Roles of MnO2 on performance, sludge characteristics and microbial community in anammox system

Huang

2019

Water

Anammox-based processes have been widely applied for the treatment of wastewater (e.g., wastewater irrigation systems and constructed wetland) which consists of bio-refractory humic substances. Nonetheless, the impacts of bio-refractory humic substances on anammox consortia are rarely reported. In the present study, three identical lab-scale anammox reactors (i.e., HS0, HS1 and HS10), two of which were dosed with humic substances at 1 and 10 mg·L−1, respectively, were operated for nearly one year. The long-term operation of the reactors showed that the presence of humic substances in influent had no significant influence on nitrogen removal rates. Despite this, comparative metagenomics showed changes in anammox microbiota structure during the exposure to humic substance; e.g., the relative abundance of Candidatus Kuenenia was lower in HS10 (18.5%) than that in HS0 (22.8%) and HS1 (21.7%). More specifically, a lower level of humic substances (1 mg·L−1) in influent led to an increase of genes responsible for signal transduction, likely due to the role of humic substances as electron shuttles. In contrast, a high level of humic substances (10 mg·L−1) resulted in a slight decrease of functional genes associated with anammox metabolism. This may partially be due to the biodegradation of the humic substances. In addition, the lower dosage of humic substances (1 mg·L−1) also stimulated the abundance of hzs and hdh, which encode two important enzymes in anammox reaction. Overall, this study indicated that the anammox system could work stably over a long period under humic substances, and that the process was feasible for leachate treatment.

Section: Reactor Operationsupporting

confidence: 70%

Section: Reactor Operationmentioning

confidence: 90%

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Metagenomics Response of Anaerobic Ammonium Oxidation (anammox) Bacteria to Bio-Refractory Humic Substances in Wastewater

Huang

2019

Water

Water Environment Research

“…The majority of Mn 2+ was detected inside anammox bacterial cells, while Zn 2+ and Cu 2+ were mainly found in nitrifying bacterial cells. Another study also demonstrated that the microbial abundance of anammox bacteria increased after long‐term effect of MnO 2 (Xu et al, 2018). It was speculated from the batch test results that anammox bacteria would be severely inhibited by the acute toxicity of Mn 2+ .…”

Section: Resultsmentioning

confidence: 91%

Long‐term domestication to Mn stresses alleviates the inhibition on anammox process

Tang

Zhang

Feng

et al. 2020

Heavy metals such as Mn2+ are common contaminants in ammonium‐rich wastewater. The information of Mn2+ effect on anammox process needs further investigation. The short‐ and long‐term effects of Mn2+ on anammox were explored by anammox granular sludge. Batch tests showed that the half inhibition value (IC50) of Mn2+ was 4.83 mg/L. The anammox activity was severely inhibited in 0.5 hr under 15 mg/L Mn2+. However, after long‐term domestication by increasing the concentration of Mn2+, both the low‐load reactor (R1) and the high‐load reactor (R2) performed well, achieving volumetric nitrogen removal rate of 6.36 kg/(m3·d) and 13.99 kg/(m3·d), respectively. The average ammonium and nitrite removal efficiency of both reactors under 200 mg/L Mn still maintained above 90%. The results from long‐term reactors’ operation showed that the serious inhibition effect indicated by the batch test was significantly exaggerated. The granules became dispersed after long‐term operation in the high‐load reactor (R2) which might be correlated to the high osmotic pressure caused by high Mn2+ load, and the mechanism needs to be investigated further. Practitioner Points The half inhibition value of Mn2+ on anammox sludge was 4.83 mg/L in batch experiment. 200 mg/L Mn2+ did not cause any inhibition on anammox process during long‐term operation. Granular sludge is finer under high nitrogen loads with 200 mg/L Mn stress.

“…Unclassified microbes, such as Family EU246070 (3.74%) and Family EU181510 (1.54%), were also measured. The Family Planctomycetaceae belongs to Phylum Planctomycetes, and some of the Family Planctomycetaceae are known as ammonium oxidation (ANAMMOX) microorganisms [50], which produce a nitrogen gas during the reduction of manganese oxide [51]. The z-score, statistically based on abundance, is shown in Figure S2.…”

Section: Microbial Diversitymentioning

confidence: 99%

Microbial Diversity Responding to Changes in Depositional Conditions during the Last Glacial and Interglacial Period: NE Ulleung Basin, East Sea (Sea of Japan)

et al. 2020

Microbial interaction with minerals are significantly linked with depositional conditions during glacial and interglacial periods, providing a unique redox condition in the sedimentary process. Abiotic geophysical and geochemical properties, including sedimentary facies, magnetic susceptibility, grain size, clay mineralogy, and distribution of elemental compositions in the sediments, have been widely used to understand paleo-depositional environments. In this study, microbial abundance and diversity in the core sediments (6.7 m long) from the northeastern slope of Dokdo Island were adapted to characterize the conventionally defined sedimentary depositional units and conditions in light of microbial habitats. The units of interglacial (Unit 1, <11.5 ka) and late glacial (Unit 2, 11.5–14.5 ka) periods in contrast to the glacial period (Unit 3, >14.5 ka) were distinctively identified in the core, showing a sharp boundary marked by the laminated Mn-carbonate (CaM) mud between bioturbated (Unit 1 and 2) and laminated mud (Unit 3). Based on the marker beds and the occurrence of sedimentary facies, core sediments were divided into three units, Unit 1 (<11.5 ka, interglacial), Unit 2 (11.5–14.5 ka, late glacial), and Unit 3 (>14.5 ka, glacial), in descending order. The sedimentation rate (0.073 cm/year), which was three times higher than the average value for the East Sea (Sea of Japan) was measured in the late glacial period (Unit 2), indicating the settlement of suspended sediments from volcanic clay in the East Sea (Sea of Japan), including Doldo Island. The Fe and Mg-rich smectite groups in Unit 2 can be transported from volcanic sediments, such as from the volcanic island in the East Sea or the east side of Korea, while the significant appearance of the Al-rich smectite group in Unit 1 was likely transported from East China by the Tsushima Warm Current (TWC). The appearance of CaM indicates a redox condition in the sedimentary process because the formation of CaM is associated with an oxidation of Mn2+ forming Mn-oxide in the ocean, and a subsequent reduction of Mn-oxide occurred, likely due to Mn-reducing bacteria resulting in the local supersaturation of Mn2+ and the precipitation of CaM. The low sea level (−120 m) in the glacial period (Unit 3) may restrict water circulation, causing anoxic conditions compared to the late glacial period (Unit 2), inducing favorable redox conditions for the formation of CaM in the boundary of the two units. Indeed, Planctomycetaceae, including anaerobic ammonium oxidation (ANAMMOX) bacteria capable of oxidizing ammonium coupled with Mn-reduction, was identified in the CaM layer by Next Generation Sequencing (NGS). Furthermore, the appearance of aerobic bacteria, such as Alphaproteobacteria, Gammaproteobacteria, and Methylophaga, tightly coupled with the abundance of phytoplankton was significantly identified in Unit 1, suggesting open marine condition in the interglacial period. Bacterial species for each unit displayed a unique grouping in the phylogenetic tree, indicating the different paleo-depositional environments favorable for the microbial habitats during the glacial and interglacial periods.