Greywater quality changes in laboratory scale vegetative biofiltration prototypes

Greywater recycling and reuse is becoming a popular choice in many water-scarce regions. Greywater is the largest component of domestic indoor wastewater. However, in many arid regions, including the United Arab Emirates (UAE), this unconventional resource is under-utilized. Although, traditionally, a biofiltration system operates using stormwater, findings have shown that the operation of biofiltration systems in arid regions can be successful using greywater. This research endeavors to assess how the quality of the effluent from a biofiltration system changes with different vegetation, both native and introduced to the arid region (UAE). The prototype biofilters, planted with twelve ornamental plant species, were irrigated daily with an equal amount of synthetic greywater and the water quality parameters were monitored on a weekly basis. Analysis of variance (ANOVA) was performed in order to statistically evaluate the consistency of results between the three replicates of each of the twelve species and, subsequently, the variation of treatment effectiveness among the twelve species with respect to eight water quality parameters. Most of the plants show a high degree of consistency between replicates; however, significant differences were observed across the selected plant species. The species Ficus nitida and Canna indica performed well in reducing pH. Except in the earlier stages of the experiment, all the systems were found to reduce turbidity by almost 100%. Overall, it was observed that Ficus nitida, Canna indica and Pennisetum setaceum performed well to improve greywater quality in the biofiltration columns

Removal of Heavy Metals in Vegetative Graywater Biofiltration Columns

This study investigates the performance of laboratory-scale vegetative biofiltration systems in reducing five heavy metals [cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn)] from synthetic graywater. Thirty-six biofiltration columns of the same design were constructed, and twelve species of ornamental plants were planted, with three specimens from each species being planted in a single column. The study was conducted for six months in an arid climate. The overall removal efficiency for Zn and Cu was found to be about 98% and 75%, respectively. It was observed that soil Zn and Cu concentrations increased from 11.24 to 26.13 mg/L and from 11.09 to 12.12 mg/L, respectively, after irrigation with graywater. Zn and Cu were mainly removed by soil accumulation and plant uptake, respectively. Both Pb and Cr increased in effluent (about 29% and 6.5%, respectively) and in soil (about 12% and 63%, respectively) after irrigation with graywater, whereas Cd increased in effluent (about 7.6%) but decreased in soil (about 46%). Finally, the plants were ranked and recommended for application based on their performance consistency and effectiveness. The species Alternanthera ficondea topped the ranking, followed by the species Ixora coccinaea, Vitex agnus, Rhoeo discolor, and Jasmine sambac