PHA Production by Biological Phosphorus Removal Process

This work discusses the use of different processes for PHA production by activated sludge enhanced biological phosphorus removal (EBPR), microaerophilic-aerobic process and aerobic periodic feeding (feast/famine conditions). 

One of the most interesting processes for phosphorus removal fi-om wastewaters is the enhanced biological phosphorus removal (EBPR). This process is based on the capacity of polyphosphate accumulating microorganisms (Poly-P bacteria) to store inside the cells large amounts of phosphorus, when submitted to alternation of anaerobiosis and aerobiosis periods. In these bacteria, phosphorus and carbon metabolisms are closely 

Fig 2 and 3 show granules of PHA inside Poly-P bacteria stained with Nile blue by bright field microscopy and by epyfluorescence microscopy, 

PHA production by Poly-P bacteria remains at relatively low levels (around 20% of the sludge dry weight). The reported values were obtained in processes where optimisation of phosphorus removal was the main concern, polymer production being a side stream goal If the objective of the process is the PHA production, cells should be harvested at the end of anaerobiosis, when they are full of PHA. 

Substrate HB (mg.g cell dry wt) HV (mg.g cell drvwt) Molar ratio (HB/HV) MJK PHA Yield PA cell drywt) 

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