Usage of Bilecik Lefke Stone and Bentonite Clay for Phosphorus Removal in Water

Abstract

The rapid increase in the world population, the development of the industry, the excessive usage of fertilizers in agriculture, and the increase in detergents and chemicals used for cleaning accelerate the pollution of water resources. Conservation and recovery of damaged water resources along with the deteriorated ecosystem is of great importance for living things. An important part of water pollution in lakes and rivers is the increase in the content of nutrients. Nutrient elements, especially phosphorus, cause the transparency of water to decrease gradually. Over time, this situation, called eutrophication, causes an algae bloom and the aquatic ecosystem is disrupted. Uncontrolled discharge of wastewater containing phosphorus in high concentrations accelerates this process. These nutrients must be removed in order to maintain water quality and reduce the risk of eutrophication. The main ways of removing phosphorus from water are physical, chemical and biological methods. Among these, as an alternative to settling with chemical substances, the usage of clay (based on fixation) has an important place. In this study, different dosages of bentonite, lefke stone and ferrous sulphate heptahydrate (FeSO4.7H2O) were used in water with three different pH values (4, 7 and 10) and three different phosphorus contents (20, 40, 60 ppm). The per cent yields of the phosphorus removed with ferrous sulphate heptahydrate, lefke stone and bentonite are 72%, 57% and 39%, respectively. In addition, it was determined that the dosage of additives used should be renewed depending on the phosphorus content of the environment and that the high pH value of the environment increased the efficiency, especially in the usage of ferrous sulphate heptahydrate. In conclusion, as an alternative to the usage of chemicals, it has been revealed that lefke stone can be used for phosphorus removal in water, and its effectiveness can be further increased with further studies.