Abstract
Extensive studies have been conducted to discover natural, efficient and cost-saving coagulants for water treatment. Meanwhile, chemical coagulants are being used conventionally in drinking water treatment. This study investigates the efficacy of diatomite as a natural coagulant in river water treatment. First, synthetic turbid water was used to validate the coagulant efficiency. Then, coagulation and flocculation behaviors were studied by using the river water samples from Langat River and Semenyih River. Turbidity removal efficiency of synthetic turbid water revealed that a low dosage of 3.5 mg/L could reach turbidity reduction of 83.46%. The turbidity reduction for Semenyih River water with initial turbidity of 31.8 NTU was achieved at 91.7% with 18 mg/L dosage at pH of 7.4 whereby, for Langat River water with an initial turbidity of 43.3 NTU, the turbidity reduction was achieved at 94.5% with a dosage of 26 mg/L at pH of 8.0. These results showed that water turbidity removal was influenced by both high and low natural organic material. This is because the best dosage of coagulant is indirectly proportional to the molar mass of natural organic material. In conclusion, diatomite is a promising material to be used as a natural coagulant in water treatment applications.
Highlights
It has been predicted that global demand for water will increase by approximately 50% by the year 2030
Coagulation is defined as a process of aggregating all the smaller particles into larger flocs which are removed through subsequent sedimentation process [10]
As mentioned by Meesuk, Benjamas and Utha-aroon (2008) the natural diatomite from Thailand can be used to remove sugarcane juice color and turbidity in an industrial process [17]. Another studies Turbidity indicates the presence of fine organic and inorganic matter, colored compounds, algae and other microorganisms. It is measured by the relative clarity of a liquid where the intensity of light scattering is directly proportional to turbidity in Nephelometric Turbidity Units (NTU) using turbidimeter [18]
Summary
It has been predicted that global demand for water will increase by approximately 50% by the year 2030. Flocculation is a process of forming larger particles to assist the sedimentation process of the suspended particles [11] In this context, many scientists have done studies in investigating the potential of diatomite as a coagulant. Diatomite is a naturally occurring sedimentary rock formed by fossilization of phytoplankton It is a biodegradable material found abundantly around the world in both fresh and seawater. The major component of silica found in diatomite derives from an external cell wall (frustules) formed surrounding the diatoms [13] This material has driven the interests of scientists for its remarkable physicochemical properties such as high porosity, surface area, and thermal resistance [14-15]. As mentioned by Meesuk, Benjamas and Utha-aroon (2008) the natural diatomite from Thailand can be used to remove sugarcane juice color and turbidity in an industrial process [17] Another studies Turbidity indicates the presence of fine organic and inorganic matter, colored compounds, algae and other microorganisms. The optimum dosage of diatomite is discussed in this paper
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