Activity Of Anammox Biomass Research Articles

Linear anionic surfactant (SDBS) destabilized anammox process through sludge disaggregation and metabolic inhibition

The increase of emerging contaminants, such as surfactants, is one of the major challenges to biological wastewater treatment. However, the potential impact of linear alkylbenzene sulphonates (LAS), a major class of anionic surfactants, on anammox process is unclear. The long-term effects of sodium dodecyl benzene sulfonate (SDBS, as a model LAS) on reactor performance, microbial community and sludge properties were investigated in this study. The presence of 5 mg L−1 SDBS promoted the release of extracellular microbial products from anammox granules and the wash-out of anammox population via effluent. Despite sludge disaggregation, the reactor performance was robust to the exposure of 5 mg L−1 SDBS due to functional redundancy. With the further increase of SDBS to 10 mg L−1, the metabolic activity of anammox biomass and the transcription and post-translation of hydrazine dehydrogenase were significantly decreased. The potential mechanism might be associated with the damage on cell membrane that induced the leakage of intracellular matrix. These results highlight the need to consider the potential risk of LAS to operation of anammox process in biological wastewater treatment plant.

Mainstream-sidestream wastewater switching promotes anammox nitrogen removal rate in organic-rich, low-temperature streams

ABSTRACT The main issues with mainstream anammox application are loss of bacterial activity by low temperatures and by a high organic content of wastewater. We demonstrate a novel switching method between sidestream and mainstream wastewater. The wastewater flow was switched between sidestream (reject water at >22°C) and mainstream (municipal wastewater at 16.5°C), so that the anammox biomass activity and biomass growth could benefit from sidestream conditions. Real sidestream wastewater (biogas plant effluent) (≈1000 mg NH+ 4-N L−1) and synthetic mainstream (municipal wastewater-like source) (≈100 mg NH+ 4-N) wastewater were used for 20 L biofilm reactor feeding. The highest total nitrogen removal rate (TNRR) of 527 g N m−3 d−1 (average TNRR 180 (±140) g N m−3 d−1) was achieved with sidestream wastewater at a low chemical oxygen demand (COD)/TN ratio of 1.1/1. For reactor feeding with mainstream, the highest TNRR achieved was 61 g N m−3 d−1. Average TNRR for mainstream of 20 (±15) g N m−3 d−1 was low due to a higher COD/N ratio of 3.2/1. The highest TNRR in a batch test was achieved at the COD concentration of 480 mg L−1, reflecting a TNRR of ≈5 mg N g−1 TSS h−1. With a high COD concentration of 2600 mg L−1 (TOC/TN = 8/1), TNRR decreased similarly in both feeds to 1.6 mg N g−1 TSS h−1. The anammox microorganism's genus Candidatus Brocadia enrichment in deammonification biofilm reactor was higher in the mainstream operation (7.6% of all bacteria) than in sidestream operation period (<0.7% of all bacteria).

Short-term effects of reduced graphene oxide on the anammox biomass activity at low temperatures

Anaerobic ammonium oxidation (anammox) is an efficient process for nitrogen removal from wastewater, but its common use is limited by its relatively high optimal temperature (30 °C). One of the major bottlenecks of the implementation of mainstream PN/A process is the low activity of the anammox bacteria at low temperature. Due to this reason over the past years, numerous researchers have attempted to overcome this limitation. Recently it was shown that the reduced graphene oxide (RGO) can accelerate the anammox bacteria activity. However all these studies were performed at high temperatures (over 30 °C). Thus, in this study, supporting the anammox process at low temperatures (10–30 °C) by the RGO was investigated for the first time. The statistical analysis confirmed that RGO significantly affects the anammox activity. The stimulation effect of RGO on the anammox bacteria activity is of particular importance at low temperatures, when drastic decrease in process activity is observed at temperatures below 15 °C. The short-term experimental results demonstrated stimulation of the anammox activity at 13 °C, up to 28% by 15 mg RGO/L, but concentrations above 40 mg RGO/L caused the process inhibition, up to 30% with 50 mg RGO/L. However, the effect of RGO probably depends on the nanomaterial dose per biomass unit and the optimal range of this value was evaluated as 20 to 45 mg RGO/g VSS (volatile suspended solids).

Effects of extracellular polymeric substances (EPS) and N-acyl-L-homoserine lactones (AHLs) on the activity of anammox biomass

This study investigated the effect of N-acyl-L-homoserine lactones (AHLs) and EPS on anammox activity, and identified the relationship between AHLs and EPS. The effects of AHLs and different EPS fractions (loosely bound (LB) and tightly bound (TB) EPS) from denitrification sludge (DS) and perchlorate reducing sludge (PRS) on anammox activity were conducted by batch experiments. Compared with the control experiment, the nitrogen removal rate was increased by 82.0%, 73.9% and 73.0%, respectively, when adding DS-EPS (integral DS EPS), PRS-EPS (integral PRS EPS) and DS-LB in anammox biomass. EPS fractions of DS and PRS contained the same kinds of AHLs, including C4-HSL, C6-HSL and C8-HSL, as identified by HPLC-MS. C4-HSL and C6-HSL at 0.1 mg L−1 concentration effectively improved the nitrogen removal rate by induceing the expression of anammox active genes during the anammox process. This study provides a new idea for efficient nitrogen removal from anammox bacteria.

Fast start-up anammox process using Acyl-homoserine lactones (AHLs) containing supernatant

N-dodecanoyl homoserine lactone (C12-HSL) was detected in the supernatant of an anammox granular sludge reactor (AGSR). C12-HSL could enhance the specific anammox activity of anammox biomass. Adding C12-HSL-containing AGSR supernatant into the continuously stirred tank reactors reduced the start-up time of the anammox process from 80 to 66days. Moreover, the nitrogen loading rate was also enhanced to 1.6 times that of the control reactor. AHLs could increase the secretion of extracellular polymeric substances and anammox obtained better enrichment with the addition of AHLs-containing AGSR supernatant. Denaturing gradient gel electrophoresis analysis further revealed that AHLs played a role in mediating microbial community parameters. In conclusion, adding AHL-containing supernatant could be an effective and economical way to accelerate the start-up of anammox.

Effects of cycle duration of an external electrostatic field on anammox biomass activity.

In this study, the effects of different cycle durations of an external electrostatic field on an anammox biomass were investigated. The total application time per day was 12 h at 2 V/cm for different cycle durations (i.e., continuous application-resting time) of 3 h-3 h, 6 h-6 h, and 12 h-12 h. Compared with the control reactor, the nitrogen removal rates (NRRs) increased by 18.7%, 27.4% and 8.50% using an external electrostatic field application with a continuous application time of 3 h, 6 h and 12 h. Moreover, after the reactor was running smoothly for approximately 215 days under the optimal electrostatic field condition (mode 2, continuous application-rest time: 6 h-6 h), the total nitrogen (TN) removal rate reached a peak value of approximately 6468 g-N/m3/d, which was 44.7% higher than the control. The increase in 16S rRNA gene copy numbers, heme c content and enzyme activities were demonstrated to be the main reasons for enhancement of the NRR of the anammox process. Additionally, transmission electron microscope observations proved that a morphological change in the anammox biomass occurred under an electrostatic field application.

Effects of short-term exposure to linear anionic surfactants (SDBS, SLS and SDS) on anammox biomass activity

This work demonstrates the feasibility of nitrogen removal from wastewater containing linear anionic surfactants, including sodium dodecyl benzene sulfonate, sodium lauryl sulfate and sodium dodecyl sulfonate, by using the anammox process.

Using three-bio-electrode reactor to enhance the activity of anammox biomass

This research was designed to investigate the effects of different electric potentials (EPs) on the anammox biomass activity in a three-electrode reactor. Electric potential difference (EPD) of 0.08V between the working and reference electrodes showed the best nitrogen removal performance. Under the optimal EPD of 0.08V, the nitrogen removal rate of reactor 2 (R2, EP applied) reached 911g-N/m3/d on day 188, which was 25.3% higher than that of reactor 1 (R1, the control). Moreover, the scanning electron microscope observation and extracellular polymeric substance analysis proved that EP application was conducive to the anammox cells growing onto the surface of electrode. Additionally, it was demonstrated that long-term EP application increased the crude enzymes activities and the cell quantities of the bio-electrode anammox reactor. Besides, transmission electron microscope observation proved the morphological variation of anammox biomass with continuous EP application.

Inhibition and recovery of continuous electric field application on the activity of anammox biomass

In this study, the effects of electric field on the activity of anammox biomass were investigated. In batch mode, experimental results demonstrated that the nitrogen removal rate enhanced by 25.6 % compared with the control experiment at the electric field of 2 V/cm with application time of 20 min. However, continuous application (24 h) of electric field impacted a mal-effect on anammox biomass during the intensity between 1 and 4 V/cm. After the electric field was removed, the activity of anammox biomass could recover within 2 weeks. This implied that the mal-effect of electric field on anammox biomass was reversible. The decrease of heme c contents and crude enzyme activity demonstrated to be the main reason for the depress of the anammox biomass activity. Transmission electron microscope observation also proved the morphological change of anammox biomass under electric field.

Effects of quinoid redox mediators on the activity of anammox biomass

This study first explored the relationship between the activity of anammox biomass/key enzymes and quinoid redox mediators, which were anthraquinone-2,6-disulfonate (AQDS), 2-hydroxy-1,4-napthoquinone (LAW) and anthraquinone-2-carboxylic acid (AQC). Experimental results demonstrated that the total nitrogen removal performance showed a downward trend with all three redox mediators (RMs) dosage increasing. For instance, when the AQC addition increased to 0.8 mM, the TN removal rate sharply reduced to 17.2 mg-N/gVSS/h, only about 20% of the control. This phenomenon might be caused by microbial poisoning with the extracellular RMs additions. Nevertheless, the crude hydrazine dehydrogenase, nitrite reductase, and nitrate reductase activities were enhanced with RMs addition, about 0.6-3 folds compared to the control experiments without RMs addition. The RMs was inferred to play the role as ubiquinol/ubiquinone (Q/QH2) during the anammox process. Furthermore, the specific ladderane membrane structure could block the contacting between RMs and the key enzymes inside anammoxosome. This might be the main reason for the contrary effects of RMs on anammox biomass and the key enzymes.

Start-up of the SHARON and ANAMMOX process in landfill bioreactors using aerobic and anaerobic ammonium oxidising biomass

The main aim of this study is to analyse the feasibility to use aerobic ammonium oxidising bacteria (AOB) and anammox/AnAOB biomass enriched from mined municipal solid waste for in situ SHARON and ANAMMOX processes in laboratory scale landfill bioreactors (LFBR) for ammonia nitrogen removal. For this purpose, three LFBRs were operated as Control (without biomass seed), SHARON (with AOB biomass seed) and ANAMMOX (with anammox biomass seed) for 315 days. Results showed nitrogen loading rate of 1.0 kg N/d was effectively removed in SHARON and ANAMMOX LFBR. In SHARON LFBR, partial nitritation efficiency reached up to 98.5% with AOB population of MPN of 5.1 × 10(6)/mL obtained. ANAMMOX LFBR gave evolution of 95% of nitrogen gas as the end product confirmed the ANAMMOX process. Nitrogen transformations, biomass development and hydrazine and hydroxylamine formation authenticated the enriched AOB and anammox biomass activity in landfill bioreactors.

Long term effects of divalent ferrous ion on the activity of anammox biomass

In this study, we explored the effects of Fe(II) on the activity of anammox biomass both in short and long terms. With the influent Fe(II) at 0.09 and 0.12 mM, continuous experiments demonstrated that the nitrogen removal rates increased 32.2% and 29.9% compared to that with normal Fe(II) level (0.03 mM). Influent Fe(II) variation could affect the total Fe, heme c levels and hydrazine dehydrogenase activity. At the Fe(II) concentration of 0.09 mM, the total Fe, heme c levels inside anammox cell and hydrazine dehydrogenase activity could increase about 2.0, 2.1 and 2.35 folds as much as that with normal Fe(II) level. However, when the Fe(II) elevated to 0.18 mM, it would cause a mal-effect on anammox bacteria and further deteriorate nitrogen removal performance. It was indicated that the appropriate increase of Fe(II) was beneficial for more heme c synthesis, enhancement of hydrazine dehydrogenase activity, the growth of anammox bacteria.

Start‐up and enrichment of a granular anammox SBR to treat high nitrogen load wastewaters

AbstractBACKGROUND: Landfill leachate is characterized by low biodegradable organic matter that presents difficulties for the complete biological nitrogen removal usually performed by conventional biological nitrification/denitrification processes. To achieve this, the anaerobic ammonium oxidation (anammox) process is a promising biological treatment. This paper presents an anammox start‐up and enrichment methodology for treating high nitrogen load wastewaters using sequencing batch reactor (SBR) technology.RESULTS: The methodology is based on the gradual increase of the nitrite‐to‐ammonium molar ratio in the influent (from 0.76 to 1.32 mole NO2−‐N mole−1NH4+‐N) and on the exponential increase of the nitrogen loading rate (NLR, from 0.01 to 1.60 kg N m−3 d−1). 60 days after start‐up, anammox organisms were identified by polymerase chain reaction (PCR) technique as Candidatus Brocadia anammoxidans. After one year of operation, NLR had reached a value of 1.60 kg N m−3 d−1 with a nitrogen (ammonium plus nitrite) removal efficiency of 99.7%. The anammox biomass activity was verified by nitrogen mass balances with 1.32 ± 0.05 mole of nitrite removed per mole of ammonium removed and 0.23 ± 0.05 mole of nitrate produced per mole of ammonium removed. Also, enrichment of anammox bacteria was quantified by fluorescence in situ hybridization (FISH) analysis as 85.0 ± 1.8%.CONCLUSIONS: This paper provides a methodology for the enrichment of the anammox biomass in a SBR to treat high nitrogen loaded wastewaters. Copyright © 2007 Society of Chemical Industry