Academic literature on the topic 'Sewage – Microbiology'

This investigation has demonstrated that levels of parasitism may provide a sensitive, biologically-based index of marine environmental pollution. Flatfish were initially selected as indicator hosts in field studies conducted at an 'accumulating' and two 'dispersing' sewage sludge dump sites in Scottish coastal waters, but the results indicated that they were unsuitable for monitoring sewage sludge dispersal. The common whelk, Buccinum undatum , was selected as an alternative host-parasite system in a seasonal study at the Garroch Head sewage sludge dump site in the Firth of Clyde, where marked spatial concentration gradients exist for a variety of trace contaminants in the sediments. Buccinum is first intermediate host to several species of larval digenean parasites. Parasite prevalence in Buccinum declined significantly along the gradient of increasing contamination of the sediments from approx. 15&'37 at 3km north of the dump to approx. 2&'37 on its periphery. At the reference site approx. 20&'37 of Buccinum were parasitised. Site, seasonal, sex and parasite effects on growth and the effects of exposure to sewage sludge on the age-prevalence relationship and host response to infection were examined. The age structures of Buccinum populations were used to compare mortalities due to fishing, parasitic infection and proximity to the dump site. Patterns in parasite prevalence recorded at the dump site were not correlated with any natural environmental or host related factors that were examined. The most commonly recorded parasite of Buccinum was Zoogonoides viviparus . Experimental studies demonstrated that the free-living miracidium and cercaria of Z.viviparus were the life-cycle stages that were most susceptible to sewage sludge. There was no evidence of sewage sludge toxicity to the parasitic stages within intermediate or flatfish definitive hosts. However, the survival of Baccinum was reduced by parasitism and experimental exposure to sewage sludge, and in a combination these two factors acted synergistically. The gradient in parasitism in Buccinum at the Garroch Head dump site is considered to result primarily from the toxic effects of trace metals on the miracidium, reducing parasite transmission to the molluscan host. The Buccinum -parasitesystem may therefore provide a sensitive and valuable index for monitoring the dispersal of these contaminants around the Garroch Head sewage sludge dump site. The potential role for a parasite-based index in marine pollution monitoring studies is discussed in the light of this investigation.

Caulobacters are gram-negative bacteria that have a biphasic life cycle consisting of a swarmer and a stalked stage. As a result they have elicited interest as a simple developmental model. Less attention has focussed on their role in the environment, although they have been found in almost every aquatic environment as well as in many soils. Caulobacters are often described as oligotrophic bacteria because of their prevalence in pristine waters but have now been isolated from the relatively nutrient-rich wastewater environment. In order to learn more about this population some basic characterization was carried out and an assay system to determine their prevalence in sewage plants was designed. Most of the organisms isolated from sewage treatment facilities had similar gross morphological features, but differed in holdfast composition, total protein profile, antibiotic resistance and restriction fragment length polymorphism, thereby indicating a greater diversity than originally assumed. Most of the organisms hybridized with flagellin and surface array genes that had previously been cloned, and only one of 155 non-Caulobacter sewage isolates hybridized with the flagellin gene probe; consequently these were used in a DNA-based enumeration strategy. DNA was isolated directly from sewage and probed with the flagellin and the surface array gene probes. The signals obtained were compared to standards made up of pooled Caulobacter DNA from the sewage isolates and non-Caulobacter DNA from organisms also present in sewage. Using this assay Caulobacters could only be detected above the 1% level, which was higher than their proportion in the wastewater environment. It appears that this approach will not be useful in monitoring Caulobacters in treatment plants unless a more highly conserved or higher copy number probe is found.<br>Science, Faculty of<br>Microbiology and Immunology, Department of<br>Graduate

Thesis (M.Dip.)--Cape Technikon, 1990<br>The die-off in the marine environment of micro-organisms that are present in sewage was investigated. A literature survey was carried out and studies were done in the laboratory, at an offshore outfall and at a surf-zone outfall. In the laboratory raw sewage was mixed with sea water at known dilutions and the die-off of faecal coliforms, faecal streptococci and coliphage was monitored. At the offshore sewage outfall a tracer, Rhodamine B.was released in the pump station and the distribution of the plume around the diffuser was determined by means of the Rhodamine B concentrations and faecal colifonns counts. At the factory surf-zone outlet the Rhodamine B was injected into the pipeline. Samples were taken at 50 and 100 meter distance from the outlet. Thedie-off of faecal colifonns, faecal streptococci and coliphage was monitored. The following results were obtained: Literature study: (i) Coliforms • Temperatures of 15 QC and lower are conducive to survival while nutrients, at a concentration as low as 2,5 mg/L organic carbon, stimulate growth. A rise in salinity has a negative effect on the organisms. • The T90 value in direct sunlight is <2 hours but vanes considerably in the dark (>35 days). Changes in weather• conditions, sunlight intensity, hours of sunlight, depth and turbidity of seawater and different seasons are the most important factors accounting for the variations in the T90 values. • It is, therefore, important for the initial dilution to be large enough. This will ensure that the bacterial counts conform to the water quality criteria, as the die-off rates in the marine environment are slow and not always adequate, except around mid day. • Faecal coliforms as a single parameter is not considered to be the best indicator of marine pollution. • The 1:4 ratio between faecal coliforms and faecal streptococci for human faeces and 1:0,7 ratio for animal waste are not applicable in the marine environment. The survival of faecal streptococci in seawater is better than that of faecal coliforms and the ratio therefore changes. (ii) Enterococci and pathogens • The T90 value for faecal streptococci is double that of coliforms and also varies in the dark. In direct sunlight any change in sunlight intensity, change the T90 values. • In general the numbers of faecal streptococci and pathogens occuring in sewage are smaller than those of coliforms, but their survival time is longer. This could lead to a situation where the water quality complies with the criteria according to the coliform counts, while a health risk may exist due to th survival of pathogens.

Ces travaux de thèse porte sur l'étude d'un procédé de traitement des eaux usées intitulé "anammox". C'est un procédé biologique reposant sur le métabolisme d'un groupe de bactéries du même nom permettant l'épuration de l'azote. Ces travaux développent une méthodologie pour leur identification et leur culture et aboutissent à la mise en application de bio-réacteur de traitement à l'échelle du laboratoire<br>This work focuses on the study of a wastewater treatment process entitled "anammox". It is a biological process based on the metabolism of a group of bacteria of the same name allowing the purification of nitrogen. This work develops a methodology for their identification, their culture and for the implementation of bioreactor treatment at the laboratory scale

Macromolecules such as proteins and polysaccharides can constitute a significant portion of dissolved organic carbon (DOC) in wastewater, but limited information is available on how these compounds are degraded in biological wastewater treatment systems. Bacteria cannot assimilate intact macromolecules but must first hydrolyze them to monomers or small oligomers. To better understand the mechanism of macromolecule degradation in wastewater treatment systems this study investigates two important questions of macromolecule metabolism. First, does hydrolysis occur in close proximity to the cell or are the hydrolytic enzymes released into bulk solution, and second, if hydrolysis is cell-associated, are hydrolyzed fragments directly assimilated into the cell or are they released back into solution? Fluorescent model substrate analogs were used to determine the location of leucine aminopeptidase and a-glucosidase activity in wastewater inoculated biofilm and suspended cultures and in trickling filter effluent. In biofilm and suspended cultures at least 93% of hydrolytic activity was cell-associated. In trickling filter effluent hydrolysis rates were at least five times higher in contact with cells and sloughed biofilm pieces than in cell-free solution. To determine whether hydrolytic fragments were directly assimilated or released into solution molecular size distributions in bulk solution were monitored using membrane ultrafiltration techniques during the degradation of the model protein, bovine serum albumin, and the model polysaccharides, dextran and dextrin, in batch and continuous suspended cultures, and in fixed-film reactor systems. Measurable amounts of macromolecule hydrolytic fragments accumulated in all reactor configurations, substrates and inocula tested. Relatively larger concentrations of hydrolytic fragments accumulated in pure culture than in wastewater culture inoculated reactors. These results support a generalized model for macromolecule degradation by bacteria that features cellbound hydrolysis of protein and polysaccharides and the subsequent release of hydrolytic fragments back into bulk solution. This hydrolysis and release is repeated until fragments are small enough ( < 1000 amu) to be assimilated by cells. A separate, but related, part of this study adapted pre-column orthophthaldialdehyde derivatization, reverse phase high performance liquid chromatographic separation and fluorometric detection to measure free and combined amino acids in unconcentrated wastewaters and to assess their treatability in wastewater treatment systems.

Because of the potential health hazards associated with the use of sludge for agricultural purposes, Dudley et al (1980) published a scheme for the routine analysis of bacteria in municipal sewage sludge. In this study, the Dudley et al scheme (1980) was modified by updating some of the procedures. Aerobically digested sludge generated by the Bowling Green Wastewater Treatment Plant, Bowling Green, Kentucky, was analyzed using the modified scheme. Sludge samples were collected once every two months over a one-year period from October 1989 to August 1990. Egg yolk-free tryptose sulfite cycloserine agar in conjunction with the revewrse CAMP test was used to assay for Clostridium perfringens. This procedure improved the one proposed by Dudley et al. (1980) by achieving a higher confirmation rate, reducing testing time, allowing for easier interpretation of results, and increasing accuracy. Selective and differential media by Rippey and Cabelli (1979) were added to the scheme to isolate Aeromonas, Aeroomonas hydrophila and Aeromonas caviae were successfully isolated wand were identified using the system by Cunliffe and Adcock (1989) for speciating aeromonads. Baird-Parker medium was compared to mannitol salt agar for effectiveness in isolating Staphylococcus from sludge. Statistical analysis showed Baird-Parker medium to be significantly more effective than mannitol salt agar. However, neither agar reduced background flora to acceptable levels. Staphylococcus isolates were subject to species identification by the API Staph Ident system (Analytab Products, Plainview, New York). Staphylococcus xylosus, Staphylococcus haemolyticus, and Staphylococcus epidermidis were found to be present in the sludge. A procedure by Ottolenghi and Hamparian (1987) was employed to isolate Salmonella in sludge. No salmonellae were isolated over the one year period. Over the year-long study, bacterial numbers, with the exception of Clostridium perfringens and the total aerobic count, fluctuated with variations in the aerobic digester temperature. Numbers decreased as temperature increased. Clostridium perfringens counts were the most consistent throughout the year and exceeded fecal coliform and fecal streptococci counts in five of the six samplings.