Ting-Nien Wu

Electrochemical removal of pentachlorophenol in a lab-scale platinum electrolyzer

This study is focused on the removal of pentachlorophenol from its aqueous phase by electrochemically induced degradation with Pt electrodes. The objective of this study was to contrast the electrochemical removal of pentachlorophenol at the oxidative and the reductive potentials, and further to understand how to apply the electrochemical treatment on PCP degradation. Lab experiments were conducted in a Pt electrolyzer, and the voltage source was supplied and precisely controlled by an electrochemical analyzer. In these experiments, the variables including electrolyte species, pH, voltage supply, and reaction time were examined to compare the efficiency of pentachlorophenol removal. Experimental results showed that pentachlorophenol was completely degraded after being electrolyzed for 1 h at-1.5 V in a 0.5 M KCl solution, while the removal of pentachlorophenol is negligible under the similar condition when 0.5 M NaNO(3) or Na(2)CO(3) was used as the electrolyte. The electrolyte concentration below 0.5 M is unfavourable for the electrochemical removal of pentachlorophenol. The removal efficiency of pentachlorophenol is slightly affected by pH, and the strong basic environment might impede the degradation of pentachlorophenol. Comparing with those under positive potentials, the experiments conducted under negative potentials have shown a better removal of pentachlorophenol with a higher current efficiency. It implies that pentachlorophenol degradation followed the reductive pathway. Based on the analysis of GC/MS, the intermediates of pentachlorophenol degradation were identified as 1,2-dichlorocyclohexane and 2-chlorocyclohexanol.

Application of Principal Component Analysis and Clustering to Spatial Allocation of Groundwater Contamination

This paper presented a case study that conventional statistical methods were applied to mining environmental monitoring database to extract the patterns of groundwater contamination. Eighty-four monitoring wells located at Chianan Plain groundwater subregion in Taiwan were selected as study area, and lab data of routine groundwater analysis including pH, EC, hardness, TDS, TOC, ammonia, nitrate, chloride, sulfate, Fe, Mn, As, Na, K, Ca and Mg were subjected to factor and cluster analysis. Principal component analysis (PCA) was utilized to reflect those chemical data with the greatest correlation, and PCA results identified four major principal components (PCs) representing 82.4% of cumulative variance. By utilizing PCA, salinization, As dissolution, organic pollution, and mineralization reasonably interpreted the possible underlying processes in the aquifer. Clustering technique was used to evaluate the similarities of water quality in groundwater samples, and 4 clusters were assigned in two-step cluster analysis (CA) in order to correspond with the number of PCs, i.e. the sources of groundwater contamination. Accordingly, CA results distributed all monitoring wells into the domain of each PC, and the domain of groundwater contamination can be spatially allocated by mapping the neighbouring wells within the identical cluster.

Investigation on indoor air quality of public sites in tainan area

This study selected 21 representative public sites for the survey of indoor air quality in Tainan area, including hospital, school, fitness center, government office, library, theater, transport station, and supermarket. Indoor air quality was first assessed by direct detection apparatus, including CO2, CO, HCHO, TVOCs, bacteria, fungi, PM10, PM2.5, O3 and temperature. Based on the results of walk-through detection, the spatial distribution of indoor air contaminants was further measured in a 24 hour period by the EPA standard method. The detailed measurements illustrated HCHO, O3, PM10 and PM2.5 concentrations are lower than the suggested threshold levels in all public sites. CO2 concentrations at hospitals and school are all exceeding category 1 threshold of 600 ppm. Bacteria exceeding the suggested threshold of 500 CFU/m3 for category 1 and 1000 CFU/m3 for category 2 is popular at most public sites. One fitness center was found exceeding the TVOCs threshold of 3 ppm, and outdoor air can be a potential source. The high levels of CO2 and bacteria were a common indoor air quality problem, and the regulated strategy of crowd control and air conditioning management was required for a healthy indoor environment.

Application of time series analysis on temporal variation of fluoride in groundwater around Southern Taiwan Science Park

This paper demonstrated a case study on how to utilize time series analysis as mining tool to track the transience of fluoride release and to predict the fluoride concentration in groundwater. Southern Taiwan Science Park was selected as study area, and seven groundwater monitoring wells located in the domain of fluoride release were subjected to time series analysis. The measured fluoride levels in groundwater are between 0.4 and 3.6 mg/L, and the series data is stationary in mean and variance during the period of 2005 and 2009. Time series analysis is a useful tool for extracting interesting pattern from ordered sequence of observations. Based on extracting information from ACF and PACF, the trend, interesting patterns, rules, or models within the original data set were filtered out. The common time series models, ARMA and ARIMA, were employed to interpret the information beneath the monitoring data of groundwater quality. Through verification by Akaikes information criterion (AIC) and Schwartzs Bayesian Information Criterion (SBC), the ARMA(1,1) model was identified as the best fitted model for data interpretation and estimation. Accordingly, this developed numerical model can effectively interpret and forecast the fluoride level in groundwater as referring the prior information.

Discovery of Temporal Variation of Arsenic in a Historical Blackfoot Disease Territory by Time Series Analysis

Time series analysis is useful tool for extracting interesting pattern from ordered sequence of observations. The Chianan Blackfoot disease region was selected as study area, and the monitoring data of arsenic in groundwater during the period of 2003 and 2008 was subjected to time series analysis. This study attempted to discover the temporal trend of arsenic level in groundwater by applying the tool of time series analysis. ARMA and ARIMA, the common time series modelling methods, were employed to interpret the information beneath the monitoring data of groundwater quality. Through further verification, the selected ARMA(1,1) model fits the data set well over the other three models. The result showed that this developed numerical model can effectively interpret and forecast the arsenic level in groundwater from area affected by salinization and high arsenic level in Chianan Plain based on the known information.

Application of Principal Component Analysis on Source Identification and Tracking of Groundwater Contamination from Southern Taiwan Science Park

This paper demonstrated a case study on how to utilize principal component analysis (PCA) as mining tool to extract the patterns of groundwater contamination. Southern Taiwan Science Park was selected as study area, and forty-five groundwater monitoring wells within the study area were used to build up groundwater quality database. Lab data of routine groundwater analysis including pH, electrical conductivity, temperature, total dissolved solid, total organic carbon, fluoride, ammonia, nitrite, nitrate, and phenols were subjected to principal component analysis. Based on the monitoring data between 2005 and 2007, the extracted information from the PCA mirrored the potential sources of groundwater contamination as salinization, arsenic dissolution, industrial leakage, mineralization, and agricultural activities. According to the depth of monitoring wells, the PCA results of two stratification groups were matched up to track the movement of groundwater contamination in the vertical profile. The vertical distribution of groundwater contamination revealed that fluoride and phenols was transported to the bottom of the unconfined aquifer. On the basis of yearly monitoring data, the PCA results of each year were matched up to track the shift of groundwater contamination with time. The possible sources of groundwater contamination resulted from agricultural activities and mineralization processes before 2005, and its significance is gradually fading out and turning to be the type of potential industrial leakage.

Comparisons of Alcohol Blending Fuels' Emission from a Laboratory Gasoline Engine

This study is aimed at examining environmental impacts of exhaust emissions imposed by various alcohol blending fuels. The tested fuels are 0%, 5%, 10%, 15% and 20% blending of methanol, ethanol or butanol alone. Rotation speeds of engine tests were controlled at 1500, 2500 and 3500 rpm to simulate slow, normal and fast speeds of vehicle driving. Gaseous emissions from engine exhaust were collected to determine the concentrations of CO, NOx, HC, BTEX, formaldehyde and acetaldehyde. Most alcohol blending fuels were found able to lower regulated emission of CO, NOx and HC as well as toxic constituents of BTEX more or less. Adversely, alcohol combustion in the engine could result in the formation of formaldehyde and acetaldehyde. Environmental impact on the release of formaldehyde should be aware and carefully controlled with the use of various alcohol blending fuels.

Assessment of aquifer salinization beneath an offshore industrial park based on solute transport calculation

The purpose of this study is to assess aquifer salinization in the coastal area of an Offshore Industrial Park in Taiwan. Study area belongs to the new Delta Holocene alluvium, which is composed of clay, silt, sand, gravel and their mixture. Groundwater quality measurements including electrical conductivity, total dissolved solids, chloride and sulfate were used as indicator to evaluate aquifer salinization. Regional groundwater flows from the middle of study area to the embracing beach, which is the typical island-type-like distribution of groundwater lens. Temporal variations of chloride concentrations in monitoring wells were simulated based on the calculation of solute transport. The simulation result matched with the observation that rainfall leaching could cause dilution of chloride concentration and lessen aquifer salinization. Solute exchange at the interface of fresh water and saline water strongly affected desalinization rate in groundwater, and thus desalinization rate was dependent on its distance from the seashore. According to the calculation of solute transport, it might take about 14 years for complete desalinization through continual rainfall leaching.

Emission characteristics of ethanol blending fuels from a laboratory gasoline engine

In Taiwan, 3% ethanol (E3) blending fuel was introduced to the market to lessen the pressure of energy deficit and carbon reduction from global warming. This study is aimed at discovering the environmental impacts of exhaust emissions imposed by ethanol blending fuels. The tested fuels are 0%, 5%, 10%, 15% and 20% of ethanol blending, and engine testing set rotation speeds at 1500, 2500 and 3500 rpm to simulate slow, normal and fast speeds of vehicle driving. Gaseous emissions from engine exhaust were collected to determine the concentrations of CO, NOx, HC, BTEX, formaldehyde and acetaldehyde. Ethanol blending fuels were found able to reduce the emission of regulated air pollutants (CO, NOx and HC) and containing toxic compounds (BTEX) more or less. However, formaldehyde and acetaldehyde emissions were greatly enhanced due to ethanol combustion in the engine. With the use of ethanol blending fuels, the environmental impact on the release of formaldehyde should be aware and carefully controlled.

Comparison of indoor air quality measurement by using direct detection apparatus and standard methods

People usually spend almost 90% of time under various indoor surroundings in their daily lives, and thus the impact of indoor air quality (IAQ) on human health has received much attention recently. In this study, 20 public sites were selected as case studies to compare the difference of indoor air quality measurements. Indoor air quality was first assessed by direct detection apparatus, including CO2, CO, HCHO, TVOCs, PM10, PM2.5, and O3. Based on the results of walk-through detection, indoor air contaminants at hot-spot location were measured in a 24 hour period by the EPA standard method. The use of direct detection apparatus has the advantages of easy operation, high mobility, rapid detection, and less cost. However, official data of indoor air quality measurement is based on the detailed measurement by Taiwan EPA’s standard methods that possess high precision and accuracy. The comparison of direct detection data and the detailed measurements by standard methods illustrated that there exists a high linear relationship for CO2, PM10 and PM2.5 measurements. It means that direct detection data of CO2, PM10 and PM2.5 are reliable, and direct detection apparatus can be applied to monitoring of these indoor air contaminants for the better control of their accumulations.