Bioslurry reactors

The washed wastewater treatment techniques are basically the same as those used for pumped groundwater. Several integrated treatment technologies have been developed that can wash soil and treat washing water, such as that by BioTrol, Inc., in which the excavated soil is first screened, then washed, and finally the contaminated water is treated. As contaminants are difficult to wash from silt and clay, the clay and silt slurry contaminated with organics is treated in a bioslurry reactor. 

The next sections discuss the removal of several groups of emerging pollutants at pre-existent concentrations from sewage sludge by means of fungal treatments in solid-phase biopiles, both under sterile and non-sterile conditions and in bioslurry reactors under sterile conditions. 

Fig. 2 Time course of ergosterol content (circle) and laccase activity (square) during a bioslurry reactor treatment of sewage sludge with T. versicolor (adapted from [148])...

Table 2 Occurrence and removal of emerging pollutants in sewage sludge after treatment in a bioslurry reactor with T. versicolor... 

Fig. 3 Comparison of solid-phase biopiles (black bars) and bioslurry reactor (gray bars) in the removal of several emerging pollutants from sewage sludge with T. versicolor. Only compounds found during both kinds of treatment are included...

The most successful uses of surfactants to accelerate desorption and enhanced biodegradation has clearly been associated with the soil-washing industry (U.S. EPA, 1989) and bioslurry reactors (Oberbremer et al., 1990 Mueller et al.y 1991b,c). Here too, however, problems have been encountered at the bench-, pilot-, and full-scale levels with inefficient removal of materials from soils and sediments containing appreciable amounts of clay (c. >25%) or organic matter (c. >10%). 

Each PAH bioremediation strategy has its own unique characteristics. In general, it can be stated that PAH biodegradation will be most rapid and extensive with bioslurry reactors, followed by solid-phase applications and in situ strategies, respectively. Of course there is a direct relationship between rate and extent of PAH biodegradation and cost of the remedial technology. As described below, site-specific criteria impact the applicability of each strategy as well as the predicted performance criteria. 

Full-scale separation/washing and bioslurry reactor operations have been used to treat creosote-contaminated soil at the former Southeastern Wood Preserving Site at Canton, Mississippi (Jerger et al., 1994 Woodhull Jerger, 1994). Here, an estimated 10 500 yd3 of soil and sludge were excavated from various process areas, stabilized with kiln dust and stockpiled for subsequent treatment. Based on the results of preliminary bench studies, four 680 000 liter reactors were eventually established to handle 7050 yd3 of the screened (200-mesh) soil fraction at a solids content of 20-25%. Other oil fractions and waters were handled separately (data and costs not reported). 

Contaminated Soils from Former Ammunition Plants Soil Washing Efficiency and Effective Process Monitoring in Bioslurry Reactors, J. Hazard. Mater. 87(1-3), 139-154, Oct. 12 (2001). 

Fuller ME and Manning JF, Microbiological changes during bioremediation of explo-sives-contaminated soils in laboratory and pilot-scale bioslurry reactors, Biores. Technol., 91, 123, 2004. 

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