Effective Inhibition of Ammonium Released from Heavily Contaminated Sediments through Selective Oxidation with Zeolite Layer

Abstract

In order to study the remediation effect of heavily contaminated sediments, the experiments to repair heavily contaminated sediments were carried out under selective and nonselective oxidation conditions. Results showed that a lot of denitrifying bacteria was detected on the surface of modified zeolite by fluorescence in situ hybridization (FISH) after inoculating both nitrifying and denitrifying bacteria for 7?days. Up to 3.69?mg/g, in-situ regeneration of ammonium on zeolite loading with high ammonium (ammonium adsorption: 4.20?m/g) was obtained, which was 1.42 times that of nonselective oxidation (2.60?mg/g). This indicated that the in-situ regeneration rate of zeolite under high ammonium adsorption (5.0?mg/g) and high bacterial inoculum (80?mL/g) was enhanced. Moreover, only 1.50?mg/L total nitrogen with 84% inhibition in the overlying water under selective oxidation conditions was observed, which was 2.37 times the inhibition percentage of modified zeolite under nonselective oxidation conditions. The results illuminated that effective inhibition of ammonium released from heavily contaminated sediments can be achieved through selective oxidation with zeolite layer. At the same time, the in-situ service life of attached biofilm-modified zeolite under selective oxidation conditions was 5.87?years, which was extended by 3?years compared with nonselective oxidation conditions.     

Transport of nitrate and ammonium ions in a sandy loam soil treated with potassium zeolite – Evaluating equilibrium and non-equilibrium equations

The increased use of nitrogen fertilizers in agriculture would cause migration of nitrogen to surface and groundwater; accordingly, would lead to water resources contamination. The objective of this study is to investigate the effect of potassium zeolite on nitrate and ammonium ions sorption and retention in a saturated sandy loam soil in a laboratory condition. The study was conducted as a completely randomized block design with four treatments of 0, 2, 4 and 8 g zeolite per kilogram soil and three replications. Ammonium nitrate fertilizer with concentration of 10 g l⁻¹ was added to soil columns and then leaching was performed. The results show that increasing potassium zeolite to soil causes reduction to the mobility of both nitrate and ammonium and enhancement of the retention of ions in soil. Ions leaching were simulated with convection–dispersion-equation (CDE) and mobile–immobile model (MIM) using HYDRUS-1D code. The results indicate that ammonium ion sorption by soil followed the Freundlich isotherm model. Absorption isotherms and dispersion (D_e) coefficient were determined through the inverse modeling for both ions. Based on the results, optimized values of Freundlich isotherm were much less than the observed amounts. This shows that the HYDRUS-1D model underestimated the adsorption parameters to predict the ammonium ion mobility in soil macropores. Since soil has been disturbed, the prediction of CDE model was equal to MIM model approximately. Both models showed that as the amount of applied zeolite increases, the dispersion (D_e) coefficient of nitrate and ammonium ions in the soil increases.     

Anaerobic digestion of swine manure under natural zeolite addition: VFA evolution, cation variation, and related microbial diversity

Batch experiments were carried out on anaerobic digestion of swine manure under 10 % of total solids and 60 g/L of zeolite addition at 35 °C. Four distinctive volatile fatty acid (VFAs) evolution stages were observed during the anaerobic process, i.e., VFA accumulation, acetic acid (HAc) and butyric acid (HBu) utilization, propionic acid (HPr) and valeric acid (HVa) degradation, and VFA depletion. Large decreases in HAc/HBu and HPr/HVa occurred respectively at the first and second biogas peaks. Biogas yield increased by 20 % after zeolite addition, about 356 mL/g VS_added with accelerated soluble chemical oxygen demand degradation and VFA (especially HPr and HBu) consumption in addition to a shortened lag phase between the two biogas peaks. Compared with Ca²⁺ and Mg²⁺ (100–300 mg/L) released from zeolite, simultaneous K⁺ and NH₄ ⁺ (580–600 mg/L) adsorptions onto zeolite particles contributed more to the enhanced biogasification, resulting in alleviated inhibition effects of ammonium on acidogenesis and methanogenesis, respectively. All the identified anaerobes could be grouped into Bacteroidetes and Firmicutes, and zeolite addition had no significant influence on the microbial biodiversity in this study.     

Development of high density mammalian cell culture system for the production of tissue-type plasminogen activator

A high cell density culture system for the anchorage dependent CHO cells was developed based on the combination ofin situ removal of ammonium ion and microcarrier culture system, and semi-fed-batch feeding of glucose and glutamine was employed to the developed culture system. The glass bead was selected as an optimum microcarrier in terms of cell growth. An ammonium ion selective zeolite, Phillipsite-Gismondine, was packed in a dialysis membrane and equipped on the agitator of spinner reactor forin situ removal of ammonium ion. The semi-fed-batch operation was employed to the novel culture system for the high density cell culture, and the results showed the cell growth was improved by 32% and tPA productivity by 250%.     

Peat,zeolite and basalt as adsorbents of ammoniacal nitrogen during manure decomposition

The effectiveness of sphagnum peat, zeolite (clinoptilonite) and basalt in reducing ammonia losses during aerobic manure decomposition was determined in an incubation experiment. Peat placed in the spent air-stream adsorbed all of the ammonia volatilized during the first 8 days of decomposition, and reduced overall ammonia losses by 59%. Zeolite reduced total ammonia losses by 16%, and basalt by 6%.All adsorbents were considerably less effective in reducing ammonia losses when mixed with the manure. Reductions in ammonia losses of 24% and 1.5% were obtained with the peat and zeolite, respectively. The addition of basalt increased losses.Ammonia and ammonium adsorption isotherms were determined for the three materials. The adsorption capacities and affinity terms of the adsorbents calculated from the isotherms, reflected their ability to reduce ammonia losses in the incubation experiment. Zeolite had both the highest affinity for ammonium and the highest ammonium adsorption capacity. The peat had a very high affinity for ammonia and a high adsorption capacity (23.4 mg NH₃–N g^–1), whereas zeolite and basalt had a much lower adsorption capacity (1.8 and 0.05 mg NH₃–N g^–1, respectively) compared with their capacity to adsorb ammonium (18.1 and 0.18 mg NH₄–N g^–1).     

Production of extracellular polymeric substances in anoxic/oxic process with zeolite carriers for nitrogen removal

During the hydraulic retention time (HRT) from 12 to 6 h, the production of extracellular polymeric substance (EPS) decreased from 82 to 70 EPS mg volatile suspended solids (VSS) g(-1) in an anoxic/oxic (A/O) reactor with zeolite carriers. Added zeolite could successfully control the EPS production by the formation of stable biofilm and the maintenance the lower chemical oxygen demand/ammonium (C/N) ratio on its surface.     

Anammox-zeolite system acting as buffer to achieve stable effluent nitrogen values

For a successful nitrogen removal, Anammox process needs to be established in line with a stable partial nitritation pretreatment unit since wastewater influent is mostly unsuitable for direct treatment by Anammox. Partial nitritation is, however, a critical bottleneck for the nitrogen removal since it is often difficult to maintain the right proportions of NO₂-N and NH₄-N during long periods of time for Anammox process. This study investigated the potential of Anammox-zeolite biofilter to buffer inequalities in nitrite and ammonium nitrogen in the influent feed. Anammox-zeolite biofilter combines the ion-exchange property of zeolite with the biological removal by Anammox process. Continuous-flow biofilter was operated for 570 days to test the response of Anammox-zeolite system for irregular ammonium and nitrite nitrogen entries. The reactor demonstrated stable and high nitrogen removal efficiencies (approximately 95 %) even when the influent NO₂-N to NH₄-N ratios were far from the stoichiometric ratio for Anammox reaction (i.e. NO₂-N to NH₄-N ranging from 0 to infinity). This is achieved by the sorption of surplus NH₄-N by zeolite particles in case ammonium rich influent came in excess with respect to Anammox stoichiometry. Similarly, when ammonium-poor influent is fed to the reactor, ammonium desorption took place due to shifts in ion-exchange equilibrium and deficient amount were supplied by previously sorbed NH₄-N. Here, zeolite acted as a preserving reservoir of ammonium where both sorption and desorption took place when needed and this caused the Anammox-zeolite system to act as a buffer system to generate a stable effluent.     

In situ removal of ammonium ions from hybridoma cell culture media: Selection of adsorbent

Various ion-exchange resins and zeolite Phillipsite-Gismondine were tested for their potential application as adsorbents for thein situ removal of ammonium ions from animal cell culture media in attempting to increase hybridoma cell density and MAb productivity. A zeolite, Phillipsite-Gismondine demonstrated the best performance in terms of NH₄ ⁺ adsorption capacity, selectivity and autoclavability among the various adsorbents tested. The biocompatibility of Phillipsite-Gismondine was also tested and the result showed improvement in cell density, viability, and antibody productivity.     

沸石滤床去除炼油废水中氨氮的研究

中国石化广州石油化工厂炼油污水NH₄-N含量高、COD/NH₄-N比低,致使其具有经氧化沟处理后出水脱氮效果不稳定的特点,为此研制开发了一种沸石滤床。将氧化沟出水沉淀后连续导入沸石滤床(ZPB)及活性炭滤床(ACB)与陶粒滤床(CPB),控制滤速1m·s^-1.运行结果表明:沸石滤床的氨氮平均去除率高于99%,COD平均去除率为24.8%,均大大高于活性炭滤床与陶粒滤床。     

Production of extracellular polymeric substances in anoxic/oxic process with zeolite carriers for nitrogen removal

During the hydraulic retention time (HRT) from 12 to 6 h, the production of extracellular polymeric substance (EPS) decreased from 82 to 70 EPSmg volatile suspended solids (VSS) g^-1 in an anoxic/oxic (A/O) reactor with zeolite carriers. Added zeolite could successfully control the EPS production by the formation of stable biofilm and the maintenance the lower chemical oxygen demand/ammonium (C/N) ratio on its surface.Revisions requested 20 July 2004; Revisions received 7 september 2004     

Control of struvite precipitation by selective removal of $${\text{NH}}^{{\text{ + }}}_{{\text{4}}} $$ with dialyzer/zeolite in an anaerobic membrane bioreactor

This study focused on the mitigation of membrane fouling caused by struvite precipitation using a dialyzer/zeolite (D/Z) unit in an anaerobic membrane bioreactor. The D/Z unit was designed to selectively remove NH(4)+ ions, one of the main components of the inorganic foulant, struvite. The maximum mass transfer coefficient for NH(4)+ through the dialyzer was estimated to be 0.92 l m(-2)h(-1), whereas the Na-substituted zeolite had the highest ion exchange capacity with respect to ammonium among intact or differently pretreated zeolites. During a single passage of dialysate through the zeolite column, substantial NH(4)+ removal (in excess of 90%) was achieved, leading to the reduction in struvite precipitation in the digester. The D/Z unit played a significant role in controlling struvite precipitation, thereby enhancing permeate flux for the case of the ceramic membrane, in which struvite fouling would be more pronounced compared to the polymeric membrane. For the polymeric membrane, however, no significant improvement in flux was observed even with the D/Z unit because the fouling of the polymeric membrane was mainly due to the deposition of biomass rather than the struvite precipitation.     

Effect of natural zeolite (clinoptilolite) on microbial decomposition processes in stored pig-slurry solids

The solid fraction (SF) of pig slurry obtained in the first stage of aerobic slurry treatment was amended with 1 and 2 % zeolite (clinoptilolite) and stored for 12 weeks under anaerobic conditions or with turning after 3 and 6 weeks of storage. In addition to that SF was mixed with 2 % zeolite, 50 % (V/V) sawdust, and both sawdust and zeolite, and stored for 6 weeks with turning after 1 and 3 weeks. Plate counts of psychrophilic, mesophilic, coliform and fecal coliform bacteria, determined during the storage, corresponded to the development of temperature, in the core of the substrates. An effect of amendment of SF with zeolite and sawdust on plate counts of selected bacteria was observed, dependent on the zeolite dose. The thermophilic phase was not reached in any of the investigated substrates. The populations of fecal coliforms in the substrate amended with 1 % zeolite and turned after 3 and 6 weeks decreased after 11 weeks down to 500 CFU/g substrate. Presented at theInternational Conference on Recent Problems in Microbiology and Immunology, Košice (Slovakia), 13–15 October 1999.     

Remediation of Nitrogen-Contaminated Sediment Using Bioreactive,Thin-layer Capping with Biozeolite

In situ amendment of nitrogen-contaminated sediment using bioreactive, thin-layer capping (BTC) with biozeolite (i.e., zeolite with heterotrophic nitrifiers as well as aerobic denitrifiers attached) was studied herein. BTC with biozeolite for nitrogen-contaminated sediment management was evaluated through long-term (170 days) sediment incubation laboratory experiments. The results showed that BTC with relatively small dose rates (<10 kg m^?2) of biozeolite reduced the total nitrogen (TN) concentration in overlying water by over 90%, so it was effective in reducing the amount of N released from sediment. Higher-dose rates of biozeolite capping achieved an even higher removal efficiency. With the DO concentration of 1.5 ～ 6.5 mg L^?1 in overlying water, the reduction efficiency of TN in overlying water using BTC was higher than that less than 1 mg L^?1. In BTC systems, biological regeneration (i.e., heterotrophic nitrifiers attached to zeolite can regenerate the zeolite ion exchange capacity for ammonium) occurred in biozeolite which was saturated with ammonium during the nitrification period. In addition, TN contents in surface sediment in BTC systems were reduced at different levels after the experiment. These findings indicate that the BTC can be a feasible remedial approach to reduce N in overlying water and sediment in eutrophic water bodies. In the BTC, N load was reduced by the added biozeolite through adsorbing ammonium (NH₄⁺-N), converting NH₄⁺-N into nitrate nitrogen (NO₃^?-N) and nitrogen gas (N₂), and assimilating inorganic nitrogen.     

Utilization of zeolite Y in the removal of anionic,cationic and nonionic detergents during purification of proteins

Summary Hydrophobie zeolite Y was used to adsorb detergents from protein solutions and within one minute the commonly used detergents sodium dodecyl sulfate, cetyl trimethyl ammonium bromide, and Triton X-100 at concentrations of 10 mg/ml were adsorbed to a level below their critical micelle concentrations. From the detergent depleted solutions 77 to 85 % of the proteins were recovered; the lower value was obtained with protein concentration below one mg/ml.     

Effects of ammonium ion removal on growth and MAb production of hybridoma cells

Production of monoclonal antibody against hepatitis B surface antigen was carried out by perfusion culture coupled with a selective removal system for ammonium ion. The removal system is composed of three sub-systems namely, cell separation by cross-flow ceramic filter, dialysis by hollow fiber module and ion-exchange by zeolite A-3 packed bed column. The ammonium ion concentration in the culture broth was effectively maintained below the inhibitory level, and the viable cell density reached 2.5×10⁷ cells ml^–1 which was three times that of conventional perfusion cultures. The monoclonal antibody accumulated to a concentration as high as 26.3×10⁵ mIU^–1. This is already almost half of the amount producedin vivo. The numerical investigation of the ammonium ion removal system showed the possibility to improve much more the performance of this perfusion cultivation system.     

Computer Simulation of the Beta Structure,with Different Lattice Ions and Reactivity,of Hydroperoxo-Metal Complexes Using an Embedded-Cluster Method

The chemical properties of beta zeolite are interconnected with its structure in a complicated way. In general terms, the strength of the acid sites in the beta phase depends strongly on its structure, topology and composition. The quantum chemical calculations of the beta zeolite cluster model have been carried out in order to predict how the cluster's local structure influences the geometric parameters and thus affects the chemical functionality of the beta zeolite. Computer simulations of a beta zeolite model with one lattice aluminium, or boron, or titanium or vanadium ions and of its acidic centres have been carried out. The acidity of the framework oxygen atoms in the vicinity of the lattice atom centre has been calculated and compared. The reactivity of catalytic species comprisingthe lattice ion and a hydroperoxo ligand has been studied as an oxidising site.     

Aqueous two-phase extraction of 2,3-butanediol from fermentation broths using an ethanol/ammonium sulfate system

Separation of 2,3-butanediol from the fermentation broth is a difficult task that has become a bottleneck in industrial production. Aqueous two-phase systems composed of hydrophilic solvents and inorganic salts could be used to extract 2,3-butanediol from fermentation broth. The ethanol/ammonium sulfate system was investigated in detail, including phase diagram, effect of phase composition on partition, removal of cells and biomacromolecules from the broths and recycling of ammonium sulfate. The highest partition coefficient (7.10) and recovery of 2,3-butanediol (91.7%) were obtained by a system composed of 32% (w/w) ethanol and 16% (w/w) ammonium sulfate. The maximum selective coefficient of 2,3-butanediol to glucose was 30.74 in the experimental range. In addition, cells and proteins could be simultaneously removed from the fermentation broth. The removal ratio of cells and proteins reached 99.7% and 91.2%, respectively. The recovery of ammonium sulfate in the bottom phase reached 97.14% when two volumes of methanol were added to the salt-rich phase.     

Influence of short-chain fatty acids on the production of spiramycin by Streptomyces ambofaciens

Summary The addition of short-chain fatty acids stimulates the production of spiramycin by Streptomyces ambofaciens cultivated on dextrins and ammonium chloride. The fatty acids were activated by two enzymatic systems. The first system (acyl-CoA synthetases) was present only during the exponential phase. The second system (acylkinases coupled with acylphosphotransferases) was synthesized during the growth phase and during the stationary phase, in which spiramycin production started. Short-chain fatty acids induced the synthesis of acylkinases and acylphosphotransferases. Added at the beginning of cultures, they increased the specific activity of these enzymes during the exponential growth phase. Added at the early stationary phase, the specific activity of these enzymes and of the spiramycin production increased. Excess ammonium in the culture considerably lowered the specific activity of acylkinases synthesized in the stationary phase, when spiramycin productiin started. This ammonium effect can be reduced by the addition of short-chain fatty acids.Offprint requests to: A. Lebrihi     

A sand-zeolite culture system for simulating plant acquisition of potassium from soils

A sand-zeolite culture system simulating plant acquisition of K from soils has been developed. The system, a mixture of synthetic zeolite IE-96 and coarse-sand, provides K concentrations comparable to soils depending on the K concentration ratios of solutions loaded onto the cation-exchange sites of the zeolite and the ionic strengths of the nutrient solutions supplied during the period of plant growth. Tomato (Lycopersicon esculentum Mill.) strain 203, PI 124163, was used in this study. An increase in the amount of the loaded zeolite per culture pot did not shift solution phase K activity ratios (AR^k) of the culture system but did result in a linear increase of plant dry matter accumulation, indicating that K bioavailability is diffusion-limited in the sand-zeolite culture system as in soils.