Book Description

This report describes a study conducted to investigate the feasibility and effectiveness of injecting an oxidant into the discharge of a hydraulic dredge in order to reduce the depletion of dissolved oxygen in an open-water disposal area. The rapid depletion of dissolved oxygen during disposal operations is caused by chemical oxidation of constituents which are present in a reduced state in the anaerobic sediments. Oxygen may also be consumed by the action of microorganisms; however, this mechanism operates much more slowly and contributes little to the immediate demand for oxygen observed in open-water disposal. Two full-scale field demonstrations were conducted as a part of the study. In the first demonstration pure oxygen was injected into the discharge line of a hydraulic dredge, and, in the second, compressed air was similarly injected. The report describes the equipment and methods used to conduct the demonstrations and the results obtained. The laboratory study section describes the chemical processes responsible for the oxygen depletion in the receiving water during dredging and dredged material disposal operations. The final chapter examines the configuration and cost of injection systems for full-scale dredging operations. alternate oxidants, such as hydrogen peroxide and ozone-enriched oxygen, are also considered.