# Solar Concentration for Wastewaters Remediation: A Review of Materials and Technologies
## 4 Wastewaters
### Model Pollutants  
In the initial studies of the solar concentration for wastewaters research field, several types of model pollutants were investigated using concentrated sunlight and AOPs [120]. The United States Environmental Protecting Agency (EPA) made an inventory of more than 800 molecules that can be degraded by advanced oxidation processes [10]. In Table 3, works that investigated BROCs from the industrial general chemical products sector are presented. The investigations collected were performed from 1999 until today, and are representative of the importance of solar collectors to the wastewater purification field. Among the pollutants tested on the water models, substances such as phenols, amines, gaseous toluene and acetaldehyde, detergents, trichloroethylene, phenolate, diverse acids and phosphates deserve attention. In terms of the solar collector employed, special emphasis was devoted to the PTC and CPC configurations (12 reports), IPC (5 reports), optical fiber (2 reports), and PDC (1 report). In terms of catalysts, all the investigations primarily reported on the use of TiO\({}_{2}\) as a catalyst material, with variations in terms of the supporting system, doping element and particle structure. As a solid catalyst, TiO\({}_{2}\) was consequently employed in the heterogeneous route for catalysis. Table 4 presents the published papers dedicated to the investigation of model waters containing dyes as the main pollutant. The first studies were reported in 1994 and continue to receive interest to the present day. Dyes such as methyl-orange, Remazol red B, rhodamine, indigo carmine, methylene blue, and reactive black 5, among others, were studied by employing either CPC or IPC solar collectors. Also, 3 investigations were performed using the homogeneous route with ferrous salts solutions, and the majority with the heterogenous one. Table 5 instead presents the use of solar photocatalysis, mostly under the heterogenous route with IPC and CPC solar collectors, to investigate the degradation of pesticides as model pollutants. In this segment of pollutants, investigations have gained attention since the year 2000. Eight miscellaneous pesticides (ethoprophos, isoxaben, metalaxyl, metribuzin, pencycuron, pendimethalin, propanil and tolclofos-methyl) were studied. Initial investigations on this sector have paved the way for further research on real water sources from extensive agriculture areas. A last BROC contaminant reported in the literature was a pharmaceutical product, as reported in Table 6. In 2005, a CPC solar collector using commercial P-25 TiO\({}_{2}\) as the catalyst and heterogeneous photocatalysis was utilized to investigate the degradation of the antibiotic Lincomycin. In another field of application of solar collectors applied for wastewater purification, solar disinfection (SODIS) was employed to study the removal of bacteria as E. Coli, faecalis and Salmonella and fungi, such as fusarium spores as shown in Table 7. Investigations were mostly developed with CPC solar collectors. Both heterogeneous and homogeneous routes are represented, with a prevalence of TiO\({}_{2}\) catalyst for the former and of ferrous solutions for the latter. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**\#** & **Reference** & **Pollutant Tested** & **Solar Collector** & **Catalyst Material** & **Catalysis Type** \\ \hline
**1** & [PERSON] et al., 1999 [21] & 4-chlorophenylned & PTR/CFC & TIO\({}_{2}\) supported and suspended & Heterogeneous \\ \hline
**2** & [PERSON] et al., 2004 [105] & gaseous toluene and acetaldehyde & PTR & P-TIO\({}_{2}\) supported & Heterogeneous \\ \hline  & [PERSON] et al., 2000 [122] & Amines & PTR & TIO\({}_{2}\) (AKI) & Heterogeneous \\  & & & P-TIO\({}_{2}\) (yrv10) suspended & & \\ \hline
**4** & [PERSON] et al., 2004 [123] & Commercial Detergents & PCC & TIO\({}_{2}\) (P-25) suspended & Heterogeneous \\ \hline
**5** & [PERSON] et al., 1992 [78] & trichotomyethylene & PTR & TIO\({}_{2}\) (P-25) suspended & Heterogeneous \\ \hline
**6** & [PERSON] et al.,