Wastewater reuse is becoming increasingly important
for water sustainability, and is essential
for the enhancement o
f access to sa
fe water
for human needs like drinking water and crop irrigation. The adequate treatment o
f contaminated wastewater is needed so that it may be used to recharge water resources. There
fore, reduction and control o
f waterborne pathogens are required
for appropriate water reuse. Advanced Oxidation Processes, which generate hydroxyl radicals, are promising treatments
for water disin
fection. The purpose o
f the current study was to evaluate and compare the e
ffectiveness o
f three solar treatments; Fe
3+/su
nlight, H
2O
2/su
nlight, and solar photo-Fenton at near-neutral pH,
for the inactivation o
f Fusarium solani and
Escherichia coli in water. Di
fferent concentrations o
f Fe
3+ (0-50 mg/L), H
2O
2 (0-10 mg/L) and Fe
3+/H
2O
2 (1/2.5, 5/10, 10/10, 50/10 mg/L) were evaluated in bottle reactors (200 mL)
for 5 h under natural solar light in the Southeast o
f Spain. The order o
f e
fficacy
for disin
fection o
f both kinds o
f microorganisms was: photo-Fenton > H
2O
2/su
nlight > Fe
3+/su
nlight.
The results for bacteria inactivation show that the highest rate was observed using photo-Fenton system with 5 mg/L of Fe3+ and 10 mg/L of H2O2, which gave a 5-log inactivation of E. coli in 10 min (0.96 kJ/L). The best results for Fusarium inactivation were found using 2.5 mg/L of Fe3+ and 5 mg/L of H2O2, which gave a 3.4-log decrease in 3 h of solar exposure (14.47 kJ/L). Moreover, sunlight with H2O2 alone showed good potential for water disinfection with only low doses of H2O2 (10 mg/L) required for 6-log inactivation of E. coli and a 3-log inactivation of F. solani.
In all cases studied, the inactivation pattern and rate is observed to be highly dependent on the type of microorganism. The spores of F. solani were more resistant than the vegetative cells of E. coli to the solar treatments.