Sludge samples from dual-layers elemental sulfur packed denitrification reactors

In this study, an S0 autotrophic denitrification reactor (SADR) and a wood-chunks and S0 mixotrophic denitrification reactor (WSMDR) with dual-layers were constructed. The lower layer filled with S0 or a combination of wood-chunks and S0, while the upper layer only filled with inert material. Nitrate contaminated wastewater were pumped to the reactors from the bottom of each layer. In this way, the intermediate products from SAD and WSMD acted as electron donors for denitrification in the upper layers, achieving effective nitrate removal and low by-products generations. The objectives of this study were to: 1) investigate denitrification performance in both reactors at different operation conditions, including flow rate and IC; 2) evaluate final sulfate and sulfide generation in the effluent during operation; and 3) perform metagenomic analysis to reveal the difference in microbial community structures between different reactors or layers, followed by clarifying the mechanism of the decreasing in by-products .