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Use of alum as a coagulant in drinking water treatment process generates an alum sludge as a waste product. Since the amount of this sludge is huge, it is crucial for a water work management to properly handle and dispose of this sludge. Reuse of this alum sludge as a solid adsorbent is one of the proposed applications for this material but modification and characterization are needed to alter and identify its properties so that optimum benefits are obtained. This paper reports characterization of raw and thermally treated alum sludge. The raw alum sludge was collected from a local water treatment plant and heated at 300 °C and 800 °C for 7 hours using a furnace before characterization using scanning electron microscopy energy (SEM), thermogravimetric (TGA), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET). The results showed that surface morphology, thermal properties, microstructure, surface area and porosity of the sludge were affected by heating temperature whereby increase the heating temperature resulted in improved thermal stability of the sludge. The results also revealed that both raw and thermally treated alum sludge were mesoporous materials and mainly compose of quartz and kaolinite. It can be said that the sludge could be a good candidate as low cost adsorbent.

Inorganic arsenic contamination has caused a remarkable impact on the contamination of soil and groundwater in many countries. Consequently, determination of inorganic arsenic on site is very crucial especially arsenic (III) which is more toxic than arsenic (V). Thus, a more rapid, simple and ecofriendly approach was developed in this study to determine arsenic (III) by incorporation of image processing technique into colorimetric method. The effects of various factors were evaluated by a 2 4 full factorial design with a blocking factor. The mass ratio of sulfamic acid to zinc powder was the most significant factor affected red, green and blue (RGB) color values and followed by reaction period. The optimum conditions for the detection were found to be using 1 g of sulfamic acid and 0.5 g of zinc powder at 5 minutes. This work also demonstrates that the developed method is able to detect arsenic (III) rapidly and easily.

Drinking of arsenic contaminated waters has been reported adversely affect our health even at a concentration level as low as 10 g/L, therefore the availability of a reliable and cheap, and an environmentally arsenic detection kit is really indispensable. Although simple field test kits have been developed, most of them use toxic mercuric salt as a color-generating reagent for arsenic detection. Hence this study was conducted to develop a simple, cost effective, and environmental friendly arsenic (III) detection method based on a colorimetric determination of arsine gas produced by arsenic-zinc powder-sulfamic acid reaction. To optimise the reaction conditions, effects of the reaction period and amount of reagents on the color formation were investigated. The best conditions to detect arsenic (III) in a 50 mL sample were found to be using 1.0 g sulfamic acid and 0.5 g of zinc powder at 10 minutes of the reaction period. The method was then used to determine concentrations of arsenic (III) in tap water samples and compared with liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS) to validate its accuracy. This study revealed that they were in good agreement for the arsenic (III) concentrations of 0 to 300 μg/L.