Search Results (5)

This study evaluated the reliability of an electronic nose in monitoring odour concentration near a wastewater treatment plant and examined the correlation between four sensor readings and odour intensity. The electronic nose chemical sensors are related to the concentration of the following chemical species: two values for the concentration of VOCs recorded via the PID sensor (VPID) and the EC sensor (VEC), and concentrations of sulfuric acid (VH₂S) and benzene (VC₆H₆). Using Random Forest and least squares regression analysis, the study identifies VH₂S and VC₆H₆ as key contributors to odour concentration (C^c_OD). Three Random Forest models (RF0, RF1, RF2), with different characteristics for splitting between the test set and the training set, were tested, with RF1 showing superior predictive performance due to its training approach. All models highlighted VH₂S and VC₆H₆ as significant predictors, while VPID and VEC had less influence. A significant correlation between odour concentration and specific chemical sensor readings was found, particularly for VH₂S and VC₆H₆. However, predicting odour concentrations below 1000 ou_E/m³ proved challenging. Linear regression further confirmed the importance of VH₂S and VC₆H₆, with a moderate R-squared value of 0.70, explaining 70% of the variability in odour concentration. The study demonstrated the effectiveness of combining Random Forest and least squares regression for robust and interpretable results. Future research should focus on expanding the dataset and incorporating additional variables to enhance model accuracy. The findings underscore the necessity of specific sensor training and standardised procedures for accurate odour monitoring and characterisation. Full article

The alcohol precipitation wastewater discharged from the production of Chinese patent medicine (CPM) has an extremely high chemical oxygen demand (COD) and poor biodegradability. In this study, the biological treatment method of anaerobic digestion coupled with simultaneous nitrification and denitrification (SND) was adopted to investigate its efficiency and to explore the mechanism of pollutant degradation in this process. The results showed that after 220 days of debugging, the coupled process operated stably. The influent COD, total nitrogen (TN), ammonium (NH₄⁺-N), and lignin concentrations were 21,000 mg/L, 400 mg/L, 200 mg/L, and 1800 mg/L, respectively. The removal efficiencies of COD, TN, NH₄⁺-N, and lignin were 97%, 85%, 96%, and 75%, respectively. Spectral detection technology analysis revealed that the wastewater contained alkanes, olefins, phenols, alcohols, unsaturated organics, aromatic compounds, and humic acids. After the treatment by each unit of the process, the three-dimensional fluorescence intensity decreased by 86%; the standard volume of fluorescence area integration declined by 78%; the stretching vibration band of aromatic compounds showed peak splitting; and the molecular weight parameter value in the ultraviolet region increased. These findings demonstrated that the humic acid substances in the wastewater were degraded, and the effect of removal of the macromolecular organic matter was remarkable. Full article

Due to low efficiency and the material choice limitations of traditional evaporation systems to treat acid wastewater, humidification and dehumidification (HDH) as the core process was applied in the treatment and reduction of wastewater with organic acid pollutant concentrations. The forecasting of pH changes and COD reduction is important for the system’s design. Therefore, a study of the pollutant removal efficiency with different parameters, such as the reaction temperature, air quantity, and flow rate was conducted with ASPEN modeling. In this article, ASPEN modeling was used to simulate the water and acid material transformation in HDH system. The process was composed of blocks, such as RadFrac, heater and split. The analysis was taken with different air quantities, tower diameters, heat loads and flow rates. The analysis indicated that the pH of the maleic acid wastewater changed from 3.0 to 5.7. The relationship between inlet quantity, air quantity, inlet heat and the clean water yield was also shown in the modeling results. Based on these studies, we determined that the model can help engineers solve the key problems of HDH systems, such as heat balance calculation, equipment selection, and the prediction of incoming and outgoing evaporation materials. Full article

Sustainable hydrogen production is one of the main challenges today in the transition to a green and sustainable economy. Photocatalytic hydrogen production is one of the most promising technologies, amongst which BiVO₄-based processes are highly attractive due to their suitable band gap for solar-driven processes. However, the performance of BiVO₄ alone in this role is often unsatisfactory. Herein we report the improvement of BiVO₄ performance with reduced graphene oxide (rGO) as a co-catalyst for the photoelectrochemical water splitting (PEC-WS) in the presence of simple functionalized benzene derivatives (SFBDs), i.e., phenol (PH), benzoic acid (BA), salicylic acid (SA), and 5-aminosalicylic acid (5-ASA) as potential photogenerated hole scavengers from contaminated wastewaters. Linear sweep voltammetry and chronoamperometry, along with electrochemical impedance spectroscopy were utilized to elucidate PEC-WS performance under illumination. rGO has remarkably improved the performance of BiVO₄ in this role by decreasing photogenerated charge recombination. In addition, 5-ASA greatly improved current densities. After 120 min under LED illumination, 0.53 μmol of H₂ was produced. The type and concentration of SFBDs can have significant and at times opposite effects on the PEC-WS performance of both BiVO₄ and rGO-BiVO₄. Full article

This study investigated acid splitting wastewater (ASW) and interphase (IF) from soapstock splitting, as well as matter organic non glycerol (MONG) from glycerol processing, as potential substrates for biogas production. Batch and semicontinuous thermophilic anaerobic digestion experiments were conducted, and the substrates were preliminary treated using commercial enzymes kindly delivered by Novozymes A/C. The greatest enhancement in the batch digestion efficiency was achieved when three preparations; EversaTransform, NovoShape, and Lecitase were applied in the hydrolysis stage, which resulted in the maximum methane yields of 937 NL/kg VS and 915 NL/kg VS obtained from IF and MONG, respectively. The co-digestion of 68% ASW, 16% IF, and 16% MONG (wet weight basis) performed at an organic loading rate (OLR) of 1.5 kg VS/m³/day provided an average methane yield of 515 NLCH₄/kg VS_added and a volatile solid reduction of nearly 95%. A relatively high concentration of sulfates in the feed did not significantly affect the digestion performance but resulted in an increased hydrogen sulfide concentration in the biogas with the peak of 4000 ppm. Full article