Polycyclic aromatic hydrocarbons (PAHs) and heavy metals found at former manufactured gas plant (MGP) sites are of major environmental concern. An investigation is made into evaluating the capability of various extractants including surfactants, cosolvents, chelating agents, acids, and cyclodextrins for removing phenanthrene, lead, and zinc from a contaminated MGP soil. The determination of the most promising extracting solutions is critical for the development of effective treatment technologies such as soil washing/flushing and electrokinetic remediation. MGP contaminated soil was silty sand with 11% organic matter containing higher levels of phenanthrene and two heavy metals (lead and zinc). Several batch tests were conducted using the soil with different extracting solutions at various concentrations to enhance the removal efficiency and to optimize the concentration of each extractant. The test results showed that both surfactants (Igepal CA-720 and Tween 80) at a wide range of concentrations were effective for the removal of phenantherene from the soil. Only selective cosolvents and cyclodextrins (n-butylamine and HPCD) at higher concentrations were found to be effective in the solubilization of phenanthrene. Selective acids (citric acid and phosphoric acid) were found to be effective in the removal of heavy metals, while chelating agents (EDTA and DTPA) resulted in a moderate heavy metal removal. Overall, none of the selected extractants removed both heavy metals and PAHs; therefore, sequential extraction schemes using the selected extractants were investigated. The sequential use of 5% Tween 80 followed by $1\mathrm{M}$ citric acid was found to remove over 90% phenanthrene and over 70% lead and nickel each from the MGP soil.

Activated sludge from a full-scale pulp-paper industry wastewater treatment plant was used as a source of microorganisms to produce biodegradable plastics (polyhydroxyalkanoates) (PHA) at $25°\mathrm{C}$ , pH 7 and at different initial sludge suspended solids (SS) concentration (5, 10, 15, and $20\mathrm{g}∕\mathrm{L}$ ) in computer controlled fermentors. Acetate was used as sole carbon source at varying concentrations $(5–20\mathrm{g}∕\mathrm{L})$ . The fresh sampled sewage sludge was found to contain PHA and the amount varied with the sampling date. The PHA productivity and concentration varied with intial sludge SS and acetate concentrations. Maximum accumulation of PHA ( $39.6\%\mathrm{w}∕\mathrm{w}$ of dry sludge SS) was observed at $15\mathrm{g}∕\mathrm{L}$ SS and $10\mathrm{g}∕\mathrm{L}$ acetate concentration. The sludge biomass increased during the process, however, the net amount of the sludge residual solids after extraction of PHA was decreased to varying degrees depending on sludge SS and acetate concentration $(5.5–36.9\%\mathrm{w}∕\mathrm{w})$ . Acetate concentration above $10\mathrm{g}∕\mathrm{L}$ was found to be inhibitory for PHA accumulation and biomass growth. Copolymers (polyhydroxybutyrates and polyhydroxyvalerates) were produced by the sludge whose molar composition varied with the batch process time.

A review of published literature and practical projects of constructed wetlands (CWs) implemented in Taiwan was conducted to highlight wetland performance in wastewater treatment for various applications. Specific opportunities and limitations as well as problems and recommendations for exploring CW technology in Taiwan were also discussed. During the last decade, the number of CWs in Taiwan increased exponentially. Up to 2006, approximately 82 full-scale CWs have been installed and more than ten systems are in construction. The size of CWs ranged from $60{\mathrm{m}}^2\text{to}80\mathrm{ha}$ to receive wastewater flow ranging from $3\text{to}\mathrm{50,000}{\mathrm{m}}^3∕\text{day}$ . Warm climates in Taiwan provide great opportunities for successful wetland treatment. However, high population density forces CWs to be built in limited spaces, leading to emphasis on multiple-use values of CWs from the public. Most of the CWs were promoted under practical projects funded by various governmental organizations to develop diverse applications, such as water quality improvement of polluted surface water bodies, wastewater on-site treatment, and reuse in rural areas, campuses, recreational areas, and green architectures, management of aquaculture water and wastewater, tertiary treatment, and miscellaneous applications. The results of water monitoring obtained from several demonstrations show that CWs achieved acceptable wastewater treatment performances in removing major pollutants, including suspended solids, organic matters, nutrients, and indicating microorganisms from wastewater influent. Several issues should be studied further so as to maximize multiple-use benefits of CWs, which include establishment of a multidisciplinary approach to planning and designing of CWs and devising strategies to obtain consistent financial support for sustaining management of well operated wetland systems.

An optimal groundwater remediation design problem generally requires determination of the location of extraction and injection wells and their pumping and injection rates once the well locations are selected. According to many researchers, the determination of an optimal well location is even more important than the optimal pumping rate in groundwater remediation problems. The objective of the study is to apply a neural network embedded Monte Carlo approach to determine potential well locations for in situ bioremediation of contaminated groundwater. The methodology developed in this study has three important components: a bioremediation simulation model, an artificial neural network, and an application of Monte Carlo simulations. This method has been further applied to an in situ bioremediation problem, for which data are adopted from the available literature. The results show that the proposed approach can successfully identify potential well locations from a set of preselected well locations, which can be further used in optimization algorithms to identify optimal well locations and the corresponding pumping rates. The advantage of this approach is that it reduces the size of the problem considerably by eliminating redundant well locations and hence the computational burden involved. Furthermore, the computational burden of Monte Carlo simulations is managed within a practical time frame by replacing the bioremediation simulation model with a trained neural network.

The combustion of fossil fuel is the major source of greenhouse gases; therefore, fuel switching is viewed as a practical method to reduce greenhouse gas emission. Hydrogen may serve as an alternative for fossil fuel and it is clean. In this study, worthless hydrogen-rich fuel gas (RG), the by-product of the production processes, was led to the fuel system of a $130\mathrm{t}∕\mathrm{h}$ industrial boiler in a full-scale petrochemistry plant to partially replace the fuel oil (FO). The result shows that, by changing the inlet RG:FO volumetric flow rate ratio from 1:5 to 1:1.5, the emission of greenhouse gas is reduced significantly. Four sets of boiler loading, including 80, 70, 60, and 50%, were applied to the boiler at the full-scale plant, and the reduction of $\mathrm{C}{\mathrm{O}}_2$ emission by $33.5\times {10}^3$ , $51.6\times {10}^3$ , $48.8\times {10}^3$ , and $44.8\times {10}^3\mathrm{t}∕\text{year}$ can be achieved, which is down by 22.9, 39.8, 43.7, and 47.2%. Meanwhile, the amount of $\mathrm{N}{\mathrm{O}}_x$ emission can be reduced by 66, 79, 25, and $18\mathrm{t}∕\text{year}$ . Therefore, the use of RG to partly replace FO has practical benefits on the reduction of greenhouse gas emission, and better operating conditions for the boiler is suggested at an inlet RG:FO ratio of 1:1.5.

The occurrence of ciprofloxacin (CIP), sulfamethoxazole (SMX), and azithromycin (AZI) was evaluated in various aqueous streams of four municipal wastewater treatment plants (WWTPs) in the Midwestern United States. Aqueous phase grab samples were collected from different locations in the WWTPs at four different times of the year. The target compounds were extracted using solid phase extraction, separated with high-performance liquid chromatography, and identified/quantified using ultraviolet and fluorescence spectroscopy (CIP and SMX) or mass spectrometry (AZI). Aqueous phase concentrations for CIP and AZI were similar to literature values while SMX concentrations were generally higher than those reported in the literature. The average aqueous phase concentrations for CIP, AZI, and SMX in the raw wastewater were 1.44, 1.11, and $18.3\mu \mathrm{g}∕\mathrm{L}$ , respectively, while the concentrations in the WWTP effluent were 0.59, 1.23, and $3.25\mu \mathrm{g}∕\mathrm{L}$ , respectively. AZI concentration was consistently lower in the winter. While some CIP and SMX removal from the aqueous phase was observed in the WWTP, such reductions were not seen for AZI. Composite sampling data indicated that CIP and SMX concentrations were significantly higher in summer than in winter.

This study developed cost functions applicable to open-cut and jacking methods, which are construction techniques of sewer systems often used in gravel strata. The cost functions obtained by linear regression, expressed as functions of pipe size and excavation depth, were used to estimate the construction costs of sewer systems. Data for several real sewer system construction projects in Taiwan were investigated to verify the accuracy of the cost functions. Analytical results revealed that estimated and real costs deviated by less than 5%, a difference less than that for cost functions currently utilized in Taiwan. The cost functions developed in this study are more realistic, practical, accurate, and easy to use than existing functions. As the Taiwanese government is now implementing the building operator transfer policies for sewer system construction, the proposed cost function should prove to be a very useful tool, allowing both government and contractors to quickly estimate sewer construction budgets.

Phytoremediation is an ecotechnological remediation for treating contaminated sites. This phytotechnology uses plants to degrade, transform, assimilate, metabolize, or detoxify hazardous pollutants from soil and aquatic and atmospheric environments. Phytoremediation is generally used as a final polishing step following the pretreatment of the high concentrations of contaminants, while it can be used alone for low-level contamination, which may be the most economical and effective remediation strategy. Phytoremediation can be used for treating many classes of contaminants including petroleum hydrocarbons, chlorinated organic compounds, pesticides, explosives, heavy metals and radionuclides, and salts existing in industrial wastes, oil spills, forestry and agricultural wastes, salty waste liquid, and landfill leachate, which may contaminate surface water, groundwater, sediments, and soils. Although phytoremediation is a complicated process to remove contaminants from different environments and still need to keep investigating its mechanisms, it is an efficient, economical, and environmentally friendly ecotechnology. As a result of these advantages, phytoremediation has considerable potential for environmental restoration of contaminated sites.