The BMP assays of the CPSMs were determined following the procedure described by Rodriguez et al. and Wang et al.. The tests were carried out in duplicate in 250 ml sterile glass serum bottles filled with 150 ml of mixture. This mixture contained 125 ml of phosphate-carbonate buffer solution (pH adjusted to 7.2 with KOH 5N), 25 ml of sludge, 0.25 g of glucose monohydrate (Gl) and the concerned CPSM at different concentrations. The different CPSMs were used for tests with 50 mg, 250 mg, 500 mg, 1000 mg and 2000 mg. The glucose monohydrate (Gl) was used as a positive control sample and a second addition of 0.25 g was done after the 100th day, by adding 2 ml of a 125 g/l aqueous solution by syringe injection through the septum. It is to note that 2 ml of the same Gl aqueous solution was also added by the same way in each BMP test with CPSM sample after the 100th day.