The C/N ratio in the R55 and R60 experiments correlated linearly with the percentage of MMLW (p < 0.05), and a significant linear correlation between EC and the percentage of MMLW was found in the R60 experiment (p < 0.05). No other significant linear correlations were found with the percentage of MMLW, and this was probably because the percentage of MMLW did not follow a significant trend as the other parameters ( Fig. 3 and Fig. 4)