Influent Nitrogen Concentration Research Articles

Feed distribution based on sensing ammonium concentration after sub-feeding to achieve target effluent nitrogen concentration in sequencing batch reactors

Conventional sequencing batch reactors (SBRs) have been developed based on nitrogen removal efficiency rather than the effluent nitrogen concentration as a design factor. The purpose of this study was to achieve the target effluent total nitrogen (TN) concentration regardless of the influent nitrogen concentration at 10 m3 pilot SBR. The desired nitrogen removal efficiency was achieved by distributing the influent one to four times in one cycle, but effluent TN concentration fluctuated as the influent nitrogen concentration varied. To achieve the target effluent TN concentration, the residual ammonia concentration after sub-feeding was adjusted to the target nitrogen concentration based on real-time ammonia sensing. When the residual ammonia concentration after sub-feeding was set at 10 or 5 mg NH4+-N L−1, the effluent TN concentration was 9.3 ± 0.6 or 4.6 ± 0.3 mg L−1, respectively, regardless of the influent TN concentration. Furthermore, complete nitrification was achieved under low temperature, from 7.2 to 13.1 °C, by controlling the aeration phase end point based on the real-time ammonia sensing. However, when the residual nitrate concentration was adjusted to a low level, the total phosphorus (TP) removal efficiency was high owing to an increase of phosphate release activity by polyphosphate accumulating organisms.

The Impact of Carbon Source as Electron Donor on Composition and Concentration of Dissolved Organic Nitrogen in Biosorption-Activated Media for Stormwater and Groundwater Co-Treatment.

Eutrophication has been a long-term issue in aquatic environments, where dissolved organic nitrogen (DON) recalcitrance is important. Bioavailable nitrogen qualification and quantification for effluents from stormwater and wastewater are always a challenge. The information in this study deepens the understanding of the interactions between carbon addition and DON decomposition through linear-ditch best management practices for stormwater and groundwater cotreatment. By running a laboratory-scale column study for nitrogen removal using green sorption media, the variation in composition and concentration of DON can be further linked to the population dynamics of microbial species that dominate the nitrification and denitrification processes. With the varying levels of influent total nitrogen concentration, the efficacy of nitrogen removal via biosorption activated media may be realized at the molecular level with ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry.

Effects of salinity on the nitrogen removal efficiency and bacterial community structure in fixed-bed biofilm CANON bioreactors

The discovery of anaerobic ammonium oxidation processes led to the development of innovative nitrogen removal technologies, which are more cost-effective and environmentally friendly than conventional activated sludge systems. In this study, the bacterial community structure was determined as well as the nitrogen removal efficiencies in four fixed-bed biofilm bioreactors, working under different salt concentrations (0, 3, 25, and 45 g L−1 of sodium chloride (NaCl)) and at hydraulic retention times (HRT) of 6 and 12 h. The influent total nitrogen concentration was 250 mg L−1. The results showed a clear inhibition in the nitrogen removal capacity of the process that was directly related to the salt concentration in the influent, most likely due to changes in the bacterial community structure; increases in the NaCl concentration provoked the inhibition of Candidatus Brocardia and Nitrosomonas, whereas heterotrophic phylotypes such as Marinobacter proliferated. An evident adaptation of the anammox microorganisms at 3 g NaCl L−1 was observed, whereas ammonia and nitrite oxidizing bacteria drastically decreased at 25 and 45 g NaCl L−1. Total nitrogen efficiencies for 6 h of HRT were 87.68, 64.25, 38.79, and 19.74%, for 0, 3, 25, and 45 g NaCl L−1, respectively. No significant effects were detected on the performance of the bioreactors and bacterial diversity under different HRT. Our study may be useful for the implementation of CANON systems at real-scale, by increasing the knowledge on the bacterial community at different NaCl concentrations and the performance of this novel technology for saline wastewater treatment.

Nitrifiers activity and community characteristics under stress conditions in partial nitrification systems treating ammonium-rich wastewater

Long-term exposure of nitrifiers to high concentrations of free ammonia (FA) and free nitrous acid (FNA) may affect nitrifiers activity and nitrous oxide (N2O) emission. Two sequencing batch reactors (SBRs) were operated at influent ammonium nitrogen (NH4-N) concentrations of 800mg/L (SBRH) and 335mg/L (SBRL), respectively. The NH4-N removal rates in SBRH and SBRL were around 2.4 and 1.0g/L/day with the nitritation efficiencies of 99.3% and 95.7%, respectively. In the simulated SBR cycle, the N2O emission factors were 1.61% in SBRH and 2.30% in SBRL. N2O emission was affected slightly by FA with the emission factor of 0.22%–0.65%, while N2O emission increased with increasing FNA concentrations with the emission factor of 0.22%–0.96%. The dominant ammonia oxidizing bacteria (AOB) were Nitrosomonas spp. in both reactors, and their relative proportions were 38.89% in SBRH and 13.36% in SBRL. Within the AOB genus, a species (i.e., operational taxonomic unit [OTU] 76) that was phylogenetically identical to Nitrosomonas europaea accounted for 99.07% and 82.04% in SBRH and SBRL, respectively. Additionally, OTU 215, which was related to Nitrosomonas stercoris, accounted for 16.77% of the AOB in SBRL.

Tracking the activity of the Anammox-DAMO process using excitation–emission matrix (EEM) fluorescence spectroscopy

Coupling of anaerobic ammonium oxidation (anammox) and denitrifying anaerobic methane oxidation (DAMO) microorganisms in a hollow-fiber membrane biofilm reactor (HfMBR) is a potential strategy for simultaneous anaerobic removal of nitrogen and methane in wastewater streams. In these systems, effluents contain dissolved organic substances from anammox and DAMO microorganisms, but their characteristics and relationships have not been investigated. In the present study, excitation-emission matrix (EEM) fluorescence spectroscopy was used to characterize effluent dissolved organic matter (EfDOM) from an Anammox-DAMO HfMBR. Four component types (Component 1–4) were identified by parallel factor analysis (PARAFAC) of EEM data. Component 1 was produced when anammox and DAMO microorganisms simultaneously starved, whereas Component 4 was only generated through the starving period of DAMO microorganisms, and the longer the starving period, the higher the fluorescence intensity of the components. Components 2 and 3 were generated via active and starving periods of co-cultures. More efficient nitrogen removal was accompanied by a higher fluorescence intensity and microbial activity. Compared to measuring both influent and effluent nitrogen concentrations, monitoring EfDOM can obtain other information about the reactor, such as nitrogen removal activity of the reactor, status of the microbes and the duration of starving period the reactor suffered, which therefore offers a complementary but direct tool for assessing reactor performance in complex co-culture systems.

Biomass granulation in an upflow anaerobic sludge blanket reactor treating 500 m3/day low-strength sewage and post treatment in high-rate algal pond.

A pilot-scale upflow anaerobic sludge blanket-moving bed biofilm (UASB-MBB) reactor followed by a high-rate algal pond (HRAP) was designed and operated to remove organic matter, nutrients and pathogens from sewage and to facilitate reuse. For an influent chemical oxygen demand (COD) concentration of 233 ± 20 mg/L, final effluent COD was 50 ± 6 mg/L. Successful biomass granulation was observed in the sludge bed of the upflow anaerobic sludge blanket (UASB) reactor after 5 months of operation. Ammonia removal in HRAP was 85.1 ± 2.4% with average influent and effluent ammonia nitrogen concentrations of 20 ± 3 mg/L and 3 ± 1 mg/L, respectively. Phosphate removal after treatment in the HRAP was 91 ± 1%. There was a 2-3 log scale pathogen removal after treatment in HRAP with most probable number (MPN) of the final effluent being 600-800 per 100 mL, which is within acceptable standards for surface irrigation. The blackwater after treatment in UASB-MBBR-HRAP is being reused for gardening and landscaping. This proper hydro-dynamically designed UASB reactor demonstrated successful granulation and moving bed media improved sludge retention in UASB reactor. This combination of UASB-MBB reactor followed by HRAP demonstrated successful sewage treatment for a year covering all seasons.

Substrate inhibition and concentration control in an UASB-Anammox process

An UASB-Anammox reactor was operated for more than one year to study the process performance variations respond to the nitrogen loading rate (NLR) and substrate concentration. The IC10 (451.1mg/L), IC50 (725.3mg/L) and the prospected threshold of influent total nitrogen (TN) concentration were simulated. A stable TN removal efficiency was obtained when the TN influent was controlled. The disequilibrium distribution of the substrate following the plug flow with the height of the reactor resulted in significant variations in specific Anammox activity from the bottom to the top of the reactor (348→3mgN/gVSS/d). With long term acclimation, the nitrogen removal capacity of Anammox sludge varied significantly, with the most activated sludge obtained in the bottom part a 100 times capacity greater than that of the top. A stable performance with high removal efficiency in the constructed UASB-Anammox reactor was obtained when the influent TN concentration was below 451.1mg/L.

High rate nitrogen removal by ANAMMOX internal circulation reactor (IC) for old landfill leachate treatment

This study aimed to evaluate the performance of a high rate nitrogen removal lab-scale ANAMMOX reactor, namely Internal Circulation (IC) reactor, for old landfill leachate treatment. The reactor was operated with pre-treated leachate from a pilot Partial Nitritation Reactor (PNR) using a high nitrogen loading rate ranging from 2 to 10kgNm−3d−1. High rate removal of nitrogen (9.52±1.11kgNm−3d−1) was observed at an influent nitrogen concentration of 1500mgNL−1. The specific ANAMMOX activity was found to be 0.598±0.026gN2-NgVSS−1d−1. Analysis of ANAMMOX granules suggested that 0.5–1.0mm size granular sludge was the dominant group. The results of DNA analysis revealed that Candidatus Kueneniastuttgartiensis was the dominant species (37.45%) in the IC reactor, whereas other species like uncultured Bacteroidetes bacterium only constituted 5.37% in the system, but they were still responsible for removing recalcitrant organic matter.

Treatment of high-strength rare-earth ammonia wastewater with two-stage anammox process

<p>In this study, a two-stage anaerobic ammonium oxidation (anammox) system—including a partial nitritation system with a biological selector (PNBS) and a granular activated carbon-based granule anammox process (GAP) —was used for the treatment of real high-strength rare-earth ammonia wastewater (HRAW). A nitrogen removal rate of 89% on average was achieved at the end of the study with the influent total nitrogen concentration of 2200 mg l<sup>-1</sup>. The nitrogen-loading rate (NLR) of 17 kg N/(m<sup>3</sup>×d) was achieved in the PNBS, and a reduced NLR of 6 kg N/(m<sup>3</sup>×d) was maintained in the GAP. To our knowledge, this is the highest NLR applied to a two-stage anammox system. A genetic analysis of the sludge samples revealed that a <em>Nitrosomonas</em><em> sp.</em> was enriched in the PNBS reactor, while, <em>Kuenenia stuttgartiensis</em><sub>,</sub><em> Uncultured bacterium clone KIST-JJY001</em>, and <em>Uncultured anoxic sludge bacterium KU2</em> were enriched in the GAP reactor.</p>

Nitrogen Removal in an Ecological Ditch Based on an Orthogonal Test

Agricultural drainage plays a vital role in the discharge of non-point source pollutants into surface-receiving waters. Sustainable drainage management to mitigate nitrogen losses from cultivated land is needed. Many factors influence nitrogen removal in agricultural drainage ditches. However, existing research has not fully considered parameter sensitivity analysis of nitrogen removal. Therefore, in this study, an ecological ditch model containing a permeable dam was built, in which the influent nitrogen concentration, suspended solid concentration, influent flow, and water level were examined as influencing factors. An orthogonal test was conducted to explore the significance of these four factors and their impacts on nitrogen removal as well as the nitrogen transport characteristics along the ditch. The results revealed that the ditches had an interception effect on nitrogen pollutants, and according to importance, the four factors are influent nitrogen concentration, water level, water flow, and suspended solid concentration in descending order. The plants and permeable dam in the ditch also played an important role in nitrogen removal.

NaH2PO4 as pH buffer in an anaerobic ammonium oxidation (anammox) reactor treating high-strength livestock manure digester liquor

In order to use livestock manure digester liquor (LMDL) as liquid fertilizer, NaH2PO4 was evaluated for its effectiveness as pH buffer in an anaerobic ammonium oxidation (anammox) reactor treating high-strength LMDL. The results show that influent total nitrogen (TN) concentration was increased from 500 to 2,200 mg/L with the addition of NaH2PO4 as a pH buffer. To the best of our knowledge, this is the highest influent TN concentration for anammox reactor in treating LMDL. An average TN removal efficiency of 85% was observed in LMDL treatment without dilution. The treated effluent may be applied directly as a terrestrial liquid fertilizer, as the effluent has a suitable balance of nitrogen and phosphorus (approximately 1:1). 16S rRNA gene analysis showed that Kuenenia stuttgartiensis and Uncultured bacterium clone KIST-JJY001, known as anammox bacteria, shared approximately 26% in genus level in the reactor. Uncultured bacterium clone Dok53, Uncultured bacterium clone KIST-JJY024, Uncultured bacterium clone FN-11, Uncultured bacterium clone KIST-JJY012, and Uncultured bacterium clone AnSal-09, which are often detected as co-occurring bacteria, were also found in this study.

CANON 공정에서 운전조건에 따른 질소 제거효율 및 미생물군집 변화

Nitrogen removal is one of the most important issues about wastewater treatment because nitrogen is a primary pollutant caused various problems such as eutrophication. We developed a CANON microbial community by using AOB and ANAMMOX bacteria as seeding sources. When 100 mg-N/L of influent ammonium was supplied, the DO above 0.4 mg/L showed a very low TN removal efficiency while the DO of 0.3 mg/L showed TN removal efficiency as high as 71.3%. When the influent ammonium concentration was reduced to 50 mg/L, TN removal efficiency drastically deceased. However, TN removal efficiency was recovered to above 70% after 14 day operation when the influent nitrogen concentration was changed again from 50 mg-N/L to 100 mg-N/L. According to the operating temperature from 37±1°C to 20±1°C, TN removal efficiency also rapidly decreased but gradually increased again up to 70.0±2.6%. The analysis of PCR-DGGE showed no substantial difference in microbial community structures under different operational conditions. This suggests that if CANON sludge is once successfully developed from a mixture of AOB and ANAMMOX bacteria, the microbial community can be stably maintained regardless of the changes in operational conditions.

Effect of influent nitrogen concentration on feasibility of short-cut nitrification during wastewater treatment in activated sludge systems

AbstractThe inhibitory effect of free ammonia and free nitrous acid on nitrite-oxidising bacteria (NOB) was studied in a laboratory-scale sequencing batch reactor with a suspended microbial culture. The reactor was operated at 15°C, with a dissolved oxygen concentration in excess of 5 mg L

Understanding the impact of influent nitrogen concentration on granule size and microbial community in a granule-based enhanced biological phosphorus removal system

To better understand the effect of influent nitrogen concentration on granule size and microbial community in a granule-based enhanced biological phosphorus removal system, three influent nitrogen concentrations were tested while carbon concentration was an unlimited factor. The results show that although ammonium and phosphate were well removed in the tested nitrogen concentration range (20–50mgL−1), granule size, the amount of phosphate accumulating organisms (PAOs) and microbial activity were affected significantly. A possible mechanism for the effect of influent nitrogen concentration on granule size is proposed based on the experimental results. The increase in proteins/polysaccharides ratio caused by high influent nitrogen concentration plays a crucial role in granule breakage. The small granule size then weakens simultaneous nitrification–denitrification, which further causes higher nitrate concentration in the effluent and lower amount of PAOs in sludge. Consequently, phosphate concentration in the anaerobic phase decreases, which plays the secondary role in granule breakage.

Nitritation and N2O Emission in a Denitrification and Nitrification Two-Sludge System Treating High Ammonium Containing Wastewater

The effective management of high ammonium containing wastewater is important for the sustainable development of the wastewater industry. A pre-denitrification and post-nitrification two-sludge system was proposed to treat high ammonium containing wastewater with low carbon-to-nitrogen (C/N) ratios. In the system, pre-denitrification was adopted to use organic carbon in raw wastewater efficiently for nitrogen removal, while post-nitrification was adopted to achieve nitritation. System performance and the characteristics of nitrous oxide (N2O) emission were examined. As to the influent chemical oxygen demand (COD) and ammonium nitrogen (NH4-N) concentration, both 800 mg/L, nitrogen removal was mainly through pre-denitrification, and the nitrogen removal percentage was 43.4%. In post-nitrification, nitritation was achieved with a nitrite accumulation efficiency of 97.8% and a NH4-N removal loading rate of 0.45 g/(L·d). With nitrite as the electron acceptor during denitrification, its removal rate increased, while the N2O emission factor decreased with increasing C/N ratios. Nitrification was affected significantly by the aeration rate. When the aeration rate was below 0.6 L/min, the NH4-N removal rate increased, while the N2O emission rate decreased with increasing aeration rates. However, when the aeration rate was above 0.6 L/min, it had little influence on N2O emission. During nitrification, N2O emission factors decreased exponentially with increasing ammonium oxidation rates.

Effects of the influent ammonium nitrogen concentration on nitrite accumulation in a biological nitritation process

Nitrogen is one of the primary elements that causes eutrophication. In recent years, more stringent environmental standards have come into effect, and nitritation processes have been promoted as a way to remove the high nitrogen content of recycle water and piggery wastewater, which have extremely high ammonium nitrogen concentrations. In this study, the effects of different influent ammonium nitrogen concentrations were evaluated with respect to the rate of nitritation. The influent ammonium nitrogen concentrations ranged from 286 to 2,620 mg/L, so the nitritation reactor was operating under fluctuating ammonium nitrogen concentrations during the experimental period. In the experiment, stable nitritation rates were observed under varying ammonium nitrogen concentrations. Methods to control the influent ammonium nitrogen concentrations were assessed for wastewater with fluctuating ammonium nitrogen concentrations. Nitritation was found to be useful process for removing nitrogen from wastewater with high nitrogen content; additionally, nitritation provides an economic advantage over nitrification.

Modelling microalgae growth in nitrogen-limited continuous culture

In this paper, based on the mathematical models of microalgae growth, the performance of microalgae growth in nitrogen-limited and light-limited continuous culture is investigated and the effect of important factors on the growth is examined. The dilution rate and the influent inorganic nitrogen concentration have been shown to have a significant influence on the growth of microalgae in continuous culture. In order to obtain a maximum productivity of microalgae, lower dilution rate is better for a lower influent inorganic nitrogen concentration and an optimal dilution rate can be obtained for a higher influent inorganic nitrogen concentration. There is an optimal influent inorganic nitrogen concentration corresponding to maximum microalgae productivity, and the optimal value for lower dilution rate is far higher than that for higher dilution rate. This paper will lay a foundation for the design of the operational parameters of continuous culture PBR (photobioreactor).

Overall functional gene diversity of microbial communities in three full-scale activated sludge bioreactors.

Understanding microbial community composition is thought to be crucial for improving process functioning and stabilities of full-scale activated sludge reactors in wastewater treatment plants (WWTPs). However, functional gene compositions of microbial communities within them have not been clearly elucidated. To gain a complete picture of microbial community, in this study, GeoChip 4.2 was used to profile the overall functional genes of three full-scale activated sludge bioreactors, the 16S rRNA gene diversities of which had been unveiled by 454-pyrosequencing in our previous investigation. Triplicate activated sludge samples from each system were analyzed, with the detection of 38,507 to 40,654 functional genes. A high similarity of 77.3-81.2% shared functional genes was noted among the nine samples, verified by the high 16S rRNA gene similarity with shared operational taxonomic units (OTUs) constituting 66.4-70.0% of the detected sequences in each system. Correlation analyses showed that the abundances of a wide array of functional genes were associated with system performances. For example, the abundances of carbon degradation genes were strongly correlated to chemical oxygen demand (COD) removal efficiencies (r = 0.8697, P < 0.01). Lastly, we found that sludge retention time (SRT), influent total nitrogen concentrations (TN inf), and dissolved oxygen (DO) concentrations were key environmental factors shaping the overall functional genes. Together, the results revealed vast functional gene diversity and some links between the functional gene compositions and microbe-mediated processes.

The impact of influent total ammonium nitrogen concentration on nitrite-oxidizing bacteria inhibition in moving bed biofilm reactor

The application of nitrification-denitrification over nitrite (nitritation-denitritation) with municipal (i.e. diluted and cold (or low-temperature)) wastewater can substantially improve the energy balance of municipal wastewater treatment plants. For the accumulation of nitrite, it is crucial to inhibit nitrite-oxidizing bacteria (NOB) with simultaneous proliferation of ammonium-oxidizing bacteria (AOB). The present study describes the effect of the influent total ammonium nitrogen (TAN) concentration on AOB and NOB activity in two moving bed biofilm reactors operated as sequencing batch reactors (SBR) at 15 °C (SBR I) and 21 °C (SBR II). The reactors were fed with diluted reject water containing 600, 300, 150 and 75 mg TAN L(-1). The only factor limiting NOB activity in these reactors was the high concentrations of free ammonia and/or free nitrous acid (FNA) during the SBR cycles. Nitrite accumulation was observed with influents containing 600, 300 and 150 mg TAN L(-1) in SBR I and 600 and 300 in SBR II. Once nitrate production established in the reactors, the increase of influent TAN concentration up to the original 600 mg TAN L(-1) did not limit NOB activity. This was due to the massive development of NOB clusters throughout the biofilm that were able to cope with faster formation of FNA. The results of the fluorescence in situ hybridization analysis preliminarily showed the stratification of bacteria in the biofilm.

Empirical regression models for estimating nitrogen removal in a stormwater wetland during dry and wet days

Due to the highly variable hydrologic quantity and quality of stormwater runoff, which requires more complex models for proper prediction of treatment, a relatively few and site-specific models for stormwater wetlands have been developed. In this study, regression models based on extensive operational data and wastewater wetlands were adapted to a stormwater wetland receiving both base flow and storm flow from an agricultural area. The models were calibrated in Excel Solver using 15 sets of operational data gathered from random sampling during dry days. The calibrated models were then applied to 20 sets of event mean concentration data from composite sampling during 20 independent rainfall events. For dry days, the models estimated effluent concentrations of nitrogen species that were close to the measured values. However, overestimations during wet days were made for NH(3)-N and total Kjeldahl nitrogen, which resulted from higher hydraulic loading rates and influent nitrogen concentrations during storm flows. The results showed that biological nitrification and denitrification was the major nitrogen removal mechanism during dry days. Meanwhile, during wet days, the prevailing aerobic conditions decreased the denitrification capacity of the wetland, and sedimentation of particulate organic nitrogen and particle-associated forms of nitrogen was increased.