Swine manure digestate treatment using electrocoagulation

ABSTRACT Anaerobic biodigestion is an appropriate alternative for the treatment of swine wastewater due to its biogas generation properties and the possibility of its application as a source of energy for heating or electricity. However, digestate can still contain high levels of turbidity, organic carbon and nutrients and must be correctly managed as a biofertilizer, or treated to avoid any impact on the environment. Considering this, electrocoagulation (EC) shows promise as a technology because of its ease of handling and high efficiency in effluent remediation. This study aimed to evaluate the performance of EC in a batch system in the treatment of swine wastewater digestate. The wastewater used in the treatment was sampled from a 10 m3 biodigestor effluent (digestate) located at Concórdia, Santa Catarina, Brazil. A batch-scale experiment was carried out to evaluate the following two variables: electrode distance (ED) and voltage applied (V). The removal efficiency levels (%) for the best operational condition (2 cm, 5 V) after 30 min were: 97 %, 98 %, 77 % and 10 % for color, turbidity, total organic carbon (TOC) and total nitrogen (TN), respectively. The EC batch system produced efficient results, underlining its promise as an alternative to be applied in the treatment of digestate

Adsorption, Kinetic and Equilibrium Studies of Cr(VI) by Hazelnut Shell Activated Carbon

The adsorption of chromium(VI) from aqueous solutions on to hazelnut shell activated carbon (HSAC) was investigated. The adsorption was carried out by varying parameters such as the agitation time, the initial solution pH, the initial Cr(VI) concentration and the temperature. The experimental data were well fitted by the pseudo-first-order kinetic model allowing the rate constants to be evaluated. The Langmuir isotherm provided the best correlation for the adsorption of Cr(VI) onto the activated carbon. The adsorption of Cr(VI) was pH-dependent. The adsorption capacity as calculated from the Langmuir isotherm was 170 mg/g at an initial pH of 1.0 for a Cr(VI) solution of 1000 mg/l concentration. Thermodynamic parameters were evaluated, indicating that the adsorption was endothermic and involved monolayer adsorption of Cr(VI)

Modelling the Effects of Adsorbent Dose and Particle Size on the Adsorption of Cr(VI) Ions from Aqueous Solutions

Activated carbon was prepared from hazelnut shell with chemical carbonization using concentrated sulphuric acid. The adsorption tests were carried out in an agitated batch system with a fixed initial Cr(VI) ion concentration and varying adsorbent particle sizes and doses. The adsorption of Cr(VI) ions correlated strongly with these two variables. Two simple empirical models were examined for predicting the percentage of Cr(VI) ion adsorbed. Both models exhibited good correlation coefficients. The best model was selected on the basis of the standard deviation between the calculated and experimental values. The Freundlich adsorption isotherm provided the best correlation for the adsorption of Cr(VI) ions onto the carbon. This isotherm was used to fit the experimental adsorption capacity data and allowed the model parameters to be calculated and correlated with the particle size

Synthesis of g-C 3 N 4 @CuMOFs nanocomposite with superior peroxidase mimetic activity for the fluorometric measurement of glucose

Herein, a novel metal-organic framework (MOF) based nanocomposite with efficient catalytic behavior is reported including flake-like copper (II) MOF (CuMOF) and graphitic C 3 N 4 nanosheets (g-C 3 N 4 ). The g-C 3 N 4 @MOF nanocomposite was simply prepared by solvothermal synthesis of CuMOF in the presence of g-C 3 N 4 . The characterization analyses using scanning electron microscopy (SEM), X-ray diffractometry (XRD) and some other techniques demonstrated a nano-porous flake-like structure for the synthesized CuMOF, which enveloped the g-C 3 N 4 nanosheets. Furthermore, the investigation of catalytic behavior of synthesized nanomaterial was implemented on H 2 O 2 based reactions. The fluorometric and colorimetric experimentations illustrated that the accompanying of g-C 3 N 4 with CuMOF had a remarkable positive effect on the catalytic behavior of obtained g-C 3 N 4 @MOF. This effect was described based on the improved affinity of nanocomposite to adsorb H 2 O 2 and also synergistic action of its components on the dissociation of H 2 O 2 to hydroxyl radicals. Finally, the analytical application of high catalytic activity of new g-C 3 N 4 @MOF was designed for the rapid and simple measurement of glucose in blood. After the enzymatic oxidation of glucose, the fluorometric method was applied for the analysis of produced H 2 O 2 using terephthalic acid as peroxidase substrate. The system led to the ultrasensitive glucose determination in the concentration range of 0.1�22 μM, with a detection limit (3S/m) of 59 nM. © 2019 Elsevier B.V

Adsorption Kinetic Models Applied to Nickel Ions on Hazelnut Shell Activated Carbons

Kinetic models describing the adsorption of Ni(II) ions on to hazelnut shell active carbon (HSAC) have been compared. Kinetic studies have also been carried out in a batch adsorber over a range of initial metal ion concentration (11.87–92.34 mg/dm 3 ), agitation speed (50–200 rpm) and adsorbent particle size (0.90–1.60 mm). The rate models evaluated included the pseudo-first order equation, the pseudo-second order equation and the Elovich equation. The results obtained showed that the pseudo-second order kinetic model correlated the experimental data well and better than the other models examined in this study