Combined liquid phase microextraction and fiber-optics-based cuvetteless micro-spectrophotometry for sensitive determination of ammonia in water and food samples by the indophenol reaction.

The Berthelot reaction for ammonia is revisited with the aim of miniaturization and addressing interferences as encountered with food and water samples. Headspace single drop microextraction of ammonia in phosphoric acid served to attain selectivity in complex matrices, and liquid-liquid microextraction of red or blue indophenol species into 1-octanol-isooctane (60:40, v/v) resulted into high sensitivity. Fiber-optics-based cuvetteless micro-spectrophotometry has been used for colorimetric determination on microliter volumes of extract. The linear dynamic range, limit of detection and enrichment factor have been found to be 0.2-3 mg kg-1, 0.14 mg kg-1 and 38, respectively, measuring red species for milk, cheese and beer (4.9-5.5% error; 4.8-6.3% RSD; n = 5); and 5-400 µg L-1, 0.4 µg L-1 and 137, respectively, measuring blue species for water samples (3.3-5.7% error; 3.6-6.8% RSD; n = 5). A plausible reaction scheme has been proposed for nitroprusside catalysis in indophenol reaction.

Extracorporeal Ammonia Clearance for Hyperammonemia in Critically Ill Patients: A Scoping Review.

INTRODUCTION: Hyperammonemia is a life-threatening condition. However, clearance of ammonia via extracorporeal treatment has not been systematically evaluated. METHODS: We searched EMBASE and MEDLINE databases. We included all publications reporting ammonia clearance by extracorporeal treatment in adult and pediatric patients with clearance estimated by direct dialysate ammonia measurement or calculated by formula. Two reviewers screened and extracted data independently. RESULTS: We found 1,770 articles with 312 appropriate for assessment and 28 studies meeting eligibility criteria. Most of the studies were case reports. Hyperammonemia was typically secondary to inborn errors of metabolisms in children and to liver failure in adult patients. Ammonia clearance was most commonly reported during continuous renal replacement therapy (CRRT) and appeared to vary markedly from <5 mL/min/m2 to >250 mL/min/m2. When measured during intermittent hemodialysis (IHD), clearance was highest and correlated with blood flow rate (R2 = 0.853; p < 0.001). When measured during CRRT, ammonia clearance could be substantial and correlated with effluent flow rate (EFR; R2 = 0.584; p < 0.001). Neither correlated with ammonia reduction. Peritoneal dialysis (PD) achieved minimal clearance, and other extracorporeal techniques were rarely studied. CONCLUSIONS: Extracorporeal ammonia clearance varies widely with sometimes implausible values. Treatment modality, blood flow, and EFR, however, appear to affect such clearance with IHD achieving the highest values, PD achieving minimal values, and CRRT achieving substantial values especially at high EFRs. The role of other techniques remains unclear. These findings can help inform practice and future studies.

Quantification of Ammonia Oxidizing Bacterial Abundances in Environmental Samples by Quantitative-PCR.

Quantitative-PCR (qPCR) enables the quantification of specific DNA targets, such as functional or phylogenetic marker genes associated with environmental samples. During each qPCR cycle, the number of copies of a gene (or region) of interest in DNA samples is determined in real time using a fluorescence-based label and compared to a standard serial dilution. Here, we describe a qPCR method to quantify the ammonia oxidizing bacteria involved in the first step of nitrification, using the amoA gene as a proxy of their abundance. The preparation of the standards from environmental samples and qPCR is presented in detail for specifically quantifying microbial abundance in environmental samples such as soil.

In vitro and in vivo Evaluation of Succinic Acid-Substituted Mesoporous Silica for Ammonia Adsorption: Potential Application in the Management of Hepatic Encephalopathy.

PURPOSE: Hepatic encephalopathy (HE) is a critical situation in which liver failure affects brain function. HE could result in a state of coma and death. The liver is the main organ for ammonium ion (NH4 +) metabolism. Hence, acute and/or chronic liver failure could lead to hyperammonemia. NH4 + is the most suspected neurotoxic agent in HE. Thus, finding new therapeutic options to decrease plasma and brain NH4 + levels has a significant clinical value. Mesoporous silica (MS) particles have revolutionized many aspects of pharmaceutical sciences, including drug delivery systems. Moreover, recently, MS has been applied as agents for the detoxification of chemicals (eg, drugs and poisons). METHODS: First, MS particles containing amine groups (MS-NH2) were synthesized in co-condensation processes. Then, the structure was modified by succinic anhydride to have MS-SA. The MS-SA was characterized (FT-IR, XRD, X-ray photoelectron spectroscopy (XPS), DLS-Zeta FESEM-EDX, and HRTEM). Then, the potential of MS-NH2 and MS-SA particles in adsorption of NH4 + was investigated in vitro and in vivo. MS-NH2 and MS-SA were incubated with increasing concentrations (0.1-10 mM) of NH4 +, and the scavenging capacity of the investigated particles was evaluated. On the other hand, different doses (1 and 5 mg/kg per day) of nanoparticles were administered to a hyperammonemia animal model. RESULTS: It was figured out that both MS-NH2 and MS-SA significantly scavenged NH4 + in the in vitro model. However, the NH4 + scavenging capability of MS-SA was more significant. Administration of MS-NH2 and MS-SA also considerably decreased the level of ammonium in plasma and brain and improved cognitive and locomotor activity in hyperammonemic animals. The effects of MS-SA were more significant than MS-NH2 in the HE animal model. CONCLUSION: Collectively, our data suggest that MS particles, especially succinic acid-functionalized MS, could act as special ancillary treatment in HE as a critical clinical complication.

Comparative assessment of modeling and experimental data of ammonia removal from pre-digested chicken manure.

The aim of this study was to interpret the development of Anammox activity by a mathematical model in an UASB reactor -originally inoculated with methanogenic granules- at which Anammox progress has been also experimentally observed while treating chicken manure digestate. Since ammonium is derived from anaerobic degradation of nitrogenous compounds in chicken manure similar to any other nitrogen-rich organic wastes; the reactor was operated intentionally at favorable conditions [i.e.; with external nitrite source for NH4 +:NO2 -≅1.0] in order to make Anammox process to prevail as operation continued. Results indicated significant ammonia removals (60% on average) although influent concentration was gradually increased up to 200 mg L-1. A modeling exercise has been undertaken to investigate the performance of the laboratory scale UASB reactor. In this scope, the experimental results were modeled by using Mantis2 model within GPS-X 6.5 simulation software that included several built in libraries. Accordingly, effluent chemical oxygen demand (COD) and total ammonia nitrogen (TAN) concentrations could be predicted with reasonably good accuracy demonstrating successful calibration. The regression coefficient (R2 ) and mean relative absolute error (MRAE) parameters were found as 0.66 and 16% and 0.70 and 19%, respectively.

Pilot Scale Study: First Demonstration of Hydrophobic Membranes for the Removal of Ammonia Molecules from Rendering Condensate Wastewater.

Hydrophobic membrane contactors represent a promising solution to the problem of recycling ammoniacal nitrogen (N-NH4) molecules from waste, water or wastewater resources. The process has been shown to work best with wastewater streams that present high N-NH4 concentrations, low buffering capacities and low total suspended solids. The removal of N-NH4 from rendering condensate, produced during heat treatment of waste animal tissue, was assessed in this research using a hydrophobic membrane contactor. This study investigates how the molecular composition of rendering condensate wastewater undergo changes in its chemistry in order to achieve suitability to be treated using hydrophobic membranes and form a suitable product. The main objective was to test the ammonia stripping technology using two types of hydrophobic membrane materials, polypropylene (PP) and polytetrafluoroethylene (PTFE) at pilot scale and carry out: (i) Process modification for NH3 molecule removal and (ii) product characterization from the process. The results demonstrate that PP membranes are not compatible with the condensate waste as it caused wetting. The PTFE membranes showed potential and had a longer lifetime than the PP membranes and removed up to 64% of NH3 molecules from the condensate waste. The product formed contained a 30% concentrated ammonium sulphate salt which has a potential application as a fertilizer. This is the first demonstration of hydrophobic membrane contactors for treatment of condensate wastewater.

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 (6.42 mmol/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.

Metal-Organic Frameworks against Toxic Chemicals.

Materials capable of the safe and efficient capture or degradation of toxic chemicals, including chemical warfare agents (CWAs) and toxic industrial chemicals (TICs), are critically important in the modern age due to continuous threats of these chemicals to human life, both directly and indirectly. Metal-organic frameworks (MOFs), atomically precise hybrid materials that are synthesized via the self-assembly of metal cations or clusters and organic linkers, offer a unique solid adsorbent design platform due to their great synthetic versatility. This review will focus on recent advancements in MOF-based adsorbent design for protection against chemical warfare agents (organophosphorus nerve agents, blistering agents, and their simulants) and toxic industrial chemicals such as H2S, NH3, SO2, CO, NO2, and NO.

Synergistically coupling membrane electrochemical reactor with Fenton process to enhance landfill leachate treatment.

Landfill leachate is challenging to treat due to its complex composition. Advanced oxidation processes such as Fenton process can be effective to treat leachate. Herein, a previously developed membrane electrochemical reactor (MER) was coupled with Fenton oxidation through providing synergistic benefits with the low solution pH, reduced organics, and ammonia removal/recovery. This two-stage coupled system reduced the leachate COD by 88%, much higher than that from the standalone Fenton process treating raw leachate. In addition, the usage of chemical reagents has been greatly reduced. At a dimensionless oxidant dose of 1.0, the coupled MER-Fenton system reduced the consumption of both FeSO4⋅7H2O and H2O2 by 39%, H2SO4 by 100%, and NaOH by 55%. Consequently, the sludge production was reduced by 51% in weight and 12% in volume. Despite electricity consumption by the MER, the coupled system cost $4.76 per m3 leachate less than the standalone Fenton treatment. More notably, direct Fenton oxidation removed only 21% of ammonia; in comparison the MER-Fenton system removed ammonia by 98% with the possibility for recovery at a rate of 30.6-55.2 kg N m-3 reactor d-1. Those results demonstrate that coupling MER with Fenton process could mitigate some inherent drawbacks of Fenton oxidation such as ineffective ammonia removal, high acid and chemical reagents dose requirements, and a large amount of sludge generation. This system may be moved towards practical applications by addressing a few challenges such as using renewable energy to power MER.

Electrochemical treatment of organic pollutants in landfill leachate using a three-dimensional electrode system.

The use of three-dimensional electrode is a new electrochemical oxidation technology for landfill leachate treatment. In this study, a particle electrode was developed using Fe/C granules, which were suspended between the cathode and the anode to create a three-dimensional electrode. The three-dimensional electrode activated sodium persulfate to treat landfill leachate. Fe/C granules were prepared by incorporating iron filings and hydrothermally carbonized biochar into alginate beads. The optimal parameters of the three-dimensional electrode for chemical oxygen demand (COD) removal from landfill leachate were determined based on a series of single factor experiments as an operating voltage of 5 V, a sodium persulfate concentration of 28 mM, and 1 g of Fe/C granules. Treatment with the three-dimensional electrode at optimized conditions achieved 72.9% removal of COD and 99.9% removal of ammonia nitrogen, resulting in landfill leachate being clear and transparent. The changes in total organic carbon, nitrite, and nitrate concentrations indicated that most organic pollution and ammonia nitrogen were converted into CO2 and N2. This study provides an alternative technology for the treatment of refractory organic pollutants.

Waste Brick as Constructed Wetland Fillers to Treat the Tail Water of Sewage Treatment Plant.

Adopting the concept of "using waste to treat waste", the waste bricks will be used for constructed wetland filling. Integrated vertical-flow constructed wetland (IVCW) studied on the purification effect in influent water under three hydraulic loads (0.15, 0.25, 0.35 m/day). The results show that the waste bricks can be used as the carrier for the growth of the system biofilm, and have positive effects on the removal of pollutants in the influent water. Under three different hydraulic load conditions, the vertical flow of CWs can significantly reduce the load of water intake. In the low hydraulic load condition of 0.15 m/day, the average removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen (TN), and total phosphorus (TP) can reach 66.52%, 72.10%, 56.53% and 91.55% in this system, respectively. The influent pool on removal efficiency of pollutants was obviously higher than that of the upper pool, especially in the inlet surface 0-30 cm ranges. This research has achieved the effect of using "waste" to treat wastewater, which has strong practical significance and popularization value.

Integration of liquid-liquid membrane contactors and electrodialysis for ammonium recovery and concentration as a liquid fertilizer.

The accumulation of ammonia in water bodies can cause eutrophication and reduce water quality. Furthermore, 80% of the ammonia in the world is consumed as fertilizer, which makes it a resource that can be recovered under the circular economy concept. Then, ammonia from wastewater can be valorised for agricultural applications. Liquid-liquid membrane contactors (LLMCs) have been postulated as a novel and eco-friendly technology for ammonia recovery, because they can convert dissolved ammonia into ammonium salts by an acid stripping solution. The concentration of the ammonium salt produced is limited by the co-transport of water in LLMC. Further concentration by electrodialysis (ED) is presented as a solution to overcome this problem. In this work, ammonia streams with different initial ammonia concentrations (1.7-4.0 g/L) were treated by LLMCs to produce liquid ammonium salt fertilizers (as NH4NO3 and NH4H2PO4). Then, these ammonium solutions were concentrated by ED in order to achieve the nitrogen content required for direct application in agriculture for fertigation. After the LLMC process, the fertilizer obtained was composed of approximately 5.1% or 10.1% (w/w) nitrogen, depending on the initial ammonia concentration. After that, it was possible to concentrate these ammonium salts by a factor of 1.6 ± 0.3 using ED with an optimal energy consumption of 0.21 ± 0.08 kWh/kg ammonium salt and 93.1 ± 4.2% of faradaic yield. This gave a liquid fertilizer composed of 15.6% (w/w) nitrogen as NH4NO3. Overall, it was possible to integrate two innovative membrane technologies for the valorisation and concentration of nutrients from ammonia wastewater streams.

Ammonia, thiocyanate, and cyanate removal in an aerobic up-flow submerged attached growth reactor treating gold mine wastewater.

The objective of the study was to investigate the nitrification process, as well as the bio-chemical removal of cyanate and thiocyanate, while treating gold mining wastewater using an aerobic up-flow SAGR. A total of six SAGRs, each packed with locally sourced pea gravel (estimated specific surface area of 297 m-2 m-3), were operated at various HRTs and tested on both low- and high-strength gold mining wastewaters. The two sets of three SAGRs were operated at HRTs of 0.45 days, 1.20 days, and 2.40 days. Nitrification was successfully achieved in all six SAGRs regardless of the wastewater strength or HRT examined. The steady-state, 20 °C surface area loading rate was determined to be 1.2 g-TAN m-2 d-1 in order to comply with an effluent discharge limit at 10 mg-TAN L-1 (i.e., with the wastewater sources examined). At all ammonia loading rates, thiocyanate was successfully removed, and residual concentrations were below 2 mg-SCN-N L-1. Cyanate appeared to be hydrolyzed and subsequently nitrified. Acute toxicity tests conducted on both daphnia and trout revealed the effluent to be safe for direct discharge.

Immobilization of Rhodopseudomonas palustris P1 on glass pumice to improve the removal of NH4 + -N and NO2 - -N from aquaculture pond water.

We conducted this research in order to investigate the potential of a new material called glass pumice for use as a microorganism immobilization carrier to improve aquaculture pond water quality. The pH adjustment capacity and the Rhodopseudomonas palustris P1 cell adsorption capacity of glass pumice were measured. The immobilized Rps. palustris P1 and the free sample were compared to determine which had an enhanced NH4 + -N and NO2 - -N removal efficiency. The results showed that glass pumice significantly affected the pH of the acid solution (P < 0.05); the pH increased from 3.0 ± 0.08 to 7.21 ± 0.13 in 12 H. Rps. palustris P1 adsorption to glass pumice was rapid and reached equilibrium within 60 Min. The Langmuir adsorption parameter data showed that glass pumice had a higher affinity for Rps. palustris P1 than SiO2 powder, with an adsorption capacity of 4.02 × 108  cells g-1 . The maximum NH4 + -N and NO2 - -N removal rates by immobilized Rps. palustris P1 were 134.82 ± 0.67% and 93.68 ± 0.14% higher than those of nonimmobilized P1, respectively. Based on the above results, we propose that glass pumice is potential as a microorganism carrier material in aquaculture water treatment.

[Optimization of the Parameters for Microalgae Immobilization and Analysis of Its Recovery Potential for Ammonia Nitrogen in Wastewater].

Application of microalgae in wastewater treatment is regarded as a potential green technology. However, its engineering application has been largely hindered because of the difficulty of biomass separation and harvesting. This study aimed to identify the key parameters influencing the process of microalgae immobilization. To do this, the study focused on immobilization technology and Scenedesmus obliquus, and employed the response surface methodology (RSM) and the Box-Behnken design (BBD). In an evaluation of the performance of microalgae beads, the fixing agent concentration, the cross-linking agent concentration, and the cross-linking time were selected as the independent variables, and the mechanical strength, the mass transfer rate, and the growth rate of immobilized microalgae beads were the response values. The optimal conditions and the uptake potential of the microalgae beads with respect to ammonia nitrogen (NH4+-N) were further explored and analyzed. The results showed that the optimal parameters for the preparation of immobilized microalgae beads were 5%, 2%, and 16 h, and the maximum removal capacity was obtained using mixotrophic cultivation with an embedding density of 1×106 cells·mL-1 and an organic matter concentration of 300 mg·L-1. In addition, the removal capacity of immobilized microalgae with respect to high concentrations of NH4+-N was significantly higher than for free-living microalgae. When the initial concentrations of NH4+-N were approximately 50 and 70 mg·L-1, NH4+-N was removed by the immobilized microalgae (after a 5-day mixotrophic cultivation) at a rate of (96.6±0.1)% and (65.2±4.5)%, respectively. With an initial NH4+-N concentration of 30 mg·L-1, the dominance of free-living microalgae was clear, with a removal rate of (97.8±0.6)% after a 3-day cultivation. However, under heterotrophic cultivation, the removal rate of NH4+-N by immobilized microalgae was generally low and gradually decreased with increasing concentrations. When the initial concentration was approximately 30 mg·L-1, the removal rate was only (49.0±3.1)%. This study provides new prospects for sustainable urban wastewater treatment, a new approach for resource recycling, and a strong theoretical foundation for the popularization and application of microalgae in wastewater treatment.

An Investigation of PS-b-PEO Polymersomes for the Oral Treatment and Diagnosis of Hyperammonemia.

Ammonia-scavenging transmembrane pH-gradient poly(styrene)-b-poly(ethylene oxide) polymersomes are investigated for the oral treatment and diagnosis of hyperammonemia, a condition associated with serious neurologic complications in patients with liver disease as well as in infants with urea cycle disorders. While these polymersomes are highly stable in simulated intestinal fluids at extreme bile salt and osmolality conditions, they unexpectedly do not reduce plasmatic ammonia levels in cirrhotic rats after oral dosing. Incubation in dietary fiber hydrogels mimicking the colonic environment suggests that the vesicles are probably destabilized during the dehydration of the intestinal chyme. The findings question the relevance of commonly used simulated intestinal fluids for studying vesicular stability. With the encapsulation of a pH-sensitive dye in the polymersome core, the local pH increase upon ammonia influx could be exploited to assess the ammonia concentration in the plasma of healthy and cirrhotic rats as well as in other fluids. Due to its high sensitivity and selectivity, this polymersome-based assay could prove useful in the monitoring of hyperammonemic patients and in other applications such as drug screening tests.

Application of Near-Infrared Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS) to the Detection of Ammonia in Exhaled Human Breath.

The qualitative and quantitative analysis to trace gas in exhaled human breath has become a promising technique in biomedical applications such as disease diagnosis and health status monitoring. This paper describes an application of a high spectral resolution optical feedback cavity enhanced absorption spectroscopy (OF-CEAS) for ammonia detection in exhaled human breath, and the main interference of gases such as CO2 and H2O are approximately eliminated at the same time. With appropriate optical feedback, a fibered distributed feedback (DFB) diode laser emitting at 1531.6 nm is locked to the resonance of a V-shaped cavity with a free spectral range (FSR) of 300 MHz and a finesse of 14,610. A minimum detectable absorption coefficient of αmin = 2.3 × 10-9 cm-1 is achieved in a single scan within 5 s, yielding a detection limit of 17 ppb for NH3 in breath gas at low pressure, and this stable system allows the detection limit down to 4.5 ppb when the spectra to be averaged over 16 laser scans. Different from typical CEAS with a static cavity, which is limited by the FSR in frequency space, the attainable spectral resolution of our experimental setup can be up to 0.002 cm-1 owing to the simultaneous laser frequency tuning and cavity dither. Hence, the absorption line profile is more accurate, which is most suitable for low-pressure trace gas detection. This work has great potential for accurate selectivity and high sensitivity applications in human breath analysis and atmosphere sciences.

Evaluation of a Cost-Effective Ammonia Monitoring System for Continuous Real-Time Concentration Measurements in a Fattening Pig Barn.

Ammonia (NH3) emission is one of the major environmental issues in livestock farming. Gas measurements are required to study the emission process, to establish emission factors, and to assess the efficiency of emission reduction techniques. However, the current methods for acquiring reference measurements of NH3 are either high in cost or labor intensive. In this study, a cost-effective ammonia monitoring system (AMS) was constructed from a commercially-available gas analyzing module based on tunable diode laser absorption (TDLA) spectroscopy. To cope with the negative measurement biases caused by differing inlet pressures, a set of correction equations was formulated. Field validation of the AMS on NH3 measurement was conducted in a fattening pig barn, where the system was compared to a Fourier-transform infrared (FTIR) spectroscopy analyzer. Under two test conditions in a fattening pig barn, the absolute error of the AMS measurements with respect to the average obtained values between the AMS and the FTIR was respectively 0.66 and 0.08 ppmv, corresponding to 5.9% and 0.5% relative error. Potential sources of the measurement uncertainties in both the AMS and FTIR were discussed. The test results demonstrated that the AMS was capable of performing high-quality measurement with sub-ppm accuracy, making it a promising cost-effective tool for establishing NH3 emission factors and studying NH3 emission processes in pig houses.

Simultaneous removal of hydrogen sulfide and ammonia using a combined system with absorption and electrochemical oxidation.

Hydrogen sulfide (H2S) and ammonia (NH3), common impurities in biogas, need to be removed before utilizing it. In this study, a combined system, which consisted of an absorption column and an electrochemical oxidation reactor, was tested to simultaneously remove these impurities. The effects of the current density and the chemical loading rate on the system performance were investigated. Firstly, the mass transfer coefficients for the absorption column were determined at various gas flow rates. More mass of NH3 was transferred, compared with that of H2S, because of its higher solubility. In the electro-oxidation reactor, reactive chlorine species (RCSs) were generated and oxidized both H2S and NH3; however, NH3 started to degrade only after H2S was completely eliminated. At a current density of 400 A/m2, the current efficiencies of H2S and NH3 were 23.1% and 5.9%, respectively. In the combined system, the removal efficiency of H2S was closely related to the mass ratio of the H2S transferred and the RCSs generated. The removal efficiency of H2S was greater than 99% when the ratio was less than 1. The mass transfer potential and the oxidation kinetics should be balanced to improve the system performance for the simultaneous removal of H2S and NH3.

Low-cost physicochemical treatment for removal of ammonia, phosphate and nitrate contaminants from landfill leachate.

Four low-cost materials, oyster shells, pumice stone, sand and zeolite were employed as adsorbents in an adsorption batch assays investigating the removal of ammonia, phosphate and nitrate from an aqueous solution. These compounds were chosen as they represent typical compounds found in landfill leachate (LFL). Assay performance was evaluated by the Langmuir and Freundlich adsorption isotherms. The top two materials, oyster shells and pumice stone, were employed as adsorbents in a fixed-bed column trial examining the effect of bed height and flow rate on the treatment of a synthetic LFL. The trial concluded that the highest rates of adsorption were achieved using bed heights of 20 cm with a flow rate of 5 mL min-1. After optimization, the system was employed for the treatment of LFL from Powerstown landfill, Carlow, Ireland. Ammonia and nitrate were effectively removed by both adsorption materials resulting in a reduction of influent ammonia and nitrate concentrations to below the national discharge limits set for these compounds of ≤4 mg L-1 and ≤50 mg L-1, respectively. In contrast, although similar high removal efficiencies were observed for phosphate, these rates were not maintained during the test period with overall results indicating reduced phosphate adsorption in comparison to the other compounds tested.