Chlorophenols are generated from a number of industrial producing processes and are extensively used as insecticides, herbicides, and fungicides. Their discharge into the environment is of great concern due to their toxicity. Bioremediation is one attractive method for managing hazardous waste contaminated sites because of its economic benefit and complete mineralization in most cases. In this study, a chlorophenol spill site was selected to evaluate the feasibility of using bioremediation technology for the remediation of chlorophenol-contaminated groundwater. Because 2,4-dichlorophenol (2,4-DCP) was one of the major contaminants appeared at this site, it was used as the target compound in this study. Microcosm experiments were constructed to: (1) determine the feasibility of applying different microbial consortia [e.g., aquifer sediments, extracted supernatant of aquifer sediments, aerobic activated sludge collected from an industrial wastewater treatment plant, and anaerobic sludge collected from an upflow anaerobic sludge bed (UASB) system] for the biodegradation of 2,4-DCP; (2) evaluate the biodegradability of 2,4-DCP under aerobic, aerobic cometabolic, iron reducing, methanogenic, and reductive dechlorinating conditions; and (3) determine the potential of enhancing 2,4-DCP biodegradation using cane molasses, biological sludge cake, and sodium acetate as the substitute primary substrates under aerobic cometabolic and reductive dechlorinating conditions. The inocula used in the microcosm study indicate that aquifer sediments, extracted supernatant of aquifer sediments, and activated sludge could metabolize 2,4-DCP directly without the addition of any extra carbon sources. In addition, indigenous microorganisms were capable of using 2,4-DCP as the sole carbon and energy source. Enhanced 2,4-DCP biodegradation was not observed under cometabolic conditions due to the substrate competition. The preferential removal of added substrates caused the decrease in 2,4-DCP degradation rates. Under anaerobic conditions, the UASB sludge could biodegrade 2,4-DCP only with the addition of sludge cake. Thus, a suitable carbon source for UASB sludge might play an important role in the removal of 2,4-DCP. Moreover, 2,4-DCP biodegradation was not detected under any anaerobic conditions (e.g., iron reduction, reductive dechlorination, methanogenesis). This indicates that anaerobic biodegradation processes might not be the dominant biodegradation patterns at this site. Results will also aid in designing a remedial system for field application.

Batch biosorption of chromium(VI) from an aqueous solution was studied using dry biomass of Fusarium sp. isolated from soil. At the initial metal ion concentration of $50\mathrm{mg}∕\mathrm{L}$ and pH 2.0, the Cr(VI) adsorbed was $12.5\mathrm{mg}∕\mathrm{g}$ of adsorbent. The Cr(VI) adsorbed increased with increasing initial metal ion concentration up to $500\mathrm{mg}∕\mathrm{L}$ . A maximum removal of $47.5\mathrm{mg}∕\mathrm{g}$ was observed at pH 2.0 at $500\mathrm{mg}∕\mathrm{L}$ initial Cr(VI) concentration. An increase in pH from 2 to 6 decreased Cr(VI) removal from $12.5\text{to}2.2\mathrm{mg}∕\mathrm{g}$ at $50\mathrm{mg}∕\mathrm{L}$ metal ion concentration. At all the concentrations, the adsorption equilibrium was obtained within $2\mathrm{h}$ . The adsorption equilibrium constants were obtained from both Freundlich and Langmuir adsorption isotherms. The organism was also found to remove $42.5\mathrm{mg}$ of Cr(VI) per gram of adsorbent from an effluent $(500\mathrm{mg}∕\mathrm{L})$ generated from an electroplating industry.

High concentrations of iron and arsenic are common in Saskatchewan groundwater. Their cost effective removal from groundwater is a challenge for small communities. Four small treatment systems were tested for iron and arsenic removal with and without ozone pretreatment using groundwater high in iron $(6.4–8.4\mathrm{mg}∕\mathrm{L})$ and arsenic $(14.5–27.2\mu \mathrm{g}∕\mathrm{L})$ . The systems tested were (1) coagulation, (2) biological activated carbon (BAC) filter, (3) slow sand filter, and (4) rapid sand filter. Coagulation removed 70% of arsenic and 85% of iron. With ozone pretreatment, the removal increased to 95% for arsenic and 93% for iron. The BAC system was highly effective in the removal of both arsenic and iron. On average, it removed 97% of arsenic and 99.8% of iron. With the ozone pretreatment, the average removal increased to 99% for arsenic and 99.9% for iron. The increase in iron removal with ozone was not statistically significant at $P=0.1$ . The slow sand filter system was also highly effective in the removal of both arsenic and iron. On average, it removed 96% of arsenic and 99.8% of iron. The ozone pretreatment did not significantly change removal rates. The rapid sand treatment system removed an average of 50% of arsenic and 99% of iron. With the addition of ozone, the average arsenic removal increased to about 65%; however, the average iron removal was only 50%. The removal of arsenic by the rapid sand filter was extremely variable and this was possibly related to media saturation and some surge in the system as the ozone off gas valve was opened and closed.

The U.S. Environmental Protection Agency Superfund Innovative Technology Evaluation (SITE) program selected the Glass Furnace Technology (GFT) treatment process for evaluation. The GFT was developed by Minergy Corporation as an ex situ remediation technology to treat river sediment contaminated with polychlorinated biphenyls (PCBs), other organic compounds, and metals. The pilot-scale demonstration of the GFT was conducted at Minergy’s GlassPack Test Center facility in Winneconne, Wisconsin. In the GFT treatment, dewatered sediment is dried, flux is added to control melting temperatures and improve the physical properties of the glass aggregate product, and then the sediment and flux mixture is melted at a temperature of about $\mathrm{1,600}°\mathrm{C}$ , removing or destroying PCBs and organic contaminants, and encapsulating metals. The product consists of glass aggregate with particles the size of coarse sand. The developer claims the glass aggregate meets state regulatory criteria for beneficial reuse. The main objectives of the SITE GFT demonstration were to determine the treatment efficiency of PCBs in river sediment when processed in the GFT and to determine whether the GFT glass aggregate product meets the criteria for beneficial reuse under relevant federal and state regulations. In August of 2001, a technology evaluation was conducted on about 17,000 pounds of river sediment dredged from the Lower Fox River in Green Bay, Wisconsin; the geometric mean concentration of polychlorinated biphenyls (PCBs) in the melter feed (dried sediment) was $27.8\mu \mathrm{g}∕\mathrm{g}$ , while the geometric mean in the glass aggregate product was $136\mathrm{pg}∕\mathrm{g}$ . Analytical data indicate that the GFT was able to significantly reduce PCB contamination in all samples. Overall, the GFT successfully removed or destroyed 99.9995% of the PCBs in the river sediment, measured as total PCBs. The GFT also reduced the concentration of dioxins and furans in dried sediment. The geometric mean of the total dioxin and furan concentrations in the melter feed was $\mathrm{116,000}\mathrm{pg}∕\mathrm{g}$ , while the geometric mean in the glass aggregate product was $2.26\mathrm{pg}∕\mathrm{g}$ , a reduction of greater than 99.9995%. Samples of the glass aggregate were crushed and subjected to ASTM and synthetic precipitation leaching procedure analyses. The results of the leaching tests indicated no detections of contaminants of concern in leachates for either method. The GFT produced glass aggregate that met Wisconsin Administrative Code Chapter NR 538 Category 2 criteria and qualified for beneficial reuse under the regulation. This qualification allows a range of uses, including as an additive to concrete, a material in floor tiles, and as construction fill. Based on information from Minergy and observations made during the SITE evaluation, the estimated treatment cost is $\mathrm{\$}38.74\text{per}\text{ton}$ of dredged-and-dewatered sediment containing 50% moisture. Unit costs are based on a $15\text{-}\text{year}$ project life expectancy and may depend on the location of the treatment facility, amount of moisture in the sediment, and potential end use of the product.

Several farms on the north seashore of Taiwan were contaminated with cadmium and lead since the early 1980s. At the contaminated site, the average soil concentrations of cadmium and lead, analyzed in 1982 and 1996, ranged from $385\text{to}44\mathrm{mg}∕\mathrm{kg}$ and $\mathrm{3,336}\text{to}464\mathrm{mg}∕\mathrm{kg}$ , respectively. In this study, the exposure and risk assessment were conducted using an environmental fate and transport model, RESRAD-CHEM, to estimate carcinogenic risk and noncarcinogenic risk for cadmium and lead on a population exposed to the pollutants. Using the concentration data of 1982, the RESRAD-CHEM model was able to appropriately estimate the residual concentrations of cadmium and lead for 1996. Since there were no carcinogenic slope factors available for several exposure pathways, the cancer risk assessment of cadmium was estimated using the inhalation pathway only. The estimated carcinogenic risks were 5.5–7.6 $\left({10}^{-6}\right)$ using the 1982 concentration data. The maximum hazard index was estimated to be 488 and significantly higher for residents living near the seashore than for residents living away from the seashore. The hazard index was found to be significantly correlated to the standard mortality ratio of nephritis for the local residents from 1982 to 1999 $(r=0.731,p=0.019)$ . The EPA of Taiwan should employ health risk management as a criterion for site remediation.

This study was conducted to investigate the cadmium removal in the free water surface and subsurface flow constructed wetland systems under different environmental conditions. Removal efficiencies of the chemical oxygen demand were found to be in the range of 79–92% for the two wetland systems. The removal efficiencies for total kjeldahl nitrogen, total phosphorus, total suspended solid, and volatile suspended solid were in the range of 64–91, 62–90, 68–91, and 50–84%, respectively. Influents were obtained by mixing a synthetic wastewater with $\mathrm{Cd}{\mathrm{Cl}}_2.{\mathrm{H}}_2\mathrm{O}$ at four concentrations 1, 5, 10, and $20\mathrm{mg}∕\mathrm{L}$ , respectively, for the four experimental runs. The mean effluent cadmium concentrations varied between 0.02 and $0.16\mathrm{mg}∕\mathrm{L}$ . Cadmium removal efficiencies were 98.6–99.4% in free water surface, and 99.3–99.9% in the subsurface flow wetland systems. The subsurface flow wetland showed slightly better performance than the free water surface wetland in terms of various pollutants’ removal. However, the two systems had similar performances in the cadmium removal.

The effect of phosphorus co-precipitation with ferric chloride $\left({\mathrm{FeCl}}_3\right)$ dosing on biological phosphorus (P) along with carbon (C) and nitrogen (N) removal was investigated in a sequencing batch reactor (SBR) for slaughterhouse wastewater treatment. Additional phosphorus removal due to chemical co-precipitation was evaluated as the difference in System P removal between Phase 1 (control—without ${\mathrm{FeCl}}_3$ dosing) and Phase 3 (with ${\mathrm{FeCl}}_3$ dosing). Phase 2 was mainly studied to improve nitrification/denitrification process with acetate addition by Filali-Meknassi et al. in 2004. Both systems (Phases 1 and 3) exhibited high P removal but a co-precipitation with ${\mathrm{FeCl}}_3$ dosing only allowed us to have an orthophosphates $\left(o\text{-}{\mathrm{PO}}_4\right)$ concentration below $1\mathrm{mg}\mathrm{P}∕\mathrm{L}$ in the effluent. Without ${\mathrm{FeCl}}_3$ addition, the total P concentration was reduced from $85\pm 12$ to $14\pm 2\mathrm{mg}\mathrm{P}∕\mathrm{L}$ (84% removal), whereas with the addition of ${\mathrm{FeCl}}_3$ an additional $11\mathrm{mg}\mathrm{P}∕\mathrm{L}$ was removed bringing the effluent P concentration to $3\mathrm{mg}\mathrm{P}∕\mathrm{L}$ (as total P). Although, during simulation of aerobic phase, a release of phosphorus was observed. The study showed that the ASM2d model with the adjustment (calibration) of seven kinetic parameters ( ${\eta }_{{\mathrm{NO}}_3}$ , ${\mu }_{\mathrm{AUT}}$ , $b_{\mathrm{AUT}}$ , $K_{{\mathrm{O}}_2}$ , $K_{{\mathrm{NH}}_4}$ , $K_h$ , ${\mu }_{\mathrm{PAO}}$ , and ${\mathrm{b}}_{\mathrm{PAO}}$ ) was capable of predicting the behavior of the laboratory SBR activated sludge and provided the profile of nutrients (phosphorus, ${\mathrm{NH}}_4–\mathrm{N}$ , ${\mathrm{NO}}_X–\mathrm{N}$ , and COD) removal.

The objective of this research is to review the current status of source water as compared with the Taiwanese source water quality standards promulgated in 1997. The total coliforms, total organic carbon (TOC) and chemical oxygen demand (COD) were selected as the major parameters for review because of their specific characteristics associated with the disinfection efficiency and disinfection by-products formation and in compliance with source water quality in Taiwan. The water treatment plant with unacceptable source water needs to improve its source water quality and establish the implementation plan based on the results of comprehensive performance evaluation. Throughout this investigation, it suggests that revisions to water quality standards be divided into two execution phases, to achieve the long-term goal of improving source water quality.