Ponding which is usually considered a low tech process can be successfully integrated with downstream Biological Nutrient Removal (BNR) facility. The PETRO system incorporating ponds and downstream trickling filter (TF) or activated sludge process (ASP) is a technology which offers simplicity of O and M combined with biological removal of P and N. It is feasible to produce in a primary facultative pond with a deep fermentation pit quantities of readily biodegradable substrates sufficient to meet the requirements of phosphate accumulating organisms (PAO) in a downstream BNR facility. Malodorous conditions are dealt with by high rate recirculation. This novel low tech approach is a step towards a more straightforward BNR process. PETRO concept features phenomenon of algae-assisted chemical P-removal in activated sludge reactor. The process results in precipitation of inorganic phosphates apparently in a form of calcium/magnesium salts. Possible mechanism of this additional process which removes up to several milligrams per litre of inorganic P is discussed.
Petro® concept: a tentative approach to biological phosphorus removal incorporating waste stabilisation ponds
O. V. Shipin, P. G. Meiring, J. R. Hoffmann; Petro® concept: a tentative approach to biological phosphorus removal incorporating waste stabilisation ponds. Water Sci Technol 1 November 2000; 42 (10-11): 223–229. doi: https://doi.org/10.2166/wst.2000.0648
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