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Table 11

Main results reported for the treatment of OMW by means of AOP combined with physico-chemical treatments

Advanced oxidation processes	Physico-chemical processes	Experimental conditions	Main results	References
Fenton's process	Coagulation–flocculation	pH: 5.1–5.3 [Fe²⁺]: 2.5, 5 and 10 g/L [H₂O₂]: 0.5, 1, 5 and 10 g/L. Lime concentration: 0–230 mg/L	(i) Coagulation–flocculation alone leads to 99.7, 78.8 and 35.5% of TSS, TPh and COD reduction, respectively (ii) The combined process leads to 98.7, 84.9 and 61.4% of TSS, TPh and COD reduction, respectively	Ginos et al. (2006)
Fenton's process	Coagulation/flocculation	pH: 3.5 Temperature: 30 °C H₂O₂/Fe²⁺: 15 H₂O₂/COD : 0.25–3	(i) In the Fenton's process, 96.8% of COD has been achieved (ii) A stronger COD reduction (99.3%) with the combined system	Lucas & Peres (2009a, 2009b)
Fenton's process	Acid cracking (AC) + lime + anionic/cationic polyelectrolyte (AP, CP)	pH: 1.7–9.2 [Fe²⁺]: 2.5, 5 and 10 g/L [H₂O₂]: 750 mg/L	(i) The pre-treatment by AC, AC + AP (5 ppm), AC + AP (10 ppm), lime and lime +AP (9 ppm) leads to a reduction of 72.5, 81.17, 73.85, 56.32 and 41.83% of COD, respectively (ii) Fenton's oxidation after AC and CP (10 ppm) treatment leads to 89% of COD removal	Gomec et al. (2007)
Fenton's process	Acid cracking (AC) + coagulation	pH: 1.5–3.5 treatment time: 4 h Temperature: 25 and 30 °C [H₂O₂] = 0.12–0.5 M [Fe²⁺] = 0.005–0.03 M	(i) AC removes 47.3, 30.1, 64.3, and 59.1% of COD, TPh, color, and aromaticity, respectively (ii) AC and Fenton process lead to 83, 98.6, 77, and 67% of COD, TPh, color and aromaticity, respectively (iii) The increase in temperature from 25 to 30 °C does not have a significant influence on the efficiency of the process	Madani et al. (2015)
Fenton's process	Ion exchange (IE)	pH: 1.5–4.5 [Fe²⁺]: 0–5 g/L [H₂O₂]: 0–6 g/L	(iv) In the Fenton's process, 80.7 and 98.2% of COD and TPh have been removed, respectively (v) The tested resin Lewatit TP 207 shows a higher affinity (100% of iron removal efficiency) toward Fe³⁺ when compared with Fe²⁺ (35%)	Reis et al. (2018)
Photo-Fenton process	Coagulation-flocculation and solvent extraction	pH: 3 Treatment time: 240 min [FeSO₄, 7H₂O]: 3.33, 5 and 6.67 g/L FLOCAN 23: 0.287, 0.07 and 0.14 [H₂O₂]: 0, 3, 4, 5 and 6 g/L [Fe²⁺]: 0, 0.2, 0.4 and 0.6 g/L	(i) The coagulation-flocculation leads to 97 ± 1.3, 72 ± 1.5, and 40 ± 1.3% of TSS, COD and TPh, respectively (ii) 36% of TPh recovery post-coagulation–flocculation was achieved by solvent extraction (iii) 73 ± 2.3 and 87 ± 3.1% removal efficiencies were achieved for COD and TPh, respectively, by combination with photo-Fenton process	Papaphilippou et al. (2013)
Fenton like process	Coagulation and acid cracking (AC)	pH: 1.5–4 Treatment time: 0–400 min Alum concentration: 1000–6000 mg/L Ferric chloride concentration : 1000–6000 mg/L Polyaluminum chloride concentration: 250–1500 mg/L [H₂O₂]: 250–3000 mg/L Zero valent iron concentration: 1–11 g/L	(i) Coagulation process removed 91.2% COD, 91.3% TPh, 98.9% TSS and 99.2% turbidity (ii) The combined process increased the BOD₅/COD ratio from 0.14 to 0.83	Yazdanbakhsh et al. (2015)
Photocatalysis, Fenton and photo-Fenton process	Coagulation	pH: 4.3–6 Treatment time: 1–2 h [H₂O₂]/[FeSO₄] ratio = 6000/600 and 15,000/1,852 (w/w) Coagulant dose: 0–600 mg/L	(i) Coagulation by chitosan was shown to remove 81% of TSS (ii) The combined photo-Fenton/coagulation system was found to be more efficient for COD removal (91%) compared to Fenton one (81%)	Rizzo et al. (2008)
Photo-Fenton Fenton process	Acidification/coagulation/flocculation	pH: 2.6 and 4.6 [H₂O₂]: 0, 15 and 30 g/L [Fe²⁺]: 0, 2, 6 and 10 Mm Coagulant dose: 0, 0.25 and 1 (w/w)	(i) The acidification followed by Fenton process leads to 15 and 60% of COD and TPh removal, respectively (ii) The acidification/coagulation/flocculation/Photo-Fenton system leads to 75 and 100% of COD and TPh removal, respectively	Gernjak et al. (2007)
Ozonation Photo-Fenton process (Fe(III)/air/solar light	Centrifugation	pH: 3 Treatment time: 60, 90 and 120 min Flow-rate: 36 L/h	(i) The pre-treatment by centrifugation leads to a reduction of 41.3% of COD (ii) Ozonation alone leads to 31.5 and 63.6% of COD and TPh removal, respectively (iii) Air/light with Fe(III)/Ozonation system leads to 40.3 and 75% of COD and TPh removal, respectively	Andreozzi et al. (2008)
UV/H₂O₂	Lime treatment	pH: 7 Temperature: 25 °C Treatment time: 7 days H₂O₂ (30%) doses: 1–10 mL/100 mL OMW	(i) 90% of color, 90% of phenol and 30% of lignin were removed by single UV/H₂O₂ (ii) The combination with lime yielded 99, 100 and 40% of color, phenol and lignin removals, respectively	Uğurlu & Kula (2007)
UV/H₂O₂	Ultrafiltration (UF)	pH: 4.5 Temperature: 27–37 °C [H₂O₂] = 2*10^–2M	(i) 94 and 100% of COD and TSS removal by using UF alone (ii) In the combined process, 75% of the initial absorbance vanished after 40 min of irradiation	Drouiche et al. (2004)
H₂O₂/UV O₃/UV	Acid cracking (AC) + ferric coagulation	pH: 2–8 Treatment time: 400–1,440 min [H₂O₂]: 750 mg/L Ozone flow-rate: 0.3 g/h	(i) For acid cracking + ferric coagulation + O₃/UV system, 98 and 99% of COD and TPh removal have been reached, respectively (ii) For acid cracking + ferric coagulation H₂O₂/UV system, 99% of both COD and TPh removal has been reached	Kestioğlu et al. (2005)
UV, O₃, O₃/UV and H₂O₂/UV	Coagulation/flocculation	pH: 5.6–9 Treatment time: 15, 30, 45, 60 and 90 min [H₂O₂]: 2% Ozone flow-rate: 40 dm³/h	(i) Over 10, 19, 37 and 39% of COD were removed by UV, O₃, O₃/UV and H₂O₂/UV process (ii) The combined systems coagulation/O₃, coagulation/O₃-UV and coagulation/H₂O₂/UV lead to COD reduction rates of 90, 95 and 94%, respectively	Lafi et al. (2010)

Advanced oxidation processes	Physico-chemical processes	Experimental conditions	Main results	References
Fenton's process	Coagulation–flocculation	pH: 5.1–5.3 [Fe²⁺]: 2.5, 5 and 10 g/L [H₂O₂]: 0.5, 1, 5 and 10 g/L. Lime concentration: 0–230 mg/L	(i) Coagulation–flocculation alone leads to 99.7, 78.8 and 35.5% of TSS, TPh and COD reduction, respectively (ii) The combined process leads to 98.7, 84.9 and 61.4% of TSS, TPh and COD reduction, respectively	Ginos et al. (2006)
Fenton's process	Coagulation/flocculation	pH: 3.5 Temperature: 30 °C H₂O₂/Fe²⁺: 15 H₂O₂/COD : 0.25–3	(i) In the Fenton's process, 96.8% of COD has been achieved (ii) A stronger COD reduction (99.3%) with the combined system	Lucas & Peres (2009a, 2009b)
Fenton's process	Acid cracking (AC) + lime + anionic/cationic polyelectrolyte (AP, CP)	pH: 1.7–9.2 [Fe²⁺]: 2.5, 5 and 10 g/L [H₂O₂]: 750 mg/L	(i) The pre-treatment by AC, AC + AP (5 ppm), AC + AP (10 ppm), lime and lime +AP (9 ppm) leads to a reduction of 72.5, 81.17, 73.85, 56.32 and 41.83% of COD, respectively (ii) Fenton's oxidation after AC and CP (10 ppm) treatment leads to 89% of COD removal	Gomec et al. (2007)
Fenton's process	Acid cracking (AC) + coagulation	pH: 1.5–3.5 treatment time: 4 h Temperature: 25 and 30 °C [H₂O₂] = 0.12–0.5 M [Fe²⁺] = 0.005–0.03 M	(i) AC removes 47.3, 30.1, 64.3, and 59.1% of COD, TPh, color, and aromaticity, respectively (ii) AC and Fenton process lead to 83, 98.6, 77, and 67% of COD, TPh, color and aromaticity, respectively (iii) The increase in temperature from 25 to 30 °C does not have a significant influence on the efficiency of the process	Madani et al. (2015)
Fenton's process	Ion exchange (IE)	pH: 1.5–4.5 [Fe²⁺]: 0–5 g/L [H₂O₂]: 0–6 g/L	(iv) In the Fenton's process, 80.7 and 98.2% of COD and TPh have been removed, respectively (v) The tested resin Lewatit TP 207 shows a higher affinity (100% of iron removal efficiency) toward Fe³⁺ when compared with Fe²⁺ (35%)	Reis et al. (2018)
Photo-Fenton process	Coagulation-flocculation and solvent extraction	pH: 3 Treatment time: 240 min [FeSO₄, 7H₂O]: 3.33, 5 and 6.67 g/L FLOCAN 23: 0.287, 0.07 and 0.14 [H₂O₂]: 0, 3, 4, 5 and 6 g/L [Fe²⁺]: 0, 0.2, 0.4 and 0.6 g/L	(i) The coagulation-flocculation leads to 97 ± 1.3, 72 ± 1.5, and 40 ± 1.3% of TSS, COD and TPh, respectively (ii) 36% of TPh recovery post-coagulation–flocculation was achieved by solvent extraction (iii) 73 ± 2.3 and 87 ± 3.1% removal efficiencies were achieved for COD and TPh, respectively, by combination with photo-Fenton process	Papaphilippou et al. (2013)
Fenton like process	Coagulation and acid cracking (AC)	pH: 1.5–4 Treatment time: 0–400 min Alum concentration: 1000–6000 mg/L Ferric chloride concentration : 1000–6000 mg/L Polyaluminum chloride concentration: 250–1500 mg/L [H₂O₂]: 250–3000 mg/L Zero valent iron concentration: 1–11 g/L	(i) Coagulation process removed 91.2% COD, 91.3% TPh, 98.9% TSS and 99.2% turbidity (ii) The combined process increased the BOD₅/COD ratio from 0.14 to 0.83	Yazdanbakhsh et al. (2015)
Photocatalysis, Fenton and photo-Fenton process	Coagulation	pH: 4.3–6 Treatment time: 1–2 h [H₂O₂]/[FeSO₄] ratio = 6000/600 and 15,000/1,852 (w/w) Coagulant dose: 0–600 mg/L	(i) Coagulation by chitosan was shown to remove 81% of TSS (ii) The combined photo-Fenton/coagulation system was found to be more efficient for COD removal (91%) compared to Fenton one (81%)	Rizzo et al. (2008)
Photo-Fenton Fenton process	Acidification/coagulation/flocculation	pH: 2.6 and 4.6 [H₂O₂]: 0, 15 and 30 g/L [Fe²⁺]: 0, 2, 6 and 10 Mm Coagulant dose: 0, 0.25 and 1 (w/w)	(i) The acidification followed by Fenton process leads to 15 and 60% of COD and TPh removal, respectively (ii) The acidification/coagulation/flocculation/Photo-Fenton system leads to 75 and 100% of COD and TPh removal, respectively	Gernjak et al. (2007)
Ozonation Photo-Fenton process (Fe(III)/air/solar light	Centrifugation	pH: 3 Treatment time: 60, 90 and 120 min Flow-rate: 36 L/h	(i) The pre-treatment by centrifugation leads to a reduction of 41.3% of COD (ii) Ozonation alone leads to 31.5 and 63.6% of COD and TPh removal, respectively (iii) Air/light with Fe(III)/Ozonation system leads to 40.3 and 75% of COD and TPh removal, respectively	Andreozzi et al. (2008)
UV/H₂O₂	Lime treatment	pH: 7 Temperature: 25 °C Treatment time: 7 days H₂O₂ (30%) doses: 1–10 mL/100 mL OMW	(i) 90% of color, 90% of phenol and 30% of lignin were removed by single UV/H₂O₂ (ii) The combination with lime yielded 99, 100 and 40% of color, phenol and lignin removals, respectively	Uğurlu & Kula (2007)
UV/H₂O₂	Ultrafiltration (UF)	pH: 4.5 Temperature: 27–37 °C [H₂O₂] = 2*10^–2M	(i) 94 and 100% of COD and TSS removal by using UF alone (ii) In the combined process, 75% of the initial absorbance vanished after 40 min of irradiation	Drouiche et al. (2004)
H₂O₂/UV O₃/UV	Acid cracking (AC) + ferric coagulation	pH: 2–8 Treatment time: 400–1,440 min [H₂O₂]: 750 mg/L Ozone flow-rate: 0.3 g/h	(i) For acid cracking + ferric coagulation + O₃/UV system, 98 and 99% of COD and TPh removal have been reached, respectively (ii) For acid cracking + ferric coagulation H₂O₂/UV system, 99% of both COD and TPh removal has been reached	Kestioğlu et al. (2005)
UV, O₃, O₃/UV and H₂O₂/UV	Coagulation/flocculation	pH: 5.6–9 Treatment time: 15, 30, 45, 60 and 90 min [H₂O₂]: 2% Ozone flow-rate: 40 dm³/h	(i) Over 10, 19, 37 and 39% of COD were removed by UV, O₃, O₃/UV and H₂O₂/UV process (ii) The combined systems coagulation/O₃, coagulation/O₃-UV and coagulation/H₂O₂/UV lead to COD reduction rates of 90, 95 and 94%, respectively	Lafi et al. (2010)