Browsing by Author "Lu, Li-An"

Now showing 1 - 4 of 4

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.
High-rate composting of barley dregs with sewage sludge in a pilot scale bioreactor
(2008-05-01)
Lu, Li-An
;
Kumar, Mathava
;
Tsai, Jen-Chleh
;
Lin, Jih-Gaw
;
環境工程研究所
The feasibility of high-rate composting of barley dregs and sewage sludge was examined using a pilot scale bioreactor. A central composite design (CCD) was used to optimize the mix ratio of barley dregs/sewage sludge and moisture content. The performance of the bioreactor was monitored as a function of carbon decomposition rate (CDR) and total volatile solids (TVS) loss rate. The optimum range of mix ratio and moisture content was found to be 35-40% and 55-60%, respectively. High CO2 evolution rate (CER) and TVS loss rate were observed after 3 days of the composting and the compost was matured/stable after 7 days. Cardinal temperature model with inflection (CTMI) was used to analyze the compost stability with respect to CER as a parameter of composting efficiency. After examining the phytotoxicity, the compost can be promoted for land application. (C) 2007 Elsevier Ltd. All rights reserved.
Photo-Fenton pretreatment of carbofuran - Analyses via experimental design, detoxification and biodegradability enhancement
(2011-10-10)
Lu, Li-An
;
Ma, Ying-Shih
;
Kumar, Mathava
;
Lin, Jih-Gaw
;
環境工程研究所
The central composite design (CCD) and response surface methodology (RSM) were employed to evaluate the effect of H(2)O(2) dosage rate (1-10 mg L(-1) min(-1)) and Fe(3+) dosage (1-100 mg L(-1)) in the photo-Fenton treatment of carbofuran and to develop the second-order polynomial equations in terms of carbofuran and dissolved organic carbon (DOC) removals and BOD(5)/DOC ratio with different reaction times. Both H(2)O(2) dosage rate and Fe(3+) dosage have significant effects on the dependable variables. Based on the results of carbofuran removal and BOD(5)/DOC ratio, H(2)O(2) dosage rate of 5.4 mg L(-1) min(-1) and Fe(3+) dosage of 59 mg L(-1) were found to be the favorable reagent dosages for carbofuran degradation. Under these conditions, the toxicity unit measured by Microtox(R) test with 5 min exposure was decreased from 47 to 6 and the biodegradability evaluated by BOD(5)/COD ratio was increased from 0 to 0.76 after 60 min reaction. The results obtained in this study demonstrate that the photo-Fenton process is a promising pretreatment before the application of biological treatment for carbofuran removal from contaminated water/wastewater. (C) 2011 Elsevier B.V. All rights reserved.
Photochemical degradation of carbofuran and elucidation of removal mechanism
(2011-01-01)
Lu, Li-An
;
Ma, Ying-Shih
;
Kumar, Mathava
;
Lin, Jih-Gaw
;
環境工程研究所
Carbofuran removal by the photo-Fenton reaction was investigated under various H(2)O(2) dosage rate (0-6 mg L(-1) min(-1)) and Fe(3+) dosage (5-50 mg L(-1)). The outcomes demonstrate that the photo-Fenton reaction was influenced by both the factors. An initial carbofuran concentration of 50 mg L(-1) was completely degraded within 30 min, and 93% dissolved organic carbon (DOC) removal was observed after 120 min of treatment at initial pH 3, H(2)O(2) dosage rate of 4 mg L(-1) min(-1) and Fe(3+) dosage of 35 and 50 mg L(-1). However, no significant improvement in the carbofuran removal was observed when the H(2)O(2) dosage rate and Fe(3+) dosage were increased beyond 4 mg L(-1) min(-1) and 35 mg L(-1), respectively. The carbofuran removal was fitted using the pseudo-first order reaction model and the highest apparent rate constant of 10.5 x 10(-2) min(-1) was obtained. Five major carbofuran intermediates were identified, which indicate that C-O bond of the carbamate group and 3-C position of the furan ring were oxidized as a result of the photo-Fenton reaction. (C) 2010 Elsevier B.V. All rights reserved.