Kinetics Of Nitrogen Removal Research Articles

Evaluating Ammonia Toxicity and Growth Kinetics of Four Different Microalgae Species.

Although wastewater with high ammonia concentration is an ideal alternative environment for microalgae cultivation, high ammonia concentrations are toxic to microalgae and inhibit microalgae growth. In this study, the ammonia responses of four widely used microalgae species were investigated. Chlorella vulgaris, Chlorella minutissima, Chlamydomonas reinhardtii and Arthrospira platensis were grown in batch reactors maintained at seven different NH4Cl concentrations at a constant pH of 8. Growth and nitrogen removal kinetics were monitored. IC50 values for the mentioned species were found as 34.82 mg-FA/L, 30.17 mg-FA/L, 27.2 mg-FA/L and 44.44 mg-FA/L, respectively, while specific growth rates for different ammonia concentrations ranged between 0.148 and 1.271 d-1. C. vulgaris demonstrated the highest biomass growth under an ammonia concentration of 1700.95 mg/L. The highest removal of nitrogen was observed for A. platensis with an efficiency of 99.1%. The results showed that all tested species could grow without inhibition in ammonia levels comparable to those found in municipal wastewater. Furthermore, it has been concluded that species C. vulgaris and A. platensis can tolerate high ammonia levels similar to those found in high strength wastewaters.

Kinetics of Nitrogen Removal from Liquid Third Generation Advanced High-Strength Steel by Tank Degassing

Kinetics of Nitrogen Removal from Liquid Third Generation Advanced High-Strength Steel by Tank Degassing

Kinetics and Removal Efficiency of Nitrogen in Constructed Wetlands Cultivated with Different Plant Species for Treating Swine Wastewater Applied at Different Rates

The present study sought to evaluate the efficiency and kinetics of nitrogen removal in Horizontal Subsurface Flow Constructed Wetlands (HSSF-CWs) cultivated with different plant species used in the treatment of swine wastewater (SWW), under different nitrogen loading rates (LRTKN). For this purpose, nine tanks measuring 2.0 × 0.5 × 0.6 m were used, one maintained without plants (CW1), while in the others two plant species were evaluated: CW3, CW5, CW7, and CW9 were planted with Tifton 85 grass (Cynodon spp.) and CW2, CW4, CW6, and CW8 were planted with cattail (Typha latifolia). The CWs received TKN application rates between 110 and 413 kg ha−1 day−1, and the removal efficiencies ranged from 27.6 to 44.9%. The average mass removal rates (MRR) for TKN and NH4+ ranged from 45.3 to 115.9 kg ha−1 day−1 and 28.9 to 66.5 kg ha−1 day−1, respectively. Tifton 85 grass and cattail contributed, respectively, to 2.22 to 8.7% and 0.03 to 1.67% of the TKN mass removed by the CWs (MRR), equivalent to extraction rates of 2.72 to 4.94 kg ha−1 day−1 and 0.04 to 1.11 kg ha−1 day−1. Coefficients estimated by conventional, modified, and residual first-order models ranged from 0.017 to 0.0187 day−1, 0.0691 to 0.1285 day−1, and 0.0298 to 0.0715 day−1, respectively. The modified first-order model and that with residual, due to their higher R2 values (R2 > 93%), indicated a good fit and considerable reliability of these equations to describe the processes of nitrogen removal from swine wastewater treated in HSSF-CW, and due to their mathematical simplicity and improvements in the representation of real behavior, they should be preferred for modeling of these systems.

Kinetics study of nitrogen removal from liquid IN718 alloy during vacuum induction melting

The kinetics of nitrogen removal from the molten IN718 alloy has been investigated by the sampling method under reduced pressure. The effects of initial nitrogen concentrations, alloying elements (carbon, titanium, and aluminum), and the intensity of inductive stirring on the nitrogen removal are discussed in the temperature range from 1773 to 1923 K. Experimental results indicate that the nitrogen removal is a 1.5th-order reaction at different initial nitrogen concentrations and temperatures, and the nitrogen removal reaction is controlled by a mixed interfacial and diffusion process. Moreover, the nitrogen removal reaction can be accelerated when the [C]+[O] = CO(g) reaction exists in the melt, and the kinetics changes gradually from a 1.5th-order reaction to a second-order reaction with increasing temperature from 1773 to 1873 K. The nitrogen removal is a second-order reaction in low-speed stirring. Meanwhile, the rate constant of nitrogen removal under the condition of where the mass transfer resistance in the gas phase is negligible, is evaluated. The rate constant of the nitrogen removal increases with increasing temperature. It is also found that titanium decreases the rate constant of nitrogen removal, and aluminum and carbon significantly increase the rate constant of nitrogen removal.

Performance of a high-rate anammox reactor under high hydraulic loadings: Physicochemical properties, microbial structure and process kinetics

In this study, a lab-scale upflow anaerobic sludge blanket (UASB) reactor was applied to studying the high-rate nitrogen removal of granule-based anammox process. The nitrogen removal rate (NRR) finally improved to 15.77 kg/m3/d by shortening hydraulic retention time (HRT) to 1.06 h. Well-shaped red anammox granules were extensively enriched inside the reactor. The results of nitrogen removal kinetics indicated that the present bioreactor has great nitrogen removal potential, because the maximum rate of substrate utilization (Umax) predicted by Stover-Kincannon model is suggested as 55.68 kg/(m3·d). Analysis of the microbial community showed that the anammox genus Candidatus Kuenenia dominated the bacterial communities. The relative abundance of Candidatus Kuenenia rose from 12.29% to 36.95% after progressively shorter HRT and higher influent substrate concentrations, illustrating the stability of nitrogen removal performance and biomass enrichment offered by the UASB in carrying out high-rate anammox process.

Bioconversion of wastewater by photosynthetic bacteria: Nitrogen source range, fundamental kinetics of nitrogen removal, and biomass accumulation

There is great potential for nitrogen removal in wastewater treatment by photosynthetic bacteria (PSB) bioconversion. Protein-rich cells can be cultured simultaneous to nitrogen removal. For the first time, efficient nitrogen source range, kinetics of nitrogen removal and biomass accumulation of PSB bioconversion technology were studied. Results are that efficient nitrogen range is 3–8000 mg·L−1, which covers most wastewaters. Biokinetics was fit to Michaelis–Menten model, Monod model and inhibition models including Haldane, Edwards, and Aiba models. The data were best fitted by Aiba model, with an R2 of 0.97. Vmax, Km, and Ki of nitrogen degradation were 0.065 d−1, 1344 mg·L−1, and 6525 mg·L−1, respectively, and μmax, Ks, and Ki of biomass accumulation were 5.88 d−1, 883 mg·L−1, and 1521 mg·L−1, respectively. PSB bioconversion technology is more suitable than others for high nitrogen wastewater treatment.

Supernatant organics from anaerobic digestion after thermal hydrolysis cause direct and/or diffusional activity loss for nitritation and anammox

Treatment of sewage sludge with a thermal hydrolysis process (THP) followed by anaerobic digestion (AD) enables to boost biogas production and minimize residual sludge volumes. However, the reject water can cause inhibition to aerobic and anoxic ammonium-oxidizing bacteria (AerAOB & AnAOB), the two key microbial groups involved in the deammonification process. Firstly, a detailed investigation elucidated the impact of different organic fractions present in THP-AD return liquor on AerAOB and AnAOB activity. For AnAOB, soluble compounds linked to THP conditions and AD performance caused the main inhibition. Direct inhibition by dissolved organics was also observed for AerAOB, but could be overcome by treating the filtrate with extended aerobic or anaerobic incubation or with activated carbon. AerAOB additionally suffered from particulate and colloidal organics limiting the diffusion of substrates. This was resolved by improving the dewatering process through an optimized flocculant polymer dose and/or addition of coagulant polymer to better capture the large colloidal fraction, especially in case of unstable AD performance. Secondly, a new inhibition model for AerAOB included diffusion-limiting compounds based on the porter-equation, and achieved the best fit with the experimental data, highlighting that AerAOB were highly sensitive to large colloids. Overall, this paper for the first time provides separate identification of organic fractions within THP-AD filtrate causing differential types of inhibition. Moreover, it highlights the combined effect of the performance of THP, AD and dewatering on the downstream autotrophic nitrogen removal kinetics.

Kinetics of nitrogen removal processes in constructed wetlands

The aim of this paper is to present a state-of-the-art review of the kinetics of nitrogen removal in constructed wetlands. Biological processes of nitrogen removal from wastewater can be described using equations and kinetic models. Hence, these kinetic models which have been developed and evaluated allow for predicting the removal of nitrogen in treatment wetlands. One of the most important, first order removal model, which is still applied, was analysed and its rate coefficients and factors were compared. This study also demonstrates the validity of Monod and multiple Monod kinetics, commonly seen today. Finally, a computational example of the reaction kinetics of nitrogen removal was also included in the study.

Nitrogen removal kinetics in wastewater stabilization pond systems in Greece

Nitrogen removal kinetics in wastewater stabilization pond systems in Greece

Effect of carbon source on nitrogen removal in anaerobic ammonium oxidation (anammox) process

Anaerobic ammonium oxidation (anammox) has been regarded as an efficient process to treat high-strength wastewater without organic carbon source. To investigate nitrogen removal performance of anammox in presence of organic carbon source can broaden its application on organic wastewater treatment. In this work, effect of carbon source on anammox process was explored. Operating temperature was set at 35±1°C. Influent pH and hydraulic retention time were 7.5 and 6h, respectively. Effluent [Formula: see text] was affected little with COD no more than 480mg/L. Independent of carbon source content, nitrite removal rate was around 99%. The variation of [Formula: see text] lagged behind [Formula: see text] at high COD content, and pH could be used as an indicator for [Formula: see text] removal. Specific anammox activity dropped from 0.39 to 0.19 [Formula: see text] at COD=720mg/L. The remodified logistic model was quite appropriate for describing the nitrogen removal kinetics and predicting the performance of anammox process in presence of carbon source.

Modeling the pH effects on nitrogen removal in the anammox-enriched granular sludge.

The aim of the study was to determine the pH effects on nitrogen removal in the anammox-enriched granular sludge. The experimental data were extracted from a 4 L completely-mixed batch reactor with the granular sludge at different initial pH values (6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5) and constant temperature T = 30 °C. Simulations were run in GPS-X 6.4 using a comprehensive mechanistic model Mantis2. Two kinetic parameters, the maximum specific growth rates of ammonia oxidizing bacteria (AOB) and anammox bacteria, were optimized at different pH scenarios. The inhibitory effects of the pH extremes on the anammox-enriched sludge were discussed in terms of the inhibition of free nitrous acid and free ammonia and metabolic mechanisms. Two different pH functions were used to examine the pH effects on the nitrogen removal kinetics. The pH optima for AOB and anammox bacteria were 7.4 and 7.6, respectively. The maximum specific growth rates of AOB and anammox bacteria at the pH optima were 0.81-0.85 d-1 and 0.36-0.38 d-1 (at T = 30 °C). The measured specific anammox activities (SAAs), predicted SAAs by Mantis2 and fitted SAAs by the Michaelis pH function at the pH optima were 0.895, 0.858 and 0.831 gN/(gVSS·d), respectively (VSS: volatile suspended solids).

Validation of a new model for the sizing of denitrification reactors, by testing full-scale plants

ABSTRACTA new deterministic model for the calculation of the specific denitrification rate (SDNR), useful for the design of pre-denitrification reactors, was tested on eight full-scale activated sludge plants. The model represents the SDNR at 20°C (SDNR20°C) as a function of the sludge loading in the denitrification reactor (F:MDEN) and the residual dissolved oxygen in the denitrification reactor (DODEN). The results proved the ability of the model in calculating the SDNR20°C. The model shows a lower degree of adaptability for small-sized plants. SDNR20°C proved to have a strong sensitivity to DODEN, mainly in correspondence with low DO concentrations (less than 2 mg L−1). The sensitivity decreases at greater DO values, but with a progressively less marked gradient, up to becoming weak only at DO concentrations greater than 0.4-0.5 mg L−1, which are rarely found in full-scale plants. DO concentrations measured in real-scale facilities are mostly in the range 0.2-0.4 mg L−1. These concentrations cause adverse effects on the kinetics of nitrogen removal, and consequently on the denitrification performance. Thus, minimizing DO in the pre-denitrification reactor is relevant. The sensitivity of SDNR20°C to F:MDEN was less important, as it is characterized by a growing linear behaviour with a low slope.

Investigating the role of co-substrate–substrate ratio and filter media on the performance of anammox hybrid reactor treating nitrogen rich wastewater

This study explored the feasibility of using the anammox hybrid reactor (AHR), which combines suspended and attached growth media, for the biodegradation of ammonical nitrogen in wastewater. The study was performed in four laboratory-scale AHRs, inoculated with mixed seed culture (1:1). The anammox process was established by feeding the AHR with synthetic wastewater, containing NH(4)-N and NO(2)-N (1:1), at hydraulic retention time (HRT) of 1 day. The reactors were gradually acclimated to a higher ammonium concentration (1200 mg/l) until the pseudo-steady state was attained. Subsequently, the reactors were operated at various HRTs (0.25-3.0 days) to optimize the HRT and nitrogen loading rate (NLR). The study demonstrated that HRT of 1 day, corresponding to 95.1% of nitrogen removal was optimal. Pearson correlation analysis indicated the strong and positive correlation of HRT and sludge retention time (SRT), whereas the NLR and biomass yield correlated negatively with the nitrogen removal efficiency (NRE). The mass balance of nitrogen showed that a major fraction (79.1%) of the input nitrogen was converted into N2 gas, and 11.25% was utilized in synthesizing the biomass. The filter media in the AHR contributed to an additional 15.4% of ammonium removal and a reduction of 29% in the sludge washout rate. The nitrogen removal kinetics in the AHR followed the modified Stover-Kincannon model, whereas the Lawrence-McCarty model best described the bacterial growth kinetics. The study concludes that the hybrid configuration of the reactor demonstrated promising results and could be suitably applied for industrial applications.

Kinetics of nitrogen removal in pilot-scale internal-loop airlift bio-particle reactor for simultaneous partial nitrification and anaerobic ammonia oxidation

The pilot-scale internal-loop-airlift bio-particle (ILAB) reactor was a novel configuration adopted to study the performance of simultaneous partial nitrification (PN) and anaerobic ammonia oxidation (ANAMMOX). The ILAB reactor was operated at different nitrogen loading rates and hydraulic retention times to investigate the nitrogen removal kinetics. The reactor showed good tolerance to substrate concentration shock while it was significantly affected by hydraulic shock. Five kinetic models including first-order model, Grau second-order model, Stover–Kincannon model, Monod model and Contois model were applied to steady-state experimental data to evaluate the substrate removal in the reactor. The Grau second-order model and Stover–Kincannon model were found to be more appropriate compared with other models to describe and predict the performance of the reactor. Both the models were evaluated by judging the linearity between experimental data and predicted values which confirmed their validity for the process.

Impacts of Cu(II) on the kinetics of nitrogen removal during the wastewater treatment process

The effects of Cu(II) on the substrate removal kinetics, including the COD, NH+4-N, and NO−x–N removal, were investigated by batch assays. Results showed that Cu(II) loading concentration of 10mg/L significantly inhibited both the organic substrate removal efficiency and its specific removal rate, and the inhibitory rate was higher in the nitrification process than in the denitrification process. The removal efficiency and the specific uptake rate of NH+4-N would be significantly inhibited by the Cu(II) loading concentration of 10mg/L. As for the denitrificantion process, the feeding concentration of Cu(II) no more than 20mg/L posed no significant inhibitory effect on the final removal efficiencies of NOx−-N, however, 5mg/L Cu(II) addition would inhibit the specific nitrogen oxides uptake rate by 32.43%. The same Cu(II) loading concentrations caused much higher inhibitory rate to the specific uptake rate of the NH+4-N than to that of the NOx−-N. Additionally, the relationships between the Cu(II) loading concentrations and their inhibitory rates to the specific removal rate of COD, NH+4-N, and NOx−-N could all be well described by regression equations.

Kinetic study on nitrogen removal performance in marine anammox bacterial culture

Kinetics of anaerobic ammonium oxidation (anammox) reaction in marine anammox bacterial culture was first investigated. The nitrogen removal performance of the reactor was compared with prediction of Monod model, modified Stover-Kincannon model, first-order and the Grau second-order substrate removal models. Based on calculations, Monod model, modified Stover-Kincannon model and the Grau second-order model proved to be more appropriate to describe the nitrogen removal kinetics of the reactor than first-order model with high determination coefficients of 0.993, 0.993 and 0.991, respectively. According to the modified Stover-Kincannon model, the maximal substrate removal rate (rm) and saturation rate constant (KB) were suggested as 7.37 and 6.41 g N/L/d, respectively. In addition, in light of the Monod model, the saturation concentration (Ks) and the maximal specific substrate removal rate constant (Rm) were determined to be 0.107 g/L and 0.952 g N/g MLVSS/d, respectively. Moreover, model evaluation was carried out by assessing the linear correlation between measured and predicted values. Both kinetics study and model evaluation showed that Monod model, modified Stover-Kincannon model and the Grau second-order substrate removal models could be used to describe the kinetic behavior or design of the marine anammox reactor.

Substrate removal evaluation of granular anammox process in a pilot-scale upflow anaerobic sludge blanket reactor

Process kinetics can present necessary information for granular anammox process but little study focused on the nitrogen removal kinetics of pilot-scale anammox granular process is available. In this study, the substrate removal kinetics in a pilot-scale anammox granular reactor were investigated by inoculating anammox granules in to an UASB reactor, which was then operated at different hydraulic retention times and nitrogen loading rates. The reactor showed good tolerance to substrate concentration shock while it was affected significantly by hydraulic shock. Molecular techniques confirmed the existence of at least four well-known anammox species and anammox cells accounted for 93.7% of total cells. Evaluation of the nitrogen removal kinetics indicated that the Grau second-order substrate removal model and the modified Stover–Kincannon model turned out to be appropriate to describe nitrogen removal of anammox granules, rather than the first-order substrate removal model, the Monod model, and the Contois model. Model evaluation was then carried out via assessing the linearity between the experimental data and predicted values, which proved the applicability of the two models. The information derived from the current study could guide and optimize the design of full-scale anammox granular reactors.

Modelling a full scale membrane bioreactor using Activated Sludge Model No.1: challenges and solutions

A full-scale membrane bioreactor (1,600 m(3) d(-1)) was monitored for modelling purposes during the summer of 2006. A complete calibration of the ASM1 model is presented, in which the key points were the wastewater characterisation, the oxygen transfer and the biomass kinetics. Total BOD tests were not able to correctly estimate the biodegradable fraction of the wastewater. Therefore the wastewater fractionation was identified by adjusting the simulated sludge production rate to the measured value. MLVSS and MLSS were accurately predicted during both calibration and validation periods (20 and 30 days). Because the membranes were immerged in the aeration tank, the coarse bubble and fine bubble diffusion systems coexisted in the same tank. This allowed five different aeration combinations, depending whether the 2 systems were operating separately or simultaneously, and at low speed or high speed. The aeration control maintained low DO concentrations, allowing simultaneous nitrification and denitrification. This made it difficult to calibrate the oxygen transfer. The nitrogen removal kinetics were determined using maximum nitrification rate tests and an 8-hour intensive sampling campaign. Despite the challenges encountered, a calibrated set of parameters was identified for ASM1 that gave very satisfactory results for the calibration period. Matching simulated and measured data became more difficult during the validation period, mainly because the dominant aeration configuration had changed. However, the merit of this study is to be the first effort to simulate a full-scale MBR plant.

The kinetics of nitrogen removal and biogas production in an anammox non-woven membrane reactor

The anammox non-woven membrane reactor (ANMR) is a novel reactor configuration to culture the slowly growing anammox bacteria. Different mathematical models were used to study the process kinetics of the nitrogen removal in the ANMR. The kinetics of nitrogen gas production of anammox process was first evaluated in this paper. For substrate removal kinetics, the modified Stover-Kincannon model and the Grau second-order model were more applicable to the ANMR than the first-order model and the Monod model. For nitrogen gas production kinetics, the Van der Meer and Heertjes model was more appropriate than the modified Stover-Kincannon model. Model evaluation was carried out by comparing experimental data with predicted values calculated from suitable models. Both model kinetics study and model testing showed that the Grau second-order model and the Van der Meer and Heertjes model seemed to be the best models to describe the nitrogen removal and nitrogen gas production in the ANMR, respectively.

Economical and technical efficiencies evaluation of full scale piggery wastewater treatment BNR plants

A method evaluating the economic efficiency of piggery waste treatment plant based on kinetics for nitrogen removal performances is executed in this study and five full scale plants were evaluated, monitored intensively during one year under steady-state conditions. The performance data from those surveyed plants were recalculated by first-order kinetic equation instead of the Monod's equation, and the nitrogen removal kinetics related with COD/TKN ratios. Two plants adapting two extreme strategies for pre treatment, 'excess phase separation', and 'minimum phase separation', were evaluated by the assessment of life cycle cost (LCC). Although the compared two plants use an opposite strategy to each other, similar evaluation results are deduced by nitrogen removal efficiencies and operational and construction costs. But the proportions of constituent elements are as different as two opposite strategies, so electrical and construction costs are inversely proportional to chemical costs and operational costs respectively.