelerated growth of algal blooms in water bodies has caused the increased occurrence of taste and odor (T&O) episodes worldwide. Even though T&O compounds have not been associated with adverse health effects, their presence can have extensive socio-economic impacts in contaminated waters. Eagle Creek Reservoir, a eutrophic water body, which supplies about 80% of Indianapolis drinking water, experiences frequent and sometimes severe odorous outbreaks. The terpenoid bacterial metabolites, 2-methylisoborneol (2-MIB) and geosmin, have been identified as the main compounds contributing to those T&O problems, which occur seasonally when the reservoir receives most of its water and nutrient loads from discharge events. In this study, ECR’s microbial community composition was assessed by a 16S next generation sequencing approach, confirming the presence of the major bacterial phyla of Cyanobacteria, Proteobacteria, Actinobacteria and Bacteroidetes, which are commonly found in freshwater environments. The relative abundance of Cyanobacteria, which are regarded as the main T&O producers in freshwater, followed the fluctuation of 2-MIB and geosmin concentrations closely. Mapping sequence analysis of a metagenomic dataset, successfully recovered the genes responsible for the synthesis of geosmin and 2-MIB, demonstrating the microbial ability for odorous compound production in ECR. Quantification of the geoA and MIBS genes in Cyanobacteria was achieved by the development and application of qPCR assays on water samples collected from the reservoir. A statistically significant positive correlation was found between MIBS gene quantity and MIB concentration for all sampling locations, implying that this assay could potentially be used as a tool for the early prediction of upcoming T&O episodes. The geoA gene detection assay, did not correlate well with geosmin concentrations, suggesting that even though the gene might be present, this does not necessarily mean that it is metabolically active.

Geosmin is a strong musty-flavored organic compound that is responsible for many taste-and-odor events in surface drinking water sources like lakes and reservoirs. The taste threshold of geosmin for humans is lower than 10 ng/L. Traditional treatment methods will not remove geosmin to this level. Additional water treatment methods must be implemented to successfully remove the geosmin and its associated flavor and odor from drinking water. Furthermore, geosmin is produced by cyanobacteria somewhat sporadically, so it is difficult to predict when taste-and-odor events are going to occur. The difficulty involved with predicting geosmin events has led most water treatment facilities to adopt reactive approaches towards geosmin treatment; these facilities typically treat for geosmin in response to complaints of an earthy off-flavor in the drinking water. This reactive approach causes issues with consumer confidence, as the flavor of the water is one of the only metrics a consumer has for judging the safety of his or her water. To enable proactive treatment of geosmin from water, more sensitive methods for geosmin detection or taste-and-odor event prediction must be developed.This study investigates the use of quantitative Polymerase Chain Reaction (qPCR) for the early detection of geosmin-producing cyanobacteria. qPCR can detect geosmin-producing cyanobacteria via their DNA. I developed a qPCR assay for this study that is capable of sensitively detecting multiple strains of the geosmin-producing Nostoc genus. The developed assay showed high sensitivity, demonstrating the possibility for its use in detecting low concentrations of geosmin-producing cyanobacteria before detectible levels of geosmin have been produced and released into the water. Through further sequencing of more geosmin-producing genera and species, the methodology outlined in this research could be applied to develop the tools necessary to predict taste-and-odor events caused by geosmin-producing cyanobacteria.