Bacteria-supported iron scraps for the removal of nitrate from low carbon-to-nitrogen ratio wastewater

Abstract

A cost-effective system for nitrate removal was developed with the key role of iron and genus Hydrogenophaga.

The contributions and mechanisms of iron-microbes-biochar in constructed wetlands for nitrate removal from low carbon/nitrogen ratio wastewater

“…29 In addition, Liu et al extracted bacteria attached to the iron mixtures soaked in wastewater, indicating that bacteria-supported iron scraps have a higher nitrate removal rate than iron scraps alone. 6 Fig. 4 could be noticed that the removal efficiency of sole iron scraps was near a half of complete removal of nitrate in a week while existence of the microbes made nitrate almost totally be removed.…”

“…Biochar, a carbon-abundant product, is produced from pyrolyzing organic materials and has attracted increasing eyes in recent years since it can generate renewable energy, such as biogas and bio-oil, 21 and absorb toxic metals and organic chemicals in soil and water. [22][23][24] Compared with our previous work, 6 the addition of biochar may improve nitrate removal. However, it has not yet been widely studied that biochar and microbes give rise to joint effect on nitrate reduction in water bodies.…”

“…Finally, centrifuge tubes were centrifuged at 6000 rpm for 10 min to collect precipitates as microbial analysis samples. 6 Through high-throughput sequencing, these microbial samples were analyzed and microbial DNA was extracted using the Fast DNA®SPIN Kit for Soil (MP, USA). 338F (5 0 -ACTCCTACGG-GAGGCAGCAG-3 0 ) and 806R (5 0 -GGACTACHVGGGTWTCTAAT-3 0 ) primers were used for PCR amplication using the thermocycler PCR system (GeneAmp 9700, ABI, USA).…”

“…5 The CWs can better reect actual nitrate removal efficiency compared to our previous batch experiments. 6 Zhang et al and Tang et al used combined reactors including multiple substrates to degrade nitrogen. 7,8 Wu et al and Zhu et al removed nitrate through different bioreactors.…”

“…The most of microbial nitrate removal methods in CWs are heterotrophic denitrication, which demands organic carbon, like sucrose, methanol, ethanol and acetate, 6 as carbon source and electron donor. In contrast, microbes carrying out autotrophic denitrication make use of inorganic matter as energy and electron donor.…”