The removal of phenolic compounds from aqueous solutions using novel adsorption techniques becomes a key research item. Of those, nanoparticles in particular, the low-cost and the high-strength aluminum oxide nanoparticles showed promising results in pollutant uptake and increase in the adsorption efficiency. This study examined various physicochemical process parameters such as temperature, pH, initial phenol concentration, and adsorbent doses, in addition to the impact of those parameters on the adsorption removal mechanism of phenol. The results highlighted that aluminum oxide nanoparticles successfully exhibited superior phenol removal from an aqueous solution in addition to a high potential regeneration of the consumed nanoparticles by HCl. For the adsorbent mass of 0.5 g, phenol adsorption uptake reached 92%. Kinetic studies performed using several models demonstrated the data best fitting with a pseudo-second-order kinetic model. Examining equilibrium studies of various isotherms, the adsorption data of phenol into aluminum oxide nanoparticles was confirmed to be controlled by film diffusion and best represented by the Langmuir isotherm. The maximum capacity of adsorption was 16.97 mg/g. For thermodynamics studies, the results indicated that the adsorption process can vary between endothermic and exothermic reactions. Such relative differences in heat generation and spontaneity in adsorption processes were demonstrated and confirmed by principal component analysis (PCA). This evidence is key for future investigations for the efficiency of adsorption conditions concerning the contaminant type and adsorbate compounds.

The impact of conductive additives on the two-phase anaerobic digestion (AD) process has been limited. Consequently, in this study, we investigated the impact of different doses of biochar (5, 10, and 15 g/L) on a batch two-stage AD, consisting of acidogenic (1st phase) followed by methanogenic (2nd phase). First, sugarcane bagasse was used as a precursor for the preparation of biochar. The prepared biochar was then employed as a conductive material in two-phase AD of food waste. Compared to the control, the hydrogen and methane production were improved in the biochar-amended digesters. Notably, 10 g/L of biochar dose was optimal for both stages. Additionally, the addition of biochar ameliorated the generation of volatile fatty acids (VFAs) during hydrogen production and the degradation of VFAs during methane production. Principal component analysis (PCA) interpreted the relative performance of the AD conditions with various biochar doses. Hydrogen was detected during the first 10 days as the main component of the biogas with a maximum ratio of 85.6% and maximum yield of 583.2 mL/g VS in the case of using biochar dose 10 g/L, while the highest methane yield (114.5 mL/g VS) was detected on the 15th day using the same biochar dose, and the highest methane ratio was 81.6%. The low content of CO₂ during the biogas production as well as the high biogas production and the effective biodegradation of food waste can support the application of the proposed system on a wider scale. Graphical abstract

Here, we report data of the principal component analysis (PCA) assessment and clustering analysis related to low-temperature thermal hydrolysis process (THP) for enhancing the anaerobic digestion (AD) of sludge in wastewater treatment plants (WWTPs) with primary sludge fermentation (Azizi et al., 2021). The PCA was examined to pinpoint the influence of different THP schemes on the variations of macromolecular compounds solubilization after low-temperature THP and the relative performances in enhancing methane potential in AD. We established 2 experimental setups with a total of 18 treatment conditions (3 exposure times, 30, 60, and 90 min at three temperature levels 50, 70 and 90 °C) in comparison to the untreated control samples. Scheme-1 comprises the THP of a mixture of (1:1 vol ratio) fermented primary sludge (FPS) and thickened waste activated sludge (TWAS); while scheme-2 comprised the THP of TWAS only. The factors employed in the assessment of the PCA encompassed the variations in the macromolecular compounds and other solubilization metrics. This included the variations in the levels of carbohydrates, lipids, proteins, and solubilization of chemical oxygen demand (COD) and volatile suspended solids (VSS). Furthermore, the evaluation considered the changes of volatile fatty acids (VFAs) and total ammonia nitrogen (TAN) with respect to time and temperature. The assessment of PCA classified the THP based on their differences and alterations that occurred after the treatment. The indices of the PCA assessments differed based on the factors of concern and the focus of each individual PCA assessment. In every individual PCA assessment, the respective contribution to the total variance in PCA analysis was calculated and manifested by the highest distribution of the principal components (PCs) axis PC1 and PC2. The differences in distributions of PCs after various PCA examinations can describe the relative influence of THP schemes and the most significant variables that can trigger major differences among THP conditions. The comparative differences demonstrated by PCA support the potential investigations of the efficiency of THPs conditions and their performance categories.

Among the available technologies, the dyna-sand filter has gained attention due to its continuous filtration and sand washing mechanism, which provides an advantage in maintaining stable operation. Nevertheless, its performance under variable heights of washout weir with constant solid loads and the optimization of its washing system remain areas that require further study. This study investigates the use of the dyna-sand filter in water treatment facilities, focusing on the alteration of the washout weir to improve efficiency and reduce washout water amount. The study evaluates the filter’s performance under fixed influent total suspended solids (TSS) concentration and constant filtration rate (ROF), aiming to demonstrate the advantages of this alteration in enhancing removal efficiency, operational stability, and water saving through a laboratory-scale pilot. The average washout discharge fell from 0.788 to 0.486 L/min, a 38.3% reduction in washout water amount. As a result, filtered water production rose by nearly 2.2%, indicating more efficient hydraulic operation. These findings confirm that raising the washout weir by 4 cm improved filtration and reduced washout water loss. This, in turn, enhanced system productivity and the quality of washwater produced, assuming a consistent flow rate and solid load.