## 3 Results and Discussion
### Stage 1--LF-DSS Treatment and M-BGS Production
#### 3.1.4. Pollutant Removal Rate

\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{4}{c}{**Biomass gained [gTS/g\({}_{\text{in}}\)]**} & \multicolumn{4}{c}{**Biomass gained [TS/g\({}_{\text{gen}}\)]**} \\ \cline{2-9}  & d 15 & d 30 & d 45 & d 60 & d 15 & d 30 & d 45 & d 60 \\ \hline COD & 3.73 \(\pm\) 0.39 & 6.70 \(\pm\) 0.51 & 6.03 \(\pm\) 0.72 & 7.74 \(\pm\) 0.93 & 6.07 \(\pm\) 0.22 & 5.63 \(\pm\) 0.47 & 5.82 \(\pm\) 0.64 & 6.98 \(\pm\) 0.88 \\ TOC & 5.11 \(\pm\) 0.68 & 5.65 \(\pm\) 0.43 & 6.05 \(\pm\) 0.88 & 8.05 \(\pm\) 1.02 & 7.11 \(\pm\) 0.83 & 7.00 \(\pm\) 0.63 & 7.25 \(\pm\) 1.01 & 9.13 \(\pm\) 1.14 \\ TP & 100 \(\pm\) 12 & 110 \(\pm\) 11 & 118 \(\pm\) 14 & 157 \The different rates of organics biodegradation produced significant variance in the loads removed during LF-DSS treatment. COD removal ranged from 44.1 \(\pm\) 3.5 gCOD/d in P1 to 60.5 \(\pm\) 4.8 gCOD/d in P4. The rates for TOC ranged from 37.7 \(\pm\) 4.4 gCOD/d in P1 to 46.2 \(\pm\) 5.5 gCOD/d in P4 (Table 5). The biomass levels in the H-PBR (Figure 13) and the proportion of heterotrophic microbes in the M-BGS were found to correlate with organic removal rates and final organic levels (Figure 14). The results indicate that changes in the taxonomic structure of the biomass did not significantly affect N and P removal from the LF-DSS. Final performance was similar across all phases of the experiment (Table 5). TN removal ranged from 67.2 \(\pm\) 2.4% in F3 to in F1, meaning that the final levels in the effluent were 15.2 \(\pm\) 1.3 mgN/dm\({}^{3}\) to 17.4 \(\pm\) 1.6 mgN/dm\({}^{3}\). The differences were not statically significant. Treatment perfor  
Figure 14: Correlations between the abundance of activated sludge microbes in the M-BGS and (**a**) organics removal and (**b**) levels of organic matter in the PBR effluent. Figure 13: Correlations between M-BGS levels and (**a**) organics removal and (**b**) levels of organic matter in the H-PBR effluent. mance for P was similar across all PBR operation phases. TP in the final effluent fell within the narrow range of 7.36 \(\pm\) 0.79 mgP/dm\({}^{3}\) to 7.69 \(\pm\) 0.82 mgP/dm\({}^{3}\), whereas P-PO\({}_{4}\) ranged from 0.98 \(\pm\) 0.23 mg/dm\({}^{3}\) to 1.25 \(\pm\) 0.30 mg/dm\({}^{3}\). Indicators of LF-DSS treatment performance (pollutant removal rate, levels in effluent, load removed and specific M-BGS biomass growth) are given in Table 5.  
It is claimed that in the symbiotic growth systems of M-BGS structures, microalgae are responsible for the intensification of the removal of nitrogen and phosphorus compounds, whereas organisms of activated sludge for biodegradation of organic compounds [40]. This mechanism may be especially important in wastewater treatment systems [41]. Traditional WWTPs based on activated sludge require costly technological solutions for the complex removal of biogenes [42]. Aerobic-anaerobic conditions must be ensured to enable the sequence of ammonification, nitrification, denitrification, and release processes, followed by accumulation of orthophosphates [43]. These are technologically complicated solutions requiring vast financial outputs for aeration and an advanced circulation system inside the installation [44]. The microalgae of the M-BGS structure are also responsible for the production of oxygen indispensable for bacteria [13]. Decreasing oxygen demand is the major obstacle in reducing energy consumption and emission levels of wastewater treatment systems based on the activated sludge method. Oxygen produced by microalgae has been proved to aid the metabolism of bacteria and improve technological and economic effectiveness [45]. On the other hand, bacterial biodegradation of pollutants results in the formation of mineralization forms of nitrogen and phosphorus, and carbon dioxide, which intensify microalgae development in M-BGS structure [46]. [PERSON] et al. (2021) [47] proved that treatment efficiency of synthetic wastewater in the M-BGS system reached 96.5% for COD, 78-85% for nitrogen compounds, and 80.8% for phosphorus compounds [47].