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Development of Bio Coagulants for Waste Water Treatment

Sahana, J. and Shruti, L Naik and Smitha, E.K. (2010) Development of Bio Coagulants for Waste Water Treatment. [Student Project Report]

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Abstract

This Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page.

Item Type: Student Project Report
Additional Information: Fluorosis is caused when the drinking water with fluoride content more than 1.50 ppm is consumed continuously. Fluorosis cripples the young and old alike. It is also know to induce aging. Fluorosis may be skeletal or dental. According to the survey of water technology mission, 25 million people in 8700 villages of 15 states are suffering with excess fluoride drinking water problem. Fluorosis is incurable; however, it can be controlled. Defluoridation is a method of reducing the fluoride content in the water to an acceptable limit. The specified limit of fluoride content is 1.00‐1.50 ppm, in order to prevent the teeth decay. According to Dr A.K.Susheela, professor AIIMS, New Delhi, there is no need for the minimum fluoride content since this requirement is met from pan, supari, tobacco, tea and several food products which have fluoride content. When there is no water source other than the excess fluoride water, then defluoridation is he only method to make source safe for drinking. Several technologies have been developed to defluoridated excess fluoride water, based on precipitation. Adsorption, ion exchange, electro chemical deposition, reverse osmosis and electrolysis NEERI, Nagapur has made extensive work on defluoridation and developed Nalgonda technique to remove excess fluoride from drinking water. Based on Nalgonda technique, several fill and draw type fluoridation plants, hand pump attached defluoridation plants and domestic defluoridation plants have been designed. Activated alumina has proved to be specific in fluoride removal. Making use of activated alumina, several domestic and community defluoridation plants are designed. The community filters are becoming defunct due to operation and maintenance problems. The present study aims at investigating the potential of using plant seeds to act as natural or biocoagulants, replacing expensive chemicals, optimizing the dosage of coagulants and its removal efficiency in the treatment of waste water contaminated with fluoride. DEPT OF BIOTECHNOLOGY, SJCE, MYS. Coagulation and flocculation are the processes used to remove the particles responsible for turbidity and color. The colloidal particles present in wastewaters generally carry a negative electrical charge. Their diameter may range between 10-4 to 10-6 mm. These particles are surrounded by an electrical double layer (due to attachment of positively charged ions from the ambient solution) and thus inhibit the close approach of each other. They remain finely divided and don’t agglomerate. Due to their low specific gravity, they dont settle out. Coagulation is accomplished by the addition of ions having the opposite charge to that of the colloidal particles. In coagulation, a coagulant (generally positively charged) is added which causes compression of the double layer and thus the neutralization of the electrostatic surface potential of the particles. The resulting destabilized particles stick sufficiently together when contact is made. Rapid mixing (a few seconds) is important at this stage to obtain uniform dispersion of the chemical and to increase the opportunity for particle-to-particle contact. Flocculation, which follows coagulation, consists of slow gentle stirring. During flocculation, the microscopic coagulated particles aggregate with each other to form larger flocs. These flocs then are able to aggregate with suspended polluting matter. These flocs are large enough to settle rapidly under the influence of gravity, and may be removed from suspension by filtration. The use of plant materials as natural coagulants to clarify turbidity of wastewaters is of common practice since ancient times. Powdered roasted grains of Zea mays were used by soldiers in Peru as a means of settling impurities in the 16th and 17th century. In India, ancient writings refer to the use of the seeds of the Nirmali treeStrychnos potatorum as a clarifier. The sap of tuna cactus (Opuntia fiscus indica) is widely used in Chili as water purifying agent. The commercially extracted products are known as Tunaflex A and B. Similarly, dried beans (Vicia faba) and peach seeds (Percica vulgaris) are widely used for this purpose in Bolivia and Peru. Tunaflex and Nirmali seeds have been successfully employed in municipal treatment plants in combination with alum.
Uncontrolled Keywords: plant seeds; biocoagulants; waste water treatment; flocculation;
Subjects: 500 Natural Sciences and Mathematics > 10 Plants
Divisions: Food Engineering
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 21 Jul 2010 06:46
Last Modified: 28 Dec 2011 10:16
URI: http://ir.cftri.com/id/eprint/9589

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