In terms of mass balance, phosphorus added by the fresh sludge (0.42 kg TP m−2) was generally retained in the sludge cake, with a higher amount in T. angustifolia (0.29 ± 0.09 kg m−2), followed by S. fluviatilis (0.27 ± 0.04 kg m−2), P. australis (0.22 ± 0.03 kg m−2),and finally the unplanted control (0.18 ± 0.04 kg m−2) (Fig. 2f)