Ammonia Removal Capacity Research Articles

Nitrogen recovery from sludge centrate by membrane contactor: Influence of operating parameters and cleaning conditions

In urban wastewater treatment, the sludge generated is treated by anaerobic digestion, to be subsequently dehydrated by centrifuges. Currently, the liquid fraction obtained in this dehydration process is recirculated at the head of the treatment plant. However, its high nitrogen and phosphorus content makes it an effluent with high added value. The recovery of these nutrients could be an excellent alternative for the production of fertilizers or other industrial applications. In this study, the use of a liquid-liquid phase membrane contactor is presented as a favorable solution for the recovery of ammoniacal nitrogen from sludge centrated. The polypropylene hollow fiber membrane was evaluated considering its ammonia removal and recovery capacity. For this, different parameters were evaluated: the influence of the type and concentration of the acid solution, the wastewater pH, the flow rates of feeding and the acid stripping solution, and the contact time. Results showed that with a contact time of 65 min, ammonia removal and recovery percentages of the order of 90% were achieved. The flow rates of the stripping and feed solutions together with the acid concentration did not have a significant influence on the removal but on the recovery. Concerning used acid, sulphuric and phosphoric acid solutions achieved better results than nitric acid solution. The most critical parameter was the pH, obtaining the highest removal and recovery of ammonium at the highest pH. Finally, a stable cleaning protocol was obtained, between preventive and moderate cleanings to avoid severe cleanings, keeping the membrane at its maximum capacity.

Functional Assessment of Cardiac Arrest Hepatocytes and Effect of Mechanical Perfusion on Function in a Rat Model

BackgroundHepatocyte transplantation has been reported to be useful for metabolic diseases and acute liver failure. However, the shortage of donors limits its widespread use. The use of livers from donors after circulatory death, which are currently unavailable for liver transplantation, may alleviate donor shortage. In this study, we investigated the effects of mechanical perfusion on cardiac arrest hepatocytes in a rat model using cardiac arrest donor livers, and we evaluated the function of cardiac arrest hepatocytes. MethodsF344 rat hepatocytes isolated from livers removed during cardiac pulsation were compared with those isolated from livers removed after 30 minutes of warm ischemia after cardiac arrest. We then compared hepatocytes isolated from livers removed after 30 minutes of warm ischemia with those isolated after 30 minutes of mechanical perfusion before isolation. The yield per liver weight, ammonia removal capacity, and adenosine diphosphate/adenosine triphosphate ratio were evaluated. ResultsThirty minutes of warm inhibition reduced hepatocyte yield but did not alter ammonia removal capacity and energy status. Mechanical perfusion increased hepatocyte yield and improved the adenosine diphosphate/adenosine triphosphate ratio after 30 minutes of warm inhibition. ConclusionThirty minutes of warm ischemic time may decrease isolated hepatocyte yield without degrading their function. If increased yields are obtained, livers from donors dying of cardiac arrest could be used for hepatocyte transplantation. The results also suggest that mechanical perfusion may positively affect the energy status of hepatocytes.

A systematic approach based on artificial intelligence techniques for simulating the ammonia removal by eighteen deep eutectic solvents

The current research attempts to model the ammonia removal capacity of deep eutectic solvents (DES) employing artificial intelligence (AI) techniques. Four well-known AI classes apply to estimate the ammonia dissolution amount in eighteen DESs. The DES chemistry (type, molar concentration of components, and water dose), equilibrium temperature/pressure, and DES-ammonia absorption enthalpy help AI models estimate the ammonia solubility in DESs. The combination of trial-and-error and statistical analysis determines the best structure of AI models first. Then, several well-established model selection strategies apply to find the highest-accurate AI class. It was found that the adaptive neuro-fuzzy inference system (ANFIS) is more reliable than the other tested AI models. The designed ANFIS model precisely estimates 1356 experimental samples of ammonia removal by DESs with the mean absolute relative deviation percent of 3.51, mean absolute deviation percent of 0.121, root mean squared error of 0.216, and correlation of determination of 0.9980. The selected AI model monitors the influence of DES components, molar dose, equilibrium pressure, and equilibrium pressure on ammonia elimination by these green solvents. Both trend and relevancy investigations approved that the ammonia absorption tendency of DESs intensifies by increasing the equilibrium pressure, absorption enthalpy, the number of moles of hydrogen bond acceptor (HBA), and molecular weight of hydrogen bound donor (HBD). In addition, increasing the equilibrium temperature, water dosage in DES structure, HBA molecular weight, and the number of HBD moles decreases ammonia removal by DESs.

New insight into ammonium removal in riverbanks under the exposure of microplastics

Riverbanks play the key role in ammonium removal from runoff entering river. Currently, microplastics (MPs) are frequently detected in riverbanks receiving urban and agricultural runoff. Nevertheless, the effect of MPs accumulation on ammonium removal in riverbanks is still unknown. We utilized sediment flow-through reactors to investigate the impact and mechanism of MPs accumulation on ammonium removal in riverbanks. These results revealed that MPs accumulation decreased ammonium removal in sediment by 8.2 %−12.8 % resulting from the reduction in nitrifier abundance (Nitrososphaera and Nitrososphaeraceae) and genes encoding ammonium and hydroxylamine oxidation (amoA, amoB, amoC, and hao) by MPs accumulation. Furthermore, MPs accumulation decreased the substrate and gene abundance of hydroxylamine oxidation process to reduce N2O emission (16.3 %−34.3 %). Notably, mathematic model verified that sediment physical properties changed by MPs accumulation were direct factors affecting ammonium removal in riverbank. It was suggested that both the biotoxicity of MPs and sediment physical properties should be considered in the ammonium removal process. To summarize, this study for the first time comprehensively clarifies the impact of MPs on the ammonium removal capacity of riverbanks, and provides information for taking measures to protect the ecological function of the riverbank and river ecosystem from MPs and ammonium pollution.

Indole-Acetic Acid Promotes Ammonia Removal Through Heterotrophic Nitrification, Aerobic Denitrification With Mixed Enterobacter sp. Z1 and Klebsiella sp. Z2.

Mixed Enterobacter sp. Z1 and Klebsiella sp. Z2 displayed an outstanding ammonia removal capacity than using a single strain. Metabolomics, proteomics, and RNA interference analysis demonstrated that the HNAD process was closely related to indole-acetic acid (IAA). Under the cocultured conditions, the excess IAA produced by Z2 could be absorbed by Z1 to compensate for the deficiency of IAA in the cells. IAA directly induced the expression of denitrifying enzymes and further activated the IAA metabolism level, thus greatly improving the nitrogen removal ability of Z1. In turn, nitrate and nitrite induced the expression of key enzymes in the IAA pathways. Moreover, Z1 and Z2 enhanced two IAA metabolic pathways in the process of mixed removal process. The activated hydrolysis-redox pathway in Z1 reduced the oxidative stress level, and the activated decarboxylation pathway in Z2 promoted intracellular energy metabolism, which indirectly promoted the process of HNAD in the system.

Bio-composite of nipa palm husk derived activated carbon/poly(butylene succinate): an effective agricultural waste based adsorbent for ammonia removal

In this work, activated materials were successfully prepared by pyrolyzing various ratios of Nipa palm husk powder to potassium hydroxide (1:1, 1:2, and 1:3) at predetermined temperatures (500℃, 600℃, and 700℃). The surface area was obtained from nitrogen isotherms using the Brunauer-Emmett-Teller (BET) equation. The surface area of the prepared activated carbon was increased with decreasing potassium hydroxide impregnation ratio and increasing pyrolyzing temperature. The highest surface area was 1,211 m2×g-1. In contrast, acidic surface functional groups investigated by Boehm’s titration were increased with decreasing pyrolyzing temperature and impregnation ratio. Ammonia removal capacity was increased with an increase in the acidic surface functional groups on prepared activated carbon. Therefore, the activated sample with the highest acidic surface functional groups contents provided the greatest ammonia adsorption of around 95% (from 100 ppm to 5 ppm), implying that ammonia removal capacity was closely related to the acidic surface functional groups on the activated carbon. Adsorptive poly(butylene succinate) was carried out by incorporating activated carbon into the poly(butylene succinate) matrix for ammonia adsorption. This adsorption increased with increasing activated carbon content so that it was found that 12 wt% activated carbon provided the highest ammonia adsorption by reducing ammonia from 108 ppm to 26 ppm.

The efficiency of zeolites in water treatment for combating ammonia – An experimental study on Yamuna River water & treated sewage effluents

This study was meant to study the effectiveness of natural and synthetic zeolites in water treatment for combating ammonia nitrogen so that specific zeolites could be utilized at waterworks and sewage disposal works. In this study, three different zeolites were utilized in their pristine state, namely natural clinoptilolite, natural mordenite, and synthetic zeolites 4A. We examined the zeolites for their ammonia removal capacity. We performed experimental studies on synthetically prepared ammonia water, the Yamuna River water, and municipally treated sewage effluents by using Jar Test Apparatus at 100 RPM. Ammonia nitrogen content was determined by nesslerization standard method using a spectrophotometer. It has been observed that all zeolites are significantly effective in treating ammonia nitrogen in artificially prepared ammonia nitrogen water without having competing ions interference. However, because competing ions interfere in natural water, its use limits ammonium ions removal. Based on the present study outcomes, the authors have suggested replacing sand media from Rapid Sand Filters and Slow Sand Filters with Mordenite and Clinoptilolite at municipal water treatment utilities to combat low amounts of ammonium ions.

Manganese oxides in Phragmites rhizosphere accelerates ammonia oxidation in constructed wetlands

Phragmites reeds are widely used in constructed wetlands (CWs) for treating wastewater. The enrichment of microorganisms and Fe/Mn plaque in Phragmites rhizospheres largely contributes to pollutant removal. However, their interactions and potential synergistic roles in water purification are poorly understood. To address the issue, we first compared the microbial community traits in the Phragmites rhizosphere and adjacent bulk soil in six long-term operated CWs. Results showed that enriched microbes and functional genes in the Phragmites rhizosphere were largely involved in Mn oxidation, resulting in a two to three times enrichment of Mn oxides in the rhizosphere. In turn, the enriched Mn oxides played significant roles in driving microbial community composition and function. To further understand the biological manganese oxidation in the rhizosphere, we identified Mn-oxidizing bacteria using genome-centric analysis and found that 92% of identified Mn-oxidizing bacteria potentially participated in nitrogen cycling. We then conducted relationships between Mn-oxidizing genes and different nitrogen cycling genes and found Mn-oxidizing gene abundance was significantly correlated with ammonia oxidation gene amoA (R = 0.65). Remarkably, complete ammonia oxidation (comammox) Nitrospira, accounting for 39.11% of ammonia oxidizers, also positively correlated with Mn-oxidizing microbes. Based on the above observations, we inferred that the use of Mn oxides as a substrate in CWs may enhance ammonia oxidation. To apply this to actual engineering, we explored treatment performance in a pilot-scale Mn-amending CW. As expected, ammonia removal capacity improved by 23.34%, on average, in the Mn-amending CW. In addition, the abundance of amoA genes increased significantly in the Mn-amending CW, indicating improved biological processes rather than chemical reactions.

High Performance Mixed-Matrix Electrospun Membranes for Ammonium Removal from Wastewaters.

Mixed-matrix electrospun membranes were developed to investigate ammonium removal from low ammonium concentration wastewaters for the first time. Particles derived from the inexpensive zeolite 13X were successfully incorporated into polyethersulfone (PES) matrices. The fabricated mixed-matrix electrospun membranes demonstrate high ammonium removal capacity reaching over 55 mg/gzeolite, more than 2.5 times higher than the previously fabricated mixed-matrix membranes via non-solvent induced phase inversion. Moreover, the membranes fabricated exhibit high permeability and ease of regeneration. Over 90% of total ammonium nitrogen (TAN) can be removed from low TAN wastewaters such as aquaculture wastewaters. In addition to zeolite 13X, other zeolite particles including zeolite Y, zeolite 3A and 4A were also incorporated into the membrane matrix. The inexpensive zeolite 13X show the highest ammonium exchange capacity. Particle type, loading and the level of its dispersion all affect TAN removal capacity.

Ammonia Removal by Metabolic Scavengers for the Prevention and Treatment of Hepatic Encephalopathy in Cirrhosis.

Effective lowering of circulating ammonia is the mainstay strategy in the prevention and treatment of hepatic encephalopathy in cirrhosis and there is increasing interest in agents with the metabolic potential for the active removal of ammonia by the liver and skeletal muscle by agents including l-ornithine l-aspartate, branched-chain amino acids, as well as the re-purposing of benzoate and phenylacetate currently employed for the control of hyperammonaemia in congenital urea-cycle enzymopathies. Based upon results of multiple systematic reviews with meta-analyses, l-ornithine l-aspartate demonstrably lowers circulating ammonia in patients with cirrhosis with concomitantly improved mental status. Distinct mechanisms responsible include optimisation of hepatic metabolic pathways for ammonia removal as well as direct hepatoprotective effects involving the release of glutathione and of nitric oxide with beneficial effects on hepatic microcirculation. l-ornithine l-aspartate also prevents cirrhosis-related sarcopenia, leading to increased capacity for ammonia removal by skeletal muscle. Branched-chain amino acids continue to be prescribed as nutritional supplements with the potential to result in improvements in liver function. Sodium benzoate, glycerol phenylbutyrate and an analogous compound l-ornithine phenylacetate were also evaluated. Glycerol phenylbutyrate was the only agent with a beneficial effect on both hyperammonaemia and hepatic encephalopathy. None were superior to lactulose for the lowering of blood ammonia.

Temperature-Dependent Ammonium Removal Capacity of Biological Activated Carbon Used in a Full-Scale Drinking Water Treatment Plant

Nitrification is a key function of biological activated carbon (BAC) filters for drinking water treatment. It is empirically known that the nitrification activity of BAC filters depends on water temperature, potentially resulting in the leakage of ammonium from BAC filters when the water temperature decreases. However, the ammonium removal capacity of BAC filters and factors governing the capacity remain unknown. This study employed a bench-scale column assay to determine the volumetric ammonium removal rate (VARR) of BAC collected from a full-scale drinking water treatment plant. VARR was determined at a fixed loading rate under different conditions. Seasonal variations of the VARR as well as impacts of the water matrix and water temperature on ammonium removal were quantitatively analyzed. While the VARR in an inorganic medium at 25 °C was maintained even during low water temperature periods and during breakpoint chlorination periods, the water matrix factor reduced the VARR in ozonated water at 25 °C by 33% on average. The VARR in ozonated water was dependent on water temperature, indicating that the microbial activity of BAC did not adapt to low water temperature. The Arrhenius equation was applied to reveal the relationship between VARR and water temperature. The actual ammonium removal performance of a full-scale BAC filter was predicted. VARR is useful for water engineers to reexamine the loading and filter depth of BAC filters.

Pomegranate peel as a new low-cost adsorbent for ammonium removal

Since adsorption is one of the best ammonium removal methods, great efforts have been made to identify new low-cost and efficient adsorbents from agricultural waste and by-products due to their abundant availability, low-cost and eco-friendly advantages, in addition to the possibility of recycling ammonium back into agricultural processes. In this study, a series of batch experiments were performed to detect new bio-adsorbents for ammonium ions removal. Among the materials tested, pomegranate peel powder showed a high affinity to adsorb ammonium ions and, furthermore, available information on ammonium adsorption by this biomaterial is still missing from the literature. First, pomegranate peel powder was characterized by the determination of different parameters such as zeta potential, iodine number, Fourier-transform infrared spectroscopy analysis, scanning electron microscopy, particle size distribution and porosity. Then, the impact of various parameters, such as pH, contact time, stirring speed, adsorbent dose and adsorbate concentration in the adsorption process, was investigated. The highest ammonium removal capacity was obtained at pH = 4 using 400 mg of pomegranate peel powder and a stirring speed of 150 rpm for an initial concentration of ammonium of 30 mg/L. The system (adsorbent, adsorbate and solution) reached equilibrium after 2 h and the data fit well with the Langmuir model with a maximum monolayer adsorption capacity of 6.18 mg/g, while kinetics were well described by the pseudo-second-order model. These results introduce pomegranate peel powder as a promising bio-adsorbent to remove and recover ammonium from aqueous solutions.

Selective Recovery of Ammonia Nitrogen from Wastewaters with Transition Metal-Loaded Polymeric Cation Exchange Adsorbents.

Extracting valuable products from wastewaters with nitrogen-selective adsorbents can offset energy-intensive ammonia production, rebalance the nitrogen cycle, and incentivize environmental remediation. Separating nitrogen (N) as ammonium from other wastewater cations (e.g., K+ , Ca2+ ) presents a major challenge to N removal from wastewater and N recovery as high-purity products. High selectivity and capacity were achieved through ligand exchange of ammonia with ammine-complexing transition metals loaded onto polymeric cation exchange resins. Compared to commercial resins, metal-ligand exchange adsorbents exhibited higher ammonia removal capacity (8 mequiv g-1 ) and selectivity (N/K+ equilibrium selectivity of 10.1) in binary equimolar solutions. Considering optimal ammonia concentrations (200-300 mequiv L-1 ) and pH (9-10) for metal-ligand exchange, hydrolyzed urine was identified as a promising candidate for selective TAN recovery. However, divalent cation exchange increased transition metal elution and reduced ammonia adsorption. Ultimately, metal-ligand exchange adsorbents can advance nitrogen-selective separations from wastewaters.

Development of an oyster shell and lignite modified zeolite (OLMZ) fixed bioreactor coupled with intermittent light stimulation for high efficient ammonium-rich anaerobic digestion process

A novel oyster shell and lignite modified zeolite (OLMZ) fixed bioreactor incorporated with intermittent light illumination process was developed for alleviating ammonia inhibition to improve efficiency of ammonium-rich anaerobic digestion (AD). The SEM morphology of the newly synthesized OLMZ showed porous structure and rough surface, with increased BET surface area compared to unmodified zeolite (UMZ). After modification with oyster shell and lignite, the metal cations content in OLMZ increased significantly and the ammonia adsorption capability of OLMZ improved by 1.3 folds compared to UMZ. Thus, the results suggested that OLMZ is a better adsorbent than UMZ for ammonia uptake. Furthermore, the pseudo-second-order kinetics and the isotherm results verified the adsorption of ammonia on OLMZ was dominated by ion exchange with high affinity for ammonia uptake. As for the anaerobic digestion, the light illuminated OLMZ fixed bioreactor process (OLMZ-I) resulted in the highest methane yield of 372 ± 30 mL/g-DOCremoved, which showed 300% increase compared to the control (124 ± 12 mL/g-DOCremoved). In addition, OLMZ-I showed higher ammonia removal capacity and stable pH which indicated that the ammonia inhibition was effectively mitigated. Correspondingly, metal cations supplementation and light stimulation in OLMZ-I showed increased ATP and coenzyme F420 implying high activation of methanogens leading to improved CH4 production. The large biomass quantity and SEM observation of microbes immobilized on the fixed OLMZ system aided by light further supported the enhanced performance of the reactor. Furthermore, the conductance of sludge in OLMZ-I bioreactor increased 3 folds compared to the control, reflecting a potential direct interspecies electron transfer (DIET) between the anaerobes was strengthened. The synergetic effects of ammonia removal, microbes immobilization, metal cations supplementation and accelerated electrical communication between methanogenic system combined with light stimulation on methanogen activation facilitated the enhancement of methanogenesis. Therefore, the OLMZ fixed bioreactor coupled with intermittent light stimulation shows great potential in practical application for bioconversion of ammonium-rich livestock waste.

Influences of organic nitrogen on the removal of inorganic nitrogen from complicated marine aquaculture water by Marichromatium gracile YL28

The sediment-water interface is not only an important location for substrate conversion in a mariculture system, but also a major source of eutrophication. This study aimed to clarify the characteristics of inorganic nitrogen (ammonia, nitrite and nitrate) removal by Marichromatium gracile YL28 in the presence of both organic nitrogen and inorganic nitrogen. The results showed that, in the presence of peptone or urea, seaweed oligosaccharides (SOS) effectively enhanced the ammonia removal capacity of YL28 (6.42mmol/L) and decreased the residual rate by 54.04% or 8.17%, respectively. With increasing peptone or urea concentrations, the removal of both ammonia and nitrate was gradually inhibited, and the residual rates of ammonia and nitrate reached 22.56-34.36% and 12.03-15.64% in the peptone system and 20.65-24.03% and 12.20-13.21% in the urea system, respectively. However, in the control group the residual rates of ammonia and nitrate reached 11.97% and 5.12%, respectively. In addition, the concentrations of peptone and urea did not affect nitrite removal, and YL28 displayed better cell growth and nitrogen removal activity in the presence of bait and SOS. Overall, the ability of YL28 to remove inorganic nitrogen was enhanced in the presence of organic nitrogen.

Investigating the effect of copper and magnesium ions on nitrogen removal capacity of pure cultures by modified non-competitive inhibition model

Copper, a common heavy metal, may be beneficial for or poisonous to microbial activity. The objective of this study was to determine the effect of different copper ion concentrations on the nitrogen removal performance of Arthrobacter arilaitensis strain Y-10 and Pseudomonas taiwanensis strain J488. The non-competitive inhibition model was employed to evaluate the 50% inhibition concentrations (IC50 values) of copper ions toward the pure strains. In the absence of magnesium ions, a low concentration of copper (0.1 mg/L) significantly enhanced the ammonium removal ability of strain Y-10 and its removal efficiency increased by 10.88% compared with the control treatment. Copper ranging from 0 to 0.1 mg/L had no significant effect on the ammonium removal capacity of strain J488. After adding 9.90 mg/L of magnesium to the basal medium, the effects of copper on nitrification of ammonium or denitrification of nitrate or nitrite were also assessed. In these conditions, 0.25 mg/L copper ions could strongly inhibit the ammonium, nitrate and nitrite removal activities for strain Y-10. For strain J488, no clear deterioration in ammonium removal efficiency was observed at copper ion concentrations below 0.5 mg/L, but 0.25 mg/L copper ions significantly inhibited nitrate and nitrite removal efficiencies, which were only 45.88% and 6.35%, respectively. The IC50 values of copper ions for nitrate and nitrite removal by strain Y-10 were 0.195 and 0.090 mg/L respectively; for strain J488, the IC50 values were 0.175 and 0.196 mg/L. The magnesium ions could improve the cell growth, nitrogen removal efficiency and copper ion resistance of bacteria.

Influence of pyrolysis temperature on production of digested sludge biochar and its application for ammonium removal from municipal wastewater

Water contamination by ammonium (NH4+) can present considerable risks to natural ecosystems. This work evaluates the potential application of biochar, produced from the pyrolysis of digested sludge, to remove ammonium from water. Anaerobic digester sludge was collected from a municipal wastewater treatment plant in Alberta, Canada, and individual biochars were produced at 50 °C temperature increments between 350 °C and 550 °C. The chemical characteristics of the resulting biochars were determined using elemental analysis, scanning electron microscopy (SEM), BET surface area analysis, and Fourier transform infrared spectroscopy (FTIR). Our findings demonstrate that the biochar yield decreased with increasing pyrolysis temperature, and biochar produced at 450 °C (BC450) had the highest ammonium removal capacity due to its higher surface area and functional group density. The Langmuir isotherm best described the observed ammonium removal capacity by the biochars, indicating that monolayer chemical adsorption may be the dominating mechanism. Biochar ammonium removal capacity was 1.2 mg NH4N per gram of biochar in municipal wastewater, which is lower than that observed in parallel experiments using a synthetic ammonium solution (1.4 mg NH4+-N/g biochar). This phenomenon is likely due to competition between ammonia and other containments for sorption to biochar surface sites. Our results demonstrate for the first time ever that biochar produced from digester sludge is a promising adsorbent for ammonium removal from municipal wastewater.

Evaluation of Natural Minerals (Zeolite and Bentonite) for Nitrogen Compounds Adsorption in Different Water Temperatures Suitable for Aquaculture

In this study, it was aimed to determine the effects of zeolite and bentonite on the ammonium adsorption at different temperatures. In this research three trial groups with 3 repetitions were created for three different water temperatures (18±0.1°C, 24±0.0°C, 27±0.0°C). Experimental groups were prepared by adding NH4+ amount of 10.5 mg/l in 2 liters of water. After that, zeolite, zeolite+bentonite and bentonite were added into the bottles as 10 gram per liter. Water temperature, pH and TAN (Total Ammonium Nitrogen) values were determined during the trial period. At the end of trial TAN values at 27 °C were recorded as 10.103±0.11 mg/l, 9.227±0.13 mg/l and 7.933±0.17 mg/l in zeolite, zeolite+bentonite and bentonite groups, respectively. At the end of trial TAN values at 24 °C were recorded as 10.027±0.17 mg/l, 9.282±0.15 mg/l and 8.336±0.15 mg/l in zeolite, zeolite+bentonite and bentonite groups, respectively. At the end of trial TAN values at 18 °C were recorded as 9.012±0.28 mg/l, 7.702±0.14 mg/l and 6.594±0.14 mg/l in zeolite, zeolite+bentonite and bentonite groups, respectively. Maximum ammonium removal capacity, qe, was found to be 0.50 mg/g in the bentonite (18 °C). The TAN values determined at 18 °C were statistically more significant (p<0.05) than the TAN values obtained at 24 °C and 27 °C.

Evaluation of Natural Minerals (Zeolite and Bentonite) for Nitrogen Compounds Adsorption in Different Water Temperatures Suitable for Aquaculture

In this study, it was aimed to determine the effects of zeolite and bentonite on the ammonium adsorption at different temperatures. In this research three trial groups with 3 repetitions were created for three different water temperatures (18±0.1°C, 24±0.0°C, 27±0.0°C). Experimental groups were prepared by adding NH4+amount of 10.5 mg/l in 2 liters of water. After that, zeolite, zeolite+bentonite and bentonite were added into the bottles as 10 gram per liter. Water temperature, pH and TAN (Total Ammonium Nitrogen) values were determined during the trial period. At the end of trial TAN values at 27 °C were recorded as 10.103±0.11 mg/l, 9.227±0.13 mg/l and 7.933±0.17 mg/l in zeolite, zeolite+bentonite and bentonite groups, respectively. At the end of trial TAN values at 24 °C were recorded as 10.027±0.17 mg/l, 9.282±0.15 mg/l and 8.336±0.15 mg/l in zeolite, zeolite+bentonite and bentonite groups, respectively. At the end of trial TAN values at 18 °C were recorded as 9.012±0.28 mg/l, 7.702±0.14 mg/l and 6.594±0.14 mg/l in zeolite, zeolite+bentonite and bentonite groups, respectively. Maximum ammonium removal capacity, qe, was found to be 0.50 mg/g in the bentonite (18 °C). The TAN values determined at 18 °C were statistically more significant (p<0.05) than the TAN values obtained at 24 °C and 27 °C.

Highly efficient nitrogen removal of a coldness-resistant and low nutrient needed bacterium, Janthinobacterium sp. M-11

A novel heterotrophic nitrification-aerobic denitrification bacterium, identified as Janthinobacterium sp. M-11, was isolated from the Songhua River. When the initial ammonium concentration was 5 mg·L−1, 98% of ammonium was removed under cold condition (2 °C) with the C/N ratio of 5 at initial pH 7 and aerobic condition, which demonstrated the significant ammonium removal capacity of M-11 with low nutrient consumption at cold temperature. Denitrification processes under aerobic and anaerobic conditions were also investigated. 89% of nitrite and 89% of nitrate were removed under aerobic condition. Under anaerobic condition, 93% of nitrite and 98% of nitrate were removed. Interestingly, a high amount of nitrite accumulation was observed in the mid-stage of anaerobic denitrification for nitrate. This special phenomenon was probably because of the existence of narG gene amplified in the strain M-11, which would encode membrane-bound nitrate reductase and accelerate the nitrate conversion rate of M-11 under anaerobic condition.