Constructed wetlands are an affordable and reliable green alternative to conventional mechanical systems for treating domestic sewage. This study investigates the potential of 14 tropical wetland plant species for removing heavy metals from domestic sewage through the bioconcentration factor (BCF), translocation factor (TF), enrichment factor (EF), and geoaccumulation index (I_geo) using batch mesocosm studies. Plants with BCF > 1 and TF > 1 are classified as phytoextractors, while species with BCF > 1 and TF < 1 are phytostabilisers. The results indicate that 11 out of 14 species are magnesium phytostabilisers, 10 are calcium phytoextractors, and no plant species demonstrate ferrum phytoextraction properties. As for manganese phytoremediation, only three species depicted phytoextraction and phytostabilisation properties. The enrichment factor (EF) for all of the studied metals with ferum as a reference metal in all of the soil samples decreased after the phytoremediation of domestic sewage experiments, indicating depletion to mineral enrichment (EF < 2). All of the soil samples are generally classified as uncontaminated based on I_geo indices. Based on the factors and indices, it is suggested that the plants may have facilitated heavy metal removal from domestic sewage through uptake into the plant tissues from the roots.

Water quality assessment and its monitoring are necessary for areas of mining activities. In Malaysia, the mining industry is the backbone of the manufacturing and construction sectors. This study used spatio-temporal water quality modeling along a reach with mining activities during high and low discharges at Sungai (river) Lebir and Sungai Aring, situated in Gua Musang, Kelantan, Peninsular Malaysia. The objective was to assess the spatio-temporal environmental impact of mining activities during the wet and dry seasons. Data were collected at different locations along the reach. Point and non-point sources were near the mining site. Overland flow calculation at the mining site was found with the widely used SCS (Soil Conservation Service) curve number method. Several scenarios were analyzed, such as baseline, worst-case, and with-mitigation. The study revealed that baseline values of all parameters were either in a natural condition or slightly polluted, except for aluminum. All parameters were estimated at a high concentration from the mining site to downstream during the worst case of the wet season. Whereas, during the worst case of the dry season, no significant differences were observed compared to baseline values. In the with-mitigation scenario, parameter concentrations were improved and similar to baseline values. Overall, the scenario selection was helpful in the environmental impact assessment. Furthermore, this study will be significant in pre- and post-mining assessment and environmental clearance.

Algal bloom phenomena are increasingly occurring in many urban lakes worldwide. To enhance understanding of how environmental factors influence the development of harmful algal bloom (HAB), a preliminary study was carried out at one of the inlets in Putrajaya Lake. Physicochemical variables, nutrients, weather conditions, chlorophyll-a, and phycocyanin were measured over two weeks. Algal indicators, namely chlorophyll-a values, were strongly correlated to dissolved oxygen (DO), pH, conductivity, turbidity and nitrate. There is no correlation recorded between chlorophyll-a with phosphate and total phosphorus. This preliminary study showed the complex relationship influencing algal development and bloom formation. Blue-green algae (BGA) was the most dominant phytoplankton assemblages during the study. A positive correlation was also observed between chlorophyll-a and solar radiation, temperature, and wind speed. Despite no strong correlation between chlorophyll-a and rainfall amount, a strong relationship between chlorophyll-a and turbidity indicated other environmental factors contributing to algal bloom occurrence. BGA density was correlated to DO, pH, turbidity, air temperature and nitrate. Management measures recommended to reduce algal bloom development include external nutrient reduction through the constructed wetland. Artificial mixing is also recommended to improve vertical mixing and circulation pattern.

Industrial wastes had contributed to environment pollution. In particular, wastewater had been increasing in any country around the world, from agricultural sectors to commercial sectors. Wastewater treatment had raised overhead costs on operational and maintenance. Many studies had been done on finding alternatives for wastewater treatment. In general, a variety of wastewater treatment processes are employed which includes primary treatment, secondary treatment and tertiary treatment. In this study, three designed systems of tertiary treatment had been observed to evaluate wastewater quality reduction. A designed system had been selected to identify the treatment efficiency using the same treatment concept of phytoremediation. There are three designs which are the large-scale design, medium-scale design and portable scale design. The differences among the designs are that the first large-scale design uses wastewater sources directed from a sewerage plant, while the second design with medium-scale uses groundwater water with nutrient loads from aquatic species. The third design with portable scale uses a customised aquarium method with conventional filtration. From the study, it was found that different solution design systems could perform treatments for different wastewater characteristics. The average range of treatment had been seen to reduce contaminated water quality between 10 to 60% on differences in water quality parameters. This identified that the constructed nature-based system (NBS) could possibly be performed as one of the wastewater treatments. Further study could be done for any sources of wastewater in future as an added value to the improvised existing design to improve surface water quality.