Development of Supercritical Fluid Extraction Procedure and Feasibility of Fenton Process on Removal 4-Nonlyphenol in Sewage Sludge

• Main Authors: Liu, Chih-Huang, 劉志皇
• Other Authors: Lin, Jih-Gaw
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/77531623821993040044

碩士 === 國立交通大學 === 環境工程與科學系 === 86 === 　　The main objective of this study is to develop the supercritical fluid extraction method. The target is the 4-nonylphenol (4-NP) in sludge. In the same time, we also discuss the feasibility of the Fenton method to treat the 4-NP in sludge. Nonylphenol polyethoxylates (NPnEO) are a major class nonionic surfactant in the world. Under anaerobic condition, NPnEO ultimately biodegrade into 4-NP, which has been shown to be a strongly estrogenic compound. 　　In this study, the CO2 was used as extraction fluid and the pentane as collection solvent. Developments of SFE method contain three procedures. First, we approach to the extractability of standard 4-NP spiking in quartz, which is without matrix effect. The purpose of study was to examm e the solubility of 4-NP in supercritical fluid. The parameters discussed in this procedure are extraction pressure, temperature, flow rate, static extraction time and dynamic extraction. Second, we research on the matrix effect with spiking standard 4-NP in non-4-NP sludge. The parameters discussed in this procedure are sludge weight, concentration of 4-NP, water contain of sludge, modifier type and dynamic extraction time. Third, the real anaerobic sludge from De-Haw sludge treatment plant was extracted by SFE. In this procedure, we examine the water contain and modifier effect in real sludge with SFE. At the end, we compared the extraction efficiency between SFE and Soxhlet extraction method. The optimal extraction conditions are: sludge weight 0.2 g, extraction pressure 97 bar, temperature 40°C, flow rate 3.0 mL/min, static extraction time 2 min, dynamic extraction time 30 min, and methanol (0.5 mL) as modifier. Under these conditions, the concentration of 4-NP in De-Hew STP were 243.89 and 266.98 by SFE and Soxhlet extraction method, respectively and the relative standard deviation were 0.86 and 2.62%. 　　The Fenton oxidation of 4-NP was investigated in sludge of De-Haw STP using a number of process conditions including initial concentrations of H2O2, initial concentrations of Fe2+, initial pH value, concentration of dissolved oxygen, and reaction time. The total solid of sludge was 1.7%. The result suggest that hydroxyl radical may cross the liquid-solid interface under aggressive reaction conditions. The optimal conditions are inital H2O2 concentration of 5,000 mg/L, initial Fe2+concentration of 500 mg/L, initial pH value of 3, dissolved oxygen kept at 35 mg/L with pure oxygen under 500 mL/min, and the reaction time of 4 hours. Under these conditions, the Fenton process did not destroy the bacteris structure. The removal ratio of 4-NP in sludge was 83.68% and the supernatant of sludge was biodegradable. The consumption of H2O2 was 185.5 mole per kg of sludge. Based on these optimization results, the estimated chemical cost for the removal of 243.89 mg/kg 4-NP in sludge was $190/ton (dry weight).