Phytoremediation performance of floating treatment wetlands with pelletized mine water sludge for synthetic greywater treatment.

PURPOSE

Buckets containing floating reed () simulated floating treatment wetlands (FTWs) and were used to improve the remediation performance of synthetic greywater (SGW). The aim of the study was to investigate the behaviour of FTWs for treatment of key contaminants within artificial greywater.

METHODS

Pelletized ochre based on acid mine water sludge was introduced to selected FTWs, because of its capability in sequestration phosphorus and other trace elements. The impact of the following four operational variables were tested in the experimental set-ups of the FTWs (four replicates each): pollutant strength (high- (HC) and low- (LC) concentrations), treatment time (2- or 7-days of hydraulic retention time (HRT)), presence or absence of macrophytes () and cement-ochre pellets.

RESULTS

The results showed that 5 - day biochemical oxygen demand (BOD) and chemical oxygen demands (COD) were significantly ( < 0.05) reduced in all wetlands. Nitrate-nitrogen (NO-N) concentrations were significantly ( < 0.05) higher, and those measurements for PO-P were significantly (p < 0.05) lower than the corresponding ones determined for the influent. The existence of ochre pellets with significantly ( < 0.05) decreased B, Cd, Cr, Cu, Mg, Ni and Zn concentrations, but increased Al, Ca, Fe and K concentrations in the effluent, with the exception of sodium (Na).

CONCLUSIONS

The FTW performances can be improved by utilising ochre-cement pellets to increase the pH of greywater. The presence of acts as a buffer to neutralise the pH of SGW. Rhizomes and biofilms mitigate increases in turbidity, TSS and colour values.