Wastewater from pharmaceutical industries cannot be properly treated in conventional purification plants. Fenton process is an effective method to treat these effluents whose applicability, however, is hampered by the necessity of dispose of a large quantity of sludge that is produced by the removal of the catalyst from the liquid phase after the treatment. To overcome these drawbacks, in this work a suitable procedure for the recovery and reuse of sludge, was developed. The experiments were conducted by treating wastewater generated from the production of anticancer active ingredients. The homogeneous Fenton process was initially optimized and temperature of 40 °C, dosages of peroxide RHC=2 gH2O2/gCOD and catalyst RIC=0.4 gFe2+/gCOD were identified as the most suitable operating conditions that allowed to reach removals of chemical oxygen demand (COD) of approximately 68%. The oxidation treatment was found to be very fast following a pseudo second-order kinetic law and reaching the stationary state in a treatment time of only 30 min. Afterwards, the sequential fractional addition of peroxide and the reuse of sludge were investigated. By feeding the H2O2 dosage in two subsequent aliquots, COD removal increased up to 78% and the biodegradability reached 61%. By reusing the sludge produced by the gradual dosing of H2O2, the efficiency was equal to that with the fresh catalyst in the first reusing cycle and around 55% in the fifth cycle. With the addition of H2O2 in two fractionated doses, a supplementation of 10% of the dosage of pure catalyst permitted to maintain efficiencies always above 78%. Graphical Abstract Fenton process is an effective method to treat effluents of industrial origin, but its applicability is made difficult by the large quantity of sludge produced. To overcome these application limitations, in the present paper a Fenton process with sludge reuse was developed for the treatment of wastewater generated in a pharmaceutical industry producing anticancer active ingredients. A series of experiments were initially conducted to identify the optimal operating conditions. These tests were conducted at pH 3 and temperatures of 20, 40 and 60 °C, by varying the dosages of Fe2+ (RIC) and H2O2 (RHC) between 0.2 and 0.6 gFe2+/gCOD and 0.5 and 5 gH2O2/gCOD, respectively. Based on the results of the first series of experiments the most suitable values of the process parameters (T = 40 °C, RIC=0.4gFe2+/gCOD, RHC=2gH2O2/gCOD) were identified. Afterwards, tests were conducted by feeding the hydrogen peroxide in sequential steps. The dosage of H2O2 in two steps allowed to increase the process performance of about 10% with respect to the test with a single addition, reaching an abatement close to 80%. Once defined the process parameters, experiments were performed by reusing the sludge produced during the treatment with a single and sequential doses of H2O2, without any supply of fresh pure catalyst and with an integration of 10%. The reuse of sludge produced by dosing the H2O2 in two sequential steps was found to be the most effective procedure. With this methodology the efficiency remained above 55% even at the fifth reusing cycle, and with a small integration of 10% fresh catalyst the COD abatement slightly increased from 78% in the first cycle to 82% in the last reuse. The defined process with sludge reuse overcomes the drawbacks related to the conventional homogenous Fenton process and, therefore, promotes the application in industrial treatment plants.

Development of Fenton Process with Sludge Reuse for the Treatment of Wastewater from a Pharmaceutical Industry Producing Anticancer Active Ingredients

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发表日期：

2025年6月3日

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Carlo Limonti,
Tiziana Andreoli,
Giulia Maria Curcio,
Elvis Gribaldo Aucancela Rivera,
Giuseppe Agostino,
Fabio Zenobi,
Alessio Siciliano

摘要

Wastewater from pharmaceutical industries cannot be properly treated in conventional purification plants. Fenton process is an effective method to treat these effluents whose applicability, however, is hampered by the necessity of dispose of a large quantity of sludge that is produced by the removal of the catalyst from the liquid phase after the treatment. To overcome these drawbacks, in this work a suitable procedure for the recovery and reuse of sludge, was developed. The experiments were conducted by treating wastewater generated from the production of anticancer active ingredients. The homogeneous Fenton process was initially optimized and temperature of 40 °C, dosages of peroxide R_HC=2 gH₂O₂/gCOD and catalyst R_IC=0.4 gFe²⁺/gCOD were identified as the most suitable operating conditions that allowed to reach removals of chemical oxygen demand (COD) of approximately 68%. The oxidation treatment was found to be very fast following a pseudo second-order kinetic law and reaching the stationary state in a treatment time of only 30 min. Afterwards, the sequential fractional addition of peroxide and the reuse of sludge were investigated. By feeding the H₂O₂ dosage in two subsequent aliquots, COD removal increased up to 78% and the biodegradability reached 61%. By reusing the sludge produced by the gradual dosing of H₂O_2, the efficiency was equal to that with the fresh catalyst in the first reusing cycle and around 55% in the fifth cycle. With the addition of H₂O₂ in two fractionated doses, a supplementation of 10% of the dosage of pure catalyst permitted to maintain efficiencies always above 78%.

Graphical Abstract

Fenton process is an effective method to treat effluents of industrial origin, but its applicability is made difficult by the large quantity of sludge produced. To overcome these application limitations, in the present paper a Fenton process with sludge reuse was developed for the treatment of wastewater generated in a pharmaceutical industry producing anticancer active ingredients. A series of experiments were initially conducted to identify the optimal operating conditions. These tests were conducted at pH 3 and temperatures of 20, 40 and 60 °C, by varying the dosages of Fe²⁺ (R_IC) and H₂O₂ (R_HC) between 0.2 and 0.6 gFe²⁺/gCOD and 0.5 and 5 gH₂O₂/gCOD, respectively. Based on the results of the first series of experiments the most suitable values of the process parameters (T = 40 °C, R_IC=0.4gFe²⁺/gCOD, R_HC=2gH₂O₂/gCOD) were identified. Afterwards, tests were conducted by feeding the hydrogen peroxide in sequential steps. The dosage of H₂O₂ in two steps allowed to increase the process performance of about 10% with respect to the test with a single addition, reaching an abatement close to 80%. Once defined the process parameters, experiments were performed by reusing the sludge produced during the treatment with a single and sequential doses of H₂O₂, without any supply of fresh pure catalyst and with an integration of 10%. The reuse of sludge produced by dosing the H₂O₂ in two sequential steps was found to be the most effective procedure. With this methodology the efficiency remained above 55% even at the fifth reusing cycle, and with a small integration of 10% fresh catalyst the COD abatement slightly increased from 78% in the first cycle to 82% in the last reuse. The defined process with sludge reuse overcomes the drawbacks related to the conventional homogenous Fenton process and, therefore, promotes the application in industrial treatment plants.