Use of multistage phytoremediation technique in wastewater treatment

Efficient treatment of wastewater before discharge into aquatic ecosystems is a requirement to prevent the detrimental effect of polluting the environment and to safeguard public health. Adoption of green technology in wastewater treatment is paramount. This study was carried out to investigate the efficiency of multistage technique in phytoremediation of wastewater. The experimental set up was a four-stage treatment system. It comprised of four columns with different arrangements of macrophytes which included Ceratophyllum demersum, Typha latifolia, Nympaea sp. and Azolla pinnata. Wastewater was sampled and put in four, twenty litres pre-sterilized plastic containers and allowed to flow to plastic troughs each containing the experimental plants from stage 1 to stage 4 with a retention time of five days. Water indicator parameters, nutrients and heavy metals in the wastewater were analysed at the beginning of the treatment process and from each trough in each column at the end of the retention time of five days for a period of 20 days to determine the changes in the levels of the parameters investigated. Means of mentioned parameters were calculated and analyzed using ANOVA and significant means separated using Tukey’s test at 5% level. Removal efficiency of the investigated parameters was calculated and the range was as follows; TDS 79.13- 82.27%, pH 14.12-16.67%, conductivity 66.92-71.48%, turbidity 67.97-80.54%, faecal coliforms 100%, faecal streptococcus 100%, phosphates 93.72-100%, nitrates 89.79-100% Cd 83.40-100%, Cu 83.39-88.60%, Ni 100%, Co 100%, Pb 100%, Mn 100%, Zn 100% and Fe 88.60-95.77%. Multistage technique was found to be efficient in wastewater treatment. This technique is a green technology which is efficient and economical hence recommended for remediation of wastewater.