“…As previously mentioned, in the MBBR, nitrification of digestate was advanced (the concentration of NH -N [27,28,29], it was reported that dissolution of phosphate driven by acidification induced by nitrification could be dominant among other biological and chemical reactions (e.g., uptake by microorganisms). According to the regression coefficients between pH values and concentrations of phosphate and calcium ions in the laboratory beaker experiment, the increases of concentrations were estimated to be 34.0 mg L -1 and 44.7 mg L -1 , respectively, when the pH values decreased from 5.9-6.1 to 4.0-4.2.…”