Variability of PM10 level with gaseous pollutants and meteorological parameters during episodic haze event in Malaysia: Domestic or solely transboundary factor?

Haze has become a seasonal phenomenon affecting Southeast Asia, including Malaysia, and has occurred almost every year within the last few decades. Air pollutants, specifically particulate matter, have drawn a lot of attention due to their adverse impact on human health. In this study, the spatial and temporal variability of the PM10 concentration at Kelang, Melaka, Pasir Gudang, and Petaling Jaya during historic haze events were analysed. An hourly dataset consisting of PM10, gaseous pollutants and weather parameters were obtained from Department of Environment Malaysia. The mean PM10 concentrations exceeded the stipulated Recommended Malaysia Ambient Air Quality Guideline for the yearly average of 150 µg/m3 except for Pasir Gudang in 1997 and 2005, and Petaling Jaya in 2013. The PM10 concentrations exhibit greater variability in the southwest monsoon and inter-monsoon periods at the studied year. The air masses are found to be originating from the region of Sumatra during the haze episodes. Strong to moderate correlation of PM10 concentrations was found between CO during the years that recorded episodic haze, meanwhile, the relationship of PM10 level with SO2 was found to be significant in 2013 with significant negatively correlated relative humidity. Weak correlation of PM10-NOx was measured in all study areas probably due to less contribution of domestic anthropogenic sources towards haze events in Malaysia.

Influence of Gypsum Waste Utilization on Properties and Leachability of Fired Clay Brick.

Wastewater treatment activities in the chemical industry have generated abundant gypsum waste, classified as scheduled waste (SW205) under the Environmental Quality Regulations 2005. The waste needs to be disposed into a secure landfill due to the high heavy metals content which is becoming a threat to the environment. Hence, an alternative disposal method was evaluated by recycling the waste into fired clay brick. The brick samples were incorporated with different percentages of gypsum waste (0% as control, 10, 20, 30, 40 and 50%) and were fired at 1050 °C using 1 °C per minute heating rate. Shrinkage, dry density, initial rate of suction (IRS) and compressive strength tests were conducted to determine the physical and mechanical properties of the brick, while the synthetic precipitation leaching procedure (SPLP) was performed to scrutinize the leachability of heavy metals from the crushed brick samples. The results showed that the properties would decrease through the incorporation of gypsum waste and indicated the best result at 10% of waste utilization with 47.5% of shrinkage, 1.37% of dry density, 22.87% of IRS and 28.3% of compressive strength. In addition, the leachability test highlighted that the concentrations of Fe and Al was significantly reduced up to 100% from 4884 to 3.13 ppm (Fe) and from 16,134 to 0.81 ppm (Al), respectively. The heavy metals content in the bricks were oxidized during the firing process, which signified the successful remediation of heavy metals in the samples. Based on the permissible incorporation of gypsum waste into fired clay brick, this study promised a more green disposing method for gypsum waste, and insight as a potential towards achieving a sustainable end product.