Long-term recovery rates

While the 8-h test results indicated a total petroleum hydrocarbons (TPH) recovery rate of 10 lb/day, this rate probably will not continue. Estimation of the expected long-term recovery rate of TPH by this short-term test data is not a reliable exercise. The data demonstrate the applicability of SVE as a recovery system, but further testing or detailed computer modeling was recommended prior to final design. 

Magar VS, RFC Brenner, GW Johnson, JF Quensen (2005b) Long-term recovery of PCB-contaminated sediments at the Lake Hartwell superfund site PCB dechlorination. 2. Rates and extent. Environ Sci Technol 39 3548-3554. 

Residual hydrocarbons will continue to serve as a source of groundwater contamination thus, remediation strategies for DNAPLs should emphasize long-term control and management (i.e., source containment, pool control, and recovery) vs. short-term fixes. Regardless of an increased level of effort (i.e., additional wells, increased pumping rates, etc.), the overall time for remediation is not expected to shorten by more than a factor of five. 

Long-term follow-up research has shown that about one-fourth of AN patients will recover and the rest will have either partial or no improvement. Mortality rates at 10 years are 6.6% and at 30 years are 18%-20% after presentation for treatment (Theander, 1985 Eckert et ah, 1995). Most follow-up studies of AN show patients with an earlier age onset (under age 18) to have a better chance of recovery. Purging behavior, self-induced vomiting, and laxative abuse are usually predictive of a worse outcome (Eckert et ah, 1995). 

Although serum bilirubin concentrations, serum aminotransferase, and serum alkaline phosphatase activities have been reported to return to normal more rapidly in hepatitis patients treated with steroids than in untreated patients (G23), these biochemical indices of apparent improvement are of no consequence in the long-term rate of recovery (G23). 

Polymers that have been suggested for mobility control in oil reservoirs include polyacrylamides, hydroxy ethyl cellulose, and modified polysaccharides which are produced either by fermentation or by more conventional chemical processes. In this paper the solution properties of these polymers are presented and compared for tertiary oil recovery applications. Among the properties discussed are non-Newtonian character for different environmental conditions (electrolytes and temperature), filterability, and long term stability. The behavior of these water soluble polymers in solution can be correlated with the effective molecular size which can be measured by the intrinsic viscosity technique. A low-shear capillary viscometer with a high precision and a capability of covering low shear rates (such as 10 sec - - for a 10 cp fluid) has been designed to measure the viscosities. The measurement of viscosities at such slow flow conditions is necessitated... 

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