Browsing by Author "Lin, JG"

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Alkaline and ultrasonic pretreatment of sludge before anaerobic digestion
(1997)
Chiu, YC
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Chang, CN
;
Lin, JG
;
Huang, SJ
;
環境工程研究所
Pretreatment of waste activated sludge (WAS) results in an improved efficiency of the subsequent anaerobic biotransformation of the organic matter to volatile fatty acids. The pretreatment process has been carried out using alkaline treatment, ultrasonic treatment (20 KHz, 120 W) and different combination of these two methods: alkaline followed by ultrasonic, as well as the combining method in which ultrasonic treatment is applied to WAS samples dosed with alkaline, The hydrolysis efficiency was evaluated based on the quantity of soluble COD (SCOD) and organic nitrogen in the pretreated WAS as well as the production of total volatile fatty acids (TVFA) in the following biochemical acid potential (BAP) test. For WAS samples with described pretreatments, the released SCOD varied from 36% to 89% of the total COD (TCOD) and soluble organic nitrogen from 34% to 42%. The TVFA/TCOD ratio of the raw WAS used in this study was less than 10%. For the alkaline pretreated WAS, the TVFA/TCOD ratio increased to 30%, and the following ultrasonic treatment enhanced the ratio 66%. Further, WAS samples pretreated using simultaneous ultrasound and alkaline treatment in which ultrasonic was applied to WAS samples dosed with 40 meq/L NaOH for 14.4 sec/mL could achieve a maximum TVFA/TCOD ratio of 84% in 21 hours, Therefore, the combination of simultaneous alkaline and ultrasound pretreatment is efficient in enhancing the production of volatile acids in WAS in order to achieve recovery of volatile fatty acids from the WAS. (C) 1997 IAWQ. Published by Elsevier Science Ltd.
Alkaline hydrolysis of the sludge generated from a high-strength, nitrogenous-wastewater biological-treatment process
(1998-07-01)
Lin, JG
;
Ma, YS
;
Huang, CC
;
環境工程研究所
;
Institute of Environmental Engineering
The production of acrylonitrile butadiene styrene (ABS, a petrochemical product) in Taiwan is one of the biggest manufactoring processes in the world. The large amount of ABS sludge generated in the wastewater treatment plant from the highly nitrogenous-wastewater contains significant amount of complex and biorefractory organic substances. Resource recovery is the optimal conception of the traditional sludge treatment for the purpose of organic matters removal. An alkaline pretreatment method is used to enhance the efficiency of biological hydrolysis of industrial wastewater sludge in the present study. The operating conditions for the alkaline pretreatment of the ABS sludge were maintained at room temperature (25+/-3 degrees C), reaction time of 24h, total solids in the feed of 0.5-2%, and NaOH dosages of 10-50 mg l(-1). Considering the increasing concentrations of soluble chemical oxygen demand and biochemical oxygen demand, the experimental results indicated that the alkaline pretreatment method was useful in biodegradability enhancement. (C) 1998 Elsevier Science I;tn. All rights reserved.
Assessment of recoverable forms of sulfur particles used in bioleaching of contaminated sediments
(2003-01-01)
Chen, SY
;
Chiu, YC
;
Chang, PL
;
Lin, JG
;
環境工程研究所
The use of recoverable sulfur particles will enhance the feasibility and reduce the cost of bioleaching process. Three different forms of sulfur particles, powder, pastilles and pellets were used to study the utilization and recovery of sulfur, used as energy source for thiobacilli in the bioleaching process. The Langmuir isotherm was used to explain the adsorption equilibrium existing between the sorbed and suspended bacteria and the maximum adsorption capacity obtained from the Langmuir isotherm was utilized to determine the specific surface area of the sulfur particles. The specific surface area of sulfur particles was found to be the determining factor in the bioleaching process and not the particle size. The rates of pH reduction, sulfate production and metal solubilization increased with increasing specific surface area of the particles. The pH reduction and metal solubilization were significantly enhanced by the reuse of recovered sulfur particles. The efficiency of metal solubilization with recovered sulfur pastilles was comparable to that with sulfur powder. This study revealed the practicability of reusing the recovered sulfur pastilles in the bioleaching process. (C) 2002 Elsevier Science Ltd. All rights reserved.
Assessment of sediment toxicity by metal speciation in different particle-size fractions of river sediment
(2003)
Lin, JG
;
Chen, SY
;
Su, CR
;
環境工程研究所
;
Institute of Environmental Engineering
Mobility and toxicity of metals associated with sediments are generally affected by metal speciation and granular compositions. Due to the various speciation patterns of heavy metals in sediments, it is not reliable to assess the potential toxicity of heavy metals on the aquatic environment with the total concentrations of heavy metals in sediments. The purposes of this study were to investigate the distribution of metal speciation in different particle-size fractions of sediments collected from two rivers (the Ke-Ya River and Ell-Ren River) in Taiwan, and to assess their potential toxicity to the aquatic ecosystem. Metals in the exchangeable, carbonate-bound and Fe/Mn oxide-bound forms obtained by sequential extraction were considered to be mobile and related with anthropogenic pollution. The degree of metal pollution and potential toxicity of sediments were higher in the lower reaches of both rivers. The metal speciation in sediments had a bimodal distribution over particle-size fractions. Heavy metals were subject to accumulation in the silt/clay fraction (< 25 mum) and coarse sand (420-2,000 mum). By normalizing the sum of the exchangeable, carbonate-bound, and Fe/Mn oxide-bound metals, it suggested that the potential toxicity to the aquatic ecosystem was caused by the fine sediments as well as coarse sediments.
Biodegradation of di-(2-ethylhexyl) phthalate in sewage sludge
(2000)
Cheng, HF
;
Chen, SY
;
Lin, JG
;
環境工程研究所
;
Institute of Environmental Engineering
Di-(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer in the production of polyvinyl chloride to impart flexibility to the product. Because of its mutagenicity and carcinogenicity, the presence of DEHP in sludge limits the application of sludge as a soil fertilizer. In this study, sludges were collected from three sewage treatment plants and thirteen wastewater treatment plants of different industries in Taiwan. A supercritical fluid extraction (SFE) was first established as an effective method for determining the concentration of DEHP in sludge. Laboratory-scale land-simulated experiments were performed to investigate the biodegradation of DEHP in sludge under various conditions (moisture, temperature, sunlight and ventilation). DEHP was found in aerobically and anaerobically digested sludges and their values significantly exceeded the restricted concentration of DEHP for sludge land application. DEHP was found to degrade in sludge under the conditions of good ventilation, sufficient sunlight and proper moisture. The indigenous microorganisms in the sludge appeared to dominate the biodegradation of DEHP in sludge. However about 70% of DEHP remained in sludge after 189 d indicating that DEHP is persistent in the environment.
Biodegradation of nitrilotriacetic acid and its metal complexes in river water
(1996)
Chen, SY
;
Lin, JG
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Chang, HT
;
交大名義發表
;
環境工程研究所
In this work, we investigated the biodegradability of both the complexing agent (nitrilotriacetic acid, NTA) and its various metal complexes in an aquatic environment. A laboratory experiment was used to simulate the rates of biodegradation of NTA and NTA-metal (Ca, Pb, Zn, and Cu) complexes in river water. A first-order reaction was applied to describe the rates of biodegradation of NTA and NTA-metal complexes. NTA became completely degraded within 2 - 3 d after acclimation for 6 d and the rate coefficient (k) was 1.56 - 4.54 d(-1). Except Ca-NTA, all NTA-metal complexes degraded at a more smaller rate than NTA. The stabilities of these complexes are in the decreasing order Cu-NTA > Pb-NTA > Zn-NTA > Ca-NTA.
Bioleaching of heavy metals from contaminated sediment by indigenous sulfur-oxidizing bacteria in an air-lift bioreactor: effects of sulfur concentration
(2004-08-01)
Chen, SY
;
Lin, JG
;
環境工程研究所
;
Institute of Environmental Engineering
The effects of sulfur concentration on the bioleaching of heavy metals from the sediment by indigenous sulfuroxidizing bacteria were investigated in an air-lift reactor. Increasing the sulfur concentration from 0.5 to 5 g/l enhanced the rates of pH reduction, sulfate production and metal solubilization. A Michaelis-Menten type equation was used to explain the relationships between sulfur concentration, sulfate production and metal solubilization in the bioleaching process. After 8 days of bioleaching, 97-99% of Cu, 96-98% of Zn, 62-68% of Mn, 73-87% of Ni and 31-50% of Pb were solubilized from the sediment, respectively. The efficiency of metal solubilization was found to be related to the speciation of metal in the sediment. From economical consideration, the recommended sulfur dosage for the bioleaching of metals from the sediment is 3 g/l. (C) 2004 Elsevier Ltd. All rights reserved.
Bioleaching of heavy metals from livestock sludge by indigenous sulfur-oxidizing bacteria: effects of sludge solids concentration
(2004-01-01)
Chen, SY
;
Lin, JG
;
環境工程研究所
;
Institute of Environmental Engineering
A technologically and economically feasible process called bioleaching was used for the removal of heavy metals from livestock sludge with indigenous sulfur-oxidizing bacteria in this study. The effects of sludge solids concentration on the bioleaching process were examined in a batch bioreactor. Due to the buffering capacity of sludge solids, the rates of pH reduction, ORP rise and metal solubilization were reduced with the increase of the solids concentration. No apparent influence of solids concentration on sulfate produced by sulfur-oxidizing bacteria was observed when the solids concentration was less than 4% (w/v). A Michaelis-Menten type of equation was able to well describe the relationship between solids concentration and rate of metal solubilization. Besides,,high efficiencies of metal solubilization were achieved after 16 d of bioleaching. Therefore, the bioleaching process used in this study could be applied to remove heavy metals effectively from the livestock sludge. (C) 2003 Elsevier Ltd. All rights reserved.
Bioleaching of heavy metals from sediment: significance of pH
(2001-08-01)
Chen, SY
;
Lin, JG
;
環境工程研究所
;
Institute of Environmental Engineering
Bioleaching process, which causes acidification and solubilization of heavy metals, is one of the promising methods for removing heavy metals from contaminated sediments. The solubilization of heavy metals from contaminated sediments is governed by the sediment pH. In the present study, the significance of pH in bioleaching of heavy metals from contaminated sediment was evaluated at different solid contents of sediments in a bench-scale reactor. Results showed that a temporal change of pH in the bioleaching process was effected by the buffering capacity of the sediment particulates. The variations of pH in this bioleaching process were calculated by a modified logistic model. It was observed that solubilization of heavy metals from sediments is highly pH-dependent. In addition, a non-linear equation for metal solubilization relating pH value in the bioleaching process was established. This allows an easier and faster estimate of metal solubilization by measuring pH in the bioleaching process. (C) 2001 Elsevier Science Ltd. All rights reserved.
BMP test on chemically pretreated sludge
(1999-05-01)
Lin, JG
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Ma, YS
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Chao, AC
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Huang, CL
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環境工程研究所
Municipal waste activated sludge (WAS) was treated with NaOH to solubilize the particulate organic matter in order to improve its digestibility when the sludge was stabilized in an anaerobic digestion process. For the WAS of 1% TS treated with 20 and 40 meq/l NaOH at ambient temperature for 24 h, the SCOD/TCOD values increased from 3.5 to 39 and 55%, respectively. Results of the BMP (biochemical methane potential) test showed that recoveries of carbon and nitrogen reached 94-105% and the methane produced was 349 ml (at 1 atm and 35 degrees C) for 1 g of COD removed. The improvement in VS removal for sludge treated with 40 meq/l of NaOH was as high as 41% over the control sludge sample, with COD removal and gas production improved by 30 and 34%, respectively, over the control. Results of the cumulative COD removal appeared to follow first-order reaction kinetics. Parameters of the first-order model such as ultimate biodegradable COD (L-u), reaction rate coefficient (k) and ultimate biodegradability (mu), were calculated using the Thomas method. The BMP test can be used as a valuable tool to study the kinetics and efficiency of anaerobic digestion processes. (C) 1998 Elsevier Science Ltd. All rights reserved.
Chemical conditioning for removal of water and phosphate from enhanced sludge
(1996)
Lin, JG
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Chang, CN
;
Hung, HC
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環境工程研究所
;
Institute of Environmental Engineering
Decomposition of 2-chlorophenol in aqueous solution by ultrasound/H2O2 process
(1996)
Lin, JG
;
Chang, CN
;
Wu, JR
;
環境工程研究所
;
Institute of Environmental Engineering
Several authors have indicated that ultrasound is effective in oxidizing organic contaminants in water and in wastewater either as the sole means of treatment or in combination with ozonation and UV irradiation. In this work we decomposed 2-chlorophenol (2-cp) in aqueous solution with ultrasound and H2O2. The experiment was conducted with a sonicator (Microson XL-2020) operated at 20 kHz. The double amplitude at the tip of the standard horn (12.7 mm) was adjusted to 0, 72 and 120 mu m, corresponding to power input 0, 125 and 160 W. The initial concentration of aqueous 2-cp solution was 100 mg/l, treated in the system with 0, 100, 200 and 500 mg/l H2O2 individually. The volume of solution was 11 in a mixing flask, and was circulated to the sonication cell at the rate 500 mL/min. Oxygen was continuously purged into the flask. The temperature of solution was kept constant at 25 degrees C and pH was controlled at 3, 5, 7, 9 and 11. The results showed the decomposition of 2-cp was effective at increased amplitude of ultrasound and concentration of H2O2, and smaller pH. At reaction duration 360 min, 2-cp decomposition with 500 mg/l H2O2 was found with 57% improvement over the control, i.e. without H2O2 addition. The pH, controlled below the pKa of 2-cp (8.49 at 25 degrees C), had significantly better decomposition of 2-cp than at greater values. The decomposition rate of 100 mg/l 2-cp was 99% at 120 mu m double amplitude with H2O2 (200 mg/L) and pH 3, after 360 min of reaction. The removal of total organic carbon was found to be only 63%. From analysis of the experimental results, the data on 2-cp decomposition appeared to follow pseudo-first-order reaction kinetics. The squared correlation coefficient, R2, of the model was greater than 0.9 for various pH values. Copyright (C) 1996 IAWQ.
Degradation of 4-nitrophenol using the Fenton process
(2000)
Ma, YS
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Huang, ST
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Lin, JG
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環境工程研究所
;
Institute of Environmental Engineering
In this study, The Fenton process was applied as a pretreatment method to treat industrial wastewater containing 4-nitrophenol (4-NP). The effect of oxidant dosages on the decomposition of 4-NP and the reaction kinetics were investigated. More than 99% of 4-NP was readily decomposed when the reaction was carried out at oxidant concentrations of 5 mM H2O2 and 5 mg/L Fe2+ for 2 hours. The total nitrogenous compounds and the nitrogen gas evolved, accounted for 88% of the initial nitrogen concentration. However, the maximum DOC removal efficiency was 30.6%; and only 1/3 of 4-NP was mineralized to carbon dioxide by the Fenton process. 4-NP degradation profiles fitted well into a pseudo first-order kinetic equation; degradation rate constant (min(-1)) of 4-NP increased from 4.3x10(-3) to 66.1x10(-3) With increasing dosages of H2O2 and Fe2+. In addition, the t value was calculated for studying the significance of simulation by the t-test. It was found that the t value was greater than the value for 99% confidence. This result suggested that the 4-NP decomposition profile could be described by the pseudo first-order kinetic equation. Biodegradability of 4-NP before and after the reaction was 0.018 and 0.594, respectively.
Effect of pre-sonication on removal of organic matters resulting from chlorinated humic acids
(1998)
Ma, YS
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Lin, JG
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環境工程研究所
;
Institute of Environmental Engineering
Humic acids are amorphous organic macromolecules that are responsible for the color of natural water. They play an important role in the formation of disinfection by-products, the stabilization of wastewater sludge, and the treatment of wastewater. An ultrasonic process is applied as a pretreatment method for the purpose of reducing the risk of chlorinated by-products. Experimental results indicate that the initial pH, ionic strength, and chlorine demand affect the amount of total organic carbon removal and Cl-2 consumption significantly. The formation of chlorinated by-products depends on both the initial pH and ionic strength. Experimental results also propose a good agreement that the humic acid can be removed efficiently by ultrasonic pretreatment under aerobic conditions. In this study, when the ultrasound/O-2 process is used as a pretreatment method, the biodegradability which is defined as the formation bf BOD5 increases with sonication time. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.
Effect of substrate concentration on bioleaching of metal-contaminated sediment
(2001-03-19)
Chen, SY
;
Lin, JG
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環境工程研究所
;
Institute of Environmental Engineering
The remediation of metal-contaminated sediment wits studied using the bioleaching process with a mixed culture of sulfur-oxidizing bacteria. The effects of substrate concentration (elemental sulfur) on sediment acidification, sulfur oxidation and metal solubilization from contaminated sediment during the bioleaching process were investigated with free-cell suspensions. Sulfur concentration greater than 0.5% (w/v) was found to be inhibitory to bacterial activity and metal solubilization from sediment. The sulfate production was well described by a substrate inhibition expression and Haldane's equation. In addition, an empirical equation related to sulfur concentration was also used to describe the metal solubilization in the bioleaching process. (C) 2001 Elsevier Science B.V. All rights reserved.
Effects of ferric ion on bioleaching of heavy metals from contaminated sediment
(2003)
Chen, SY
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Lin, JG
;
Lee, CY
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環境工程研究所
;
Institute of Environmental Engineering
Bioleaching is one of the promising procedures for removal of heavy metals from contaminated sediments. The advantages of this biotechnology are that it is easy, efficient, less costly and friendly to the environment. However, the principal disadvantage of this process is its slow kinetics in metal solubilization, which may limit practical application of the bioleaching process. In order to enhance the rate and efficiency of metal solubilization, the ferric ion was used as a catalytic agent in the bioleaching process. It was found that the sediment pH apparently decreased in the bioleaching after addition of ferric ion. The metal solubilization increased quickly after the addition of ferric ion. The rate of metal solubilization was enhanced by the addition of ferric ion, especially for Cr and Pb. An increase in the amount of ferric ion added increased the final efficiency of metal solubilization. The highest final efficiency of metal solubilization was obtained in the bioleaching with 1 g/L of ferric ion. Besides, the growth of sulfur-oxidizing bacteria was not affected by addition of ferric ion in the bioleaching. It was concluded that the kinetics of metal solubilization were enhanced by addition of ferric ion in the bioleaching process.
Efficiency evaluation of PTA wastewater treatment with the ultrasound/H2O2 process
(1997)
Liu, CH
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Ma, YS
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Lin, JG
;
交大名義發表
;
環境工程研究所
In this study, we used the ultrasound/hydrogen peroxide (H2O2) process to treat the pure terephaltic acid (PTA) industrial wastewater. The BOD5 and TOC of raw PTA wastewater were 13,200 and 6,390 mg/L, respectively. Several semi-and non-volatile organics, such as benzoic acid, 4-methyl benzaldehyde, phenyl acetic acid, and 4-ethyl benzoic acid were detected in PTA wastewater by GCD (HP GCD 1800A). In the present paper, we discussed the effect of ultrasound/H2O2 process with various concentrations of H2O2 and pH values on mineralization and biodegradability of PTA wastewater. Mineralization of PTA wastewater was evaluated by the ratio of TOC removal and biodegradability by real residual BOD5 over theoretical residual BOD5. The results show that the lower the initial pH value and the higher the concentration of H2O2, the higher ratio of mineralization was found. During the reaction time, the ORP value at pH 3 was greater than at pH 7 and 11. The pH value affected ORP value more significantly than H2O2 dosage in this work. The biodegradability increased with the amount of TOC removal by ultrasound/H2O2 process but decreased with the amount of TOC removal by ultrasound only. The optimum condition to pretreat PTA wastewater with ultrasound/H2O2 process before biological treatment was pH 3 and H2O2 200 mg/L. However, when ultrasound/H2O2 process was used as a sole treatment without biological treatment, the optimum pH value was also controlled at 3, but the concentration of H2O2 must increase upto 500 mg/L. Under such conditions, the ratio of mineralization was 70%.
Efficiency of supercritical fluid extraction for determining 4-nonylphenol in municipal sewage sludge
(1999-04-23)
Lin, JG
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Arunkumar, R
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Liu, CH
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環境工程研究所
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Institute of Environmental Engineering
When the sewage sludge containing the persistent, lipophilic, metabolite 4-nonylphenol (4-NP) has been disposed of in the environment it's toxic nature can lead to serious health risks to human beings and can also affect plants and aquatic organisms. Supercritical fluid extraction (SFE) is a new and powerful technique for extracting the organic contaminants from the solid phase. The present study was conducted to investigate optimal conditions for the quantitative extraction of 4-NP by SFE and to determine the concentration of 4-NP in municipal sewage sludge. The effect of several parameters such as temperature, pressure, static extraction time, dynamic extraction time, CO2 flow-rate, sample mass and modifier on the extraction were investigated. The optimal conditions for die extraction of the spiked sample were fluid pressure 97 bar, temperature 40 degrees C, flow-rate 3.0 ml/min, static extraction time 2 min, dynamic extraction time 5 min and modifier methanol (0.5 ml). Extracts were analyzed by gas chromatography-mass spectrometry. Concentration of 4-NP in the anaerobically degraded sludge of the De-flaw Sewage Treatment plant in Taiwan was found to be 243.9 mg/kg. The extraction efficiency of the SFE method was compared with the conventional Soxhlet extraction method. The overall recovery of the SFE method was found to be greater and the results indicate that SFE is an efficient method for extracting 4-NP from sewage sludge. (C) 1999 Elsevier Science B.V. All rights reserved.
Enhancement of anaerobic digestion of waste activated sludge by alkaline solubilization
(1997-12-01)
Lin, JG
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Chang, CN
;
Chang, SC
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環境工程研究所
;
Institute of Environmental Engineering
The performance of an anaerobic digestion fed with waste activated sludge (WAS) pretreated with NaOH was examined The sludge was periodically collected from a municipal wastewater-treatment plant. The laboratory work was run in four I-I semi-continuous anaerobic digestion reactors. Reactor-A was fed with untreated WAS at 1% total solids (TS). The other three reactors, B, C and D, were respectively fed with WAS (1% TS) pretreated with 20 meq/l NaOH, WAS (1% TS) pretreated with 40 meq/l NaOH, and WAS (2% TS) pretreated with 20 meq/l NaOH. The reactors were operated at 35 degrees C at four hydraulic retention rimes - 20, 13, 10 and 7.5 days. The performances of reactors B, C and D, in terms of chemical oxygen demand (GOD), volatile solids (VS) removal, and gas production, were superior to that of reactor A. At a retention time of 10 days, the COD removals of reactors A, B, C and D were 38, 46, 51 and 52%, respectively. The gas productions of reactors B, C and D were, respectively, increased by 33, 30 and 163% over that of reactor A. The sludge dewaterability was examined by capillary suction rime (CST). The dewaterability of digested sludge was improved in reactors B, C and D. Capillary suction of digested sludges gave times in the range 148-389 s, compared with 309-735 s for undigested sludges. (C) 1997 Elsevier Science Ltd.
Enhancement of decomposition of 2-chlorophenol with ultrasound/H2O2 process
(1996)
Lin, JG
;
Chang, CN
;
Wu, JR
;
Ma, YS
;
環境工程研究所
We investigated the effects of pH, ionic strength, catalyst, and initial concentration on both decomposition of 2-chlorophenol (2-cp) and removal of total organic carbon (TOC) in aqueous solution with ultrasonic amplitude 120 mu m and H2O2 (200 mg/l). When the initial concentrations of 2-cp was 100 mg/l and the pH was controlled at 3, the rate of 2-cp decomposition was enhanced up to 6.6-fold and TOC removal up td 9.8-fold over pH controlled at 11. At pH 3, the efficiency of decomposition of 2-cp was 99% but the removal of TOC was only 63%; a similar situation applied at pH 7 and 11. Hence intermediate compounds were produced and 2-cp was not completely mineralized. When the concentration of ionic strength was increased from 0.001 to 0.1 M, the rate of 2-cp decomposition was enhanced only 0.3-fold, whereas the TOC removal was not enhanced. In comparison of the effects of pH and ionic strength, pH had greater influence on both 2-cp decomposition and TOC removal than ionic strength. The effect of a catalyst (FeSO4) on decomposition of 2-cp was insignificant comparing with direct addition of H2O2 The reaction rate at a smaller initial concentration of 2-cp (10 mg/l) was more rapid than at a greater one (100 mg/l). The rate of 2-cp decomposition and TOC removal appeared to follow pseudo-first-order reaction kinetics. Copyright (C) 1996 IAWQ. Published by Elsevier Science Ltd.