Persulfate Process Activated by Homogeneous and Heterogeneous Catalysts for Synthetic Olive Mill Wastewater Treatment

Abstract

Wastewaters from the olive oil industry are a regional environmental problem. Their phenolic content provides inherent toxicity, which reduces the treatment potential of conventional biological systems. In this study, Sulfate Radical based Advanced Oxidation Processes (SRbAOPs) are compared with advanced oxidation processes (namely Fenton’s peroxidation) as a depuration alternative. Synthetic olive mill wastewaters were submitted to homogeneous and heterogeneous SRbAOPs using iron sulfate and solid catalysts (red mud and Fe-Ce-O) as the source of iron (II). The homogenous process was optimized by testing different pH values, as well as iron and persulfate loads. At the best conditions (pH 5, 300 mg/L of iron and 600 mg/L of persulfate), it was possible to achieve 39%, 63% and 37% COD, phenolic compounds and TOC removal, respectively. The catalytic potential of a waste (red mud) and a laboratory material (Fe-Ce-O) was tested using heterogenous SRbAOPs. The best performance was achieved by Fe-Ce-O, with an optimal load of 1600 mg/L. At these conditions, 27%, 55% and 5% COD, phenolic compounds and TOC removal were obtained, respectively. Toxicity tests on A. fischeri and L. sativum showed no improvements in toxicity from the treated solutions when compared with the original one. Thus, SRbAOPs use a suitable technology for synthetic OMW.

Treatment of Agro-Industrial Wastewaters by Coagulation-Flocculation-Decantation and Advanced Oxidation Processes—A literature Review

“…The application of SR-AOPs was shown to be very effective in the treatment of agroindustrial wastewaters. For example, in the work of Domingues et al [18], the application of PS/Fe 2+ in the treatment of OMW achieved a total polyphenols removal of 63%.…”

Synthesis of MMT−CuFe2O4 Composite as a Peroxymonosulfate Activator for the Degradation of Reactive Black 5

“…Studies have reported that the activation of oxidants such as PMS can be carried out by homogeneous and heterogeneous catalysts to produce SO 4 ⋅ − and ⋅OH [66] . To identify active species in the MMT−CuFe 2 O 4 /PMS system, the employment of ethanol (EtOH) and tert‐butanol (TBA), as probe reagents, was considered.…”

“…Studies have reported that the activation of oxidants such as PMS can be carried out by homogeneous and heterogeneous catalysts to produce SO 4 *À and * OH. [66] To identify active species in the MMTÀ CuFe 2 O 4 /PMS system, the employment of ethanol (EtOH) and tert-butanol (TBA), as probe reagents, was considered. Ethanol has the ability to scavenging both * OH (1.2 × 10 9 -2.8 × 10 9 M À 1 s À 1 ) and SO 4 *À (1.6 × 10 7 -7.7 × 10 7 M À 1 s À 1 ), while TBA is an operative scavenger for * OH (3.8 × 10 8 -7.6 × 10 8 M À 1 s À 1 ).…”

Heterogeneous Activation of Persulfate by Nickel Oxide/Strontium Carbonate Composite for Sulfamethoxazole Degradation in Water

“…Persulfate is a strong oxidizing agent widely used in environmental fields like water purification and soil remediation [1]. In its pure form, persulfate has relatively low reactivity; however, it can be activated, producing sulfate radicals (SO 4…”