Browsing by Author "Chen, Shen-Yi"

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Biodegradation of tetramethylammonium hydroxide (TMAH) in completely autotrophic nitrogen removal over nitrite (CANON) process
(2016-06)
Chen, Shen-Yi
;
Lu, Li-An
;
Lin, Jih-Gaw
;
環境工程研究所
;
Institute of Environmental Engineering
This study conducted a completely autotrophic nitrogen removal over nitrite (CANON) process in a continuous anoxic upflow bioreactor to treat synthetic wastewater with TMAH (tetramethylammonium hydroxide) ranging from 200 to 1000 mg/L. The intermediates were analyzed for understanding the metabolic pathway of TMAH biodegradation in CANON process. In addition, N-15-labeled TMAH was used as the substrate in a batch anoxic bioreactor to confirm that TMAH was converted to nitrogen gas in CANON process. The results indicated that TMAH was almost completely biodegraded in CANON system at different influent TMAH concentrations of 200, 500, and 1000 mg/L. The average removal efficiencies of total nitrogen were higher than 90% during the experiments. Trimethylamine (TMA) and methylamine (MA) were found to be the main biodegradation intermediates of TMAH in CANON process. The production of nitrogen gas with 15N-labeled during the batch anaerobic bioreactor indicated that CANON process successfully converted TMAH into nitrogen gas. (C) 2016 Elsevier Ltd. All rights reserved.
Enhancement of metal bioleaching from contaminated sediment using silver ion
(2009-01-30)
Chen, Shen-Yi
;
Lin, Jih-Gaw
;
環境工程研究所
;
Institute of Environmental Engineering
A silver-catalyzed bioleaching process was used to remove heavy metals from contaminated sediment in this study. The effects of silver concentration added on the performance of bioleaching process were investigated. High pH reduction rate was observed in the bioleaching process with silver ion. The silver ion added in the bioleaching process was incorporated into the lattice of the initial sulfide through a cationic interchange reaction. This resulted in the short lag phase and high metal solubilization in the bioleaching process. The maximum pH reduction rate and the ideal metal solubilization were obtained in the presence of 30 mg/L of silver ion. When the added silver ion was greater than 30 mg/L, the rates of pH reduction and metal solubilization gradually decreased. The solubilization efficiencies of heavy metals (Cu, Zn, Mn, Ni and Cr) were relatively high in the silver-enhanced bioleaching process, except Pb. No apparent effect of silver ion on the growth of sulfur-oxidizing bacteria was found in the bioleaching. These results indicate that the kinetics of metal solubilization can be enhanced by the addition of silver ion. (C) 2008 Elsevier B.V. All rights reserved
Mass transfer efficiency inside the polyvinyl alcohol-sodium alginate carriers: kinetic changes of immobilized anammox bacteria
(1970-01-01)
Chen, Wen-Hsing
;
Lin, Jih-Gaw
;
Wei, Yi-Lin
;
Chen, Shen-Yi
;
環境工程研究所
BACKGROUND Mass transfer inside the plain polyvinyl alcohol (PVA)-sodium alginate (SA) carriers was determined to correlate with nitrogen removal by anaerobic ammonium-oxidation (anammox) bacteria in this study. The anammox bacteria immobilized by the PVA-SA material for nitrogen removal were inoculated into a sequencing batch reactor (SBR) operated at a hydraulic retention time of 4 days and a temperature of 35 +/- 1 degrees C while another identical reactor inoculated with the un-immobilized biomass was run for comparison. RESULTS Results show that the total nitrogen removals were 81 and 92% for the immobilized and un-immobilized biomass, respectively, when the ammonium- and nitrite-nitrogen, both at 200 mg N L-1, were fed into the SBRs. The poorer performance observed from the immobilized biomass was due to the lower mass transfer efficiency. The obtained diffusion coefficient of the ammonium-nitrogen and specific surface area were 15.2 x 10(-6)cm(2)s(-1)and 29.35 m(2)g(-1)gel beads, respectively. In addition, the mass transfer efficiency influenced the kinetics of the immobilized anammox bacteria. Results indicate that the ammonium-nitrogen removal rate of the un-immobilized biomass was 28 to 34% greater than that of the immobilized biomass, while the nitrite-nitrogen removal rate was greater by 9 to 24% for the un-immobilized biomass. This influence was more significant at high levels of ammonium- and nitrite-nitrogen concentrations. CONCLUSION Increasing the mass transfer efficiency inside the plain PVA-SA carriers was needed before using the PVA-SA carriers to immobilize anammox bacteria. (c) 2020 Society of Chemical Industry
Nano-bubble flotation technology with coagulation process for the cost-effective treatment of chemical mechanical polishing wastewater
(2007-12-01)
Tsai, Jen-Chieh
;
Kumar, Mathava
;
Chen, Shen-Yi
;
Lin, Jih-Gaw
;
環境工程研究所
The feasibility of nano-bubble flotation technology (NBFT) with coagulation/flocculation process for the enhanced treatment of chemical mechanical polishing (CMP) wastewater was investigated through laboratory and pilot-scale experiments. As a precursor, the effective combination of activator/collector was identified using a laboratory-scale flotation reactor. The results showed that polyaluminum chloride (PAC)/sodium oleate (NaOl) was the best combination of activator/collector, respectively and its application in the NBFT with coagulation process increased the wastewater clarification efficiency by 40% as compared with traditional coagulation/flocculation process. More than 95% turbidity, total solids and total silica removal efficiencies were observed in the pilot-scale flotation experiments. From the results, it was found that NBFT with coagulation process could be performed effectively at an optimum PAC concentration of 50-60 mg/L (as Al), NaOl concentration of 5-10 mg/L with a recycle ratio of 10-20% and I h hydraulic retention time HRT. The cost and performance assessment reflected that CMP wastewater could be treated efficiently at a minimum cost using the present approach. (c) 2007 Elsevier B.V. All rights reserved.
Treatment of campus domestic wastewater using ambient-temperature anaerobic fluidized membrane bioreactors with zeolites as carriers
(2019-01-01)
Chen, Wen-Hsing
;
Tsai, Cheng-Yu
;
Chen, Shen-Yi
;
Sung, Shihwu
;
Lin, Jih-Gaw
An anaerobic fluidized-bed bioreactor (AFBR) connected with an anaerobic fluidized membrane bioreactor (AFMBR) in series with natural zeolites as carriers was used to treat the campus domestic wastewater (chemical oxygen demand (COD) of 130 +/- 38 mg/L) at ambient temperature (20-35 degrees C) in this study. Results indicate that the attached growth of anaerobic microbes was observed on the surface of zeolite and 95% of COD were removed in the AFBR after 30 days of batch operation. When the AFBR-AFMBR system was run with a HRT from 3 to 4 h, the COD, biochemical oxygen demand (ROD), and suspended solid (SS) were removed by 84, 87, and 96%, respectively, with the corresponding effluent COD, BOD, and SS of 20, 8, and 2 mg/L, respectively. Overall, 41% of the COD removal was attributed to coupling with sulfate reduction by sulfate-reducing bacteria in this study. In the AFMBR, the transmembrane pressure remained lower than 0.2 bar at the membrane flux of 10 L/m(2)-h. The membrane module was operated consecutively for 333 days without chemical cleaning. In addition, the maximum substrate utilization rate of 37 g/L-d determined based on the modified Stover-Kincannon equation elucidates that the organics in the campus domestic wastewater were readily biodegraded. This facilitated the AFBR-AFMBR system removing the organics to the levels lower than the discharging limits.
Variations of metal distribution in sewage sludge composting
(2008)
Nomeda, Sabiene
;
Valdas, Paulauskas
;
Chen, Shen-Yi
;
Lin, Jih-Gaw
;
環境工程研究所
In the study, the variations of heavy metal distributions (of Cu, Mn, Pb, and Zn) during the sewage S]sludge composting process were investigated by sequential extraction procedures. The total content of Cu and Zn ill the composted mixture increased after the composting process, Mn and Zn were mainly found in mobile fractions (exchangeable fraction (H), carbonate fraction (F2), and Fe/Mn oxide fraction (F3)). Cu and Pb were strongly associated with the stable fractions (organic matter/sulfides fraction (F4) and residual fraction (F5)). These five metal fractions were used to calculate the metal mobility (bioavailability) in the sewage sludge and composted mixture. The mobility (bioavailability) of Mn, Pb, and Zn (but not Cu) increased during the composting process. The metal mobility in the composted mixture ranked in the following order: Mn > Zn > Pb > Cu. (c) 2007 Elsevier Ltd. All rights reserved.