Browsing by Author "Pan, JR"

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Behavior of membrane scaling during crossflow filtration in the anaerobic MBR system
(2006)
You, HS
;
Huang, CP
;
Pan, JR
;
Chang, SC
;
環境工程研究所
Fouling of membrane bioreactor (MBR) has been studied intensively. Because of the high concentration of carbonates, scaling can be a serious problem in anaerobic bioreactor, which attracts little attention. In this study, the wastewater was treated with an anaerobic process followed by either a submerged or a side-stream aerobic membrane reactor. The wastewater was spiked with calcium to investigate the effect of scaling on membrane filtration. Very little scaling was detected in the external membrane system (the side-stream MBR). Results from chemical cleaning of internal membrane system indicated that the flux decline caused by membrane scaling was far more severe than that by membrane fouling. However, the flux decline from membrane scaling can be effectively recovered by the chemical cleaning of EDTA and NaOCl. Fouling of membrane bioreactor (MBR) has been studied intensively. Because of the high concentration of carbonates, scaling can be a serious problem in anaerobic bioreactor, which attracts little attention. In this study, the wastewater was treated with an anaerobic process followed by either a submerged or a side-stream aerobic membrane reactor. The wastewater was spiked with calcium to investigate the effect of scaling on membrane filtration. Very little scaling was detected in the external membrane system (the side-stream MBR). Results from chemical cleaning of internal membrane system indicated that the flux decline caused by membrane scaling was far more severe than that by membrane fouling. However, the flux decline from membrane scaling can be effectively recovered by the chemical cleaning of EDTA and NaOCl.
Biotreatment of H2S- and NH3-containing waste gases by co-immobilized cells biofilter
(2000-08-01)
Chung, YC
;
Huang, CP
;
Tseng, CP
;
Pan, JR
;
環境工程研究所
Gas mixture of H2S and NH3 in this study has been the focus in the research area concerning gases generated from the animal husbandry and the anaerobic wastewater lagoons used for their treatment. A specific microflora (mixture of Thiobacillus thioparus CH11 for H2S and Nitrosomonas europaea for NH3) was immobilized with Ca-alginate and packed inside a glass column to decompose H2S and NH3. The biofilter packed with co-immobilized cells was continuously supplied with H2S and NH3 gas mixtures of various ratios, and the removal efficiency, removal kinetics, and pressure drop in the biofilter was monitored. The results showed that the efficiency remained above 95% regardless of the ratios of H2S and NH3 used. The NH3 concentration has little effect on H2S removal efficiency, however, both high NH3 and H2S concentrations significantly suppress the NH3 removal. Through product analysis, we found that controlling the inlet ratio of the H2S/NH3 could prevent the biofilter from acidification, and, therefore, enhance the operational stability. Conclusions from bioaerosol analysis and pressure drop in the biofilter suggest that the immobilized cell technique creates less environmental impact and improves pure culture operational stability. The criteria for the biofilter operation to meet the current H2S and NH3 emission standards were also established. To reach Taiwan's current ambient air standards of H2S and NH3 (0.1 and 1 ppm, respectively), the maximum inlet concentrations should not exceed 58 ppm for H2S and 164 ppm for NH3, and the residence time be kept at 72 s. (C) 2000 Elsevier Science Ltd. All rights reserved.
Coagulation of high turbidity water: the effects of rapid mixing
(2002-03-01)
Kan, CC
;
Huang, CP
;
Pan, JR
;
環境工程研究所
;
Institute of Environmental Engineering
High turbidity water during the rainy season has long been a challenge to the waterworks in Taiwan. Coagulation is the critical process for solving this problem; however the dispersion of coagulants in, the concentrated solid phase is very difficult. in this study, the effects of rapid mixing on the PACI coagulation of high turbidity water were investigated in terms of turbidity and particle count. operational parameters of coagulant dosage, coagulant concentration and mixing intensity in the rapid-mixing step exhibited great impacts on the residual turbidity and particle count of the simulated system. Aggregation degree, as evaluated by the Photometric Dispersion Analyser (PDA), was influenced by the intensity of rapid mixing. Poor rapid mixing failed to induce aggregation to effectively coagulate the small and hard to settle particles.
Comparison of autotrophic and mixotrophic biofilters for H2S removal
(1998-04-01)
Chung, YC
;
Huang, CP
;
Pan, JR
;
Tseng, CP
;
環境工程研究所
We demonstrate that the facultative chemoautotroph Thiobacillus novellus CH3 removes hydrogen sulfide (H2S) gas in continuous reactors under nutrient-limiting conditions. Extensive tests including removal characteristics, metabolic products, and removal efficiencies of H2S by T. novellus CH3 were conducted in autotrophic and mixotrophic environments. The optimal pH value and temperature required to remove hydrogen sulfide are found to be pH 7 and 26 degrees C. The biofilter had an H2S removal efficiency greater than 99.5% under the mixotrophic condition after l0-day operation. The results show that the maximum removal rate and saturation constant were 1.9 g S/d per kg bead and 69.2 ppm, respectively. The main metabolic product of H2S oxidation was determined to be sulfate, but the conversion ratio was dependent on the growth environment. These results suggest that the mixotrophic potential of T. novellus CH3 biofilter provides a significant advantage in HS removal over autotrophic biofilters.
Dewatering characteristics of algae-containing alum sludge
(1999-05-01)
Pan, JR
;
Huang, CP
;
Chuang, YC
;
Wu, CC
;
環境工程研究所
The presence of algae in source waters not only causes problems in the water treatment process, but also complicates the treatment and disposal of sludge. This has become a major concern in Taiwan because of the increasing eutrophication of water sources. The purpose of this study was to determine the effects of algae during aging process on the characteristics of potable water treatment residuals and investigate their conditioning in order to provide water treatment plants with guidelines for treating algae-containing sludge. In this study, we measured the bound water content and CST to evaluate the influence of algae and their exudates on sludge conditioning. The change in zeta potential was monitored during sludge aging. During the aging process up to 5 days, the surface charge of sludge became more negative and the dewaterability was enhanced by algal exudates. Microphotographs of the algae-containing sludge suggest that algae and their exudates cause the bio-flocculation phenomenon. (C) 1999 Elsevier Science B.V. All rights reserved.
Effect of biofiltration on particle characteristics and flocculation behavior
(2005-06-01)
You, HS
;
Huang, CP
;
Cheng, HS
;
Pan, JR
;
環境工程研究所
Biodegradable dissolved organic material and ammonia present problems for conventional water treatment processes and may contribute to biological instability in the treated water. One solution may be to use a biological process upstream of the regular water treatment process. Biofiltration may be cost-effective in removing ammonia and the precursors of trihalomethanes but the characteristics of the biotreated effluent may affect to the subsequent coagulation process. A continuous flow biological filter packed with reticulated polyurethane foam markedly altered the particle size distribution and the charge density of the mixed liquor, shifting the granulometric distribution toward larger sizes. The mean and median diameter of the particles increased from 9.7 and 5.9 mu m to 97.6 and 37.1 mu m, respectively. The average charge density of the biofilter effluent (7.6 meq dm(-3)) was much lower than that of the raw water (12.7 meq dm(-3)). The optimum coagulant dosage for the subsequent coagulation was reduced substantially from 10 mg dm(-3) to 1 mg dm(-3) as Al due to the lowered charge density of the mixed liquor and the enhanced cation bridging of the extracellular polymers on the bioparticle surface. (c) 2005 Society of Chemical Industry.
Effects of surfactant addition on dewatering of alum sludges
(2002-12-01)
Huang, C
;
Pan, JR
;
Fu, CG
;
Wu, CC
;
環境工程研究所
In Taiwan, surfactants are frequently used in the flotation process to aid in solid/liquid separation. Their effect on the dewatering of alum sludge was investigated. Various amounts of cationic and anionic surfactants were added to sludge samples, and the dewatering characteristics of the sludge and the water content of sludge cakes were evaluated. Both surfactants improved the dewatering of the sludge by lowering the specific resistance to filtration, decreasing the bound water content, and increasing the dewatering rate of the sludge. Different combinations of anionic and cationic surfactants and polyelectrolytes were also experimented on to study the effect of surfactant addition on the dewatering characteristics of polyelectrolyte-conditioned sludge. Experimental results indicated that both cationic and anionic surfactants adversely affected the dewatening of the conditioned sludge. The addition of surfactant to the oppositely charged polyelectrolyte proved to be most detrimental to sludge dewatering due to the precipitation between surfactant and polyelectrolyte. The addition of cationic surfactant to the cationic polyelectrolyte-conditioned sludge had the least effect.
Filtration behaviors of Giardia and Cryptosporidium - Ionic strength and pH effects
(2001-11-01)
Hsu, BM
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Huang, CP
;
Pan, JR
;
環境工程研究所
;
Institute of Environmental Engineering
The laboratory-scale filtration tests of Giardia cysts and Cryptosporidium oocysts in both 2 mm-Phi glass beads and 2 mm-Phi polystyrene beads filters were conducted to investigate their filtration behaviors. The protozoan parasites were used as target particles. while the chemical system altered by changing the electrolyte concentration and pH, The results significantly indicate that ionic strength have a positive effect on the removal efficiencies for Giardia cysts and Cryptosporidium oocysts. The removal efficiency of two filters for Giardia cysts slightly decreased from pH 2.4 to 8.7 and decreased significantly in pH as pH up to 8.7, while that for Cryptosporidium slightly rippled beyond pH 8.7, and with the decrease in pH up to pH 8.7. The experimental collision efficiencies from the interactions between colloids and the filter media were calculated with a semi-empirical approach of the single sphere model and clean-bed filtration theory. The results also indicated that experimental collision efficiencies for (oo)cysts corresponded to the (oo)cysts removal efficiencies in all trials, and oocysts exhibits higher collision efficiencies than cysts. (C) 2001 Elsevier Science Ltd. All rights reserved.
Optimal condition for modification of chitosan: A biopolymer for coagulation of colloidal particles
(2000-02-01)
Huang, CP
;
Chen, SC
;
Pan, JR
;
環境工程研究所
;
Institute of Environmental Engineering
Chitosan, an acetylated derivative of chitin, is a biodegradable cationic polymer. Chitosan can be a promising substitute for alum in the coagulation process, because of its potential feasibility in coagulation without posing any health threat as the residual aluminium and other synthetic polymers do. In this study, various pretreatment conditions were tested in search of the optimum chitosan modification. Batch tests with synthetic source water suggest that the optimal pretreatment condition to prepare modified chitosan coagulant is deacetylation by 45% alkali solution for 60 min, followed by dissolution in 0.1% hydrochloric acid. (C) 2000 Elsevier Science Ltd. All rights reserved.
Reuse of fresh water sludge in cement making
(2004)
Pan, JR
;
Huang, C
;
Lin, S
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環境工程研究所
;
Institute of Environmental Engineering
With the increasing demand for high quality water, a large quantity of chemical agent must be added in the water purification process, which in turn generates enormous amount of fresh water sludge. Of all the options for sludge disposal, sludge reuse has been considered most economical and environmentally sound. This study evaluated the possibility of incorporating fresh water sludge in the making of Portland cement through the sintering process. The goal was to search for the optimal condition to maximize the replacement of clay with the fresh water sludge. Characteristics of fresh water sludge were collected and analyzed. The analysis showed that water source and water treatment process dominate the characteristics, particularly the chemical composition of the fresh water sludge. The fresh water sludge was mixed with the cement clay in various percentages, from 0% to 100%, as raw material for cement-making. The effects of its addition on the sintering condition and the quality of cement were evaluated. The analysis of the clinkers showed that the addition of the fresh water sludge did not change the phase form and the f-CaO content of the cement. The compressive strength of the masonry increased with the increasing addition of fresh water sludge. All cement products made from various replacement ratios met the Chinese National Standard of first degree Portland cement.
Reuse of water treatment plant sludge and dam sediment in brick-making
(2001)
Huang, C
;
Pan, JR
;
Sun, KD
;
Liaw, CT
;
環境工程研究所
In this study, an attempt was made to use water treatment plant (WTP) sludge and dam sediment as raw materials for brick-making through the sintering process. The sinter of dam sediment fired at 1,050 degreesC had a less than 15% ratio water absorption, and its compressive strength and bulk density met the Chinese National Standard (CNS) for first level brick. The WTP sludge sinter made under the same operating condition exhibited higher water absorption, larger shrinkage, but poorer compressive strength. When fired at 1,100C, the shrinkage of the WTP sludge sinter was as high as 45%, although its compressive strength and water absorption of WTP sludge brick still met the standard for the first level brick. To reuse WTP sludge in an economical way, mixtures of various proportions of WTP sludge to dam sediment are used as raw materials. A satisfactory result was achieved when the ratio of the WTP sludge was less than 20% of the mixture. Results of tests indicated that the sinter of dam sediments which are fired at a temperature of 1000-1100 degreesC has reached the requirement for the brick.
Treatment of wastewater containing nano-scale silica particles by dead-end microfiltration: evaluation of pretreatment methods
(2005-07-10)
Pan, JR
;
Huang, CP
;
Jiang, W
;
Chen, CS
;
環境工程研究所
Chemical mechanical polishing (CMP) is the, process to planarize wafer in the IC manufacturing. In the process, a large amount of ultra pure water is used to clean the surface of the wafer, which generates large quantity of wastewater containing high concentration of nano-scale silica particles. The wastewater is generally treated with the traditional coagulation/sedimentation process, producing large quantity of sludge. In this study, a microfiltration (MF) process coupled with chemical pretreatment was investigated to separate the nano-scale particles from the CMP wastewater to reclaim the water. Wastewater was filtered through a polytetrafluoroethylene membrane of pore size 0.5 mu m at a low vacuum pressure (0.65 kg/cm(2)). The permeate flux was monitored and the degree of irreversible fouling of the membrane was estimated. The SEM images of the fouled membrane and the cake layer were used to diagnose the mechanism of membrane fouling. Several coagulants and flocculants were tested for their potential use prior to microfiltration. Polyaluminurn chloride (PACl) plus cationic polyacrylamide (PAA) were selected for pretreatment, and their effects on permeate flux and fouling of the membrane were examined. The results indicated that PACl improved silica removal substantially. The addition of trace amount of PAA effectively increased the size of the flocs, and subsequently enhanced the permeate flux. The performance of the dead-end MF operation depended strongly on the turbidity of the influent. The addition of oxidant, i.e. Chlorine, after the flocculation reduced the irreversible fouling and promoted flux recovery of the membrane.