Investigation of Solid-Phase Buffers for Sulfur-Oxidizing Autotrophic Denitrification
Abstract:This paper investigates biological denitrification using autotrophic microorganisms that use elemental sulfur as an electron donor. In this process, for each gram of nitrate-nitrogen removed, approximately 4.5 g of alkalinity (as calcium carbonate) are consumed. Because denitrification is severely inhibited below pH 5.5, and alkalinity present in the influent wastewaters is less than the alkalinity consumed, an external buffer was needed to arrest any drop in pH from alkalinity consumption. A packed-bed bioreactor configuration is ideally suited to handle variations in flow and nitrate loading from decentralized wastewater treatment systems, as it is a passive system and thus requires minimal maintenance; therefore, a solid-phase buffer packed with the elemental sulfur in the bioreactor is most suitable. In this research, marble chips, limestone, and crushed oyster shells were tested as solid-phase buffers. Bench- and field-scale studies indicated that crushed oyster shell was the most suitable buffer based on (1) the rate of dissolution of buffer and the buffering agent released (carbonate, bicarbonate, or hydroxide), (2) the ability of the buffer surface to act as host for microbial attachment, (3) turbidity of the solution upon release of the buffering agent, and (4) economics.
Document Type: Research Article
Publication date: December 1, 2007
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- Water Environment Research® (WER®) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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