http://www.bashanfoundation.org/gmaweb/pdfs/P-removal.pdf

Recent advances in removing phosphorus from wastewater and its future use as fertilizer (1997-2003).

Advances in enhanced biological phosphorus removal: from micro to macro scale.

Hydrolysis and acidification of waste activated sludge at different pHs

Volatile fatty acids (VFAs), the carbon source of biological nutrients removal, can be produced by waste activated sludge (WAS) anaerobic fermentation. However, because of high protein content and low carbon to nitrogen mass ratio (C/N) of WAS, the production of VFAs, especially propionic acid, a more preferred VFA than acetic acid for enhanced biological phosphorus removal (EBPR), is limited. After the addition of carbohydrate (rice was used as the model matter) to the WAS anaerobic fermentation system to balance the C/N ratio, the effect of pH on WAS protein conversion and VFAs production was investigated in this paper. Experimental results showed that the addition of carbohydrate matter caused a remarkable enhancement of WAS protein conversion and protease activity, and an apparent synergistic effect between WAS and carbohydrate matter was observed. The study of pH effect revealed that pH influenced not only the total VFAs production but the percentage of individual VFA. The maximal VFAs production (52...

Enhancement of waste activated sludge protein conversion and volatile fatty acids accumulation during waste activated sludge anaerobic fermentation by carbohydrate substrate addition: the effect of pH.

Model-based design of horizontal subsurface flow constructed treatment wetlands: a review.

Optimisation of Noosa BNR plant to improve performance and reduce operating costs

Nitrogen removal in a SBR using the OGAR process control system.

Performance of the full-scale biological nutrient removal plant at Noosa in Queensland, Australia: nutrient removal and disinfection

Noosa WWTP is publicly owned and privately operated by Australian Water Services. The process includes primary sedimentation, raw sludge fermentation, biological nutrient removal (BNR), sand filtration and ultraviolet (UV) disinfection. An innovative feature of the plant is the supplementary carbon dosing facility to avoid the use of metal salts (alum or ferric) for phosphorus removal. The average flow treated during 2000 was 9.0 ML/d. The annual 50 percentile effluent quality requirements for nutrients are total N < 5 mg/L and total P < 1 mg/L. The objectives of this project were to: determine the cause of variability in phosphorus removal; develop a strategy to control the variability in phosphorus removal; and minimise the operating cost of supplementary carbon dosing while achieving the effluent quality requirements. An investigation of chemical and microbiological parameters was implemented and it was concluded that there were several factors causing variability in phosphorus removal, rather than a single cause. The following four major causes were identified, and the control strategies that were adopted resulted in the plant achieving annual 50 percentile effluent total P = 0.37 mg/L and total N = 3.0 mg/L during 2001. First, phosphorus removal was limited by the available VFA supply due to consumption of VFA by other organisms competing with phosphate accumulating organisms (PAO), and due to diurnal variations in the sewage VFA and phosphate concentrations. Therefore, supplementary carbon dosing was essential to make allowance for competing reactions. Second, increasing the fermenter VFA yield via supplementary carbon dosing with molasses was found to be an effective and economic way of ensuring reliable phosphorus removal. Third, nitrate in the RAS resulted in consumption of VFA by denitrifying bacteria, particularly with process configurations where the RAS was recycled directly into the anaerobic zone. Incorporating a RAS denitrification zone into the process rectified this problem. Finally, glycogen accumulating organisms (GAO) were observed in BNR sludge samples, and consumption of VFA by GAO appeared to cause decreased phosphorus removal. Better phosphorus removal was obtained using VFA derived from the fermenter than dosing an equivalent amount of acetic acid. It was hypothesized that GAO have a competitive advantage to use acetate and PAO have a competitive advantage to use propionate, butyrate or some other soluble COD compound in the fermenter effluent. Contrary to popular belief, acetate may not be the optimum VFA for biological phosphorus removal. The competition between PAO and GAO for different VFA species under anaerobic conditions requires further investigation in order to control the growth of GAO and thereby improve reliability of biological phosphorus removal processes.

M. Thomas

Papers

Optimisation of Noosa BNR plant to improve performance and reduce operating costs

Nitrogen removal in a SBR using the OGAR process control system.

Performance of the full-scale biological nutrient removal plant at Noosa in Queensland, Australia: nutrient removal and disinfection

Optimisation of Noosa BNR plant of improve performance and reduce operating costs