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Updated: Feb 25, 2026

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Published on: October 15, 2015
Effect of oyster shell medium and organic substrate on the performance of a particulate pyrite autotrophic
Shuang Tong1, Justine L Stocks2, Laura C Rodriguez-Gonzalez2
1School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China; Department of Civil and Environmental Engineering, University of South Florida, 4202 E. Fowler Ave, ENB 118, Tampa, FL 33620, USA.
Abstract:
The use of pyrite as an electron donor for biological denitrification has the potential to reduce alkalinity consumption and sulfate by-product production compared with sulfur oxidizing denitrification. This research investigated the effects of oyster shell and organic substrate addition on the performance of a particulate pyrite autotrophic denitrification (PPAD) process. Side-by-side bench-scale studies were carried out in upflow packed bed bioreactors with pyrite and sand, with and without oyster shells as an alkalinity source. Organic carbon addition (10% by volume wastewater) was found to improve PPAD denitrification performance, possibly by promoting mixotrophic metabolism. After organic carbon addition and operation at a six-hour empty bed contact time, total inorganic nitrogen (TIN) removal reached 90% in the column with oyster shells compared with 70% without. SEM images and biofilm protein measurements indicated that oyster shells enhanced biofilm growth. The results indicate that PPAD is a promising technology for treatment of nitrified wastewater.
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