Uptake Of Ammonium Ions Research Articles

Co-utilization of microalgae and heterotrophic microorganisms improves wastewater treatment efficiency

Wastewater treatment using the activated sludge method requires a large amount of electricity for aeration. Therefore, wastewater treatment using co-culture systems of microalgae and heterotrophic microorganisms, which do not require aeration, has attracted attention as an energy-saving alternative to the method. In this study, we investigated different combinations of microalgae and heterotrophic microorganisms to improve the efficiency of wastewater treatment. Three types of microalgae and five heterotrophic microorganisms were used in combination for wastewater treatment. The combination of Chlamydomonas reinhardtii NIES-2238 and Saccharomyces cerevisiae SH-4 showed the highest wastewater treatment efficiency. Using this combination for artificial wastewater treatment, the removal rates of total organic carbon, PO43−, and NH4+ reached 80%, 93%, and 63%, respectively, after 18 h of treatment. To the best of our knowledge, this is the first study to show that a combination of green algae and yeast improves the efficiency of wastewater treatment. Transcriptome analysis revealed that the combined wastewater treatment altered the expression of 1371 and 692 genes in C. reinhardtii and S. cerevisiae, respectively. One of the main reasons for the improved wastewater treatment performance of the combination of green algae and yeast was the increased expression of genes related to the uptake of phosphate and ammonium ions in the green algae. As both the green algae C. reinhardtii and the yeast S. cerevisiae are highly safe microorganisms, the establishment of their effective combination for wastewater treatment is highly significant.Key points• Combination of various microalgae and heterotrophic microorganisms was tested• Combination of green algae and yeast showed the highest efficiency• This is the first report that this combination is effective for wastewater treatment

Uptake and distribution of the inorganic components NH4+ and NO3− in PM2.5 by two Chinese conifers

Plants can effectively purify PM2.5 in the air, thereby improving air quality. Understanding the mechanisms of the uptake and distribution of PM2.5 in plants is crucial for enhancing their ecological benefits. In this study, the uptake and distribution of the water-soluble inorganic compounds ammonium (NH4+) and nitrate (NO3−) ions in PM2.5 by the two native Chinese conifers Manchurian red pine (Pinus tabuliformis) and Bunge's pine (P. bungeana) were investigated using a one-time aerosol treatment method combined with 15N tracing. The results showed the following: (1) Plants can efficiently uptake NH4+ (0.08–0.21 μg/g) and NO3− (0.03–0.68 μg/g) from PM2.5. Manchurian red pine uptakes these compounds more effectively with increases of 2.01-fold for NH4+ and 1.02-fold for NO3− compared with Bunge's pine. (2) The aboveground organs of the plants uptake and distribute more 15N than the belowground organs. The branches had the highest unit mass uptake (0.08–1.60 μg/g) and rate of distribution (16.91–53.60 %) for NH4+, while the leaves had the highest unit mass uptake (0.15–1.18 μg/g) and rate of distribution (50.78–84.88 %) for NO3−. (3) The ability of the aboveground organs to uptake 15N is influenced by the concentration of PM2.5, which showed an overall increase with increasing concentrations with some fluctuations in specific organs. However, the belowground organs were not affected by the concentration of PM2.5. (4) A larger specific leaf area, root-shoot ratio, branch biomass ratio, coarse root biomass ratio, and lower trunk biomass ratio favors the uptake of NH4+ from PM2.5, whereas these traits had a minimal influence on the uptake of NO3−. Manchurian red pine uptaked significantly more NH4+ compared with Bunge's pine, which benefited from the traits described above. These findings further revealed the mechanism of PM2.5 uptake by plants and its relationship with PM2.5 concentration and plant traits, and provided a scientific basis for how to effectively utilize plants to reduce PM2.5 pollution and purify the environment in areas with different pollution concentrations.

Phosphorylation regulation of nitrogen, phosphorus, and potassium uptake systems in plants

The uptake of ammonium, nitrate, phosphorus, and potassium ions by roots is mediated by specific ion transporter or channel proteins, and protein phosphorylation regulation events occurring on these proteins and their regulators determine their ultimate activity. Elucidating the mechanism by which protein phosphorylation modification regulates nutrient uptake will advance plant breeding for high nutrient-use efficiency. In this review, it is concluded that the root nutrient absorption system is composed of several, but not all, members of a specific ion transporter or channel family. Under nutrient-starvation conditions, protein phosphorylation-based regulation of these proteins and associated transcription factors increases ion transporter- or channel-mediated nutrient uptake capacity via direct function activity enhancement, allowing more protein trafficking to the plasma membrane, by strengthening the interaction of transporters and channels with partner proteins, by increasing their protein stability, and by transcriptional activation. Under excessive nutrient conditions, protein phosphorylation-based regulation suppresses nutrient uptake by reversing these processes. Strengthening phosphorylation regulation items that increase nutrient absorption and weakening phosphorylation modification items that are not conducive to nutrient absorption show potential as strategies for increasing nutrient use efficiency.

Epilepsy dynamics of an astrocyte-neuron model with ammonia intoxication

Experimental records in the cerebral cortex indicate that ammonia injection can lead to seizures. Considering that astrocytes play a vital role in mediating the uptake and absorption of ammonium ions in the extracellular space of the cortical circuit, we constructed a new astrocyte neuron coupling model, which is composed of a neuron and its astrocytes connected through the extracellular space, taking into account of the influence of extracellular ammonium ions. The numerical results verified the previous experimental observation that obtained epileptic firing modes of neurons and postsynaptic GABA reversal potential depolarization triggered by ammonia injection. In addition, we also determined the concentration–response relationship between the ammonium ion concentration and the time of entering epilepsy and predicted the threshold of the ammonium ion concentration for the onset of epilepsy.

The effect of different green alkali modification processes on the clinoptilolite surface as adsorbent for ammonium ions; characterization and application

Abstract Clinoptilolite natural zeolite was modified by different alkali bearing salts (K, Na, Ca, and Mg) by a green process in the presence of green tea extract as promising green adsorbents for ammonium ions. The modified products displayed significant enhancement in the ion exchange capacities, the surface area, and the morphological properties which was supported by different characterization techniques. The novel modified products achieved stunning adsorption capacities for ammonium ions with experimental qmax of 162 mg/g, 190 mg/g, 230 mg/g and 296 mg/g for K/clinoptilolite, Na/clinoptilolite, Ca/clinoptilolite, and Mg/clinoptilolite, respectively. The theoretical values which were obtained from the equilibrium model are 197.5 mg/g, 219.7 mg/g, 256.2 mg/g, and 340 mg/g for the same products in the order. The adsorption systems of all the prepared adsorbents are highly fitted with both the Pseudo-First order and Pseudo-Second order model with preferences for the first model. Additionally, the uptake of ammonium ions by them is of a monolayer form and of higher fitting with the Langmuir model than the other models considering the correlation coefficient and Chi-squared (χ2) values. The theoretical adsorption energies of K/Clinoptilolite (0.64 kJ/mol), Na/Clinoptilolite (0.76 kJ/mol), Ca/Clinoptilolite (0.9 kJ/mol), and Mg/Clinoptilolite (0.81 kJ/mol) signify physisorption mechanism close to the values of zeolite ion exchange process or coulumbic attractive forces. The modified clinoptilolite products are of high reusability values and applied effectively in the purification of real groundwater and sewage water.

Preparation of modified Chinese medical stone and its performance on the removal of low-concentration ammonium from water

The ammonium ion occurrence in excess consequences in the adverse effects on the ecosystem, and human health. The experiment was conducted using the Chinese medical stone to remove ammonium ion from the water. The Chinese medical stone was modified by citric acid monohydrate and designed to identify the ammonium ion uptake capacity by the MMS and focused on evaluating the adsorption and kinetics isotherm, modifier’s concentration, contact time and initial concentration effects on MMS performance. The modification process was well-appointed by mixing and shaking at 180 rpm; at 60 °C; for eighth, at mixing ratio 1:20 of the UMMS with 0.2 mol concentration of citric acid monohydrate solution. The optimum adsorption performance was determined using Beaker sequence batch test method. The SEM micrographs; BET and FTIR of UMMS and MMS tests have undertaken and evaluated. The result showed that the maximum adsorption amount of MMS to ammonium ions was 5.38 mg/g at 50 mg/L ammonium ion concentration by the experiment, and the qe max was 3.5 mg/g from Langmuir equation. The ammonium adsorption by the MMS had fitted for both the Langmuir isotherm and the Freundlich isotherm models and also adapted to the kinetic parameter pseudo-second-order model shows a superior expectation of the sorption kinetics.

Mechanochemistry-Based Synthesis of Highly Crystalline γ-Zirconium Phosphate for Selective Ion Exchange.

Highly crystalline γ-zirconium phosphate has been synthesized by a novel minimalistic approach and investigated as a selective ion exchanger for cesium, ammonium and potassium. In contrast to current solution-based preparations, the mechanochemistry-based synthesis provides easy access to γ-zirconium phosphate with short synthesis times and low crystallization temperature. The addition of NaF as a mineralizer increases the crystallinity of γ-zirconium phosphate, which forms micrometer-sized uniformly shaped rectangular platelets. The crystalline material has extremely high selectivity to cesium even in the presence of 1000- or 500-fold excess Na+ or Ca2+, respectively. The removal efficiency was >98% in the pH range of 2-5.5. As an ion exchanger for purification of dialysate, crystalline γ-zirconium phosphate shows higher uptake of ammonium and potassium ions than the amorphous gel compound currently used in sorbent cartridges. This sustainable protocol opens up opportunities for many practical applications of γ-zirconium phosphate.

Interaction of Different Wheat Genotypes and Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate Using 15N Isotope Tracing Techniques

ABSTRACTTo investigate the effect of applying 15N-labeled ammonium sulfate with or without a nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on fertilizer use efficiency and crop productivity of different wheat genotypes, a field trial was conducted at the Nuclear Agricultural Department’s farm of Iran in 2013–2014. The treatments included five wheat genotypes with different 13 C isotope discrimination and three fertilizer treatments, an unfertilized control, 15N-labeled ammonium sulfate, and 15N-labeled ammonium sulfate with DMPP in three replications. Soil samples were taken after 2, 4, and 6 weeks after sowing and also at harvest time. Results from 15N experiment showed that DMPP delayed nitrification of ammonium for 42 days. Genotypes with lower discrimination index had greater uptake of ammonium ions which led to increase crop yield and nitrogen fertilizer use efficiency. The results also suggested that the use of DMPP may not be beneficial in some fast growing wheat genotypes.

Sampling of ammonium ion in water samples by using the diffusive-gradients-in-thin-films technique (DGT) and a zeolite based binding phase

We have investigated the possibility of sampling ammonium ion using the diffusive-gradients-in-thin-films technique (DGT) by introducing a novel binding agent that is based on micro-sized zeolite. The performance of zeolite-DGT was characterized by measurement of the following parameters: (1) the diffusion coefficient of ammonium ion in hydrogel; (2) the adsorption rate of ammonium ion by the zeolite binding gel; (3) the elution efficiency, and (4) the effects of pH, ionic strength and interfering ions on DGT. The method was validated by studying the uptake of ammonium ion from in freshwaters by zeolite gels which was found to be fast enough to meet the requirements of DGT. The concentrations determined via DGT agreed well with the concentrations determined in bulk solutions. Sampling of ammonium ion using zeolite-DGT was consistent over the pH 3 to 8 range and the 0.001 to 10 mM ionic strength range. The method also performs predictably in natural waters containing various metal ions. The technique is considered to be a viable passive tool for sampling ammonium from aqueous solutions.

Using immobilized cyanobacteria and culture medium contaminated with ammonium for H2 production in a hollow-fiber photobioreactor

An inorganic culture medium contaminated with ammonium was used to generate molecular hydrogen by cyanobacteria. First, ammonium ion uptake by immobilized on hollow fibers cells of cyanobacterium Anabaena variabilis was studied in flasks and in a photobioreactor. Next, after the ammonium was removed from water, H2 production by hollow fibers-immobilized cyanobacterial cells was investigated in flasks and in a photobioreactor. The photobioreactor was designed so that the growth medium with ammonium from a medium reservoir (where ammonium ion concentration was measured) was cycled through a photobioreactor column with hollow fiber-attached cells. The ammonium ion uptake efficiency by attached cells in the photobioreactor was found to be 90% after 25 days. The depletion of the ammonium in water inside a photobioreactor stimulated H2 production by cyanobacteria which was observed at an average rate of 18 mL·g dw−1·h−1 for three months.

Gigantic Swelling of Inorganic Layered Materials: A Bridge to Molecularly Thin Two-Dimensional Nanosheets

Platy microcrystals of a typical layered material, protonated titanate, have been shown to undergo an enormous degree of swelling in aqueous solutions of various amines, including tertiary amines, quaternary ammonium hydroxides, and primary amines. Introducing these solutions expanded the crystal gallery height by up to ~100-fold. Through systematic analysis, we determined that ammonium ion intercalation is predominantly affected by the acid-base equilibrium and that the degree of swelling or inflow of H2O is controlled by the osmotic pressure balance between the gallery and the solution environment, both of which are relatively independent of electrolyte identity but substantially dependent on molarity. In solutions of tertiary amines and quaternary ammonium hydroxides, the uptake of ammonium ions increases nearly linearly with increasing external concentration before reaching a saturation plateau, i.e., ~40% relative to the cation-exchange capacity of the crystals used. The only exception is tetrabutylammonium ions, which yield a lower saturation value, ~30%, owing to steric effects. The swelling behaviors in some primary amine solutions differ as a result of the effect of attractive forces between amine solute molecules on the solution osmotic pressure. Although the swelling is essentially colligative in nature, the stability of the resultant swollen structure is heavily dependent on the chemical nature of the guest ions. Intercalated ions of higher polarity and smaller size help stabilize the swollen structure, whereas ions of lower polarity and larger size lead readily to exfoliation. The insight gained from this study sheds new light on both the incorporation of guest molecules into a gallery of layered structures in general and the exfoliation of materials into elementary single-layer nanosheets.

Uptake and assimilation of ammonium ions by cucumber seedlings from solutions with different pH and addition of heavy metals

Influence of Cu<sup>2+</sup>, Cd<sup>2+</sup>, Pb<sup>2+</sup> and Fe<sup>2+</sup> in various pH conditions (5.0, 6.0, 7.0) on the uptake and assimilation of NH<sub>4</sub><sup>+</sup> by cucumber seedlings was estimated. Every metal in different pH of uptake solution distinctly reduced ammonium absorption calculated from NH<sub>4</sub><sup>+</sup> depletion. Copper and ferric ions, but not cadmium or lead, astonishingly decreased the uptake of ammonium from solution at pH 5.0. Cu<sup>2+</sup> was also very active at pH 6.0. The accumulation of ammonium in roots of metals-treated seedlings at the same time was high. The high level of ammonium in root cells despite of its low uptake probably resulted from disturbance in NH<sub>4</sub><sup>+</sup> assimilation. Both glutamine synthetase (GS) and NADH-glutamate dehydrogenase (NADH-GDH) - the major enzymes in ammonium assimilation, were inhibited after one hour of plant exposition to the metals. Similarly as in the case of ammonium uptake, the influence of pH was visible only in combination with copper and ferric ions. The strongest reduction of enzyme activities was observed for Cu<sup>2+</sup> and Fe<sup>2+</sup>, in pH 5.0 and 6.0. The various metals absorption by roots from solutions with different pH was not dedected. The data show correlation between metal inhibition of GS and NADH-GDH activities and metal inhibition of ammonium absorption.

Removal of ammonia by clinoptilolite

The important advantage of zeolite applied to water treatment is its high porosity when comparing to other minerals. The porosity results in good hydrodynamic properties (the increase in the pressure loss on the zeolite filters is 1.5-2.0 times smaller than in the case of sand filters) and adsorption roperties, and in turn high capacity which allows for adsorption of contaminants (a clinoptilolite filter allows for removal of phytoplankton and bacteria). The increase in the application of artificial fertilizers and gradual contamination of water resulted from discharging industrial wastewater into the environment led to the contamination of the environment by nitric compounds. Wastewater contains about 15-50 mg dm-3 of nitric compounds (based on nitrogen) – ammonia salts constitute about 55-60% whereas organic forms of proteins, pesticides and aminoacids about 40-50%. Natural clinoptilolite could be applied to remove ammonium ions from water and wastewater. The ammonium ion uptake behaviour of clinoptilolite is connected to the processes of ion exchange. The main aim of this investigation is to evaluate the adsorption capacity of clinoptilolite towards ammonium ions. According to the obtained results the adsorption capacity of clinoptilolite for the removal of ammonium ions demonstrates its potential application in the treatment of water, wastewater and sanitary landfill leachate contaminated with ammonia. The highest adsorption capacity of clinoptilolite towards ammonium ions of 3.79 mg g-1 was found for the initial concentration of 300 mg L-1. The highest removal level reached by clinoptilolite for ammonium was of 99.74% for the initial concentration of ammonia of 50 mg L-1. The effect of exposure time on maximum uptake of ammonia was found to be insignificant.

Ammonium Ion Removal with a Natural Zeolite in Monodispersed and Segregated Fluidized Beds

This study focuses on the dynamic behavior of ammonium ion uptake during continuous operation with respect to liquid by means of ion exchange with a natural zeolite in fluidized and segregated flui...

Improving the ammonium ion uptake onto natural zeolite by using an integrated modification process

Detailed investigation on the development of physical and chemical properties of a natural calcium-rich zeolite modified by an integrated process, as well as the relation between the development and ammonium ion uptake (AIU), was conducted. This process consisted of pretreatment (grinding and sieving), sodium salt modification and calcination. Both pretreatment and salt modification largely increased BET surface area, total pore volume and average pore diameter of the raw zeolite. Individual calcination at temperature above 150 °C caused framework collapse, losses of partial clinoptilolite and production of X-ray amorphous material, resulting in pore blockage and the decreases in pore volume and BET surface area. However, the introduction of sodium ion enhanced the heat resistance of the raw material from 150 to 400 °C, and Na + ion treatment followed by calcination could effectively improved pore and surface properties of zeolite, thus leading to the significant enhancement in ammonium ion exchange and adsorption capabilities.

Adsorption characteristics of ammonium ion by zeolite 13X

With synthetic wastewater, lab-scale batch experiments and column experiments were carried out to investigate the adsorption characteristics of ammonium ion by zeolite 13X which is a hydrothermally synthetic byproduct accompanied with preparation of potassium carbonate from insoluble potash ores. The Langmuir and Freundlich models were applied to describe the equilibrium isotherms for ammonium ion uptake and the Langmuir model agrees very well with experimental data. Thermodynamic parameters including changes in the standard free energy (Δ G 0), enthalpy (Δ H 0) and entropy (Δ S 0) were also calculated. The results show that the exchange process of ammonium ion by zeolite 13X is spontaneous and exothermic. The pseudo second-order kinetic model was found to provide excellent kinetic data fitting ( R 2 > 0.999). The effects of relevant dynamic parameters, such as influent flow rate, adsorbent bed height and initial ammonium ion concentration on the adsorption of ammonium ion were examined, respectively. The Thomas model was applied to predict the breakthrough curves and to determine the characteristic parameters of column useful for process design and was found suitable for describing the adsorption process of the dynamic behavior of the zeolite 13X column. The total adsorbed quantities, equilibrium uptakes and total removal percents of ammonium ion related to the effluent volumes were determined by evaluating the breakthrough curves obtained at different conditions.

Utilization of steel-making slag for the uptake of ammonium and phosphate ions from aqueous solution

Steel-making slag, a waste by-product of the Steel Industry, constitutes a major disposal problem. In the present study, excellent adsorbent materials for reducing eutrophication in wastewaters have been prepared from this slag. Heated samples of acid-treated slag and mixtures of slag with kaolinite and Al(OH) 3 were examined to determine their uptake capacities for NH 4 + and PO 4 3− from aqueous solutions. In general, the equilibrium pH of the solution increased in comparison to initial pH with the uptake of target ions, the sample activated slag-Al(OH) 3 showing the smallest change. The highest PO 4 3− uptake capacity was obtained with the slag-Al(OH) 3 mixture heated at 900 °C whereas the highest uptake of NH 4 + was found in the slag-Al(OH) 3 mixture heated at 800 °C. The uptake rates for PO 4 3− and NH 4 + by the slag-Al(OH) 3 mixture heated at 900 °C were 2.91 and 0.65 μmol/(g min), respectively. It was shown that heating slag composites prior to incorporation into wastewater treatment filters resulted in an increased degree of NH 4 + and PO 4 3− uptake.

AC impedance analysis of polyaniline–montmorillonite nanocomposites

Investigation of the electrical properties of polymer–clay nanocomposites is important in the development of nanoelectronic devices. These nanocomposites may be prepared by intercalating suitable monomers within interlayer spaces of expanding layered clay materials, followed by in situ polymerization. We made use of this approach to prepare montmorillonite–polyaniline nanocomposites by ion-exchanging the intergallery cations for anilinium ions and subsequently polymerizing the anilinium ions by peroxydisulphate in the acidic medium to yield emeraldine salt form of polyaniline intercalated in montmorillonite (ES1-MMT). The emeraldine salt form of polyaniline contains one positive charge per three monomer units, and hence, polymerization of anilinium ions reduces the number of cations present within the interlayer. Charge compensation thus requires uptake of required amount of cations from the solution. Further, the emeraldine salt form of polyaniline can be neutralized by treating with excess base such as ammonia. Thus, the neutralization of emeraldine salt results in an uptake of ammonium ions for charge balance. We have, therefore, neutralized ES1-MMT using aqueous ammonium hydroxide, and the cations inserted into the interlayer were again exchanged for anilinium ions. The latter was polymerized in acidic medium to yield more polyaniline in its emeraldine salt form (ES2-MMT). By repeating this procedure we have also prepared ES3-MMT. X-ray diffraction (XRD) spectra recorded at 150 °C reveal the enhancement of d-spacing upon increased amounts of polymer formation, and the Fourier transform infrared (FTIR) analysis also supports this by showing enhanced absorption due to bands typical of emeraldine salt (for example, B–NH+ = Q, where B and Q stand for benzanoid and quinoid, respectively). Careful analyses of FTIR spectra reveal that the polymer is present within the interlayers, as well as adsorbed onto the external surfaces and is bound to clay layers through hydrogen bonding. In this publication, we report the electrical properties of such ES-MMT nanocomposites. Alternating current (AC) impedance analysis shows that the nanocomposites are highly conducting materials, and their bulk conductivity enhances in the order ES1-MMT < ES2-MMT < ES3-MMT. The materials are pure electronic conductors as revealed by the direct current polarization studies. Further, their conductivities decrease with increasing temperature as of pure electronic conductors. By treating kaolinite with anilinium ions in acidic medium followed by peroxydisulphate ions, emeraldine salt–kaolinite (ES-KAL) composites have also been prepared. Because kaolinite is a non-expanding clay, the ion exchange is not possible, and hence, the polymer cannot be incorporated into the interlayer. This is indeed shown in the XRD analysis. The polymer can only reside out of the kaolinite particles. FTIR spectra reveal the hydrogen bonding between the polymer and kaolinite outer surfaces. AC impedance spectra of ES-KAL do not show high bulk conductivity. Thus, the comparison of AC impedance spectra of ES-KAL with ES-MMT systems clearly indicates that the bulk conductivity of the latter systems is predominantly due to intercalated polyaniline.

Ammonium exchange in aqueous solution using Chinese natural clinoptilolite and modified zeolite

In this study, the Chinese natural clinoptilolite (sample 1) was fused with sodium hydroxide prior to hydrothermal reaction, and it was transformed to modified zeolite Na–Y (sample 2). The uptake of ammonium ion from aqueous solutions in the concentration range 50–250 mg NH 4 +/l on to the two samples was compared and the equilibrium isotherms have been got. The influence of other cations present in water upon the ammonia uptake was also determined. The cations studied were potassium, calcium and magnesium. In all cases the anionic counterion present was chloride. The results showed that sample 2 exhibited much higher uptake capacity compared with sample 1. At the initial concentration of 250 mg NH 4 +/l, the ammonium ion uptake value of sample 2 was 19.29 mg NH 4 + g −1 adsorbent, while sample 1 was only 10.49 mg NH 4 + g −1 adsorbent. For the natural clinoptilolite, the effect of the metal ions suggested an order of preference K + > Ca 2+ > Mg 2+. These contrasted with the modified zeolite, where the order appeared to be Mg 2+ > Ca 2+ > K +.

Simultaneous uptake of ammonium and phosphate ions by compounds prepared from paper sludge ash

Al-containing CaO–SiO 2–H 2O phases were prepared by hydrothermal treatment of mixtures of paper sludge ash (PSA) with various silica and calcia sources and their properties were determined with particular reference to the simultaneous uptake of ammonium and phosphate ions, which are implicated in the eutrophication of lakes and ponds. After examination of various silica and calcia sources, Ca(OH) 2 and SiO 2 sol were selected as the most appropriate starting materials. Dry milling was found to be superior to wet milling in avoiding contamination from the milling media during mixing. Nine samples with three different Ca/Si ratios and Al 2O 3 contents were prepared with various mass ratios of Ca(OH) 2, PSA and SiO 2. The chemical compositions of the hydrothermal products of these mixtures moved towards the tieline of CaSiO 3-PSA, with respect to the starting compositions. The major phase formed in all samples was poorly crystalline C–S–H(I), with hydroxysodalite also formed in the Al-containing mixtures. All the products showed a capacity for the simultaneous uptake of ammonium and phosphate ions. The saturated sorption capacities calculated from the Langmuir equation ranged from 0.9 to 2.4 mmol/g for the ammonium ion and from 3.3 to 5.2 mmol/g for the phosphate ion. Since the sorption capacities for both ions increased with increasing Ca contents of the product, substitution of Ca 2+ for NH 4 + and the formation of calcium phosphate phases such as apatite and brushite by precipitation are thought to be the main sorption mechanisms.