The agricultural use of sewage sludge is limited by the presence of toxic metals and pathogens. The simultaneous sludge digestion and metal leaching (SSDML) process has been developed to resolve this problem. In the present study, the performance of the SSDML process for the elimination of total coliforms, fecal coliforms, fecal streptococci, and coliphages from sewage sludge was verified by shake flask, laboratory bioreactor, and pilot plant bioreactors. The effect of pH, sludge solids concentration, temperature, and sludge types on the bacterial indicator's removal was evaluated. The results showed that the SSDML process was more efficient than the conventional mesophilic aerobic sludge digestion process for the elimination of bacterial (2.5 to >7.0 log units reduction) and viral (>8.0 log units reduction) indicator microorganisms.

A reactive polymer, alkyl quaternized poly(4-vinylpyridine) (PVP) was synthesized and coated on the surface of silica gel to test its ability to remove Cr(VI) from water. Batch experiments were conducted with the coated gel to determine the effect of the Cr(VI) concentrations on the rate of sorption and the influence of other anions on the Cr(VI) adsorption. The concentrations of Cr(VI) had a pronounced effect on the rate of sorption. The adsorption of Cr(VI) was influenced to some extent by other anions. The relative effect in decreasing order for ${\mathrm{SO}}^{\mathit{2}{\mathit{-}}_{\mathit{4}}}$, Cl⁻, and CH₃COO⁻ ions on the adsorption of Cr(VI) was ${\mathrm{SO}}^{\mathit{2}{\mathit{-}}_{\mathit{4}}}$ > Cl⁻ > CH₃COO⁻. Chromium adsorbed on the coated gel was easily recovered under certain conditions. NaOH was a good desorption reagent for Cr(VI) with a desorption efficiency of up to 90%. The desorption rate was very fast. After desorption, the coated silica gel could be reused.

Aberdeen Proving Ground (APG) is currently listed on the Superfund National Priorities List because of past waste handling practices at 13 “study areas.” Concern has been expressed that anthropogenic radioisotopes may have been released at some of the study areas, with the potential of posing health risks to human or ecological receptors. This concern was addressed by thoroughly searching archival records, sampling and analyzing environmental media, and performing an aerial radiation survey. The aerial radiation survey techniques employed have been used over all U.S. Department of Energy and commercial reactor sites. Use of the Aerial Measurement System (AMS) allowed investigators to safely survey areas where surveys using hand-held instruments would be difficult to perform. In addition, the AMS delivered a full spectrum of the measured gamma radiation, thereby providing a means of determining which radioisotopes were present at the surface. As a quality check on the aerial measurements, four ground truth measurements were made at selected locations and compared with the aerial data for the same locations. The results of the survey revealed no evidence of surface radioactive contamination. The measured background radiation, including the cosmic contribution, ranged from 4 to 11 μR/h.

The hypothesis evaluated was that the extent to which a contaminated soil undergoes weathering prior to treatment affects the degree of chemical loss that occurs during bioremediation. The hypothesis was evaluated using soils from field sites. Nine soils from petroleum and related industry sites were obtained and characterized for chemical composition. The chemical characterization data were used to identify the extent of prior weathering of hydrocarbons in the soils. Based on such a weathering evaluation, the potential for further chemical loss in a bioremediation process was predicted. Those predictions were then compared with the results of biotreatability studies. Shake flask and solid-phase biotreatability studies were conducted on the soils to determine the rate and extent of hydrocarbon loss in the soils due to bioremediation. The predictions of biodegradation potential agreed well with the actual biotreatability results for seven of the nine soils used in the evaluation. These included both soils (A, E, and I) in which there was significant chemical loss during the biotreatability studies and soils (B, C, F, and J) that did not experience significant chemical loss during the biotreatability studies. Soil K had a moderate decrease in chemical concentrations during bioremediation, whereas no decrease was predicted. The results from this study indicated that it is possible to make screening level judgments about the hydrocarbon loss that may occur due to bioremediation based on simple hydrocarbon characterization information. The results also indicated that hydrocarbon composition and weathering should be considered before initiating bioremediation projects.

Flare pits have been used by the upstream oil and gas industry for decades to store and/or burn produced fluids at well sites, compressor stations, and batteries. Waste at such sites, or flare pit (FP) waste, usually contains high levels of hydrocarbons, metals, and salts. At present, bioremediation by land application is the most common method practiced by the oil and gas industry to treat FP waste. High rate slurry-phase and solid-phase biotreatment methods are viable alternatives to the low cost yet inefficient land treatment option. An ultimate biotreatability screening tool is needed to assess the viability of each treatment method. The effects of salinity, nutrient, soil type, and temperature on the ultimate biotreatability of FP waste were investigated using 2 L slurry reactors. The results showed an initial decrease in petroleum concentrations; however, biodegradation decreased or ceased with time, leaving recalcitrant compounds. Within a week, the majority of saturated hydrocarbons degraded to low levels. Aromatics remained stable, while the level of polar compounds fluctuated. Temperature (30–40°C), salinity levels (up to 40 dS/m), and nutrient concentrations (above 350 mg N/L as ammonium nitrogen) exhibited no statistically significant effects on hydrocarbon degradation. The primary effect of waste composition was highly significant; with higher soil clay content resulting in lower biodegradation. Results indicate that slurry phase experiments may serve as a screening tool; however, caution should be exercised because slurries do not contain some of the microflora found in the solid phase (e.g., fungus).

An aluminum company that produces an oily wastewater upgraded their wastewater treatment facilities to prevent ground and surface water contamination. Applying pilot-scale data collected over a 2.5 year period, the following treatment train was proposed: gravity separation → tubular ultrafiltration (TUF) → unlined hybrid wetlands. TUF residual was to be concentrated using a high-shear rotary ultrafiltration (HSRUF) system. Full-scale operation differed from what was initially proposed due to several phenomena unforeseen in the pilot-study/design phase. TUF permeate produced during full-scale operation was of much higher quality than that observed during the pilot-scale study (<10 mg/L compared with 66 mg/L O/G). Therefore, the hybrid wetlands were not constructed. A significant amount of free-oil formed in the TUF feed tanks (average: 1,420 L/day), resulting in the oil concentration of the TUF feed streams remaining at <20%, greatly prolonging run lengths and reducing the volume of TUF residual that required treatment. Thus, the HSRUF system was not required to concentrate the residual. The following modified full-scale treatment train is currently operating: gravity separation → TUF → lined permeate holding pond → direct discharge to receiving water.

Characterizing and monitoring contaminated bedrock aquifers remains an enormous challenge with important consequences. Investigations of bedrock aquifers are challenging for two principle reasons: heterogeneity and costs. This paper demonstrates that successful characterization is possible and describes a strategy using borehole geophysics and multilevel wells that greatly increases the chances of success. A cost evaluation shows that, while these methods can be expensive, proper application may reduce long-term monitoring costs. The increasing use of low-flow sampling techniques and the rising popularity of monitored natural attenuation remedies should lead to increased application of this strategy. The case study site is a hilltop landfill overlying a heterogeneous bedrock aquifer and surrounded by homes using domestic wells. Borehole geophysical and heatpulse-flowmeter data identified 1–2 water-bearing zones (WBZs) per 30 m drilled. Multilevel wells focused sampling on WBZs and provided detailed plume characterization and monitoring that will help to protect local domestic wells. Review of logs from monitoring well MW-8 shows how borehole geophysics identified seven individual WBZs, and sampling of the multilevel well revealed important variations in chemical and potentiometric signatures between the WBZs. This detailed characterization was necessary to support the site conceptual model and demonstrated that domestic wells were not threatened.