Expediting remedial designs and assessments

A successful air-based remediation system, now frequently chosen for sites contaminated with VOCs, demands a thorough understanding of the nature and distribution of the VOCs and the soil air permeabilities. Considering likely remediation methods during the site investigation allows collection of all data needed for method selection and design within a single, highly efficient site visit. A case history illustrates how to integrate several data collection and testing activities into a single site visit.     

SITE Demonstration of Enhanced In-Situ Bioremediation of Chlorinated and Nonchlorinated Organic Compounds in Fractured Bedrock

A field demonstration of an enhanced in-situ bioremediation technology was conducted between March 1998 and August 1999 at the ITT Industries Night Vision (ITTNV) Division plant in Roanoke, Virginia. The bioremediation process was evaluated for its effectiveness in treating both chlorinated and nonchlorinated volatile organic compounds (VOCs) in groundwater located in fractured bedrock. Chlorinated compounds, such as trichloroethene (TCE), in fractured bedrock pose a challenging remediation problem. Not only are chlorinated compounds resistant to normal biological degradation, but the fractured bedrock presents difficulties to traditional techniques used for recovery of contaminants and for delivery of amendments or reagents for in-situ remediation. The demonstration was conducted under the U.S. Environmental Protection Agency's Superfund Innovative Technology Evaluation (SITE) program. The SITE program was established to promote the development, demonstration, and use of innovative treatment technologies for the cleanup of Superfund and other hazardous waste sites. This article presents selected results of the demonstration and focuses on understanding the data in light of the fractured bedrock formation. © 2002 Wiley Periodicals, Inc.     

Biomonitoring with Gammarus pulex at the Meuse (NL), Aller (GER) and Rhine (F) rivers with the online Multispecies Freshwater Biomonitor

Biological early warning systems represent a set of tools that may be able to respond to certain chemical monitoring requirements of recent European legislation, the Water Framework Directive (WFD2000/60/EC), that aims to improve and protect water quality across Europe. In situ biomonitoring was performed along the rivers Meuse (NL), Aller (GER) and Rhine (F) within the frame of the European Union-funded Project SWIFT-WFD. Gammarus pulex was used as a test organism during the evaluation of the Multispecies Freshwater Biomonitor(R) (MFB), an online biomonitor to quantitatively record different behaviour patterns of animals. At the river Meuse G. pulex reacted to pulse exposure of either a mixture of trace metals or of several organic xenobiotics, by showing up to 20% decreased locomotory activity (already at the 1st pulse) and increased mortality (at 2nd or 3rd pulse only). G. pulex deployed within the MFB system were observed to survive well at the monitoring station on the Aller (100%) and monitoring did not result in the measurement of chemical irregularities. In contrast, deployment at the monitoring station on the Rhine river demonstrated that the test organism was able to detect chemical irregularities by up to 20% decreased locomotory activity in the animals. The MFB proved to be an alert system for water quality monitoring at sensitive sites and sites with accidental pollution.     

Bacterial removal and protozoan grazing in biological sand filters

The objective of the study was to investigate the importance of protozoan predation as a biological removal mechanism in sand filters used for purification of bacteria from wastewater. Eleven sand filter columns were seeded with a high dose of wastewater (70 mm d(-1)) and a high concentration (10(8) colony forming units [CFU] mL(-1)) of Aeromonas hydrophila (American Type Culture Collection [ATCC] 14715) for a period of 30 d. Water samples from three filter outlets were analyzed for the concentration of A. hydrophila. In addition, one filter column was sacrificed each sampling day for the quantification of A. hydrophila, culturable bacteria (heterotrophic plate counts, HPC), total bacterial counts, and protozoa in the sand. The mean removal efficiency of A. hydrophila in the sand filter columns was 4.7 log units. The concentration of A. hydrophila in the sand filter effluent, however, had a clearly time-dependent pattern from high (log 6) and unstable concentrations to low and more stable levels (log 2). The removal efficiency of A. hydrophila correlated significantly (P = 0.0005, r2 = 0.6) with numbers of protozoa in the sand filters. Significantly higher (P < 0.05) concentrations of A. hydrophila were observed in sand filter effluents from columns treated with the protozoan inhibitor cycloheximide, compared with nontreated columns. Results from the present study show that protozoan grazing plays an important role as a bacterial removal mechanism in sand infiltration systems.