The contamination of water by heavy metals is a worldwide environmental problem. Phytoremediation and constructed wetlands have become increasingly popular as more sustainable and environmentally friendly techniques of removing heavy metals from the wastewater. This study, therefore, investigated the phytoremediation of nickel by Alocasia puber (A. puber) in a constructed wetlands (CW) microcosm. This study identified the optimum conditions for nickel (Ni) removal from wastewater using response surface methodology (RSM) with central composite design (CCD). Two operational variables were assessed: exposure time and initial Ni concentration. The optimum conditions for the maximum removal of Ni from water were an exposure time of 10 days and 99.76 mg/L initial Ni concentration. The results indicated that 95.6% removal was achieved under the optimized conditions, with a high correlation coefficient (R² = 0.97) between the statistical model and the experimental data. Field emission scanning electron microscopy images showed anatomical changes in the A. puber samples due to Ni exposure, and transmission electron microscopy images revealed some internal damages in the A. puber, but visual Ni toxicity symptoms, such as necrosis and chlorosis, were not observed in the A. puber. This study demonstrated that A. puber planted in a constructed wetland microcosm was able to remediate wastewater contaminated with Ni.

Corbicula fluminea serves as traditional food to the local people in Kelantan, Malaysia. Concerns regarding river contamination, smoking method, and associated adverse effects on public health had been increasing. Hence, this study aims to measure the level of heavy metals (Cd, Cu, Mn, Pb, and Zn) and assess human health risk in C. fluminea consumption at Kelantan. Heavy-metal analysis was done using flame atomic absorption spectrophotometry, while human health risk was assessed using provisional tolerable weekly intake (PTWI), target hazard quotient (THQ), and hazard index (HI). The estimated weekly intake (EWI) for all metals was found within PTWI, while THQ for Cd, Cu, Mn, Pb, and Zn was 0.12, 0.06, 0.04, 0.41, and 0.03, respectively. The HI was calculated at 0.61 which is less than 1, considered as the safe consumption level. Therefore, C. fluminea consumption in this study was found safe from the health risk of noncarcinogenic effect over a lifetime.

Water pollution by toxic heavy metals is a global environmental problem. It has led to the development of alternative technologies for heavy metals removal from contaminated sites. Constructed wetland microcosm by using Alocasia puber is a possible treatment method for wastewater containing heavy metals. Synthetic wastewater with heavy metals Cd, Cr, Cu, Ni, and Zn were used in this study. Several heavy metals concentrations (5 mg/L, 10 mg/L and 100 mg/L) were used in the systems. Six different hydraulic retention times (HRTs) (2, 4, 6, 8, 10 and 12 days) were tested in the present study. The results obtained showed removal efficiencies of heavy metals of >99% after day 12. The removal of Ni from 10 mg/L solutions (initial concentrations) recorded the best removal efficiency. Heavy metal translocation factor (TF) was found to be less than 1 for all metals tested, which confirmed the significance of roots as heavy metals accumulator compared to stems or leaves of A, puber. Therefore, this study concluded that A, puber has a great potential as an important component in constructed wetlands for water contaminated with heavy metals.

The removal of dyes from textile wastewater effluent has become a vital process nowadays since dye are widely used in textile industries. It is well known that activated carbon (AC) is a good adsorbent for dye removal and it is widely used in industries for wastewater treatment. Palm Kernel Shell (PKS) was used in this research in order to reduce the amount of waste PKS which also known as agricultural waste. Purpose of this study was to examine the characteristics and adsorption efficiency on methylene blue (MB) dye by palm kernel shell activated carbon (PKSAC). The PKS was carbonized at 400 °C for 1 hour, impregnated in KOH with ratio 1:1 and then carbonized again at 800 °C for 15 minutes. Various parameters were investigated like pH of the MB dye solution, initial dye concentration and flow rate. The optimum conditions for the removal of MB dye are: original pH, 150 mg/L of initial dye concentration and 1 mL/min of flow rate. SEM and TGA were carried out to determine the surface morphology and weight loss of the sample respectively. It is proved that PKS can be used in preparing AC. Hence, it was concluded that PKSAC have the ability to be an alternative low cost adsorbent.

Oil and grease wastewater is produced from many sources such as industry and municipal. The discharge of oil and grease in wastewater system causes bad effect towards the environment and wastewater system itself. Palm Kernel Shells (PKS), an agricultural waste was chosen to see its ability in removing oil and grease in wastewater. The PKS was carbonized at 400 °C, activated with KOH and carbonized again at 800 °C. The parameter affecting oil and grease removal such as different oil and grease concentration, contact time and flow rate were studied. The oil and grease removal study was conducted by the column adsorption method and followed by the gravimetric method to identify the remaining oil and grease. PKS activated carbon shows maximum removal of 99.89% at flow rate 1mL/min after 6 hours contact time with 5%w/v initial concentration of wastewater. SEM micrograph of PKS activated carbon after adsorption of oil and grease shows that oil and grease has covered the pores of the surface of the PKS activated carbon. Overall, the PKS activated carbon has the ability in removing oil and grease which indicates that PKS can be used as a alternative treatment in removing oil and grease.