Ting-Yu Chen

Removing of Nano-Particles from Semiconductor Wastewater Using a Hybrid Treatment System

Packaging process is one of the main manufacturing steps in the wafer fabrication industries. However, nano-particles would be produced during the packaging process. The produced nano-particle-contained wastewater has characteristics of dark color and high turbidity. Because the nano-particles would usually result in the clogging of the membrane filtration system when it is used for water treatment and reclamation, the application of a pre-treatment system is required to extend the membrane life. The objective of this study was to develop a pre-treatment system for packaging wastewater treatment before membrane system was applied for further water quality improvement. In this laboratory-scale study, a hybrid treatment system containing a chemical coagulation/flocculation followed by ultra-filtration (UF) membrane technology was developed for the wafer fabrication wastewater treatment. The chemical coagulation/flocculation unit was used as the pre-treatment process to improve the efficiency of the following ultra-filtration (UF) membrane system. The packaging wastewater was collected from a wafer fabrication factory and used to evaluate the feasibility of the coagulation/flocculation process on nano-scale particle removal. Results show that approximately 98% of turbidity could be removed at pH 7 when 2.2 mg/L of polyaluminum chloride (PAC) (used as coagulant) and 0.5 mg/L of polyacrylamide (cPAM) (used as flocculant) were added during the coagulation/flocculation process. Results indicate that the coagulation/flocculation is a feasible pre-treatment process for nano-particle removal before UF membrane is applied for further water purification. Results from this study will be helpful in designing a scale-up system for practical applications.

Application of oxygen-releasing material to enhance in situ aerobic bioremediation

Contamination of groundwater by petroleum-hydrocarbons is a widespread environmental problem. Generally in plumes of petroleum-hydrocarbon contamination, the dissolved oxygen (DO) demand imposed by biodegradation of organic contaminants exceeds the DO available creating anaerobic conditions within the plume core and mid-plume areas. The objectives of this bench-scale study were to (1) develop oxygen-releasing materials for continuous oxygen supplement, (2) determine the optimal components of the studied oxygen release material, and (3) evaluate the oxygen release rate and lifetime of this material. Moreover, the potential of using a passive oxygen release material to clean up aquifers contaminated by petroleum hydrocarbons was also studied. Bench experiments were conducted to design and identify the components of the oxygen-releasing materials. The mixtures of the oxygen release material were prepared by blending gypsum, calcium peroxide (CaO2), sand, and water together at a ratio of 1：0.5：0.14：0.75 by weight. Cement was used as a binder and regular medium filter sand was used to increase the permeability of the mixture. Calcium peroxide releases oxygen upon contact water (2CaO2 + 2H2O → O2 + 2Ca(OH) 2). The designed material with a density of 1.1 g/cm3 was made of 3.5-cm cube for the batch experiment. Results show that the oxygen release rate of the material is 0.025 mg/day/g. The oxygen release material is able to remain active in oxygen release for more than three months. With the application of this developed oxygen release material, the contaminated subsurface can remain an aerobic environment for subsequent aerobic bioremediation. For the future field application, the developed materials can be placed in remediation wells, trenches, horizontal wells, or barriers. Thus, the passive biobarrier system has advantages over conventional system including less maintenance, cost-effectiveness, no above-ground facilities, no groundwater pumping and reinjection, no air pollution problems, and groundwater remediation in situ. The proposed treatment system would be expected to provide a more cost-effective alternative to remediate petroleum-hydrocarbon contaminated aquifers. This technology can also be applied for other hazardous waste contaminated sites.

Production of Bacterial Cellulose by Gluconacetobacter xylinus Using Taguchi Methods

The production of bacterial cellulose (BC) from Gluconacetobacter xylinus could be improved by the Taguchi method. Both the initial pH and glucose concentration are the important factors to affect the production of the BC. The optimum combination of these factors and levels is the G. xylinus ATCC 23768, YPD as the basic growth medium, initial pH=4.5, glucose concentration = 5% (w/v), acetic acid concentration= 1.5% (v/v) and liquid height=7.2 cm. After the modified of factors and the levels, the maximum BC concentration and wet film thickness could be increased 37.5% to 0.557 g-dry cellulose/L and 39.0% to 3.92 mm, respectively.

Evaluation the Heat Environment for Using Phenolic Resin as Heat Insulation Construction Material

In this research, two buildings were constructed using phenolic insulation along with considerations of various experimental elements and condition. These environmental factors include natural ventilation, forced ventilation, the mist system, and shading. The results show that when the building is well insulated, the heat transported across the well is effectively prevented indicating that the phenolic resin is effective in insulating the building. Under full sunshine, the room temperature is 10 °C lower than the ambient temperature under full sunshine with the best insulation effect observed at 10:00 am. Shading will provide additional insulation effect to lower the room temperature by 3 °Cmore; the insulation efficiency can also be improved by ventilating the room. Results at 12:00 noon show that shading can effectively reduce solar radiation on the wall whereas force ventilation will carry away heat to reduce the room temperature. Shading will always be effective in reducing the room temperature by about 4 °C, and at 14:00, forced ventilation is the most effective in lowering the room temperature.

Evaluation of Cooling Wall System and Phenolic Resin as Thermal Barrier in Buildings

In recent years, thermal barrier technologies have become an important energy-saving for space heating and cooling of residential and commercial buildings in many countries. Building energy efficiency can be improved by implementing either active or passive energy efficient strategies. Improvements to heating, ventilation and air conditioning systems etc. can be categorized as active strategies, whereas, improvements to building envelope elements can be classified under passive strategies. Using cooling wall system and phenolic resin as thermal barrier are one of the effective passive strategies. Cooling wall system is composed of galvanized iron pipes located inside of walls. Fluid flows inside the pipes and then supply constant cooling temperature. In the study, system using of groundwater as renewable energy source for pipes cooling. The groundwater at depth of more than 5 meters below the surface has constant temperature year round. Lower temperature groundwater would cool the pipes of system by heat exchange process to achieve the cooling effect of wall. The phenolic resin is proposed as construction materials to use its thermal insulation property for developing a comfortable living and working indoor environment. The phenolic resin is an environmental friendly material, and an excellent thermal barrier. In this research, cooling wall system and phenolic resin were evaluated to reduce the thermal transfer from sunlight into the buildings, thus reducing the electricity consumption needs for air conditioning of the buildings.

Production of Bacterial Cellulose Using Different Carbon Sources by Two-Stage Cultivation Strategy

The production of bacterial cellulose (BC) from Gluconacetobacter xylinus could be improved by the two-stage cultivation strategy. The jar fermentor was applied at first stage to increase cell concentration. At the second stage, the bacteria statically grew within beaker. Three different fraction of cell volumes were cultured in modified YPD-glucose medium or YPD-molasses one. In the modified YPD-molasses medium, the BC yield were highest in this study when the consuming rate of reducing sugars (RS) was 0.181 g-dry BC L-1 d-1 and the BC production rate was 0.183 g-dry BC/g-RS, respectively. The modified YPD-glucose medium could get the maximum pellicle thickness of 5.56±0.64 mm and water content of 99.4%, respectively.