The former Nebraska Ordnance Plant has groundwater contaminated with a mixture of trichloroethylene (TCE) and the high explosive RDX that is treated in a system of eight granular activated carbon (GAC) contactors. A mathematical model was utilized to simulate alternative operating scenarios along with variable influent concentrations. In this study, blending effluent from parallel columns resulted in the lowest GAC usage rate when the target effluent $C∕C_0$ was $>0.3$ . Lead-lag operation was best when the target effluent $C∕C_0$ was $<0.1$ . Only between a target effluent $C∕C_0$ of 0.1 and 0.3 did the percent of the mass transfer zone (MTZ) contained in the column become important. Even then, selection was more sensitive to changes in the target effluent $C∕C_0$ value than the percent of the MTZ contained in the column. Decreasing the TCE influent concentration prior to the GAC treatment system by air stripping may reduce the GAC replacement costs but has significant new capital costs. Because contaminant levels in the extraction wells vary, influent segregation has the potential to reduce GAC usage rates by up to 65% with a relatively low capital expenditure.

Case studies of stakeholders in the United Kingdom and United States are presented. Recently, the United Kingdom nuclear industry has begun to consult stakeholders more widely. Methods of engagement within the British industry have varied. Discussions have been with the understanding that engagement with stakeholders will be “dialogue based” and “inform” final decisions. Engagement is being carried out at several levels: at the national level [via the Nuclear Decommissioning Authority’s (NDA) National Stakeholder Group (NSG)]; local site level (via Site Stakeholder Groups); and project level (usually via the best practicable environmental option process). Preliminary findings of a questionnaire issued to all members of the United Kingdom’s NDA NSG, and associated subgroups focused on stakeholder perceptions of the engagement process. In the United States, the Department of Energy’s Savannah River Site (SRS) Citizens Advisory Board, in Aiken, S.C., reviewed seismic designs for the salt waste processing facility at SRS. The final design, proposed by the Defense Nuclear Facilities Safety Board, provoked heated debate among all parties. Theory and future research are reviewed.

The objective of this investigation was performed to assess the effects of bromide and ammonia concentrations on the formation of ozonation and chlorination by-products including bromate, trihalomethanes (THMs), and haloacetic acid (HAAs). The results of this investigation reveal that increasing bromide, ozone dosage, and decreasing ammonia concentrations would enhance the bromate formation. Bromate formation was inhibited by ammonia significantly when the bromide concentration was introduced above $1.0\mathrm{mg}∕\mathrm{L}$ . Moreover, the range of percent of bromide incorporation for bromate was between 1.2 and 2.3%. Bromide would generate more bromide-containing species of THMs and HAAs formation indicating the higher bromine incorporation factor (BIF) value of THMs and HAAs. Ammonia reduced the THMs and HAAs formation obviously, but the effect of ammonia on BIF value is insignificant. Results of the factor analysis suggest that the principle parameters such as ozone, bromide, and reaction time should be utilized for developing the kinetics-based model for bromate prediction.

Given the increase in demands on water resources, optimal management policy has been sought for minimum resource utilities and maximum environmental benefits. Since the water resource system is complicated and has many uncertainties, artificial intelligence techniques, like fuzzy set theory or a genetic algorithm (GA), enable us to identify optimal decision variables more efficiently and incorporate uncertainty considerations. In this study, multiobjective programming was developed for a realistic application in Kinmen Island, Taiwan, against the scarce water resource. Three alternatives, including a desalination facility, additional activated carbon equipment for the current wastewater treatment plant (WTP), and constructed wetlands were designed to improve water quality and to ensure sufficient water supply. The GA technology is employed to search for the best solutions from the three alternatives. In addition, the fuzzy goal of cost and water quantity represented is utilized to determine the optimal control policy by the degree of satisfaction. In the optimal management of this case study, the desalination facility receives 17.8% of the treatment water, and 20.7 and 61.5% of the treatment water allocated to the current WTP and constructed wetland, respectively. The GA and fuzzy multiobjective programming are proven to facilitate the determination of the optimal solution for Kinmen’s water resource management.

Constructed wetlands are growing in popularity as a natural and economical alternative for purifying contaminated water worldwide. This paper summarizes the results of implementation of constructed wetlands in the treatment of metal containing water and evaluates their performance with respect to various metal removal mechanisms. Metal contaminated waters including acid mine drainage, storm runoff, sewage, and industrial wastewater are also evaluated regarding their removal efficiency within various types of constructed wetland systems. The role of vegetation within wetland systems is also examined to determine the possibility of enhancing the metal removal efficiency for future applications.

Microwave energy has been widely used in several domestic, industrial, and medical applications such as food sterilization, organic/inorganic syntheses, polymerization, dehydration, analyses and extraction, and biological destruction. This paper summarizes the potential applications of microwave energy as remedial alternatives for various types of wastes and diverse contamination of soils, sludge, or wastewaters. The major subjects covered in the paper are focused on sludge processing, medical waste treatment, contaminated soil remediation, wastewater remediation, activated carbon regeneration, and integrated remedial methodology. The extent of microwave treatment and microwave-assisted application promoting a specific technology has been highlighted relative to the conventional methods. Also, a few novel microwave involved processes, and the integrated experimental design of remedial schemes were presented. The application of microwave energy was proven to be superior to the use of conventional heating on accelerating reaction rates, improving yields, and selectively activating or suppressing reaction pathways. Besides the thermal effect, the nonthermal effect caused by microwave irradiation and its influence on the specific remediation cases have also been discussed. When applying the integrated remedial methodology, the effects of microwave irradiation improving the photocatalytic capacity of ${\mathrm{TiO}}_2$ have been detailed. Conclusively, microwave technology is a potentially viable and powerful alternative to the decontamination of soil, sludge, wastewater, as well as the treatment of certain types of waste.

The groundwater contaminated with chlorinated solvents poses daunting challenges for environmental remediation. Conventional treatment technologies such as pump-and-treat and bioremediation are costly and may require lengthy treatment periods. In situ chemical oxidation can be cost competitive with conventional treatment technologies and can destroy the contaminants rather than transferring them to another media. Four oxidants including hydrogen peroxide (Fenton’s reagent and Fenton-like), permanganate, persulfate, and ozone commonly employed in the chemical oxidation process are evaluated in this paper. The applicability of various oxidizing agents in subsurface contaminant remediation is also reviewed. Chemical oxidation technologies are effective and inexpensive alternatives. The merits also include that oxidation is relatively unaffected by contaminant characteristics and concentration. Future development-related chemical oxidation technology including a treatment train system, application of zero-valent iron nanoparticles in chemical oxidation processes, and solubilizer enhanced chemical oxidation are depicted. The summaries of this review paper regarding the chemical oxidation are applicable for designing in situ chemical oxidation systems.

Leaching of Cd, Cr, Cu, Pb, Ni, and Zn from fresh and partially decomposed municipal solid wastes using acid digestion (AD), multiple extraction procedure (MEP), toxicity characteristic leaching procedure (TCLP), and equilibrium leach test (ELT) was carried out. Sequential extraction studies were conducted to evaluate the mobility of heavy metal ions by fractionating into exchangeable, acid extractable, oxidizable, reducible, and residual fractions. The extraction efficiency of the tests decreased in the following order: $\mathrm{AD}>\mathrm{MEP}>\mathrm{TCLP}>\mathrm{ELT}$ . Less than 45% of the metal contents were in bioavailable (exchangeable and acid extractable) form, except Ni. Total and TCLP extractable metal contents were within the limits prescribed for USEPA compost and TCLP regulating limits, respectively.