## 3 Results and Discussion  
Improvement in the Functional Status of Bacterial Cells due to Environmental Factors in the Zero-Emission System of POME Final Discharge  
The functionality of the bacterial cells was differentiated into the proportion of viable and dead cells as visualized in Figure 3a. After excluding the dead proportion, the viable proportion of bacterial cells was further differentiated into their nucleic acid contents which were the HNA (active) and LNA (dormant) cells (Figure 3b). The rainwater sample, which was introduced on day 1, showed a high proportion of dead bacterial cells with around 70%. The proportion of LNA cells in the rainwater sample was also higher (70%) than that in the POME final discharge (20%). The result is reflected in the BOD\({}_{5}\) reading where rainwater had a low BOD\({}_{5}\) concentration which was 2.7 \(\pm\) 0.9 mg/L (Figure 4a) proving that there was less of the bacterial community present in the rainwater. This was due to the limited nutrient content in the rainwater contributing to the low proportion of viable bacterial cells, and hence the proportion of HNA cells, which corresponds with the study by [PERSON] et al. [33]. In this study, the initial nutrient contents, including potassium (Figure 4b), ammonium nitrogen, ammonia, and nitrate (Figure 4c), were reported at a very low concentrations in the rainwater. Figure 3: Shifts in the contents of **(a)** viable and dead and **(b)** high nucleic acid, HNA, and low nucleic acid, LNA in the bacterial cells calculated to a scale of 100 in the water samples collected daily from the constructed artificial river water system. Days 2-7: introduction of POME final discharge; days 8-15: implementation of zero-emission of POME final discharge. Notes: FD-POME final discharge; RW-Rainwater; 1-15-River water system running days. On the other hand, POME final discharge had the highest proportion of viable bacterial cells (85%) and HNA cells (70%) (Figure 3). This was expected since the BOD\({}_{5}\) recorded  
Figure 4: The daily measured (**a**) biological oxygen demand (BOD\({}_{5}\)), (**b**) potassium content, (**c**) ammonia nitrogen, ammonia, and nitrate contents, (**d**) total suspended solids (TSS), (**e**) volatile suspended solids (VSS), (**f**) chemical oxygen demand (COD) of water samples in the constructed artificial river water system during the introduction of POME final discharge (I) and after the implementation of zero-emission of POME final discharge (II) from day 1 to day 15. Notes: The error bars represent the standard error of triplicate experiment, FD: POME final discharge, RW: Rainwater. for POME final discharge was at 163.45 \(\pm\) 6.94 mg/L (Figure 4a), which may have been due to the carried over nutrient content that originated from the palm oil fruit [34] and the abundance of bacteria that actively work to biodegradable the contaminants in the POME final discharge [21]. From Figure 4b,c, it is obvious that the nutrient contents of POME final discharge were extremely high compared to the rainwater. Following the introduction of POME final discharge into the system on day 2, the proportion of viable bacterial cells increased to 60%, which was almost two times that of the initial proportion of the viable bacterial cells in the rainwater. This proportion was further increased as a result of the introduction of POME final discharge into the system until day 4, but it showed quite a steady trend from day 5 to day 7. The existing bacterial loads in the POME final discharge were introduced into the system which contributed to the increase in the viable bacterial cells in the receiving water. The introduction of the POME final discharge into the artificial river water system on day 2 also caused the proportion of HNA cells in the receiving water to increase to 42.7% (Figure 3b). According to [PERSON] et al.