A characteristic study of the coagulation floc from different Coagulants by using an on-line Nephelometric Turbidimeter Monitoring System

• Main Authors: Ying-Ru Shie, 謝盈如
• Other Authors: Wên-Pa Chêng
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/09928062993205190919

碩士 === 國立聯合大學 === 環境與安全衛生工程學系碩士班 === 97 === In a water treatment plant, the dosage control of coagulants depends generally on the results from Jar tests. Improper coagulant and dosages may lead to a useless operation and may increase the quantity of chemical sludge. Particle aggregation (coagulation/flocculation) is a vitally important process in water and wastewater treatment and can have very significant effects on the efficiency of solid-liquid separation operations. But, the physical characteristics of the floc may be more influential in determining turbidity removal efficiency. For example, large compact flocs have a high settling rate that results in treated water of low residual turbidity, whilst large and porous flocs aid filtration due to high permeability. Due to the limited strength of the floc, the coagulation floc might be eaily broken under the external force. It will cause the ineffective settlement and separation during the solid-liquid separation process. Thus, the floc characterization measured using floc monitoring was studied to index the real coagulation efficiency. In this research, to set up a Nephelometric turbidimeter monitoring system (NTMS) which the Nephelometric turbidimeter coupled with a data acquisition unit was used to measured water turbidity for on-line monitoring every second in the coagulation process. The turbidity fluctuations were then analyzed as basis for the evaluation of particle size. In addition, the image analysis was used to measure the floc characteristics in the different slow speed coagulation conditions, which different coagulation conditions flocs formed by the particle size, floc strength and floc fractal dimension and other characteristics. And by the slow mixing of the turbidity when the value of the amplitude of standard deviation (SD) to replace the Photometric Dispersion Analyzer (PDA) for the flocculation index (FI) test, experimental results show that different velocity gradient (G), the coagulation particle size, the theoretical strength of flocs and floc fractal dimension values with SD shown excellent correlation, so the future will be able to use the continuous online turbidity monitoring system was slow turbidity to inferred floc of coagulation structural properties.