Effects of magnetic field on the properties and nutrient contents of sewage

Abstract

The capabilities of common sewage treatment methods to achieve an allowable standard limit are well known to be a universal problem. Magnetic treatment, a physical treatment method, is an alternative approach for cost-effective treatment of sewage. This research is mainly focused on the potential of magnetic treatment in enhancing the removal of pollutants primarily turbidity and nutrient contents (NO3-N and PO43-) in sewage. Besides, the existence of any changes in dissolved oxygen and pH levels of sewage during the treatment were also observed. The magnetic circulation flow method with the employment of magnetic device which consists of 6 pairs of non-parallel magnets (north and south poles facing each other) was applied in this study. Different magnetic field strengths (0.16 and 0.55 T), treatment periods (5, 14, and 24 hours), and flow rates (1, 4, and 8 mL/s) were paid much attention as magnetic treatment parameters in this study. The study reveals that higher magnetic strength, longer treatment period, and lower flow rate was significantly enhance the removal of turbidity, NO3 -N, and PO43- in sewage. However, the dissolved oxygen and pH levels of sewage were not affected under such condition. Experimental design with a magnetic strength o f 0.55 T, treatment period of 24 hours, and flow rate of 1 mL/s shows higher removal percentage of turbidity, NO3 -N, and PO43- compared to control system as the settling time further increased. The percentage o f turbidity removal is 91.3 to 97.9% compared to 45.8 to 55.3% without magnet, so as NO3-N is 94.7 to 95.8% compared to 68.2 to 70.4% without magnet, and PO43- is 96.7 to 97.2% compared to 45.6 to 45.7% without magnet. The settling time was found out to be most suitable at 20 minutes. In a nutshell, the magnetic field has a great potential in enhancing sewage treatment efficiency by significantly accelerated the removal of pollutants in sewage