Taiwan EPA Research Articles

Simultaneous removal of PCDD/Fs, pentachlorophenol and mercury from contaminated soil

Pentachlorophenol (PCP), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and mercury were simultaneously removed from heavily contaminated soil using a continuous pilot-scale thermal system (CPTS). Operating the system at 700 °C with 22 min of retention time ensured that the residual contaminants in remediated soil are lower in concentration than the soil standards of Taiwan EPA require. Both PCP and PCDD/Fs are effectively destroyed during the treatment at high temperatures in the CPTS, but significant dechlorination of PCDD/Fs is also found, resulting in lower net destruction efficiencies of TCDD/F and PeCDD/F-congeners, compared with those of highly chlorinated Hx-, Hp- and OCDD/F congeners. Moreover, 2,3,7,8-TetraCDD is significantly formed if the retention time is not long enough for total destruction. Inadequate reaction time (or retention time) even may lead to a rise in TEQ-value due to incomplete dechlorination. Mercury is significantly desorbed from contaminated soil and discharged through the exhaust. For PCP and PCDD/Fs, the exhaust discharge percentages including both the remediated soil and the exhaust are <0.03% and 1.14% of the input, respectively, achieved with 700 °C and 33 min retention time. In contrast, some 97.8% of input mercury rate is desorbed and discharged via the exhaust, so that the latter should be carefully cleaned via efficient air pollution control devices, whereas this contribution focuses on the conditions required for reaching adequate soil cleaning.

Effects of high ammonia loads on nitrogen mass balance and treatment performance of a biotrickling filter

A biotrickling filter packed with coal slag as packing medium was continuously used for more than 9 months under high ammonia loading rates of up to 140g/m3/h. Nitrogen mass balance and microbial community analysis were conducted to evaluate the inhibitory effects of high ammonia concentration and metabolic by-products on the rates of nitrification. Ammonia removal efficiency reached above 99% at an empty bed retention time of as low as 8s when inlet concentrations were below 350ppm. The maximum and critical elimination capacities of the biotrickling filter were 118g/m3/h and 108.1g/m3/h, respectively. Kinetics analysis results showed that less than 2.5s was required for the biotrickling filter with pH control to treat ammonia at concentrations of up to 500ppm in compliance with the Taiwan EPA standard (outlet NH3<1ppm). Results of mass balance and microbial community analysis indicated that complete removal was mainly contributed by the activities of autotrophic ammonia oxidizing bacteria and not by physical absorption or adsorption at low loading rates. However, at high inlet loadings, ammonium became the dominant by-product due to inhibitory effects of high ammonia concentration on the bacterial community.

Assessment of volatile organic compounds and particulate matter in a dental clinic and health risks to clinic personnel

This study was conducted to assess (1) levels of volatile organic compounds (VOCs) and particulate matter (PM) in a dental clinic in southern Taiwan and (2) dental care personnel's health risks associated with due to chronic exposure to VOCs. An automatic, continuous sampling system and a multi-gas monitor were employed to quantify the air pollutants, along with environmental comfort factors, including temperature, CO2, and relative humidity at six sampling sites in the clinic over eight days. Specific VOC compounds were identified and their concentrations were quantified. Both non-carcinogenic and carcinogenic VOC compounds were assessed based on the US Environmental Protection Agency's Principles of Health Risk Assessment in terms of whether those indoor air pollutants increased health risks for the full-time dental care professionals at the clinic. Increased levels of VOCs were recorded during business hours and exceeded limits recommended by the Taiwan Environmental Protection Agency. A total of 68 VOC compounds were identified in the study area. Methylene methacrylate (2.8 ppm) and acetone (0.176 ppm) were the only two non-carcinogenic compounds that posed increased risks for human health, yielding hazard indexes of 16.4 and 4.1, respectively. None of the carcinogenic compounds increased cancer risk. All detected PM10 levels ranged from 20 to 150 μg/m3, which met the Taiwan EPA and international limits. The average PM10 level during business hours was significantly higher than that during non-business hours (P = 0.04). Improved ventilation capacity in the air conditioning system was recommended to reduce VOCs and PM levels.

Disinfection of indoor air microorganisms in stack room of university library using gaseous chlorine dioxide.

As with all indoor public spaces in Taiwan, the stack rooms in public libraries should meet the air quality guidelines laid down by the Taiwan Environmental Protection Administration. Accordingly, utilizing a university library in Taiwan for experimental purposes, this study investigates the efficiency of gaseous chlorine dioxide (ClO2) as a disinfection agent when applied using three different treatment modes, namely a single-daily disinfection mode (SIM), a twice-daily disinfection mode (TWM), and a triple-daily disinfection mode (TRM). For each treatment mode, the ClO2 is applied using an ultrasonic aerosol device and is performed both under natural lighting conditions and under artificial lighting conditions. The indoor air quality is evaluated before and after each treatment session by measuring the bioaerosol levels of bacteria and fungi. The results show that for all three disinfection modes, the application of ClO2 reduces the indoor bacteria and fungi concentrations to levels lower than those specified by the Taiwan EPA (i.e., bacteria <1500CFU/m(3), fungi <1000CFU/m(3)), irrespective of the lighting conditions under which the disinfection process is performed. For each disinfection mode, a better disinfection efficiency is obtained under natural lighting conditions since ClO2 readily decomposes under strong luminance levels. Among the three treatment modes, the disinfection efficiencies of the TWM and TRM modes are very similar under natural lighting conditions and are significantly better than that of the SIM mode. Thus, overall, the results suggest that the TWM treatment protocol represents the most cost-effective and efficient method for meeting the indoor air quality requirements of the Taiwan EPA.

Unpresendant Piggery Waste Resource and Resurvive Approach

Piggery waste is one the tree major water pollution sources in Taiwan. Piggery waste should be viewed as resource and not waste. Conventionally, three stage wastewater treatments are too costly and hard to operate. Direct application to soil can be a remedy if the application rate is careful managed. Taiwan EPA ambitiously launches piggery manure direct apply to soil policy. It might the panacea to water pollution control.

Detoxification of hazardous dust with marine sediment

Hazardous electric arc furnace dust containing dioxins/furans and heavy metals is blended with harbor sediment, fired at 950–1100°C to prepare lightweight aggregates. Dust addition can lower the sintering temperature by about 100°C, as compared to a typical industrial process. After firing at 950°C and 1050°C, more than 99.85% of dioxins/furans originally present in the dust have been removed and/or destructed in the mix containing a dust/sediment ratio of 50:100. The heavy metals leached from all fired mixes are far below Taiwan EPA legal limits. The particle density of the lightweight aggregates always decreases with increasing firing temperature. Greater addition of the dust results in a considerably lower particle density (mostly <2.0gcm−3) fired at 1050°C and 1100°C. However, firing at temperatures lower than 1050°C produces no successful bloating, leading to a denser particle density (>2.0gcm−3) that is typical of bricks.

Effect of secondary gas injection on the peanut shell combustion and its pollutant emissions in a vortexing fluidized bed combustor

Peanut shell is a common agricultural waste in Asia, and its high calorific value is suitable to be used as a fuel. In this study, a vortexing fluidized bed combustor (VFBC) with silica sand as the bed material was used for peanut shell combustion. There was no indication of bed agglomeration during combustions for as long as 12h. The temperatures and gas concentrations were measured along the axial direction at various operating conditions, including excess oxygen ratio and secondary gas flow rate. Results show that CO emission decreases with rising excess oxygen ratio and secondary gas flow rate, while NOx emissions show a reverse trend. To meet the minimum CO and NOx emission standards of Taiwan EPA, excess oxygen ratio ranging from 40% to 55% and secondary gas flow rate ranging from 1.56 to 2 Nm(3)/min are found optimal for crushed peanut shell combustion in a VFBC.

Comparison of Three VOC Measurement Techniques for tVOC Monitoring Regulated by Taiwan EPA in Indoor Air Quality

Background: The Indoor Air Quality (IAQ) regulation has been enforced in Taiwan since November 2012: including CO2, CO and total volatile organic compounds (tVOCs). The tVOC is defined as the conce...

Investigation on Dioxin Level of Flue Gas, Ambient Air, Vegetation and Soil Nearby Large-Scale MSWI in Taiwan

We set up information about Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) level in flue gas, ambient air, banyan leaves and soil nearby Muzha MSWI, located in the north of Taiwan. Total PCDD/F I-TEQ concentrations in flue gas are 0.0995, 0.0711ng I-TEQ/Nm3, respectively, in spring, autumn, all below the emission limit regulated by Taiwan EPA, 0.1ng I-TEQ/Nm3 . The mean PCDD/F concentrations in ambient air nearby Muzha MSWIs are 0.0283, 0.0357, 0.0391 and 0.05638pg I-TEQ/Nm3, respectively at four seasons. The mean PCDD/F concentrations in banyan leaves nearby are 3.86, 0.873ng I-TEQ/kg, respectively in spring, autumn. The mean PCDD/F concentrations in soil nearby are 1.733, 2.061ng I-TEQ/kg, respectively in spring, autumn, much lower than the emission limit in soil regulated by Taiwan EPA, 1000ng I-TEQ/kg. By comparing the PCDD/F concentration of sample at upwind and downwind sampling sites, the PCDD/F influence from Muzha MSWI on nearby ambient air, vegetation and soil is not obvious.

Variations of model performance between QUAL2K and WASP on a river with high ammonia and organic matters

Two water quality models, Water Quality Analysis Simulation Program (WASP) and QUAL2K, were selected and applied to evaluate the performance variations of a river with high ammonia and organic matters in southern Taiwan. Through the appraisal of fit levels with the mean absolute percentage error method, the overall model results of WASP were better than those of QUAL2K. Assimilative capacity of the concerned Tonggang River simulated by WASP is 16.5% more than that by QUAL2K to achieve the Class B water quality standards regulated by Taiwan EPA. The total invested capital for clean pig farming and sewage interception estimated by WASP was $65,402 and $12,381,600 less by QUAL2K, respectively. Levels of water quality improvement and respective costs of several proposed pollutant reduction strategies including sewage interception and clean pig farming practice were also evaluated. This study demonstrates that variations of the model results occurs as using WASP and QUAL2K to estimate the improvement effects of water quality under various reduction strategies. Therefore, more efforts are required to verify the robustness and suitability of the proposed models.

SF6 usage and emission trends in the TFT-LCD industry

Several fluorinated compounds (FCs) used in electronics manufacturing, including SF6, perfluorocarbons (PFCs), and hydrofluorocarbons (HFCs) are extremely potent greenhouse gases. These compounds are classified as global warming pollutants to be controlled by the United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol. Thin film transistor liquid crystal display (TFT-LCD) manufacturing is a major source of SF6 emissions, in which these gases are used for equipment cleaning and plasma etching. The respective Environmental Protection Administration of the Republic of China, Taiwan and the Environmental Protection Agency of the United States collaboratively strive in encouraging high technology manufacturers to improve annual reporting of FCs emissions and implement emission reduction practices and technologies.In the TFT-LCD industry, FCs account on average for 30% of total greenhouse gas emissions; 80% of emissions originate from the etching process and 20% from the chemical vapor deposition (CVD) chamber cleaning process, which is in compliance with Taiwan EPA data reports from 2005 to 2010. The leading TFT-LCD manufacturers are Japan, Korea, and Taiwan. The World LCD Industry Cooperation Committee (WLICC) subsequently established an aggressive climate protection action plan in 2001. This study focuses specifically on SF6 usage and emission factors reflecting common TFT-LCD manufacturing practices.

Risk Management and Regulatory Control of Toxic Chemicals in Taiwan

In this paper, we describe the evolution of Toxic Chemical Substances Control Act (TCSCA) regulated by Taiwan Environmental Protection Administration during the past two decades. The TCSCA was originally drafted for the management of utilization and operation of toxic chemical substances from cradle to grave. Following the 921 earthquake in central Taiwan in 1999, the newly issued Disaster Prevention and Mitigation Act further required that the risk management and disaster mitigation from all listed toxic chemicals must also be regulated in TCSCA. Since then, significant modification in the Act and new regulations are added and implemented. In addition, Taiwan EPA is also established information and monitoring centres and seven emergency response teams. These facilities provide 24-hour service and have at least 25 people on duty at all times. The main tools used by these facilities are environmental monitoring equipment, personal protection equipment, and response equipment for leak patching and chemical transfer. The increased regulatory control and response capabilities have greatly reduce the occurrence and potential impact from toxic chemicals incidents as evident from the incident statistics.

Disinfection efficiency of chlorine dioxide gas in student cafeterias in Taiwan

In Taiwan, the food and drink requirements of students and faculty members are met by student cafeterias. The air quality within these cafeterias should satisfy the guidelines laid down by the Taiwan Environmental Protection Agency (Taiwan EPA). Accordingly, this study performed an experimental investigation into the efficiency of two different gaseous chlorine dioxide (ClO2) treatments in disinfecting a local student cafeteria, namely a single, one-off application and a twice-daily application. In both cases, the ClO2 was applied using strategically placed aerosol devices. The air quality before and after disinfection was evaluated by measuring the bioaerosol levels of bacteria and fungi. Moreover, a stepwise discriminant analysis method was applied for predicting the residual concentrations of bacteria and fungi, as a function of the environmental parameters and the ClO2 concentration. The experimental results showed that the average background levels of bacteria and fungi prior to ClO2 disinfection were 972.5 ± 623.6 and 1534.1 ± 631.8 colony-forming units (CFU)/m3, respectively. A single ClO2 application was found to reduce the bacterial and fungal concentration levels by as much as 65% and 30%, respectively. By contrast, a twice-daily ClO2 application was found to reduce the bacterial and fungal concentration levels by as much as 74% and 38%, respectively. The statistical analysis results showed that the residual bacterial concentration level was determined primarily by the number of individuals present in the cafeteria, the temperature, and the ClO2 concentration, whereas the residual fungal concentration level was determined mainly by the temperature, the total number of suspended particles, and the ClO2 concentration. Thus, the integrated results suggest that the air quality guidelines prescribed by the Taiwan EPA for student cafeteria can best be achieved by applying ClO2 twice daily using an appropriate deployment of aerosol devices. Implications: ClO2 gas can destroy all manner of microorganisms, including bacteria, spores, fungi, viruses, and even protozoans, in indoor environments. Moreover, it is popularly known that bioaerosols are able to grow and propagate on a wide variety of building materials and indoor surfaces. Thus, through optimal ClO2 disinfection methodology, the indoor microbial contaminants can be decreased and the residual concentrations of bacteria and fungi as a function of the environmental parameters and the ClO2 concentration can be predicted via some statistical techniques.

Indoor Air Quality Investigation of Public Sites in Isolated Islands within Taiwan Strait

The selected 21 public sites for indoor air quality (IAQ) investigation located at Penghu and Kinmen Islands (Taiwan). IAQ measurements include CO2, CO, HCHO, TVOCs, bacteria, fungi, PM10, PM2.5, O3 and temperature, which were conducted during year 2010 and 2011. The results showed that the concentrations of CO, HCHO, PM10 and PM2.5 were below Taiwan EPA’s suggested IAQ threshold levels at all public sites. CO2 concentrations at hospitals and school are all exceeding category 1 threshold of 600 ppm. Besides, the levels of O3 and bacteria for hospitals and fungi for schools were all higher than the suggested IAQ threshold levels. One supermarket was found exceeding the suggested IAQ threshold levels on TVOCs and CO2. The theater was found exceeding the suggested bacteria threshold. This study discovered that the high CO2, bacteria and fungi levels occurred at various public sites. Accordingly, the regulated strategy of crowd control and air conditioning management was required for a healthy indoor environment.

The Incentive Mechanism with RFID Technology for Suppliers to Design Environmentally-Friendly Electrical and Electronic Equipment

Taiwan EPA has promulgated Resource Recycling Act in 2002, which is formulated to conserve natural resources, reduce waste, promote recycling and reuse of materials, mitigate environmental loading, and build a society in which resources are used in a sustainable manner. [1] Since 1998, the recycling of waste large household appliances such as televisions, washing machines, refrigerators, and air conditioners, etc. has been implemented; waste electric fans and waste computer keyboards were also included in 2007. Although recycling in Taiwan initiated early, whether waste electrical and electronic equipment recycling is just the process of decomposition, recycling, incineration, and landfill, rather than extending the product lifespan, need further studies to confirm that.The Recycling Fund Management Board takes charge of the operation of recycling mechanism in Taiwan. The funds mostly paid by the businesses as the recycling, clearance and disposal fees. Such fees now are unified under the same products specifications. The existed system can’t provide products under the same specifications but with longer lifespan more preferential fees, which means that there is no incentive for the suppliers to improve the design of products.With Radio Frequency Identification (RFID) inserted in, the household appliances will not only have the basic information about the product, but also can keep track of the purchase and maintenance record, as well as the disposal date and location, during the use stage of that product. Such record provides information on the service life of the product, and the recycling fees paid by businesses could be returned relative to the lifetime to the consumers accordingly. The new mechanism incentives the suppliers to consider the product durability in design and manufacture stages that helps achieve the goal to make products decomposable, recyclable, and lifetime extended.

Sustainable management strategies for an urban-type and low dissolved oxygen stream using measured biochemical coefficients

A water quality model, QUAL2K, with the measured biological coefficients was employed to develop sustainable management strategies for an urban-type stream. To master the data of hydrological and receiving water quality, three surveys were conducted at 20 sampling stations along the Wan-Nian stream in the Pingtung city of southern Taiwan. Then the biochemical coefficients including deoxygenation, nitrification, and reaeration rate coefficients, and sediment oxygen demand were measured and incorporated with influent pollutant loadings and boundary conditions to calibrate and verify the developed model. Simulation evaluated with the mean absolute percentage error method fits reasonably well except for a suspended solid sampled on 16 January 2011. The improvement goal for attaining the water quality of the Wan-Nian stream was set at Class C regulated by the Taiwan EPA. The assimilative capacity of the stream studied to Carbonaceous Biochemical Oxygen Demand (CBOD) and NH3–N was estimated to be around 1,399 and 79 kg day-1, but the collected sewage was about 5,831 and 189 kg day-1, respectively, far exceeded its self-purification capacity. After reducing the pollutant loadings, the model results revealed that the water quality could reach the minimum Class C criteria. Water quality management strategies such as wastewater interception and diversion to the treatment plant as well as installation of contact aeration treatment units were drafted according to the model results after pollutant reduction. The present study demonstrates that the simulation analysis using QUAL2K is promising to frame the water quality management strategies of an urban-type river.

Effect of Temperature and CaO Addition on the Removal of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Fly Ash from a Medical Waste Incinerator

The effects of thermal treatment temperature and CaO addition on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) content in the fly ashes from a medical waste incinerator with high chlorine content (7.5%) were investigated. Two kinds of batch mode were examined: without CaO addition under the temperature range of 50–850°C, and with CaO addition at various Ca/Cl molar ratios (CCR = 0.8–44.3) at 250°C. The results show that the PCDD/F content in raw fly ash was 6.20 ng I-TEQ/g. When elevating the temperature from 50 to 400°Cwithout CaO addition, the PCDD/F content dramatically increased from 5.38 to 575 ng I-TEQ/g. Even at 850°C, the PCDD/Fs were not destructed apparently and were still with a concentration of 401 ng I-TEQ/g. However, with the addition of CaO at CCR = 17.7 at only 250°C, the removal ratio of PCDD/Fs reached to 87.2% and the PCDD/F content was significantly reduced to 0.889 ng I-TEQ/g, which meets the soil pollution standard of Taiwan EPA (1 ng I-TEQ/g) and could be considered as backfill. CaO addition was proven efficiently to enhance the reduction rate of PCDD/Fs in fly ashes during the thermal treatment at a low temperature, as well as inhibit the formation of PCDD/Fs.

Characterization of Indoor-Air Bioaerosols in Southern Taiwan

This study investigated indoor air quality (IAQ) at 39 public sites in southern Taiwan including hospitals, schools, office buildings, hypermarkets, libraries, railway stations, theaters, etc. Indoor air quality was preliminarily assessed using handy digital apparatus. Items detected include carbon dioxide (CO2), carbon monoxide (CO), formaldehyde (HCHO), total volatile organic compounds (TVOCs), total bacteria counts (TBC), total fungi counts (TFC), PM10, PM2.5, ozone (O3) and temperature. Based on the results of walk-through detection, the spatial distribution of indoor air contaminants was further measured over a 24 hour period using the EPA standard method. Major indoor air pollutants were found to include CO2, TBC, and TFC. The measured CO2 concentrations ranged between 438 and 1527 ppm, and only 38.9% of them met the Taiwan EPA suggested threshold of 600 ppm. In the schools and hospitals (Category 1), the measured TFC and TBC concentrations ranged from 62 to TNTC CFU/m3 and from 196 to 4875 CFU/m3, respectively. 33% TFC and 83% TBC concentrations exceeded the suggested threshold, and CO2 concentrations were moderately correlated with TBC levels. In a case study of hospital bioaerosols, high TBC and TFC levels were effectively lowered through disinfectant housekeeping as well as ClO2 spray. Three filamentous fungus genera were identified as Cladosporium perangustum, Cladosporium tenuissimum, and Fusarium incarnatum from outdoor samples with high TFC concentrations.

Characteristics of waste catalyst reused as latent hydraulic materials

This study investigated the pozzolanic reactions and engineering properties of waste catalyst (WC)‐blended cements in relation to various replacement ratios (0–40%). The latent hydraulic characteristics were evaluated at various curing ages by examining the hydration products and compressive strength of the waste catalyst blended cement (WCBC) pastes. The results indicate that the WC contained Al2O3 (59 w/w %), SiO2 (39 w/w %), and CaO (0.1 w/w %) and the pozzolanic activity index of the WC was 117%. The heavy metal leaching concentrations all met the Taiwan EPA regulatory limits. The early compressive strength of the resultant blended cement pastes (1–28 days) was lower than that of the ordinary Portland cement (OPC); however, WCBC pastes with a replacement of cement by up to 20% showed a later compressive strength (60–90 days) similar to that of OPC paste. The hydrated WCBC pastes were similar to OPC pastes in terms of hydration product composition. The main hydration products in the WCBC pastes were Ca(OH)2 and C‐S‐H (Tobermorite). The results indicate that it is indeed feasible to use WC as one of the mineral components for cement. © 2011 American Institute of Chemical Engineers Environ Prog, 32: 94–98, 2013.

Electroplating sludge metal recovering with vitrification using mineral powder additive

Electroplating sludge is a potential secondary metal resource. In this study, vitrification process was employed to recover the metal from plating sludge, and the mineral powder additive was used to improve the recovery efficiency of vitrification process. Plating sludge was collected from an industrial Ni electroplating workshop in Taiwan. Mineral powder composed of dolomite, limestone, and cullet was employed as the reductant additive to improve the efficiency of producing metallic ingot in the vitrification process. The metals Al, Ca, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were analyzed with an atomic adsorption spectrometer (AAS). Ni, Fe, and Cr are potential candidates for recovery using the vitrification process due to their relatively high mass content. To determine the optimal efficiency, vitrification processes were performed with additive to sludge mass ratios of 5:5, 6:4, 7:3, 8:2, and 9:1. The results indicate that the optimal metal recovery efficiency of Ni, Fe, and Cr was achieved at an additive to sludge ratio of 8:2. In addition, the toxicity characteristic leaching procedure (TCLP) test results for the slag meet the Taiwan EPA's regulated level of Cr(VI), Cr, Pb, and Cu. To examine the changes in microstructure, the crystalline phases of slag were analyzed with XRD. The XRD patterns show that the appearance of pseudowollastonite improves the metal recovery efficiency, whereas the appearance of diopside and quartz decreased efficiency. The preliminary economic analysis indicated that the vitrification was not only a feasible but also a cost-effective technology for the electroplating sludge treatment in this study. However, the practical application should further depend on the building cost of the plant and financial support from the government.