Alireza Pendashteh

The efficiency of removing chemical oxygen demand (COD) and turbidity from wood wastewater was investigated using a sequencing batch reactor (SBR) and the photo‐Fenton process. A total of 94.78% of COD reduction and 99.9% of turbidity removal were observed under optimum conditions of SBR, which consisted of an organic loading rate (OLR) of 0.453 kg COD m⁻³ day⁻¹, mixed liquor suspended solids (MLSS) of 4564 mg L⁻¹, and cycle time of 48 h. A magnetic α‐Fe₂O₃@TiO₂@SO₃H nanocatalyst was prepared as a heterogeneous Fenton reagent. The Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy‐dispersive X‐ray (EDX), and elemental mapping (MAP) analyses were performed to determine the structure and morphology of synthesized photocatalyst. The response surface methodology (RSM) was used to optimize the process based on a central composite design (CCD). The maximum photocatalytic degradation of 87.54% and COD reduction of 83.35% were achieved at a dosage of 0.6 g L⁻¹ of catalyst, 30 mg L⁻¹ of H₂O₂, and pH of 3.5 for 45 min. The results indicated that a combination of the SBR process and α‐Fe₂O₃@TiO₂@SO₃H could be used as an effective method for the treatment of wood wastewater.Practitioner Points: A combination of the SBR and photo‐Fenton process was introduced as an impressive method for wood industry wastewater treatment. The efficiencies of COD, BOD₅, NO₃‐N, PO₄‐P, and color removal were obtained according to the standard limits in Iran. To our knowledge, this study is the first report of the use of synthesized α‐Fe₂O₃@TiO₂@SO₃H photocatalyst for the wood industry wastewater treatment.

In this study, we investigated the efficiency of photocatalytic degradation and chemical oxygen demand (COD) reduction from woodchips industry wastewater using α-Fe₂O₃@TiO₂@SO₃H. A magnetic α-Fe₂O₃@TiO₂@SO₃H was prepared as a heterogeneous photo-Fenton catalyst. The Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and elemental mapping (MAP) analyses were performed to determine the structure and morphology of synthesized photocatalysts. The response surface methodology (RSM) was used to optimize the photo-Fenton process based on a Box-Behnken design (BBD). The parameters such as catalyst dosage, H₂O₂ dosage, pH, and contact time on photocatalytic degradation and the reduction of COD were studied. The maximum photocatalytic degradation of 93.75% and COD reduction of 86.54% were achieved at a dosage of the catalyst of 1 g L⁻¹, H₂O₂ dosage of 40 mg L⁻¹, and a pH of 3.5 at 45 min. The kinetics of the photo-Fenton process was studied for the woodchips wastewater treatment under optimum conditions. The pseudo-second-order kinetic model for photocatalytic degradation and COD reduction was obtained. The results indicated that a α-Fe₂O₃@TiO₂@SO₃H could be used as an effective heterogeneous photocatalyst for the treatment of woodchips industry wastewater. Graphical abstract Preparation and application of α-Fe₂O₃@TiO₂@SO₃H for photocatalytic degradation and COD reduction of woodchips industry wastewater

The article presents the results of chemical analysis for the content of heavy metals in the waters of the fields in the northern part of the Caspian Sea. The content of heavy metals in water is a complex and informative indicator of the degree of water pollution and can be used in environmental monitoring of water bodies. An analysis was carried out on the content of eleven heavy metals at the Kashagan, Kalamkas Kairan and Aktoty deposits for the period from 2006 to 2019. All results were averaged with indication of their minimum, maximum and average values, and were also compared with the MPC of these heavy metals. Among the eleven heavy metals, only one metal is characterized by a content below the MPC, this is barium. The barium content was determined by sweat in all samples, but at the same time they did not exceed the MPC in all samples. A slight excess of the MPC is typical for such metals as cadmium, arsenic and zinc. Almost in all samples, except for one sample, cadmium was found, but at the same time it did not exceed 0.3 MPC. The maximum value was determined in samples from the Kashagan field. Arsenic was found only in 3.4% of samples, mainly in deep-water areas of the Kalamkas field, in which the content did not exceed 1.3 MPC. The zinc content was found in most samples with no excess of more than 0.3 MPC. The rest of the elements are high and highly high in content such as mercury, lead, vanadium, chromium, copper, nickel, and iron. The content of mercury was found in the samples over 1%, but with an excess of 10 to 47 MPC. The content of lead was found in the samples over ten percent, with an excess of 11 to 60 MPC. Vanadium was found in samples of about 20%, with an excess in the range of 2-6 MPC. Chromium was found in most samples with an excess of 3 to 29 MPCs at Kalamkas in 2014 and Kashagan in 2019. Copper content was found in samples of about 90%, with high concentrations at Kashagan in 2006 and 2010 up to 10-38 MPC. Nickel is found in most samples with a level of 0.9-1.1 MPC. The content of iron was found in more than 10 percent of samples with an excess of 15-60 MPC with a decrease of almost 3 times from 2006-2010 to 2011-2019.

In the present research, the efficiency of turbidity and chemical oxygen demand (COD) reduction from the wood industry wastewater (WIW) by the use of a combined coagulation–flocculation–decantation (CFD) – Fenton process was studied. Firstly, the performance of three coagulants such as ferric chloride (FeCl₃), aluminum sulphate (alum), and polyaluminum chloride (PACl) was evaluated. The polyacrylamide (PAM) was used as a flocculant. The results showed that the polyaluminum chloride had a high removal efficiency. The COD reduction of 84.1% and turbidity removal of 82.0% of were obtained in coagulation–flocculation–decantation (CFD). Secondly, Fenton process was optimized, by the use of a response surface methodology (RSM), with application of a central composite design (CCD). The maximum turbidity and COD removal obtained by this process were 94.1% and 72.5% respectively, under optimal conditions ([Fe²⁺] = 250 mg/L, [H₂O₂] = 500 mg/L, pH 3.5, time 60 min). The kinetics of COD and turbidity removal were determined by the model of first order. In conclusion, the combination of coagulation–flocculation–decantation (CFD) – Fenton process presented as a remarkable method for wood wastewater treatment.Practitioner points: A combination of coagulation–flocculation–decantation and Fenton process was introduced for the wood industry wastewater treatment. A designed experimental approach for treatment of wood industry wastewater using a Fenton process was studied. The yields of COD, BOD₅, N‐NO₃, P‐PO₄, and dye removal were obtained according to the standard limits in Iran.

A pilot was designed to study the removal efficiencies of total chemical oxygen demand (TCOD) and phosphate by a combined biological and chemical method. Two stages of Up-flow anaerobic sludge blanket (UASB) reactor and advanced oxidation processes was operated in batch mode. The UASB reactor was operated with hydraulic retention time of 26 h. UASB removal efficiency of TCOD and phosphate were 62.2 and 36.5%, respectively. Fenton process was used as a post-treatment so as to remove organic matter and nutrients. At this stage, the removal efficiencies of TCOD and phosphate were investigated considering the effect of parameters such as pH, hydrogen peroxide and Fe (II) dose based on Taguchi experimental design. Accordingly, under optimum conditions, pH = 3, 1000 mg/l of H₂O₂ and 400 mg/l of Fe (II) the removal efficiencies of TCOD and phosphate reached 95.41 and 85.29%, respectively. The combined method removed TCOD and phosphate up to 98.6 and 90.5%, respectively.

In this study three modeling approaches consisting Modified Stover-Kincannon, multilayer perceptron neural network (MLPANN) and B-Spline quasi interpolation were applied in order to predict effluent of up-flow anaerobic sludge blanket (UASB) reactor and also to find the reaction kinetics. At first run, the average total chemical oxygen demand (TCOD) removal efficiency was 48.3% with hydraulic retention time (HRT) of 26 h and 63.8% with HRT of 37 h, at OLR of 0.77–1.66 kg TCOD/m³ d. At the second run, UASB reactor operated with OLR of 1.94–3.1 kg TCOD/m³ d and achieved the average TCOD removal efficiency of 64.74 and 72.48% with HRT of 26 and 37 h, respectively. The Modified Stover-Kincannon performed well in terms of kinetic determination with a high value of regression coefficient over 0.98. The B-Spline quasi interpolation and MLPANN indicated a great fit for effluent prediction with average R of 0.9984 and 0.9986, and MSE of 157.6050 and 129.7796, respectively; however, they gave no information about reactions occurred in the system.

This study was performed to evaluate the potential of acclimated halophilic microorganisms, commercial microorganisms, and microorganisms from polluted soil to degrade crude oil in high salinity oily wastewater (synthetic produced water) at different salt concentrations ranging from zero to 250,000 mg L⁻¹ of total dissolved solids (TDS). The highest degradation of crude oil (>60%) was found for acclimated halophilic microorganisms at TDS of 35,000 mg L⁻¹. An increase in the TDS concentrations above 145,000 mg L⁻¹ leads to a significant decrease in the growth of microorganisms. The results showed that efficiency of the commercial microorganisms was less than the acclimated halophilic microorganisms. The oil biodegradation followed substrate inhibition kinetics and the specific growth rate were fitted to the Haldane model. The biokinetic constants for the saline oily water at TDS of 35,000 mg L⁻¹, i.e., Y, K_s, µ_max, and 1/K_i, were 0.21 mg MLSS/mg crude oil, 0.27 mg L⁻¹, 0.019 h⁻¹, and 0.002 mg L⁻¹, respectively.