## 3 Results and Discussion
### Monitoring of Decolorization of TB and BR in RTWW: COD and FTIR Analyses  
It should be mentioned that there are few attempts to treat RTWW with BES; most studies have focused on STWW [30]. In this study, we have evaluated the BES using STWW and then validated with RTWW containing naturally the same dyes used in STWW treatment experiments with a concentration that varies from 300 to 500 depending on the tanning process. The RTWW containing TB and BR among other constituents (0.7 mg/L anionic detergents, 9\(\times\) 10\({}^{3}\) mg/L chlorides, 777 mg/L sulfates, and 102 mg/L suspended matters) was fed into the BES with SCD or SSM inoculums. Attempts to form a bioanode were conducted by chronoamperometry at \(-\)0.1 V/SCE. Constant electrode polarization was maintained for 30 days and 15 days, respectively, when SCD and SSM were used as inoculum. A maximal current production of 2.0 and 0.8 A/m\({}^{2}\) were obtained, respectively (Figure 5(a)). As shown in Figure 5C,D, initial CVs clearly show the absence of an electroactive biofilm; reduction currents were recorded from \(-\)0.2V, which corresponds to the electrochemical reduction in some compounds present in the reaction medium to be treated; during this phase, the biofilm has not yet reached its maturity. Final CVs were performed at the end of each experiment; remarkable differences in the general appearance of the CVs were identified compared to their initial states, confirming the activity of biofilms; the oxidation plateau was maintained in the range of \(-\)0.2 to +0.3 V with maximum peaks of 4 and 2A for SCD and SSM, respectively. The CVs results clearly demonstrated the formation of a biocatalyst biofilm on the conducting surface for a polarization period that exceeded 15 days. It is noteworthy that TB and BR decolorization rates obtained in the case of RTWW treatment are comparable to those observed when using glucose as co-substrate with STWW experiments. Based on thesedata, it is apparently unnecessary to add an additional co-substrate to initiate the cometabolism reaction with RTWW. In fact, carbohydrates and other complex organic materials present in RTWW could be used by the microbial community to increase the electrochemical process. It is estimated that the concentration of carbohydrates in textile effluent could reach up to 22.000 \(\pm\) 0.151 mg/L [31]. In fact, the water evacuated during the tanning process carries a significant chemical load that comes from the sizing products--mainly starches and their derivatives, carboxymethyl cellulose, and galactomannans. In addition, various additives are present in the dye formulations. Since these substances are not absorbed or fixed by the fibers, they are discharged into the wastewater with considerable COD load. Such additives are buffer systems composed of acetate, thickeners composed of carboxymethyl cellulose, and dispersants composed of ethylene oxide copolymers and detergents [32]. Based on these data, the treatment of real textile wastewaters in a BES may not require the addition of a co-substrate to enhance the co-metabolism reaction. This could significantly reduce the treatment cost by avoiding the mobilization and addition of co-substrates. Table 2 shows different decolorization and COD removal rates obtained after treatment of RTWW when SCD or SSM sediments were used as inoculum. A COD removal rate of 85 vs. 30\(\%\) in control reactor, respectively), and decolorization rates of 88\(\%\) for TB and 84\(\%\) for BRwere reached when used SCD sediment. The COD removal rate in the control reactor was 67\(\%\). However, a low COD removal rate was obtained when used SSM as inoculum (46 vs. 30\(\%\) in control reactor, respectively), the decolorization rates of TB and BR were 72 and 81\(\%\), respectively. Results obtained with RTWW confirm the efficiency of microbial community naturally hosted in the SCD inoculum. Previous studies have shown that the decolorization efficiency of dyes in bioelectrochemical systems was better than that in biological anaerobic reactors [33; 34].