There is growing evidence that even low levels of phosphorus (< 0.1mgL-1) entering natural water systems can cause eutrophication. Waste water treatment plants discharge over 23kT of phosphorus into UK surface waters per year. The Water Framework Directive requires that this be greatly reduced. Although many processes have been developed, they are often complex and energy intensive. This thesis aimed to assess how a novel process using dewatered water treatment works residuals (DWTR) could be engineered to maximize phosphorus removal from waste water treatment plant effluents while minimising system complexity and energy use. An extensive yearlong experiment was operated at two sites to investigate how phosphorus removal rates varied over time in relation to DWTR type, phosphorus concentration, hydraulic retention time (HRT) and scale. DWTR from eight different water treatment works were used in 35 experimental models of dimensions 0.1Ø x 1m and two meso scale beds 1x1x0.8m. The most significant factors effecting P removal rate were found to be DWTR type and media particle size. Total P removal varied between 58-95% for the 8 different DWTR over the year. Increasing particle size from 0.6-2 to 6-20mm reduced P adsorption capacity by 30% on average with 6 hours HRT and 5mgL-1 TP input. The key physical and chemical properties of the DWTR were measured to assess the effect of the parameters on the P removal ability of the media. No significant relationship (p < 0.05) between the amount of Al, Fe, Ca or Mg in the media and its P removal ability were found. An idealised adsorption system using DWTR as the media would operate with 2 to 3 beds in series with a minimum HRT of 6 hours and maximum particle size of 6mm and depth of 1m. Computer models of such a system predict >95% TP removal for over two years of operation.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:720915 |
| Date | January 2017 |
| Creators | Gersten, Benjamin |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/103678/ |
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