Rapid industrial development causes serious problem all over the world such as depletion of natural aggregates and creates enormous amount of waste material from construction and demolition activities. Quantities of polymer wastes also have been increased these recent years due to the boost in industrialization and the rapid improvement in the standard of living. In Malaysia, most of polymer wastes is abandoned and not recycled. This situation causes serious problems such as wastage of natural resources and environmental pollution. Polymer products such as synthetic fibers, plastics and rubber belong to petrochemical compound and not easily biodegradable even after a long period. One of the ways to reduce this problem is to utilize waste materials in the production of concrete. Use of these materials not only helps in getting them utilize in cement, sand, aggregate, concrete and other construction materials, it helps in reducing the cost of concrete manufacturing, but also has numerous indirect benefits such as reduction in land-fill cost, saving in energy and protecting the environment from possible pollution effects. An experimental research is made on the utilization of plastic waste, High Density Polyethylene (HDPE) as coarse aggregates in concrete with a percentage replacement of 10 %, 20 % and 30 %. The laboratory tests include slump test, compressive strength and water absorption were conducted in this research. The samples content 10 % of HDPE has better performance in term of strength.

Abstract. The concentration of six heavy metals such as Cu, Cr, Ni, Cd, Zn and Mn were studied in the soils around Perlis. The aim of the study is to assess the heavy metals contamination distribution due to industrialisation and agricultural activities.

The ability of Pleurotus ostreatus spent mushroom compost for the biosorption of Iron (III) from aqueous solutions was investigated. The study was conducted in batch experiments under varying operating conditions. The optimum Iron (III) biosorption was achieved at an initial pH ranging from 4 to 5, contact time of 10 minutes and initial Iron (III) concentration of 50 mg/L using half-saturation constant of 0.4 g biosorbent dosages. The results indicated that the Iron (III) biosorption onto Pleurotus ostreatus spent mushroom compost were well fitted with the Langmuir isotherm model and a second-pseudo order kinetic model.

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Abstract. In Asia, Climbing perch (Anabas testudineus) is commonly found in paddy fields and irrigation systems. Due to its habitat, Climbing perch is exposed to toxic pesticides used in paddy fields such as metaldehyde which is one of the most widely used molluscicide. This study aims to determine the acute toxicity Lethal Concentration50 (LC50) of metaldehyde and its effect on the behaviour and physical changes of the Climbing perch. The fish mortality responses to six different metaldehyde concentrations ranging from 180 to 330 mg/L were investigated. The 96-h LC50 values were determined and analysed using three different analysis methods which is arithmetic, logarithmic and probit graphic. The LC50 values obtained in this study were 239, 234 and 232 mg/L, respectively. After 96-h of exposure to metaldehyde, the fish showed a series of abnormal behavioural response in all cases: imbalance position, and restlessness of movement. The LC50 values show that metaldehyde is moderately toxic to the Climbing perch indicating that metaldehyde is not destructive to Climbing perch. However, long term exposure of aquatic organisms to the metaldehyde means a continuous health risk for the fish population as they are more vulnerable and it is on high risk for human to consume this toxicated fishes.

The ability of biosorbents, which are a combination of orange peels and tea waste to treat copper (II) using the biosorption method was examined. The experiment was performed under batch biosorption studies with various operating parameters. The pH, biosorbent dosage, contact time, and initial copper (II) concentration were optimized from pH 3 - 8, 0.25 - 1.0 g, 2 - 20 minutes and 10 - 100 mg/L, respectively. The findings found that a pH of 5.5, a biosorbent dosage of 0.75 g, a contact period of 5 minutes, and an initial copper (II) concentration of 10 mg/L were shown to be the best operating parameters for copper (II) biosorption. For isotherm models, the experimental data for copper (II) biosorption was fitted to the Langmuir isotherm with R2 value of 0.7775 compared to the Freundlich isotherm model with R2 value of 0.1073. The value for RL was 0.4, indicating that copper (II) biosorption using the combination of orange peels and tea waste is favourable. For kinetic models, the experimental data for copper (II) biosorption was well fitted to the pseudo-second-order kinetic model with R2 value of 0.9865 compared to the pseudo-first-order kinetic model with R2 value of 0.1006. In conclusion, the combination of orange peels and tea waste functions very well for biosorption of copper (II).

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Timah Tasoh Lake is surrounded by various types of land use activities ranging from industrial, agricultural and quarrying activities. These activities will affect the water quality and a threat to the ecosystem of the lake. A study was conducted in Timah Tasoh catchment areas with the aim to investigate the water quality parameters such as physical, chemical and biological in the Timah Tasoh Lake. The water quality study involved in-situ measurement and laboratory analysis. National Water Quality Standard (NWQS) for Malaysia was applied. The study concludes that the water quality was varied between stations and tends to decrease from upstream towards the lake (downstream).