Removal of arsenic from simulated groundwater by adsorption using fly ash from sub-bituminous and bituminous coal

Arsenic contamination has become an increasingly recognized world-wide predicament in recent years. It has caused serious environmental problems on living organisms all over the world. Several areas in the Philippines such as Mindoro and Davao have already been contaminated. In response to this problem, the Philippine Department of Health has set a standard for drinking water of 10ug/L as the limit for arsenic content (Philippine National Standard for Drinking Water). With this, the need for an efficient and economical method related to the development of arsenic removal to meet this standard is emphasized. Adsorption is a widely used method in removing arsenic from water. In this study, fly ash was used as an adsorbent to remove the total arsenic from simulated groundwater. Fly ash, a by-product of coal power stations are considered as wastes and are commonly disposed in landfills. The arsenic removal capacity between sub-bituminous fly ash from Batangas Coal-Fired Thermal Power Plant and and bituminous fly ash from Mirant Pagbilao Power Plant in Quezon as adsorbents were investigated separately. Both fly ash contain iron ranging from 3.86% to 15.4%. The burning of sub-bituminous coal produces a Class C fly ash while burning of a bituminous coal produces Class F fly ash. The chief difference between Class C and Class F fly ash is in the amount of calcium, silica, alumina, and iron content in the ash. Batch experimentation was conducted at constant pressure, temperature, pH, contact time and agitation speed. Parameters that were varied include initial arsenic concentration and fly ash dosage. The contact time and point of zero charge of both fly ash was determined to be 12 hours and at the pH of 10, respectively. Results have indicated that the highest arsenic removal occurred at 0.1ppm of arsenic concentration. Sub-bituminous fly ash showed higher adsorption efficiency as compared to bituminous fly ash at 80.47% arsenic removal at a dosage of 4g/L when compared to bituminous fly ash which exhibited 69.87% removal. The arsenic removal efficiency was found to be dependent on fly ash dosage. As the dosage was increased from 0.5g/L to 4g/L, an increase in the removal efficiency was also observed by 46.30 80.47% for sub-bituminous fly ash and 32.06 69.87% for bituminous fly ash