Effect of Locally Available Fruit Waste on Treatment of Water Turbidity

Abstract

Turbidity is one of the main problems associated with surface water treatment. Chemical coagulants are already being used for treatment but their enormous cost, human and environmental issues associated with their use have led to searching for alternatives like natural coagulants (plant-based). Although the use of natural coagulants for drinking water treatment has been discussed for a long time, the practice is still not employed in most poor developing countries, probably due to availability of materials and their usage as food crops. Therefore locally available fruit waste are now being evaluated for their suitability. Laboratory scale studies using jar test experiments were performed on river water containing synthetic turbidity of kaolinite to analyze the effect of Mangifera indica (Duncan mango)  and Citrus aurantiifolia (key lime) seeds as  locally available fruit waste on treatment of water turbidity. Experiments were carried out using different turbidity levels classified as low, medium and high: 50, 100 and 150 NTU with pH kept constant at 7.25.  Results indicated that the seed extracts of Duncan mango and key lime have coagulating potential. They were very effective for treatment of medium and high water turbidity. For treatment of high water turbidity using the seed extracts of Duncan mango and key lime as primary coagulants, 92.0 % and 91.1 % turbidity removal were achieved.  Compared to alum, the turbidity removal effectiveness was: alum > Duncan mango seed extract>key lime seed extract for all water turbidity levels. The pH of the treated water were within neutral (basic) due to the buffering capacity of the seed extracts. Result further indicated that the seed extracts of Duncan mango and key lime have the potential for use as coagulant aids with alum as primary coagulant for treatment of low, medium and high water turbidity.

Keywords: Mangifera indica, Citrus aurantiifolia, Turbidity, Natural coagulants, Seed extracts, Fruit waste