Magnetic iron oxide nanoparticle enhanced microwave pretreatment for anaerobic digestion of meat industry sludge.

Our study investigates the effects of iron oxide (Fe3O4) nanoparticles combined microwave pretreatment on the anaerobic digestibility and soluble chemical oxygen demand (SCOD) of meat industry sludge. One of our main objectives was to see whether the different microwave-based pretreatment procedures can enhance biogas production by improving the biological availability of organic compounds. Results demonstrated that combining microwave irradiation with magnetic iron oxide nanoparticles considerably increased SCOD (enhancement ratio was above 1.5), the rate of specific biogas production, and the total cumulative specific biogas volume (more than a threefold increment), while having no negative effect on the biomethane content. Furthermore, the assessment of the sludge samples' dielectric properties (dielectric constant and loss factor measured at the frequency of 500 MHz) showed a strong correlation with SCOD changes (r = 0.9942, R2 = 0.99), offering a novel method to evaluate pretreatment efficiency.

Investigation of Different Pre-Treatment Techniques and 3D Printed Turbulence Promoter to Mitigate Membrane Fouling in Dairy Wastewater Module.

This study investigates the enhancement of dairy wastewater treatment using chemical and physical pre-treatments coupled with membrane separation techniques to reduce membrane fouling. Two mathematical models, namely the Hermia and resistance-in-series module, were utilized to comprehend the mechanisms of ultrafiltration (UF) membrane fouling. The predominant fouling mechanism was identified by fitting experimental data into four models. The study calculated and compared permeate flux, membrane rejection, and membrane reversible and irreversible resistance values. The gas formation was also evaluated as a post-treatment. The results showed that the pre-treatments improved UF efficiency for flux, retention, and resistance values compared to the control. Chemical pre-treatment was identified as the most effective approach to improve filtration efficiency. Physical treatments after microfiltration (MF) and UF showed better fluxes, retention, and resistance results than ultrasonic pre-treatment followed by UF. The efficacy of a three-dimensionally printed (3DP) turbulence promoter was also examined to mitigate membrane fouling. The integration of the 3DP turbulence promoter enhanced hydrodynamic conditions and increased the shear rate on the membrane surface, shortening filtration time and increasing permeate flux values. This study provides valuable insights into optimizing dairy wastewater treatment and membrane separation techniques, which can have significant implications for sustainable water resource management. The present outcomes clearly recommend the application of hybrid pre-, main- and post-treatments coupled with module-integrated turbulence promoters in dairy wastewater ultrafiltration membrane modules to increase membrane separation efficiencies.

Comparison of filtering models for milk substitutes.

Membrane-based methods of filtering are becoming increasingly popular in the food industry, but membrane fouling significantly affects filtration performance, making the characterisation of fouling mechanisms critical. This study examined the applicability of three mathematical models. The resistance-in-series model divides the total resistance into membrane resistance, reversible resistance and irreversible resistance. The Hermia models distinguish four basic blocking mechanisms, namely complete blocking, standard blocking, intermediate blocking and cake filtration. The Makardij model analyses the flux-reducing or -enhancing effects. In the experiments, different models were investigated and compared. The feed solution was two milk substitute drinks (soy and oat) that were ultrafiltered under different operating parameters (transmembrane pressures: 0.05-0.1 MPa, stirring rate: 100-400 min-1). By fitting the data to the models, the most characteristic blocking mechanism and the rate constant that most influenced flux could be determined.

Detection of the efficiency of microwave-oxidation process for meat industry wastewater by dielectric measurement.

Our experimental work focused on the applicability of a quite novel process for wastewater treatment, i.e. a microwave (MW) irradiation-enhanced Fenton-like method. The aim of our research was to detect and evaluate the efficiency of this oxidation process, during the treatment of meat industry wastewater containing a high concentration of organic material. The efficiency was defined by the measurement of the change in COD (chemical oxygen demand, with an initial COD value of 1,568 mg L-1), and with the determination of dielectric parameters during the process. It can be summarized that MW irradiation could assist in a Fenton-like oxidation process to achieve higher organic matter removal. Furthermore, our experimental results and statistical analysis show that there can be found a correlation between the effects of applied MW energy and the dosage of H2O2/FeSO4. If the intensity of MW irradiation and the amount of FeSO4 were set higher, the decrease of COD and the increase of tanδ (the dielectric loss tangent) were definitely more significant. With the application of 60 kJ MWE and a 0.14 mgFe2+/mgCOD dosage, the COD removal efficiency was more than 40%, and the increment of tanδ was nearly threefold. Considering the effects of MW-specific process parameters, it can be concluded that the power intensity of MW-oxidation treatment has a significant effect on COD decrease, if the irradiated MW energy was set at lower (30-45 kJ) levels.