Iranian Journal of

Background and Objective: Coagulation, which is carried out by mixing coagulants such as alum, ferric chloride and poly aluminum chloride PAC with raw water, is one of the main processes in conventional water treatment plants. Sludge from this process contains high amounts of coagulants with high economic value. Therefore, if these coagulants are recovered, in addition to reducing the risks relate to sludge disposal, the expenses related to the supply of fresh coagulant in water or wastewater treatment plant may decrease.
Materials and Methods: To access related documentation, ScienceDirect, Google scholar and other databases were searched using keywords such as “coagulant recovery”, “water residuals management”, etc. More than one hundred fifty documents were investigated based on the content validity and thematic relation. Gathered contents were classified and summarized under the titles of “recovery methods”, “repeated recoveries”, “recovery regarding economic aspect” and “advantages and disadvantages of methods”.
Results: Use of new methods such as combination of membrane and chemical processes or ion exchange membrane processes leads to the recovery of coagulants with a similar quality to the commercial ones. In case of using conventional and less costly methods such as acid digestion, quality of recovered coagulants is not comparable with those of commercial ones, which are used in water treatment.
Conclusion: Different coagulants recovery methods were investigated to determine the reuse strategies. It is likely that using of recovered coagulants through conventional methods is in accordance with the related regulations of the wastewater treatment plants. Industrial use of novel processes for recovery of coagulants with higher quality needs precise technical and economical investigations.
 

Background and Objective: Antibiotics are hardly decomposable and resistant contaminants in the environment that according to their anti-biological properties, it is necessary to eliminate or reduce the amount of them before entering the environment. Therefore, the main goal of this research is to investigate the Fenton and Fenton-like process efficiency for the treatment of wastewater containing Spiramycin antibiotic.
Materials and Methods: The effect of independent variables including pH, contact time, oxidant concentration (H₂O₂), and catalyst concentration (Fe²⁺ and Fe³⁺) on the COD removal efficiency were measured using COD meter. The ranges and number of experiments were assigned by RSM (Response surface method) using design expert software.
Results: The optimum conditions of Fenton process with treatment efficiency of 63.31% were obtained at pH 4, hydrogen peroxide concentration of 50 mg/L, Fe²⁺ concentration of 75 mg/L and contact time of 5 min. The optimum conditions of Fenton-like process with treatment efficiency of 51.21% were obtained at pH 3, hydrogen peroxide concentration of 60 mg/L, Fe³⁺ concentration of 137.5 mg/L and contact time of 32.5 min. Based on the ANOVA analysis results, the f value in Fenton method indicates that the model is significant.
Conclusion: According to the results, Fenton oxidation process was selected as the optimum method to remove COD from synthetic wastewater containing Spiramycin antibiotic which may be applied as an efficient method for the treatment of wastewaters containing antibiotic.

Background and Objective: Dyes are among the most widespread pollutants found in industrial wastewater. The aim of this study is to investigate the potential of vineyard wood waste as a green adsorbent for the removal of polyazo solophenyl dye from aquatic environments.
Materials and Methods: In this laboratory research, two forms of adsorbents modified with H₂SO₄ and NaOH were used. Data obtained from dye adsorption in synthetic solutions were fitted to isotherm, kinetic, and thermodynamic models, with all calculations performed using Excel software. Zeta potential analysis, along with FTIR, BET, and FESEM-EDS instrumental analyses, was conducted to determine the properties of the adsorbent. Additionally, the desorption rates of the adsorbents were analyzed.
Results: The results showed that the highest color removal efficiency for the adsorbent modified with H₂SO₄ was achieved at a contact time of 180 minutes and a reaction temperature of 50 °C, while for the adsorbent modified with NaOH, the highest efficiency was observed at a contact time of 105 minutes and a reaction temperature of 25 °C. For both adsorbents, the optimal pH was 4, and the optimal adsorbent dosage was 1 g. The adsorption data for both modified adsorbents followed the pseudo-second-order kinetic model, while the equilibrium data aligned with the Freundlich and Temkin isotherm models. The adsorption capacities were found to be 22.27 mg/g and 9.87 mg/g for the adsorbents modified with acid and base, respectively, under optimal conditions.
Conclusion: This study introduces a novel, low-cost adsorbent derived from natural waste for water pollution removal, transforming the current approach into a cost-effective and eco-friendly solution.