Supplemental aeration system design for the Houston Ship Channel

Abstract

The oxygen demand on the Houston Ship Channel exceeds its natural assimilative capacity and dissolved oxygen (DO) is depleted so that warm weather and low flow commonly produce zero DO concentration in the upper 14 miles of the channel. The objective of this study is to develop and demonstrate a technique for designing an in-channel supplemental aeration system so that it might be considered as an alternative to advanced waste treatment. A mathematical model is used to calculate the capacity of supplemental aeration system capable of producing 2 and 4 milligrams per liter (mg/1) DO in the channel under critical conditions, and to locate aeration equipment for maximum efficiency. Accurate simulation of oxygen dynamics is critical and extensive effort is made in modeling oxygen sources and sinks. Model verification is conducted under both steady state and dynamic conditions. A general system design consisting of required oxygen transfer capacities under critical and average conditions, and site locations is developed. Sidestream oxygenation, diffused aeration, diffused oxygen, and surface aeration systems are evaluated for their ability to meet the requirements of the general design, for their economic desirability, and for their physical feasibility. Sidestream oxygenation is selected for preliminary design. The 1975 cost of supplemental aeration by side-stream oxygenation is estimated at 2.0 to 2.5 cents per pound of oxygen transferred.