Bottom ash treatment by using seawater with Citrus aurantifolia

Abstract

The combustion process of coal from a coal-burning power station in TNB Janamanjung Sdn. Bhd. for production of energy was produced a primary by-product called coal ash. The huge amount of bottom ash was considered harmful to the environment and typically disposed of on-site disposal systems without any further use. The environment can be polluted since the toxic elements such as heavy metals that exist in the ash could pose a danger to public health. To overcome these problems, an effective treatment needs to be done to overcome the problems. The purpose of this research is to study the possibility of developing a new technique to reduce heavy metal elements by using seawater as a washing method and Citrus aurantifolia as leaching methods. A good alternative from the use of citric acid from the Citrus aurantifolia was discovered to be substitute strong acids such as HCl in the leaching process since citric acid can react as an organic acid which fewer negative effects compared to the stronger acid to humans and the environment. The bottom ash was rinsed and soaked in the seawater for 24 hr before the leaching process by using Citrus aurantifolia. The result showed that the heavy metals content such as copper (Cu), zinc (Zn), and arsenic (As) can be decreased after the removal process. In fact, the results show that the heavy metal removal up to 92% for As when the bottom ash was soaked until 72 hr but for Cu and Zn, the removal efficiency higher when the bottom ash was soaked at 20 hr. In conclusion, the optimum time to remove heavy metal from bottom ash by using Citrus aurantifolia was determined but the efficiency differs with the time taken to soak the bottom ash in the acid solution.