Treatment of wastewater using response surface methodology: a brief review

Response surface methodology (RSM) is widely applied to gathering knowledge on the interactions among parameters that require optimization during the treatment of wastewater. It can be used to optimize parameters during the process of treating wastewater, e.g., landfill leachate. The experimental design methods are useful to evaluate the parameters involved in a treatment with the minimum number of experiments. This will reduce the need for reagents and materials for experiments, which finally causes both time and expense to be increased. Anaerobic digestion of wastewater technologies escalated depending on the design configuration of the reactor. Several important parameters are taken into consideration in designing an anaerobic reactor such as operating conditions, seed sludge, wastewater composition and mixing. To construct a highly efficient degradation system, it is necessary to optimize such effective parameters. As a result, the advanced statistical design is used for process characterization, optimization and modelling. In this paper, the fundamentals of RSM and its application in the anaerobic treatment of wastewater was discussed in brief. The various works done in an anaerobic reactor using RSM for prediction and optimization are given

Optimisation of heavy metals uptake from leachate using red seaweed gracilaria changii

Heavy metal is one of the pollutants in landfill leachate besides organic and inorganic pollutants. The presence of heavy metal is alarming due to its harmful nature; makes it incompatible to be discharged into water bodies before treatments. There are many treatment techniques to remove heavy metals from wastewater, where some of them even involve the coupling of one or more techniques to facilitate and improve the removal efficiency. However, the adsorption using seaweed is one of the known techniques to eliminate heavy metals from wastewater efficiently. Therefore, this study introduced a new adsorbent for heavy metal adsorption: red seaweed Gracilari changii. The effect of operational parameters such as leachate pH (2-7), seaweed dosage (2-10 g), rpm (10-100), and contact time (10-60 min) on the optimum adsorption of Gracilaria changii was studied. At optimum pH (pH=5), seaweed dosage (10g), rpm (rpm=50) and contact time (30min), Gracilaria changii showed maximum metal ion removal of 45%, 35%, and 30% for Fe2+, Cr6+ and Ni2+ respectively. The adsorption was rapid and reached equilibrium after t=30min in general. This optimisation result can be used as a reference to study the effect of different dosages of the adsorbent towards the removal rate

Treatment of landfill leachate using granular multi-stage anaerobic reactor: optimisation through response surface methodology

One of the most hazardous sources of pollution these days is landfill leachate. This harmful wastewater is not only affecting the environment, but also the health of beings surrounding the landfills. Numerous treatments have been used to treat this recalcitrant wastewater; however, anaerobic treatment has been in focus in recent years. In this study, we investigated the interactive effects of chemical oxygen demand (COD), leachate percentage and pH on the performance of a granular multi-stage anaerobic reactor (GMSAR) treating landfill leachate. Response surface methodology (RSM) was utilised to project the interaction effects of the operating conditions of the treatment system in terms of COD removal and biogas yield. The optimum region of the GMSAR was acquired at influent COD of 1239 mg/L, a leachate percentage of 14.2% and a pH of 7.3. These variables resulted in a 71.9% COD removal and 65.9mL/d of biogas yield. The percentage of leachate and COD influent resulted respectively in the most effective parameters on the COD removal and biogas yield of GMSAR

VAP Code: A Secure Graphical Password for Smart Devices

In parallel to the increasing purchase rate of the smart devices, attacks on these devices are also increasing in an alarming rate. To prevent these attacks, many password-based authentication schemes are proposed. Among them, graphical password schemes are preferred on these devices due to their limited screen size and a lack of full sized keyboard. Again, existing graphical password schemes are susceptible to various attacks, among which shoulder surfing, smudge attack, and brute force attack are the most prominent. Hence, in this paper, we propose Vibration-And-Pattern (VAP) code, a new graphical password scheme that is resilient against these three major attacks. To evaluate the usability of our proposed scheme, a usability study has been conducted on 122 participants of various age groups from different demographics