Full-scale trials of external nitrification on plastic media nitrifying trickling filter

Master Thesis


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University of Cape Town

In South Africa, many wastewater treatment plants (WWTP) still make us of their rock filled trickling filters. Instead of using them for organics removal and nitrification, there is growing interest in integrating them with biological excess P removal activated sludge (BEPRAS) systems in an external nitrification flow scheme (Hu et al., 2000). In such a scheme, the full influent flow (after primary settling) is discharged to the anaerobic reactor of the BEPRAS system, after which the activated sludge is separated from the water by internal settling tanks. The clarified supernatant is pumped to the trickling filter for nitrification and the activated sludge to the anoxic reactor of the BEPRAS system, where the nitrified water rejoins the main BEPRAS system. This external nitrification BEPRAS system has several advantages over continuing to use the trickling filters for organics removal and nitrification, such as significantly reduced oxygen demand (~50%) and biological N and P removal on the full wastewater flow. To date full-scale studies in South Africa have been performed only with rock media trickling filters, for example that at Daspoort WWTP (Muller et al., 2004, 2006a, b). This report describes an investigation on the full-scale operation of a plastic media nitrifying trickling filter (NTF) at the 1 Ml/d Citrusdal WWTP.

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