Recovery of dredged material for beneficial use: the future role of physical separation processes.

Sediments dredged from navigational waterways have historically been disposed in confined disposal facilities (CDFs) or in open water. When sediments are contaminated, open water disposal is typically not an alternative, and sediments are placed in CDFs. Many CDFs are nearing capacity, and siting and constructing new facilities is both difficult and expensive. In many cases, CDFs contain both clean and contaminated dredged material. Removal of materials suitable for beneficial use (BU) is one alternative under consideration to extend the life of existing CDFs, as is separation of recoverable materials at the time of disposal. Several technologies for recovery of clean materials or treatment of contaminated materials for beneficial use are presently under evaluation. Physical separation technologies have been demonstrated to have potential in reducing the volume of sediment that must be managed with confined disposal, but there are several technical issues that remain to be addressed. Determination of beneficial use specifications, physical and chemical characterization of dredged material, overall site characterization, selection of suitable unit operations, management of liquid and solid residuals, and cost/benefit analysis, are all important aspects to successful implementation of separation processes. Several of these elements are presently being evaluated in research conducted by the US Army Corps of Engineers, at the ERDC Waterways Experiment Station (WES).

Relationship of hemoglobin level and duration of hospitalization after total hip arthroplasty: implications for the transfusion target.

We analyzed the relationship of hemoglobin level and duration of hospitalization of patients who underwent primary cemented total hip arthroplasty for degenerative joint disease at our institution. Retrospectively, we reviewed the medical records of 332 patients treated during a 16-month period (May 6, 1989, to Aug. 20, 1990). The following variables were analyzed: number of postoperative days to dismissal from the hospital, level of hemoglobin preoperatively and at dismissal, decrease in hemoglobin level from preoperatively to time of dismissal, patient age, surgeon, and blood products transfused. No correlation was found between level of hemoglobin at dismissal, preoperative hemoglobin level, or decrease in hemoglobin concentration from preoperatively to time of dismissal and number of days to dismissal from the hospital. Advanced age was associated with a longer hospital stay. A slight but statistically significant difference was noted in duration of hospitalization among patients operated on by different surgeons. Patients who received both autologous and homologous blood required more transfusion (3.8 units) and had a longer hospital stay (10.7 days) than did patients who received autologous blood only (2.4 units and 9.5 days) or homologous blood only (2.6 units and 10.2 days). We conclude that variation in hemoglobin levels among patients in our study was unrelated to duration of hospitalization. This finding suggests that transfusion of autologous or homologous blood to achieve a higher hemoglobin level (higher transfusion target) solely for shortening hospital stay is unwarranted.

Prestorage removal of Yersinia enterocolitica from red cells with white cell-reduction filters.

Prestorage removal of phagocytic white cells (WBCs) may increase the survivability of contaminating bacteria in units of stored red cells. Fourteen units of whole blood were inoculated with 65 colony-forming units per mL of Yersinia enterocolitica (serotype O:3) and processed into AS-3-preserved red cells. Five red cell units were filtered with a prototype third-generation filter and five red cell units with a second generation filter. WBC reduction was performed on the day of collection. Four red cell units were not filtered. Three noninoculated whole blood units served as negative controls; two were filtered (one with each type of WBC-reduction filter) and one remained unfiltered. All red cell units were then stored at 4 degrees C for 42 days. One of the five filtered red cell units (20%) in each filter group supported growth of Y. enterocolitica. In contrast, 4 (100%) of 4 unfiltered inoculated red cell units had growth (p = 0.04). Overall, 2 (20%) of 10 units of WBC-reduced red cells supported the growth of Y. enterocolitica, as compared to 100 percent of unfiltered red cell units after inoculation (p = 0.015). Bacterial contamination was not detected in any of the three noninoculated units. It can be concluded that prestorage WBC filtration significantly reduces the potential for growth of Y. enterocolitica in red cells stored at 4 degrees C for 42 days.

Visual identification of bacterially contaminated red cells.

There have been increasing numbers of reports of transfusion-acquired Yersinia enterocolitica bacteremia (including several fatal cases). Fifteen units of whole blood were inoculated with various concentrations of Y. enterocolitica serotype 0:3 and processed into AS-3 preserved red cells (RBCs). Consistent growth of the organism was found at inoculum concentrations greater than or equal to 10 colony-forming units per mL. In all 13 units of RBCs that supported the growth of Y. enterocolitica, a darkening in color (due to hemolysis and a decrease in pO2) was observed in the bag. The attached sample segments, which were sealed from the main unit, remained sterile and did not darken. This color change was apparent in all the contaminated units by Day 35, which was 1.5 to 2 weeks after the bacteria were first detected in cultures of the blood. Hence, by comparison of the color of the segment tubing with that of the unit itself, units grossly contaminated with Y. enterocolitica can be identified prior to transfusion. Moreover, review of photographs on file at the Centers for Disease Control revealed this dramatic color change in 2 units of blood that caused transfusion-transmitted sepsis (Enterobacter agglomerans and an unidentified gram-negative bacillus, not Yersinia sp.), which demonstrated that the color change was not limited to Y. enterocolitica. This method of visual identification of contaminated units of blood could decrease the incidence of posttransfusion bacterial sepsis.