## 2 Principal Textile Colored WW Characteristics and Composition
Considering some wet textile processes and operations, the main characteristics of WW produced from the textile industry, i.e., a cotton fabric manufacturing plant, are summarized in Table 2[10]. The composition of textile WW varies from country to country (factory to factory or mill to mill) and depends on the equipment used for each operation/process, the type of processing, the types of textiles produced (i.e., fabric, fiber, carpet, yarn, etc. ), the type of fabric, fabric mass/weight/length, season, and fashion trends [10; 19]. Some textile effluent characteristics reported in different countries for different types of textiles are summarized in Table 3[29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42]. Numerous researchers have examined textile WW treatment technologies and the efficiency of pollutant removal using simulated synthetic WWs in the form of aqueous solutions (individual or mixed dye solutions) or prepared synthetic textile WW (i.e., a diluted prepared dyeing bath at ratios of 1:100, 1:1000, or even 1:10,000 dyebath/tap water or deionized/distilled water) considering the validated dyebath formulations of a few textile factories for certain colors used in textile fabrics/fibers of different origins (natural: wool and cotton; synthetic: polyester, polyacrylic, polyamide, etc.) [40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53; 54; 55; 56; 57; 58; 59; 60; 61; 62; 63; 64; 65; 66; 67; 68; 69]. Different effluent mixtures can be found in industrial sewer systems from certain textile productive that contain water used for rinsing/washing or even rainfall and stormwater, which is why the composition of non-treated textile WWs can be constituted of numerous inorganic and organic species, including different types of residual dyes (for different colors of textile products) at different concentrations (0.05-3000 mg/L) used for dyeing/finishing steps but also auxiliary agents for each step of the wet textile finishing processing (e.g., starch, waxes, and enzymes used in _de-sizing_; NaOH, surfactants, soaps, fats, pectin, oils, and waxes used in _scouring_; H\({}_{2}\)O\({}_{2}\), sodium silicate, organic stabilizers, and alkalis used in _bleaching_; metals, salts, surfactants, and pH adjustment reagents used in _dyeing_; solvents, formaldehyde, metals, and urea used in _printing_; and softeners, solvents, resins, and waxes used in other _finishing_ processes [4; 10; 12; 15]. In this context, a lot of scientific reports have discussed the experimental results obtained in relation to textile WWs, especially simulated dye-containing effluents, the application of different single or combined treatments for the removal of persistent colored contaminants, the presence of emerging pollutants, and the fulfilment of standardized limitations of WW quality indicators for further discharge into aquatic receptors or intended for reuse/recycle. Certain prepared synthetic WWs that reflect some dyebath formulations are briefly presented in Table 4[21; 28; 30; 34; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53]. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Indicators \({}^{*}\)** & **Processing De-Sizing** & **Sosuring** & **Bleaching** & **Mercerizing** & **Dyeing/Printing/ Finishing** \\ \hline pH & - & 10–13 & 8.5–9.6 & 5.5–9.5 & 5–10 \\ \hline Color (ADMI), [color units] & - & 650–700 & 153–190 & - & 1450–4750 \\ \hline Total suspended solids (TSSs), [mg/L] & 16,000–32,000 & 7600–17,400 & 2300–14,400 & 600–1900 & 500–14,100 \\ \hline Total dissolved salts (TDSs), [mg/L] & - & - & 4800–19,500 & 4300–4600 & 50–500 \\ \hline COD-Cr, [mgO\({}_{2}\)/L] & 4600–5900 & 8000–8600 & 6700–13,500 & 1600–1700 & 1100–4600 \\ \hline BOD\({}_{5}\), [mgO\({}_{2}\)/L] & 1700–5200 & 100–2900 & 100–1700 & 50–150 & 10–1800 \\ \hline Water usage, [L/kg cotton] & 3–9 & 26–43 & 3–124 & 232–308 & 8–300 \\ \hline \end{tabular}  
* Principal quality indicators for textile WW produced from wet cotton processing (adapted from a report by [PERSON] and [PERSON] (2012) [10]).  
\end{table}