Optimisation of operating conditions during coagulation-flocculation process in industrial wastewater treatment using Hylocereus undatus foliage through response surface methodology

Response Surface Optimization on Ferrate-Assisted Coagulation Pretreatment of SDBS-Containing Strengthened Organic Wastewater

Sodium dodecylbenzene sulfonate (SDBS), an anionic surfactant, has both hydrophilic and lipophilic properties and is widely used in daily production and life. The SDBS-containing organic wastewater is considered difficult to be degraded, which is harmful to the water environment and human health. In this study, ferrate-assisted coagulation was applied to treat SDBS wastewater. Firstly, a single-factor experiment was conducted to investigate the effect of the Na2FeO4 dosage, polyaluminum chloride (PAC) dosage, pH and temperature on the treatment efficiency of SDBS wastewater; then, a response surface optimization experiment was further applied to obtain the optimized conditions for the SDBS treatment. According to the experimental results, the optimal treatment conditions were shown as follows: the Na2FeO4 dosage was 57 mg/L, the PAC dosage was 5 g/L and pH was 8, under which the chemical oxygen demand (COD) removal rate was 90%. Adsorption bridging and entrapment in the floc structure were the main mechanisms of pollution removal. The ferrate-assisted coagulation treatment of strengthened SDBS wastewater was verified by a response surface experiment to provide fundamental understandings for the treatment of the surfactant.

Preparation and modification methods of defective titanium dioxide-based nanoparticles for photocatalytic wastewater treatment-a comprehensive review

The rapid population growth and industrial expansion worldwide have created serious water contamination concerns. To curb the pollution issue, it has become imperative to use a versatile material for the treatment. Titanium dioxide (TiO₂) has been recognized as the most-studied nanoparticle in various fields of science and engineering due to its availability, low cost, efficiency, and other fascinating properties with a wide range of applications in modern technology. Recent studies revealed the photocatalytic activity of the material for the treatment of industrial effluents to promote environmental sustainability. With the wide band gap energy of 3.2 eV, TiO₂ can be activated under UV light; thus, many strategies have been proposed to extend its photoabsorption to the visible light region. In what follows, this has generated increasing attention to study its characteristics and structural modifications in different forms for photocatalytic applications. The present review provides an insight into the understanding of the synthesis methods of TiO₂, the current progress in the treatment techniques for the degradation of wide environmental pollutants employing modified TiO₂ nanoparticles, and the factors affecting its photocatalytic activities. Further, recent developments in using titania for practical applications, the approach for designing novel nanomaterials, and the prospects and opportunities in this exciting area have been discussed.

Determination and Removal of Selected Pharmaceuticals and Total Organic Carbon from Surface Water by Aluminum Chlorohydrate Coagulant

In the present research, the removal of Total Organic Carbon (TOC) and erythromycin (ERY), fluoxetine (FLX), amoxicillin (AMO), colistin (COL), ethynylestradiol (EE), and diclofenac (DIC) from surface water by coagulation is studied. The concentration of selected pharmaceuticals in 24 surface water samples originating from some rivers located in Lesser Poland Voivodeship and Silesia Voivodeship, Poland, was determined. The removal of TOC and pharmaceuticals was carried out using the application of Design of Experiments (DOE), Response Surface Methodology (RSM), and by addition of aluminum chlorohydrate (ACH) as a coagulant. The study found that the concentration ranges of ERY, FLX, AMO, COL, EE, and DIC in analyzed water samples were 7.58−412.32, 1.21−72.52, 1.22−68.55, 1.28−32.01, 5.36−45.56, 2.20−182.22 ng/L, respectively. In some cases, concentrations lower than 1 ng/L were determined. In optimal conditions of coagulation process of spiked surface water (pH = 6.5 ± 0.1, ACH dose = 0.35 mL/L, Time = 30 min; R2 = 0.8799, R2adj = 0.7998), the concentration of TOC, ERY, FLX, AMO, COL, EE, and DIC was decreased by 88.7, 36.4, 24.7, 29.0, 25.5, 35.4, 30.4%, respectively. Simultaneously, turbidity, color, Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Total Nitrogen (Total N), and Ammonium-Nitrogen (N-NH4) were decreased by 96.2%, >98.0%, 97.8%, 70.0%, 88.7%, 37.5%, respectively. These findings suggest that ACH may be an optional reagent to remove studied pharmaceuticals from contaminated water.