However, other research (Jiang et al., 2009) has reported that it was unnecessary to remove the nitrogen and phosphorus, and the fermentation liquid can be used directly for PHA production.
The PHA content reached 72.9% DCW when activated sludge was submitted to the aerobic feeding and discharge (AFD) process using the alkaline fermentation liquid of excess sludge as carbon source.
One of the remarkable strategies adopted by the study was that the fermented liquid was pre-diluted with tap water to about 1300 mgCOD/L, which was just one third of the actual liquid. Morgan-Sagastume et al. (2010) reported that a PHA-accumulated biomass could be obtained from the actual high-pressure thermal hydrolysis (400 mgCOD/L) with high levels of nutrients, but the PHA content in the sludge was only 25% DCW.