Efficient nitrogen removal via simultaneous ammonium assimilation and heterotrophic denitrification of R-1.

Although diverse microorganisms can remove ammonium and nitrate simultaneously, their metabolic mechanisms are not well understood. R-1 showed the maximal NH removal rate 9.94 mg L·h and 2.

Potential electron acceptors for ammonium oxidation in wastewater treatment system under anoxic condition: A review.

Anaerobic ammonium oxidation has been considered as an environmental-friendly and energy-efficient biological nitrogen removal (BNR) technology. Recently, new reaction pathway for ammonium oxidation under anaerobic condition had been discovered. In addition to nitrite, iron trivalent, sulfate, manganese and electrons from electrode might be potential electron acceptors for ammonium oxidation, which can be coupled to traditional BNR process for wastewater treatment.

Respiration and growth of R-1 with nitrous oxide as an electron acceptor.

Unlabelled: In the nitrogen biogeochemical cycle, the reduction of nitrous oxide (NO) to N by NO reductase, which is encoded by gene, is the only biological pathway for NO consumption. In this study, we successfully isolated a strain of denitrifying R-1 from sewage treatment plant sludge. This strain has strong NO reduction capability, and the average NO reduction rate was 5.

Ferric and sulfate coupled ammonium oxidation enhanced nitrogen removal in two-stage partial nitrification - Anammox/denitrification process for food waste liquid digestate treatment.

Liquid digestate of food waste is an ammonium-, ferric- and sulfate-laden leachate produced during digestate dewatering, where the carbon source is insufficient for nitrogen removal. A two-stage partial nitrification-anammox/denitrification process was established for nitrogen removal of liquid digestate without pre-treatment (>300 d), through which nitrogen (95 %), biodegradable organics (100 %), sulfate (78 %) and iron (100 %) were efficiently removed. Additional ammonium conversion (20 %N) might be coupled with ferric and sulfate reduction, while produced nitrite could be further converted to di-nitrogen gas through anammox (75 %) and denitrification (25 %).

Micro-aeration and low influent C/N are key environmental factors for achieving ANAMMOX in livestock farming wastewater treatment plants.

Anaerobic ammonium oxidation (ANAMMOX)-mediated system is a cost-effective green nitrogen removal process. However, there are few examples of successful application of this advanced wastewater denitrification process in wastewater treatment plants, and the understanding of how to implement anaerobic ammonia oxidation process in full-scale is still limited. In this study, it was found that the abundance of anaerobic ammonia-oxidizing bacteria (AnAOB) in the two livestock wastewater plants named J1 and J2, respectively, showed diametrically opposed trends of waxing and waning with time.

Spatial difference in nitrogen removal pathways and microbial functional diversity in an EGSB reactor during the start-up of PD/Anammox.

The start-up of a relatively high nitrogen load PD/Anammox in an EGSB reactor was achieved through strategies of bioaugmentation, mass transfer enhancement, and COD/NO-N control, with NRR of 5.2 g N/L/d. Longitudinal heterogeneity in EGSB reactor induced divergent nitrogen conversion pathways and enriched different functional microorganisms between stratified sludge.

A critical review of exogenous additives for improving the anammox process.

Anammox achieves chemoautotrophic nitrogen removal under anaerobic and anoxic conditions and is a low-carbon wastewater biological nitrogen removal process with broad application potential. However, the physiological limitations of AnAOB often cause problems in engineering applications, such as a long start-up time, unstable operation, easily inhibited reactions, and difficulty in long-term strain preservation. Exogenous additives have been considered an alternative strategy to address these issues by retaining microbes, shortening the doubling time of AnAOB and improving functional enzyme activity.

A mixed blessing of viruses in wastewater treatment plants.

Activated sludge of wastewater treatment plants harbors a very high diversity of both microorganisms and viruses, wherein the latter control microbial dynamics and metabolisms by infection and lysis of cells. However, it remains poorly understood how viruses impact the biochemical processes of activated sludge, for example in terms of treatment efficiency and pollutant removal. Using metagenomic and metatranscriptomic deep sequencing, the present study recovered thousands of viral sequences from activated sludge samples of three conventional wastewater treatment plants.

Nitrification mainly driven by ammonia-oxidizing bacteria and nitrite-oxidizing bacteria in an anammox-inoculated wastewater treatment system.

Anaerobic ammonium oxidation (anammox) process has been acknowledged as an environmentally friendly and time-saving technique capable of achieving efficient nitrogen removal. However, the community of nitrification process in anammox-inoculated wastewater treatment plants (WWTPs) has not been elucidated. In this study, ammonia oxidation (AO) and nitrite oxidation (NO) rates were analyzed with the incubation of activated sludge from Xinfeng WWTPs (Taiwan, China), and the community composition of nitrification communities were investigated by high-throughput sequencing.

Biogas energy generated from livestock manure in China: Current situation and future trends.

This article investigates the current status of the livestock industry (cattle, pigs, sheep, and poultry) in China and assesses the potential for biogas production from anaerobically digested livestock manure. According to calculation results based on the latest data of livestock released by the National Bureau of Statistics of China in 2018, China produced 2 × 10 kg of manure pollution in 2017, with pig waste representing the largest single manure source. Biogas that can be converted from high organic containing manure is a kind of clean bioenergy with low carbon footprint.

Survival strategies of ammonia-oxidizing archaea (AOA) in a full-scale WWTP treating mixed landfill leachate containing copper ions and operating at low-intensity of aeration.

Recent studies indicate that ammonia-oxidizing archaea (AOA) may play an important role in nitrogen removal by wastewater treatment plants (WWTPs). However, our knowledge of the mechanisms employed by AOA for growth and survival in full-scale WWTPs is still limited. Here, metagenomic and metatranscriptomic analyses combined with a laboratory cultivation experiment revealed that three active AOAs (WS9, WS192, and WS208) belonging to family Nitrososphaeraceae were active in the deep oxidation ditch (DOD) of a full-scale WWTP treating landfill leachate, which is configured with three continuous aerobic-anoxic (OA) modules with low-intensity aeration (≤ 1.

Specific and effective detection of anammox bacteria using PCR primers targeting the 16S rRNA gene and functional genes.

Anaerobic ammonium-oxidizing (anammox) bacteria play an important role in the nitrogen cycle by coupling ammonium and nitrite to produce dinitrogen gas (N). Polymerase chain reaction (PCR) is a fast, simple, and sensitive method that is widely used to assess the diversity, abundance, and activity of the slow-growing bacteria. In this review, we summarize and evaluate the wide variety of PCR primers targeting the 16S rRNA gene and functional genes (hzo, nir, and hzs) of anammox bacteria for their effectiveness and efficiencies in detecting this group of bacteria in different sample types.

Nanoarchitectured structure and population dynamics of anaerobic ammonium oxidizing (anammox) bacteria in a wastewater treatment plant.

Studies on microbial community and population dynamics are essential for the successful development, monitoring and operation of biological wastewater treatment systems. Especially for novel or sustainable systems such as the anaerobic ammonium oxidizing (anammox) process that are not yet well explored. Here we collected granular microbial sludge samples and investigated a community of anammox bacteria over a period of four years, divided into eight stages in a full scale simultaneous partial nitrification, anammox and denitrification (SNAD) process for treating landfill leachate.

Activity and Metabolic Versatility of Complete Ammonia Oxidizers in Full-Scale Wastewater Treatment Systems.

The recent discovery of complete ammonia oxidizers (comammox) contradicts the paradigm that chemolithoautotrophic nitrification is always catalyzed by two different microorganisms. However, our knowledge of the survival strategies of comammox in complex ecosystems, such as full-scale wastewater treatment plants (WWTPs), remains limited. Analyses of genomes and transcriptomes of four comammox organisms from two full-scale WWTPs revealed that comammox were active and showed a surprisingly high metabolic versatility.

Complex microbial nitrogen-cycling networks in three distinct anammox-inoculated wastewater treatment systems.

Microbial nitrogen removal mediated by anaerobic ammonium oxidation (anammox) are cost-effective, yet it is time-consuming to accumulate the slow-growing anammox bacteria in conventional wastewater treatment plants (WWTPs). Inoculation of anammox enriched pellets is an effective way to establish anammox and achieve shortcut nitrogen removal in full-scale WWTPs. However, little is known about the complex microbial nitrogen-cycling networks in these anammox-inoculated WWTPs.

A xylan-degrading thermophilic and obligate anaerobe Xylanivirga thermophila gen. nov., sp. nov., isolated from an anammox dominant wastewater treatment plant, and proposal of Xylanivirgaceae fam. nov.

In our search for novel anaerobes with potential carbohydrate polymers degrading activity, we have isolated a xylan-degrading bacterial strain SYSU GA17129 from an anammox bacteria dominant wastewater treatment plant. Phylogenetic analysis of the 16S rRNA gene sequence indicated the strain SYSU GA17129 belong to the order Clostridiales and shared highest sequence identity with Caldicoprobacter faecalis DSM 20678 (89.9%).

The short- and long-term inhibitory effects of Fe (II) on anaerobic ammonium oxidizing (anammox) process.

The application of the anammox process has great potential in treating nitrogen-rich wastewater. The presence of Fe (II) is expected to affect the growth and activity of anammox bacteria. Short-term (acute) and long-term effects (chronic) of Fe (II) on anammox activity were investigated.

Metagenomic and metatranscriptomic analyses reveal activity and hosts of antibiotic resistance genes in activated sludge.

Wastewater treatment plants (WWTPs) are a source and reservoir for subsequent spread of various antibiotic resistance genes (ARGs). However, little is known about the activity and hosts of ARGs in WWTPs. Here, we utilized both metagenomic and metatranscriptomic approaches to comprehensively reveal the diversity, abundance, expression and hosts of ARGs in activated sludge (AS) from three conventional WWTPs in Taiwan.

Assessment of molecular detection of anaerobic ammonium-oxidizing (anammox) bacteria in different environmental samples using PCR primers based on 16S rRNA and functional genes.

Eleven published PCR primer sets for detecting genes encoding 16S ribosomal RNA (rRNA), hydrazine oxidoreductase (HZO), cytochrome cd -containing nitrite reductase (NirS), and hydrazine synthase subunit A (HzsA) of anaerobic ammonium-oxidizing (anammox) bacteria were assessed for the diversity and abundance of anammox bacteria in samples of three environments: wastewater treatment plant (WWTP), wetland of Mai Po Nature Reserve (MP), and the South China Sea (SCS). Consistent phylogenetic results of three biomarkers (16S rRNA, hzo, and hzsA) of anammox bacteria were obtained from all samples. WWTP had the lowest diversity with Candidatus Kuenenia dominating while the SCS was dominated by Candidatus Scalindua.

Current advances in molecular methods for detection of nitrite-dependent anaerobic methane oxidizing bacteria in natural environments.

Nitrite-dependent anaerobic methane oxidation (n-damo) process uniquely links microbial nitrogen and carbon cycles. Research on n-damo bacteria progresses quickly with experimental evidences through enrichment cultures. Polymerase chain reaction (PCR)-based methods for detecting them in various natural ecosystems and engineered systems play a very important role in the discovery of their distribution, abundance, and biodiversity in the ecosystems.

Biodegradation of tetramethylammonium hydroxide (TMAH) in completely autotrophic nitrogen removal over nitrite (CANON) process.

This study conducted a completely autotrophic nitrogen removal over nitrite (CANON) process in a continuous anoxic upflow bioreactor to treat synthetic wastewater with TMAH (tetramethylammonium hydroxide) ranging from 200 to 1000mg/L. The intermediates were analyzed for understanding the metabolic pathway of TMAH biodegradation in CANON process. In addition, (15)N-labeled TMAH was used as the substrate in a batch anoxic bioreactor to confirm that TMAH was converted to nitrogen gas in CANON process.

Start-up of simultaneous partial nitrification, anammox and denitrification (SNAD) process in sequencing batch biofilm reactor using novel biomass carriers.

Simultaneous partial nitrification, anammox and denitrification (SNAD) process was started-up in a 2.5L sequencing batch biofilm reactor (SBBR) using novel biomass carriers. The SNAD process took only 51d for start-up at nitrogen loading rate (NLR) and organic loading rate (OLR) of 120 and 60g/m(3)-d, respectively.

Effect of zinc on anammox activity and performance of simultaneous partial nitrification, anammox and denitrification (SNAD) process.

In the present study, short-term effects of zinc on anammox activities and long-term effect of zinc on the performance of simultaneous partial nitrification, anammox and denitrification (SNAD) process were evaluated. The anammox activity decreased with increasing zinc concentration and exposure time in short-term tests. The IC50 value of zinc was found to be 6.

Removal of pharmaceuticals and organic matter from municipal wastewater using two-stage anaerobic fluidized membrane bioreactor.

The aim of present study was to treat municipal wastewater in two-stage anaerobic fluidized membrane bioreactor (AFMBR) (anaerobic fluidized bed reactor (AFBR) followed by AFMBR) using granular activated carbon (GAC) as carrier medium in both stages. Approximately 95% COD removal efficiency could be obtained when the two-stage AFMBR was operated at total HRT of 5h (2h for AFBR and 3h for AFMBR) and influent COD concentration of 250mg/L. About 67% COD and 99% TSS removal efficiency could be achieved by the system treating the effluent from primary clarifier of municipal wastewater treatment plant, at HRT of 1.