Johan Sohaili

Magnetic Field Application and its Potential in Water and Wastewater Treatment Systems

This review is intended to critically convey information on water magnetization and to discuss each application that employs magnetic field as an aid in wastewater treatment. The magnetically assisted wastewater treatments are presented and compared in terms of performances with those of conventional treatment systems. The advantages and limitations of magnetic field application are discussed in order to evaluate their environmental benefits. The main conclusion from the literature review is that magnetic field application has the potential to improve the physical performance in terms of solid-liquid separation mainly through aggregation of colloidal particles. The application is also significant in influencing the biological properties through the improvement of bacterial activity. Both of these enhancements lead towards increase in efficiency of the water and wastewater treatment performances.

Converting non-metallic printed circuit boards waste into a value added product

The aim of this study was to investigate the feasibility of using nonmetallic printed circuit board (PCB) waste as filler in recycled HDPE (rHDPE) in production of rHDPE/PCB composites. Maleic anhydride modified linear low-density polyethylene (MAPE) was used as compatibilizer. In particular, the effects of nonmetallic PCB and MAPE on mechanical properties of the composites were assessed through tensile, flexural and impact testing. Scanning electron microscope (SEM) was used to study the dispersion of nonmetallic PCB and MAPE in the matrix. Nonmetallic PCB was blended with rHDPE from 0–30 wt% and prepared by counter-rotating twin screw extruder followed by molding into test samples via hot press for analysis. A good balance between stiffness, strength and toughness was achieved for the system containing 30 wt% PCB. Thus, this system was chosen in order to investigate the effect of the compatibilizer on the mechanical properties of the composites. The results indicate that MAPE as a compatiblizer can effectively promote the interfacial adhesion between nonmetallic PCB and rHDPE. The addition of 6 phr MAPE increased the flexural strength, tensile strength and impact strength by 71%, 98% and 44% respectively compared to the uncompatibilized composites.

Encapsulation of nonmetallic fractions recovered from printed circuit boards waste with thermoplastic

The present work includes a process for encapsulation by combining substantially simultaneously dry nonmetallic printed circuit boards (PCBs) powder and recycled high-density polyethylene (rHDPE) in an extruder to form a homogenous matrix. The extruded materials were then molded into standard tensile, flexural, and impact properties testing specimens. Nonmetallic PCB mainly consists of large amount of glass fiber–reinforced epoxy resin materials. Incorporation of 50 wt% nonmetallic PCB in rHDPE matrix had increased the flexural strength and modulus by 35% and 130%, respectively. Tensile strength reported to be constant without much improvement. However, the Young’s modulus has increased by 180%, with incorporation of 50 wt% nonmetallic PCB. The addition of 6 phr (parts per hundred) maleated polyethylene (MAPE) resulted in 2-fold increase in tensile and flexural strength. Regarding the leaching properties, Cu was identified as the metal that leached at the highest level from the raw nonmetallic PCB, at 59.09 mg/L. However, after the nonmetallic PCB was filled in rHDPE/PCB composites, the concentration of Cu was reduced far below the regulatory limit, to only 3 mg/L. Thermal properties of composites were studied, and it was found out that incorporation of nonmetallic PCB fillers in rHDPE resulted in low thermal conductivity, whereas mechanical strength of the composites showed maximum improvements at 220 °C. Overall, the encapsulation technique using nonmetallic PCB waste has formed a monolithic waste form that provides a barrier to the dispersion of wastes into the environment. Implications Nonmetallic materials reclaimed from waste PCBs were used to analyze the chemical composition, and it was found that nonmetalllic PCBs mainly consist of glass fiber–reinforced epoxy resin materials. With such millions of glass fibers in nonmetallic PCBs, there are mass-excellent supporting bodies that enhance the mechanical properties of composites. In fact, utilization of nonmetallic PCB waste as filler in composites can dramatically restrain the solubility of heavy metals in leachate solution, thus making it safe to be used in practical products.

Cadmium and lead removal from municipal landfill leachate using carbon adsorbent made from oil palm shell

This paper focused on adsorption process for metals removal from landfill leachate using oil palm shell as adsorbent. Raw shells were grinded to sizes of about 2 mm, followed by heating in at 420°C for a period of 4 hours. Batch test indicated a removal of more than 60% Cd and Pb from leachate samples. The removal process agrees with the Freundlich isotherm model. Column test for continuous flow performance shows efficiency ranging 30% and 80% for Cd and Pb. The efficiency depended on Empty Bed Contact Time, which was verified in the range of 20-100 min.

Influence of magnetic treatment on the improvement of landfill leachate treatment

Magnetic treatment is an alternative simple approach by which landfill leachate treatment could be improved. The purpose of landfill leachate treatment is to remove the Suspended Solids, Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD). Based on experiment by using circulation flowing system with a magnetic strength of 0.55 T, it was shown that the leachate quality could be improved. The results showed that the removal percentages of above 60% for SS, COD and BOD. This study concluded that magnetic technology has the potential to be used for improving the removal of SS and organic concentration from landfill leachate.

Dose Response and Exposure Assessment of Household Hazardous Waste

This study was conducted to assess the risk of health hazards to employees working in local authorities in Malaysia especially workforce involved in waste management. Therefore, the four steps process of Health Risk Assessment has been identified, which include hazard identification, exposure assessment, dose response assessment and risk characterization. It was estimated approximately 22,388 tons of wastes generated every year in Malaysia and around 2.2 % out of that amount were consisting of hazardous household waste (HHW) with mean average generation for each person per day was around 0.02 kg. The waste generation is expected to increase 2 to 3 % per year and estimated to reach approximately 31 million of tones per day in the year 2020. In this study, the household hazardous wastes (HHW) were analyzed for their permissible dose level and the existing hazard level, hazard index and cancer index. Cancer Index for dermal exposure is found to be 5.8 × 10–7 mg/m3, for Inhalation dust 1.4× ×10–1 mg/m3, which falls under Low Risk and for Inhalation aerosol is 5 × ×10–2 mg/m3, under Medium Risk. Extra care must be taken for the management of HHW as if it is improperly managed, it will fall into High Risk.

Waste-to-Wealth: Bio-Recycling Centre as Living Laboratory Element toCreate Integrated Bio-Waste Management for Institution

Waste-to-wealth has been used as the concept to address the environmental problem by changing the traditional view of waste as an end product to be disposed off. Raising awareness on environmental issue and turn it into potential value has seen as a big challenge to the university, as most system relies on operational behavior. Typically, the bio-waste management in campus facing with issues of poor waste management by contractor, unsystematic disposal management, the ineffective mechanism of waste segregation which eventually lead to the involvement of high and burdensome operational cost. This short communication reports the current bio-recycling initiatives implemented in the Universiti Teknologi Malaysia (UTM) and provides some viewpoint in the conclusion to improve the current bio-recycling implementation with an objective to address problems that have been aforementioned and highlights its market potential for institutional income.

Optimization of activated sludge physical properties by magnetic field via response surface modeling

In this study, activated sludge was exposed by magnetic field exhibited from NdFeB – type of permanent magnets. The exposure was aimed to improve the physical properties of the activated sludge used in treating wastewater. Hence, it was hypothesized that the magnetically-exposed activated sludge is potential in enhancing the efficiency of removal performances of the wastewater treatment processes. The influence of magnetic field, exposure time, biomass concentration and mixing intensity on turbidity reduction, aggregation and settling velocity was thoroughly investigated. Response surface methodology (RSM) was applied for experimental design, analysis and optimization. Based on the results, magnetically-exposed activated sludge displayed certain trends showing that its properties were positively affected by magnetic field. At the optimum conditions of magnetic field of 88.0 mT, exposure time of 38.5 hrs, biomass concentration of 3380 mg/L and mixing intensity of 345 rpm achieved 68.3%, 60.1% and 0.0104 cm/s of turbidity reduction, aggregation and settling velocity, respectively.