Nitrate removal in a combined bioelectrochemical and sulfur autotrophic denitrification system under high nitrate concentration: effects of pH

Abstract

A combined bioelectrochemical and sulfur autotrophic denitrification (CBSAD) system was established to treat high concentration nitrate under different pH conditions in this study. The microbial communities and structures were evaluated to deeply reveal the nitrate removal mechanisms in this combined system. When initial pH was adjusted to 6.5, the CBSAD system obtained 66.45% denitrification efficiency. The combined system achieved highest nitrate removal efficiency of 96.84% at pH 7.5. However, nitrate removal efficiency decreased to 87.05% when initial pH increased to 8.5. Microbial analyses demonstrated that pH value slightly influenced the bacterial abundances and bacterial species in this CBSAD system under high nitrate concentration condition. Proteobacteria was the most dominant phylum in this system, which accounted for more than 90% of the total phyla. Epsilonproteobacteria, Betaproteobacteria, and Gammaproteobacteria were the most important classes for denitrification process. Genus Sulfurimonas was primarily responsible for high nitrate removal in this CBSAD system.

Treatment of nitrate-contaminated groundwater using microbially enhanced permeable reactive barrier technology

“…The SSS and SW reactors have better pH buffering performance, where scallop shells can provide a certain alkaline source for the reactor, highlighting the important role of scallop shells in stabilizing the pH of the reactor. 33 As shown in eqn (1), in the SAD process, some SO , combined with the results of the analysis in section 3.1.1, showed that the SW and SC reactors had poor denitrification performance, further indicating that no significant SAD process occurred in the SW and SC reactors. Notably, the SO 4 2− accumulation rate (Fig.…”

“…The SSS and SW reactors have better pH buffering performance, where scallop shells can provide a certain alkaline source for the reactor, highlighting the important role of scallop shells in stabilizing the pH of the reactor. 33…”

Pyrite-Based Autotrophic Denitrifying Microorganisms Derived from Paddy Soils: Effects of Organic Co-Substrate Addition

“…Actinobacteria were found in denitrification systems in previous research [ 25 , 44 , 45 ], and showed good nitrate removal abilities and chromium reduction efficiency under neutral conditions for higher denitrification [ 46 ]. Proteobacteria and Firmicutes were found to be the dominant phyla in a laboratory-scale combined bioelectrochemical and sulfur autotrophic denitrification system and an expanded granular sludge bed reactor for the simultaneous biological removal of sulfate, nitrate, and lactate [ 47 , 48 ]. Proteobacteria contains many types of metabolic bacteria, and is responsible for the removal of COD and nitrogen, making Proteobacteria the most abundant phylum in sewage treatment and sulfur autotrophic denitrification processes [ 35 , 49 , 50 , 51 ].…”

“…Betaproteobacteria and Epsilonproteobacteria were the main denitrification bacteria in large sulfur/limestone autotrophic denitrification filters under low-temperature conditions [ 52 ]. Bacteroidia has been reported in a combined bioelectrochemical and sulfur autotrophic denitrification system, an anoxic–aerobic sequential batch reactor, and a mining clarifying pool [ 48 , 50 , 59 , 60 ], suggesting that some microorganisms in the Bacteroidia class might play a role in the denitrification process. Acidobacteria are a major microbial class in the phylum Acidobacteria.…”

“…In the A24 treatment, the most dominant bacterium was Pseudomonas (60.82%), a widely studied heterotrophic denitrifier [ 80 , 81 ]. In recent years, this bacterium has also been found to play a vital role in manganese autotrophic denitrification, iron autotrophic denitrification [ 81 ], heterotrophic/sulfur autotrophic denitrification [ 58 ], and bioelectrochemical denitrification [ 48 ]. Other dominant genera (relative abundance > 3%) were Ramlibacter (11.75%), Magnetospirillum (5.65%), and Azospirillum (5.47%).…”