Sodium Alginate Beads Research Articles

Denitrification potential of sodium alginate gel beads immobilized iron–carbon, Zoogloea sp. L2, and riboflavin: Performance optimization and mechanism

A kind of gel beads loaded with iron–carbon powder (Fe–C), Zoogloea sp. L2, and riboflavin (VB2) were prepared through cross–linking of sodium alginate (SA) to establish an immobilized bioreactor. The optimal ratio of SA beads was adjusted by orthogonal experiment. The change of oxidation–reduction potential (ORP) and the concentration of Fe2+ and Fe3+ showed that the addition of VB2 as a redox mediator can promote denitrification. Under the optimal conditions (carbon to nitrogen (C/N) ratio = 2.0, pH = 7.0, and hydraulic retention time (HRT) = 8 h), the nitrate removal efficiency (NRE) of bioreactor reached 98.48% (1.99 mg L–1h−1). Furthermore, Fourier transform infrared spectrometer (FTIR), Fluorescence excitation–emission matrix (EEM), X–ray diffraction (XRD), and gas chromatography (GC) analysis revealed that the immobilization and denitrification of the immobilized bioreactor were excellent. High throughput sequencing also showed that Zoogloea played a vital role in nitrate removal.

A novel immobilization technique for the development of sustainable anammox gel beads for low nitrogen loadings

This study aimed to develop a sustainable anammox gel beads using sodium alginate (SA) mixed with three different support materials including sodium silicate (SS), polyvinyl alcohol (PVA), and colloidal silica (CS). A detailed characterization and comparison of anammox gel beads were conducted using four lab-scale semi-continuous stirred tank reactors (Semi-CSTRs) and SA–SS beads showed superior durability with better reactor performance. SA–SS (B2) beads showed the minimum reduction effective diameter of 24% in comparison to SA (B1) beads, SA–PVA​ (B3) beads, and SA–CS(B4) beads of 98%, 57%, and 96%, respectively indicating higher integrity of B2 beads. Moreover, R2 reactor containing B2 beads showed the maximum biomass retention after 30 days of operation, relative to the initial mass of 72% compared to R1, R3, and 3%, 44%, and 5%, in R1, R3, and R4, respectively. Total nitrogen removal efficiencies of 8%, 80%, 64%, and 10% were achieved by R1, R2, R3, and R4 reactors, respectively. The diffusion coefficients (De) of ammonium in anammox gel beads was maximum for B2 beads (26.2μm2/s) compared to B1 (18.8μm2/s), B3 (22.4μm2/s), and B4 (13.9μm2/s) beads indicating the enhanced internal mass transfer.

Fipronil degradation kinetics and resource recovery potential of Bacillus sp. strain FA4 isolated from a contaminated agricultural field in Uttarakhand, India

This study investigates the potential role of Bacillus sp. FA4 for the bioremediation of fipronil in a contaminated environment and resource recovery from natural sites. The degradation parameters for fipronil were optimized using response surface methodology (RSM): pH - 7.0, temperature - 32 °C, inocula - 6.0 × 108 CFU mL−1, and fipronil concentration - 50 mg L−1. Degradation of fipronil was confirmed in the mineral salt medium (MSM), soil, immobilized agar discs, and sodium alginate beads. The significant reduction of the half-life of fipronil suggested that the strain FA4 could be used for the treatment of large-scale fipronil degradation from contaminated environments. The kinetic parameters, such as qmax, Ks, and Ki for fipronil degradation with strain FA4, were 0.698 day−1, 12.08 mg L−1, and 479.35 mg L−1, respectively. Immobilized FA4 cells with sodium alginate and agar disc beads showed enhanced degradation with reductions in half-life at 7.83 and 7.34 days, respectively. The biodegradation in soil further confirmed the degradation potential of strain FA4 with a half-life of 7.40 days as compared to the sterilized soil control’s 169.02 days. The application of the strain FA4 on fipronil degradation, under different in vitro conditions, showed that the strain could be used for bioremediation and resource recovery of contaminated wastewater and soil in natural contaminated sites.

Effect of biomass immobilization and reduced graphene oxide on the microbial community changes and nitrogen removal at low temperatures

The slow growth rate and high optimal temperatures for the anaerobic ammonium oxidation (anammox) bacteria are significant limitations of the anammox processes application in the treatment of mainstream of wastewater entering wastewater treatment plant (WWTP). In this study, we investigate the nitrogen removal and microbial community changes in sodium alginate (SA) and sodium alginate–reduced graphene oxide (SA-RGO) carriers, depending on the process temperature, with a particular emphasis on the temperature close to the mainstream of wastewater entering the WWTP. The RGO addition to the SA matrix causes suppression of the beads swelling, which intern modifies the mechanical properties of the gel beads. The effect of the temperature drop on the nitrogen removal rate was reduced for biomass entrapped in SA and SA-RGO gel beads in comparison to non-immobilized biomass, this suggests a ‘‘protective” effect caused by immobilization. However, analyses performed using next-generation sequencing (NGS) and qPCR revealed that the microbial community composition and relative gene abundance changed significantly, after the implementation of the new process conditions. The microbial community inside the gel beads was completely remodelled, in comparison with inoculum, and denitrification contributed to the nitrogen transformation inside the beads.

Fabrication of hesperidin self-micro-emulsifying nutraceutical delivery system embedded in sodium alginate beads to elicit gastric stability

Poor bioavailability of hesperidin (HES) due to its gastric instability and low aqueous solubility limits its clinical application. The objective of presented work was to incorporate self-microemulsifying drug delivery system of HES (SMEDDS-HES) into alginate beads. The alginate beads were characterized for their size and morphology by using motic microscopy and scanning electron microscopy. The selected beads formulation (BF 7) revealed particle size (1.3 ± 0.117 mm), entrapment efficiency (87.4 ± 2.2%), circularity (0.9987), aspect ratio (0.9950), and swelling index (81.75 ± 2.14%). The encapsulation of HES in beads was assured by Fourier transform infrared spectroscopy study. The in vitro drug release kinetic of beads was performed in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). The results revealed negligible release of HES (3.52 ± 0.8%) from beads in SGF after 2 h, and in SIF (after 8 h), the beads showed burst release (72.52 ± 3.5%) of HES. Antidiabetic and histopathological studies on experimental rat revealed promising hypoglycemic activity of beads which sought for its ability to protect HES in the stomach. The shelf life of optimized bead formulation was estimated 1079 days suggesting excellent stability of HES after encapsulation. Finally, developed beads formulation was considered a promising approach in oral delivery of HES.

Adsorption of cationic dyes, drugs and metal from aqueous solutions using a polymer composite of magnetic/β-cyclodextrin/activated charcoal/Na alginate: Isotherm, kinetics and regeneration studies

In this work, we successfully synthesized novel polymer gel beads based on functionalized iron oxide (Fe3O4), activated charcoal (AC) particles with β-cyclodextrin (CD) and sodium alginate (SA) polymer (Fe3O4/CD/AC/SA), by a simple, reproducible and inexpensive method. These beads proved to be versatile and strong adsorbents with magnetic properties and high adsorption capacity. The composites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, vibrating sample magnetometry, adsorption at −196 °C, high resolution transmission electron microscopy, thermogravimetric analysis and point of zero charge measurements. Two dyes, two drugs and one metal were used to test the adsorption capability of the prepared polymer nanocomposite. The adsorbent showed good removal efficiencies for the studied pollutants, especially the cationic dyes and the metal, when compared to other low-cost adsorbents. The saturated adsorption capacity of Fe3O4/CD/AC/SA reached 5.882 mg g−1 for methyl violet (MV), 2.283 mg g−1 for brilliant green (BG), 2.551 mg g−1 for norfloxacin (NOX), 3.125 mg g−1 for ciprofloxacin (CPX), 10.10 mg g−1 for copper metal ion (Cu(II)). The adsorption isotherm studies showed that data fitted well with Langmuir and Temkin isotherms models. The kinetic data showed good correlation coefficient with low error function for the pseudo-second order kinetic model. The data analysis was carried out using error and regression coefficient functions for the estimation of best-fitting isotherm and kinetic models, namely: chi-square test (χ2) and sum of the squares of errors (SSE). The activation energy was found to be 47.68 kJ mol−1 for BG, 29.09 kJ mol−1 for MV, 28.93 kJ mol−1 for NOX, 4.53 kJ mol−1 for CPX and 17.08 kJ mol−1 for Cu(II), which represent chemisorption and physisorption behavior of sorbent molecules. The polymer composites can be regenerated and easily separated from aqueous solution without any weight loss. After regeneration, the Fe3O4/CD/AC/SA beads still have good adsorption capacities up to four cycles of desorption and adsorption. The results indicate that the polymer gel beads are promising adsorbents for the removal of different categories of toxicants (like dyes, drugs and metal) in single adsorbate aqueous systems. Thus, the novel Fe3O4/CD/AC/SA beads can be effectively employed for a large-scale applications as environmentally compatible materials for the adsorption of different categories of pollutants.

Six fruit and vegetable peel beads for the simultaneous removal of heavy metals by biosorption

ABSTRACT In this study, a comparison between the biosorption performance of six fruit and vegetable peels, namely kiwifruit (KP), apple, banana, cucumber, orange and potato immobilized on sodium alginate beads has been made. Inductively coupled plasma coupled with mass spectroscopy was used for measuring the concentration of metal ions in solution before and after biosorption. A range of kinetic models were also applied to the biosorption batch data. The results showed that biosorption percentage of the ions were different on the various beads. For example, the decreasing order of biosorption by one KP bead at equilibrium was Cd > Cu > Hg > Ni > Pb > Cr > As, with approximately 92%, 84%, 80%, 75%, 67%, 34%, and 17% simultaneous removal of ions, respectively. The fastest biosorption was seen with Cd and Pb, as both reached equilibrium by 24 h. Equilibrium time of all other ions occurred by 48 h. While all beads in their unmodified form were suitable for the removal of divalent cations, KP bead showed significantly higher removal of the anion hexavalent Cr. Biosorption of Cd, Hg and Ni was limited by both pseudo-first order and pseudo-second order reaction rates. For Cr and Cu, the reaction was controlled by film diffusion and pseudo-first order rates. At a higher solution concentration, the preference of ions biosorbed as well as their percentage removed changed. Overall, the results indicated that KP beads show promise as a cost-effective method for removing toxic ions by biosorption, especially hexavalent chromium from drinking water.

Development and optimization of Fe3+-crosslinked sodium alginate-methylcellulose semi-interpenetrating polymer network beads for controlled release of ibuprofen

In this study, ionically crosslinked beads of sodium alginate (NaAlg) and methylcellulose (MC) were prepared as semi-interpenetrating polymer networks (semi-IPN) in the size range of 1.97 ± 0.09–1.22 ± 0.13 mm by crosslinking with FeCl3 and loaded with ibuprofen (IBU), which is a nonsteroidal anti-inflammatory drug. The highest 93.33% entrapment efficiency of IBU was achieved, and the drug release behaviors, mean particle size, and entrapment efficiency of beads were investigated in terms of the polymer composition, a ratio of ibuprofen to polymer, exposure time to crosslinker, and concentration of the crosslinking agent. Semi-IPN formulations prepared were also characterized using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), X-ray Diffraction (X-RD), and scanning electron microscopy (SEM). It was observed that IBU-loaded beads displayed better release performance with an increase amount of NaAlg in the structure. Finally, the optimum IBU release was obtained as 93.9% for beads containing 66.7% (w/w) NaAlg, 33.3% (w/w) MC, IBU/polymer ratio of 1/4, FeCl3 concentration of 0.1 M, and crosslinking time of 90 min. The in vitro release rate was fitted to five empirical equations, and the diffusion exponent n, which indicated that the release mechanism of IBU from beads followed the Anomalous and Case II transport mechanism.

Immobilization of the extracellular recombinant Lucky9 xylanase from Bacillussubtilis enhances activity at high temperature and pH.

In the paper industry, chlorine is often used to treat the pulp for bleaching. After pulping, a large amount of xylan is present in the fiber. Xylanase can be used to degrade xylan in an eco-friendly process called biobleaching, which can help minimize the usage of chlorine in the delignification process. However, a bottleneck in the adoption of biobleaching is the cost of xylanase and the requirement that xylanase be active and stable at extreme conditions. Here, we investigated whether using sodium alginate beads to immobilize an extracellular xylanase from Bacillussubtilis (Lucky9) can reduce the potential cost of enzyme usage. The optimal pH and the activity of the immobilized enzyme were increased at optimal temperature compared with the free enzyme. In addition, immobilized xylanase was shown to be more stable than free xylanase. The results of this study suggest that the immobilized xylanase has potential applications in the biobleaching industry.

English

English

Removal of ammonia in water systems using cell immobilization technique in surrounding environment

Cell immobilization can be characterized as any strategy that restrains the free development of cell. The Sequencing Batch Reactor is utilized for the expulsion of alkali utilizing Nitrifying Bacteria by immobilized in sodium alginate beads. The ammoniacal nitrogen removal efficiency was evaluated at different pH from 7 to 9 and different nitrogen loading rates from 150 to 350 mg/L and hydraulic retention times (HRT) of 24, 48 and 72 h. The optimization of operating parameters such as pH, nitrogen loading rate and HRT was studied. The influent and effluent was analyzed for ammoniacal nitrogen, nitrite nitrogen and nitrate nitrogen. The highest removal of ammoniacal nitrogen was accomplished (89%) at pH 8 and the nitrogen loading rate of 350 mg/L with 72 h hydraulic retention time. The result indicates that the removal efficiency of ammoniacal nitrogen increase with increase in HRT and Nitrogen loading rate. Smelling salts oxidizing microorganisms were immobilized by polyvinyl liquor (PVA) and sodium alginate. The immobilization conditions and smelling salts oxidation capacity of the immobilized microscopic organisms were explored. The accompanying immobilization conditions were seen to be ideal: PVA-12%; sodium alginate-1.1%; calcium chloride-1.0%; inoculum focus-1.3 immobilized balls/mL of immobilized medium; pH-10; and temperature-30 °C. The immobilized smelling salts oxidizing microscopic organisms displayed solid alkali oxidation capacity significantly subsequent to being reused multiple times. The smelling salts nitrogen expulsion pace of the immobilized alkali oxidizing microscopic organisms arrived at 90.30% under the ideal immobilization conditions. When contrasted and smelling salts oxidizing microorganisms immobilized by sodium alginate alone, the microscopic organisms immobilized by PVA and sodium alginate were better with deference than pH opposition, the quantity of reuses, material cost, heat obstruction, and alkali oxidation capacity.

Development of alginate/inulin carrier systems containing non-conventional Amazonian berry extracts

Different carriers, such as the combination of sodium alginate and inulin, have been employed to protect foods against environmental effects. The goal of this work was to use the ionic gelation encapsulation process to produce microparticles containing Clidemia rubra extract, ranging the concentration of inulin from 1.5 to 3.5 g inulin.100 g−1 of solution. Characteristic signals of sugars, organic acids and phenolic compounds were identified in the extract using the 1H NMR technique. The carriers containing inulin presented significant difference in the moisture content when compared to the pure sodium alginate beads. The produced beads were found in the range of 0.81–1.06 mm. The addition of inulin to sodium alginate was significant for the encapsulation efficiency (EE) of the antioxidant compounds when compared to the beads formed only using pure sodium alginate. The microspheres presenting inulin and sodium alginate presented higher content of spherical particles. The addition of 2.5 g inulin.100 g−1 of solution allowed its incorporation into the pores of the beads, favoring a possible chemical interaction between inulin and sodium alginate. This interaction resulted in a different crystal structure and better EE. Furthermore, beads containing inulin presented higher protection of the encapsulated bioactive compounds during the gastric phase.

Viability of Lactobacillus rhamnosus GG in Simulated Gastrointestinal Conditions and After Baking White Pan Bread at Different Temperature and Time Regimes.

This study investigated theviability of encapsulated and un-encapsulated (free cell) Lactobacillus rhamnosus GG (LGG) in bread baked at different baking conditions (180°C for 30min, 220°C for 20min, and 250°C for 15min) and in simulated gastrointestinal conditions. The cell was encapsulated either with sodium alginate, singly or in combination with chitosan, cassava starch, and hi-maize resistant starch. There was complete loss of viability of un-encapsulated LGG after baking. Significantly (P < 0.05) higher viability was recorded for LGG encapsulated with sodium alginate + cassava starch + chitosan beads (SCCB) and sodium alginate + hi-maize resistant starch + chitosan beads (SHCB) compared to sodium alginate beads (SAB) and sodium alginate + cassava starch beads (SSB). Lactobacillus rhamnosus GG encapsulated with SHCB gavethe highest viability (P < 0.05) after subjection to simulated gastric and intestinal juices. Theincorporation of LGG did not have significant (P < 0.05) influence on volume, specific volume, moisture, ash, fat, and fiber contents of bread. The lowestmoisture content was obtained at baking condition of 180°C for 30min, while thehighest value was at 250°C for 15min. Baking condition did not cause significant (P > 0.05) change in fat, ash, and carbohydrate content of bread. Theencapsulation of LGG with multiple layers of encapsulating materials significantly preserved its viability during baking and in simulatedgastrointestinal conditions.

Layered Silicate-Alginate Composite Particles for the pH-Mediated Release of Theophylline.

Numerous natural and synthetic clay minerals have proven to be excellent drug carriers for high drug-loaded and sustained release formulations due to their considerable ion exchange, adsorption, and swelling capacities. Moreover, the synthetic smectite clays have added advantages in terms of compositional purity and controlled cation exchange capacity in comparison to natural clays. This study involves the intercalation of theophylline (TP) in a synthetic clay, Laponite® (LP), followed by the inclusion of the resulting intercalates into sodium alginate (SA) beads to achieve pH-controlled drug release. Maximum intercalated drug incorporation of 68 mg/g was obtained by ion exchange at pH 1.2 and confirmed by an increase in basal spacing of the clay from 12.9 to 15.5 Å. TP release from the binary LP-TP intercalates in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) was found to be 40% and 70%, respectively. LP-TP particles were also incorporated in an SA matrix via polymer crosslinking using CaCl2(aq) to improve the pH selective release. The ternary polymer-clay-drug composite particles effectively prevented the release of TP at low pH in SGF and resulted in sustained release in SIF, with 40% dissolution within 120 min.

Manufacturing and performance of environment-friendly lightweight aggregates with core-shell structure

The production of lightweight aggregates (LWAs) involves much energy consumption and emission of pollution during the sintering process. The increasing worldwide demand for functional concrete for use in modern construction has promoted this negative trend to a more serious level. This study reports an artificial lightweight capsule aggregates (CAs) based on an encapsulation technology from the viewpoint of green manufacturing. The novel CAs are composed of a fly ash-cement inorganic shell and sodium alginate organic core. A series of experiments were conducted to study the influences of the rotation rate, duration time, curing conditions and surface conditions for sodium alginate beads (SAB) on the physical and mechanical characteristics of the CAs. The results indicate that CAs with a wet density of 1340 kg/m3 and corresponding crush strength of 2.46 MPa can be achieved. The CAs density can be further decreased by a third via sodium alginate dehydration. CAs with optimized performance can be synthesized by using a rotation rate of 150 rpm, duration time of 30 s and C/A ratio of 2.0. A low rotation rate and high duration time have a negative effect on the CAs characteristics. A saturated surface dry (SSD) condition process for the SAB was found to greatly contribute to the optimization of CAs density. Findings from this study can provide a novel and viable way to reuse industrial wastes and biomass resources to manufacture core-shell structured LWAs with stable and adjustable performance. These artificial LWAs have great application potential in the preparation of the advanced lightweight concrete.

Metal nanoparticles decorated sodium alginate‑carbon nitride composite beads as effective catalyst for the reduction of organic pollutants

Herein, a simple method is used for fabrication of carbon nitride (g-C3N4) incorporated sodium alginate (Alg) beads. The alginate carbon nitride beads (Alg-CNBs) were prepared by introducing the g-C3N4 dispersed Alg aqueous solution to a divalent Ca2+ ions solution. Alg-CNBs were further treated with different transition metal salt solutions. The surface coated transition metal ions on Alg-CNBs were reduced to zero-valent state (M0), through strong reducing agent NaBH4, and used for the catalytic reduction of different organic dyes. The surface morphology of all catalysts was investigated by FE-SEM and metal uptake capacity was investigated by ICP-OES. The prepared M0/Alg-CNBs (where M0 = Ag0, Ni0, Fe0 and Cu0) catalysts were tested against the reduction of 4-nitrophenol (4-NP) to recognize the fastest one. Among all the catalysts, the Cu0/Alg-CNBs efficiently reduced 4-NP to 4-aminophenol (4-AP). Cu0/Alg-CNBs was used further for the reduction of methyl orange (MO), congo red (CR), 2-nitrophenol (2-NP) and 2,6-dinitrophenol (2,6-DNP). The MO, CR and 4-NP was reduced with rate constant of 0.135, 0.077 and 0.384 min−1, respectively. For large scale and continuous reduction of 4-NP to 4-AP, the column was packed with 0.15 g catalyst and the reducible reactants were passed through it. A reduction of 4-NP up to 97–99% was achieved by simply passing it through column packed with catalyst under gravity. Similarly, effects of changing initial dye concentration, catalytic dosage and NaBH4 performance has been investigated for the reduction process. Also, the prepared catalyst beads can be easily prepared, recovered simply by discarding the dye after completion of the reaction, recyclable and its good catalytic activity.

Improving performance of microbial fuel cell by enhanced bacterial-anode interaction using sludge immobilized beads with activated carbon

Performance of a microbial fuel cell (MFC) is greatly influenced by capability of anode material in promoting attachment of electrogenic bacteria on its surface, which assists in higher electron transfer with minimal electrode resistance. In this investigation, feasibility of different anode materials made of stainless-steel (SS) mesh cage filled with sodium alginate beads matrix containing either bacterial inoculum (Ic) or activated carbon (AC) or combination of both (AC-Ic) was evaluated and performance was compared with MFCs operated with bare carbon felt and SS mesh as an anode material. Superior performance was exhibited by MFC having anode containing bead matrix with AC-Ic in SS mesh cage, which exhibited a maximum power density of 2.6 W/m3 and chemical oxygen demand (COD) removal efficiency of 91.6 ± 2.1 % due to enhanced bacterial-electrode interaction. Furthermore, the cost of bead-based electrodes was seventeen folds cheaper than carbon felt electrode, making it ideal for pilot-scale MFCs.

A prebiotic-based biopolymeric encapsulation system for improved survival of Lactobacillus rhamnosus

Fructooligosaccharides (FOS) improve viability of probiotics and gastrointestinal health. FOS and alginate as encapsulation material, can provide better structure of beads to improve the survival of probiotics. The present study focused on FOS extraction from banana peel to encapsulate L. rhamnosus and explore its in vitro survival through structural interactive optimization of encapsulation materials. FOS and sodium alginate (SA) were used for encapsulation of L. rhamnosus with different formulations, e.g., Mo (100% SA), M1 (75% SA + 25% FOS), M2 (50% SA + 50% FOS), M3 (25% SA + 75% FOS) and M4 (FOS 100%). The stability of free and encapsulated L. rhamnosus was assessed using gastrointestinal conditions. All the treatments provided better encapsulation efficiency except M4. Microencapsulation significantly maintained viability of L. rhamnosus using simulated gastric conditions, bile salt, low pH and during storage. M2 was considered as the best encapsulation treatment for survival of L. rhamnosus. The SA beads have pores but addition of FOS improved the structure of the beads. Fourier transform infrared spectrometry results showed the presence of FOS and SA in the respective treatments. Principal component analysis (PCA) explained differences among bead formulations using spectral data. In simulated gastric juice, maximum viability was observed (8.5 ± 0.1 log CFU/mL) due to increased concentration of FOS. The FOS were extracted from banana peel and successfully used as a prebiotic encapsulation material for effective delivery of L. rhamnosus. The different combinations of wall materials provided an opportunity to develop beads with better structure and protection.

An in vitro study on hexavalent chromium [Cr(VI)] remediation using iron oxide nanoparticles based beads

This study focused on a kind of high efficiency and low cost iron oxide nanoparticles (IONPs) synthesis and loaded with sodium alginate beads used for remediation of hexavalent chromium [Cr (VI)] contaminated water. Due to high toxicity and mobility of Cr (VI) is considered to be a toxic pollutant. The synthesized IONPs were characterized by UV–vis and FTIR spectroscopy analysis. The IONPs loaded alginate beads was characterized and its chromium remediation property was evaluated by diphenyl carbazide assay and batch experiment was performed at different pH ranges (pH 1–7). The present study revealed that Cr (VI) is effectively reduced by IONPs loaded alginate beads nearly 90 % at pH 2.5 with the average size of 2 mm and the stability of the interacted particle observed around 60 min at 500 rpm. Finally it was demonstrated that, a cost effective method for the in situ remediation of Cr (VI) was achieved by IONPs loaded alginate beads.

Effective nitrogen removal from ammonium-depleted wastewater by partial nitritation and anammox immobilized in granular and thin layer gel carriers

This study investigates the effect of physicochemical conditions on the partial nitritation and anammox treatment by immobilized ammonia oxidizers under ammonium-deplete conditions. The impact of oxygen and temperature was studied by measuring the activity of immobilized aerobic and anaerobic ammonia-oxidizing organisms (Ammonia-oxidizing bacteria (AOB) and archaea (AOA), and Anammox bacteria) embedded in polyvinyl alcohol – sodium alginate (PVA-SA) beads and in thin layer poly-ethylene glycol hydrogels. Beads and flat hydrogels were incubated in a fluidized bed reactor (FBR) and in two flow cells, respectively. Both systems were fed with synthetic wastewater (15 mg N–NH4+/L) at different temperatures (20 °C and/or 30 °C) and different dissolved oxygen (DO) concentrations (0.1, 0.3, 0.5 and/or 1 mg/L) over 152 and 207 days, respectively. The FBR system had a maximum removal rate of 1.7 g-N/m3/d at 0.1 mg O2/L, corresponding to 80% removal efficiency, while a high aerobic ammonia-oxidizing activity but a partial oxygen inhibition of Anammox bacteria were observed at higher DO concentrations. In both flow cells, nitrogen removal efficiency was highest (80%) at 30 °C and 1 mg O2/L while removal was less favorable at lower DO and lower temperature. Our results indicate a potential use of hydrogel beads for an energy efficient technology with reduced aeration demand for treating low ammonia wastewater, while layered hydrogels are a possible first step for biological treatments of wastewater using tangential flow. In addition, we provide blueprint drawings of the flow cells, which may be used to 3D-print the apparatus for other applications.