Scale removal in water pipeline with a magnetic field

Abstract

Magnetic water treatment (MWT) is a green concept of water treatment where the magnetic device is installed to the system. This concept is intended to cater to scale problem as it is the most common problem experienced in water pipeline which causes the reduction of system performance. This leads to the pipeline becoming clogged and causing potential damage. Scale is a soluble salt known as calcium carbonate, CaCO3, which usually develop due to the mineral content of the water itself and external factors from surroundings. Calcium carbonate, can be found in almost every type of scale in various water system, is the ingredient of scale. Conventional treatment was used in controlling the scale, but it is harmful to the system and environmentally unfriendly. Thus, water treatment with the application of magnetic field is an alternative for future practice. This study was conducted experimentally in the laboratory where all the samples and variables were installed and conducted in 4 phases. The first phase of this study was aimed to determine the variables of this study. In order to obtain the optimum results, the variables selected were orientation of magnetic devices, the flow rate of water and the intensity of magnetic field under 18 days of operation time. Magnetic devices for treating scale in used water pipes are subjected to different magnetic orientations under inverted and non-inverted, with one control device without magnet. The water flow rate used were 1.0 mL/s, 2.0 mL/s and 3.0 mL/s and the magnet intensity were 0.1 Tesla, 0.3 Tesla and 0.5 Tesla respectively. All these flow rates and magnet intensities were applied and conducted simultaneously under those orientations. These variables were applied in order to achieve the objectives of the next phase of the study, which were water sample characteristics and morphology structure of scale. The final phase for this study was formulating the empirical relationship of scale removal efficiency using Response Surface Methodology (RSM). The results showed that inverted orientation was 28% greater rate of scale removal compared to that of non-inverted which was 20%. For variables of water flow rate, greater flow rate of 3.0 mL/s (78%) gave better results than lower flow rate. Regarding magnetic intensity, the higher the intensity of permanent magnet used, the greater the rate of scale removal. Hence, under inverted orientation with 3.0 mL/s water flow rate and magnetic intensity of 0.5 Tesla, the experiment results of scale removal under MWT was 57% compared to 0.3 Tesla (43%) and 0.1 Tesla (23%). The morphology structure of scale was analysed under Field Emission Scanning Electron Microscope (FESEM) and X-Ray Diffraction (XRD) resulting in the crystal form of scale ranged from harder crystal (calcite) to softer crystal (vaterite and aragonite). From the analysis of Three Dimension Response Surface Plot, it was found that scale removal efficiency had the effects and interaction towards magnet intensity of 0.5 Tesla, water flow rate of 2.98 mL/s and 18 days of operation time under inverted orientation. Experimental validation demonstrated a scale removal prediction of 37.527 mg/L and the observed results from experiments was 36.9 mg/L representing an error of only 1.7%. The outcome of the study bridges the knowledge of magnetic water treatment and will aid the concept to the future practices in water treatment as our world is now ingeared towards sustainable and environmentally friendly treatment.