Sulfur utilization in the systems of biological wastwater denitrification

Abstract

This paper focuses on the study of the possibility of using mineral carriers from sulfur (bio-sulfur/elementary sulfur) in anaerobic wastewater treatment systems under autotrophic denitrification conditions. The theoretical aspects of the work are based on the biochemical formalization of the studied processes using the systemic-synergetic approach for the description of the patterns of autotrophic denitrification microorganisms based on the principles of autocatalysis of natural systems. Special software was used in the work to identify the necessary ecological and trophic groups of microorganisms and implement the schemes of trophic interactions in association of denitrification microorganisms. The taxonomic classification was assigned based on the KEGG database (Kyoto Encyclopedia of Genes and Genomes). Bio-filtration set-up system was formed for carrying out the process wastewater denitrification with using bio-sulfur and gaseous sulfur. The filtration method is used under anaerobic conditions along with immobilization on the carrier based on sulfur autotrophic denitrifying bacterial species such as Thiobacillus denitrificans and Thiomicrospira denitrificans. Thus, sulfur conversion leads to the reduction of nitrates to nitrites and, ultimately, the release of molecular nitrogen. The mechanisms of sulfur conversion in natural ecosystems make it possible to conclude its expediency of use it as a sorption sulfur-containing mineral carrier in wastewater purification systems with further conversion to an organic form (with microbial cell carbonate). The interactions pathways model in the association of heterotrophic and autotrophic denitrification bacteria in the process of wastewater and sewage sludge purification was formed under condition of elementary sulfur presence. Energetic and synthesis reactions for an autotrophic denitrification were described. The implementation of wastewater treatment systems with autotrophic denitrification process use will provide an opportunity to expand the application scope of by-products such as gaseous sulfur and bio-sulfur that currently minimal recycling in traditional industrial processing.

Keywords

• denitrification
• bio-sulfur
• gaseous sulfur
• wastewater
• mineral carrier