Environmental Remediation Potential of Ferrous Sulfate Waste as an Eco-Friendly Coagulant for the Removal of NH3-N and COD from the Rubber Processing Effluent

Abstract

The present study was conducted to determine the potential of utilizing the FeSO4·7H2O waste from the titanium manufacturing industry as an effective coagulant for treating industrial effluent. In this study, the secondary rubber processing effluent (SRPE) was treated using ferrous sulfate (FeSO4·7H2O) waste from the titanium oxide manufacturing industry. The FeSO4·7H2O waste coagulation efficiency was evaluated on the elimination of ammoniacal nitrogen (NH3-N) and chemical oxygen demand (COD) from SRPE. The central composite design (CCD) of experiments was employed to design the coagulation experiments with varying coagulation time, coagulant doses, and temperature. The coagulation experiments were optimized on the optimal elimination of NH3-N and COD using response surface methodology (RSM). Results showed that coagulant doses and temperature significantly influenced NH3-N and COD elimination from SRPE. The highest NH3-N and COD removal obtained were 98.19% and 93.86%, respectively, at the optimized coagulation experimental conditions of coagulation time 70 min, coagulant doses 900 mg/L, and temperature 62 °C. The residual NH3-N and COD in treated SPRE were found below the specified industrial effluent discharge limits set by DoE, Malaysia. Additionally, the sludge generated after coagulation of SRPE contains essential plant nutrients. The present study’s finding showed that FeSO4·7H2O waste generated as an industrial byproduct in a titanium oxide manufacturing industry could be utilized as an eco-friendly coagulant in treating industrial effluent.

Ferrous Industrial Wastes—Valuable Resources for Water and Wastewater Decontamination

“…One of the most efficient and reliable processes consists of using coagulant for water and wastewater decontamination. Generally, the use of ferrous sulfate in industrial coagulation–flocculation processes is preferred to aluminum sulfate, which generates sludge with higher toxicity and implicitly requires more expensive inertization methods [ 32 , 37 , 38 ]. Coagulation–flocculation remains the most advantageous technique applied in the depollution of liquid effluents of organic and inorganic substances [ 37 , 38 ].…”

“…The use of FeSO 4 ·7H 2 O, as a waste from the titanium oxide manufacturing industry, as a coagulant for the treatment of industrial effluents, is well known. Conclusive results regarding the ability to act as a coagulant were obtained in the case of the purification of secondary effluents from rubber processing processes (SRPE), especially for the elimination of ammoniacal nitrogen (NH 3 -N) and chemical oxygen content (COD) [ 32 ]. These effluents generate large amounts of wastewater, about 20,500 L of wastewater/1 ton of rubber, which contain important amounts of inorganic and organic pollutants [ 39 , 83 ].…”

“…These effluents generate large amounts of wastewater, about 20,500 L of wastewater/1 ton of rubber, which contain important amounts of inorganic and organic pollutants [ 39 , 83 ]. To increase the efficiency of the studied process, the dose of coagulant (approximately 900 mg/L) and the temperature (62 °C) are two important factors in determining removal efficiencies for NH 3 -N and COD of approximately 98.19% and 93.86%, respectively, after 70 min of coagulation time [ 32 , 84 ]. The advantage of applying this type of waste with coagulant function is, in addition to lowering the concentrations of the analyzed indicators below the limits imposed by the legislation, and the possibility of using the resulting sludge as fertilizer, with a high content of nutrients.…”

“…Mohammad Ilias et al indicated that FeSO 4 ⋅7H 2 O waste from the titanium industry represented an effective coagulant for secondary rubber processing effluent (SRPE), with high efficiencies for ammoniacal nitrogen (NH 3 -N) and chemical oxygen demand (COD) removal [ 32 ].…”

“…The use of wastes with iron content as raw materials integrated into the circular economy concept was intensively studied for the sintering process, pig iron production, ferroalloys or other steel products, or pigment and cement industry [ 31 ]. Moreover, due to the advanced investigations, these wastes could be converted into valuable advanced micro and nanomaterials, such as iron oxides, ferrates, or FeSO 4 , with high potential as adsorbents or coagulants for water and wastewater treatment [ 8 , 30 , 32 , 33 , 34 , 35 , 36 ].…”