Dissolved Solids Removal from Waste Water by Algae
Publication: Transactions of the American Society of Civil Engineers
Volume 128, Issue 3
Abstract
The aim of the investigation reported in this paper was to reclaim waste water for eventual re-use. The objective was not only to remove solids but to reduce the dissolved salts concentration which normally increases by 100 to 300 parts per million (ppm) in the domestic use of water, by permitting residential sewage after secondary treatment by the activated sludge process to flow through a third stage algae pond. The study was so designed that the system operated under natural conditions.
The pond, constructed as a third stage to follow the secondary clarifier, was operated at four flow rates. The clarifier effluent was the most suitable in terms of low suspended solids, low BOD, and high algae growth rates, for input to the algae pond. Comparison of the influent and effluent water quality by physical and chemical analysis was made at each flow rate.
Scenedesmus was found to be the predominant algal species, with much smaller concentrations of Chlorella, Euglena, and Diatoms. Scenedesmus grew on the sides and the bottom of the pond, and appeared to be suitable for a continuous flow system. Chemical analysis indicated that considerable quantities of bicarbonates, the nitrogen series, ammonia, nitrates, and organic nitrogen, and phosphates were removed by the algae. Magnesium and calcium were also removed, with less clear indication of the removal of potassium and sulphates. Sodium and chloride showed no appreciable reduction.
The pond effluent water was clear, odorless, and meets United States Public Health (USPHS) standards for potable waters, with the single exception of bacterial count. The dissolved oxygen content of the pond effluent was high and the dissolved solids concentration was reduced to approximately local tap water levels.
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Published In
Transactions of the American Society of Civil Engineers
Volume 128 • Issue 3 • January 1963
Pages: 84 - 102
Copyright
© 1963 American Society of Civil Engineers.
History
Published in print: Jan 1963
Published online: Feb 10, 2021
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