## 3 Results
### Rainfall and Wastewater Treatment Parameters  
The values in Tables 2 and 3 are shown in relation to the rainfall and each wastewater parameter. The correlation between rainfall and the incoming pH (Average pH In) was very weakly negative (r = \(-0.18,p\) = 0.387), indicating that changes in rainfall had a minimal impact on the pH levels in the incoming water. A weak positive correlation (r = 0.331, \(p\) = 0.052) was observed between rainfall and the outflow pH (Average pH Out), suggesting that higher rainfall may lead to a slight increase in the pH levels in the outflow water.  
The rainfall showed a moderate negative correlation (r = \(-0.516\), \(p\) = 0.027) with the total phosphorus concentrations in the incoming water (Average P Tot In), indicating that increased rainfall tends to reduce the total phosphorus levels in the incoming water, possibly due to dilution effects. The correlation between the rainfall and total phosphorus in the outgoing water (Average P Tot Out) was weakly negative (r = \(-0.31\), \(p\) = 0.154), suggesting a small inverse relationship, with rainfall slightly decreasing the phosphorus concentrations in the outflow.  
The correlation between the rainfall and chemical oxygen demand (COD) in the incoming water (Average COD In) was moderately negative (r = \(-0.536\), \(p\) = 0.019), implying that higher rainfall generally leads to lower COD levels in the incoming water, likely due to dilution effects. Similarly, a moderate negative correlation (r = \(-0.509\), \(p\) = 0.021) was observed between the rainfall and COD levels in the outgoing water (Average COD Out), suggesting that increased rainfall results in a reduction in the COD levels in the outflow water, again likely due to dilution effects.  
For the biological oxygen demand (BOD\({}_{5}\)) in the incoming wastewater (Average BOD\({}_{5}\) In), a moderate negative correlation (r = \(-0.531\), \(p\) = 0.020) was observed, indicating that higher rainfall generally reduces the BOD\({}_{5}\) levels in the incoming wastewater. However,  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  
the correlation between the rainfall and BOD\({}_{5}\) levels in the outgoing water (Average BOD\({}_{5}\) Out) was very weakly positive (r = 0.032, \(p\) = 0.867), showing no significant impact of rainfall on the BOD\({}_{5}\) levels in the outflow water.  
Rainfall had a very weak negative correlation with the amount of total suspended solids (TSSs) in the incoming water (Average TSSs In) (r = \(-\)0.09, \(p\) = 0.746), suggesting that rainfall had a negligible effect on the TSS levels in the incoming water. However, a moderate positive correlation (r = 0.439, \(p\) = 0.023) was observed between the rainfall and TSS levels in the outgoing water (Average TSSs Out), indicating that higher rainfall may increase the TSS levels in the effluent, possibly due to the washout of suspended solids.  
The rainfall showed a strong negative correlation with the nitrogen concentrations in the incoming water (Average N-Total In), with a correlation coefficient of r = \(-\)0.749 and a \(p\) = 0.001, suggesting that increased rainfall significantly lowers the nitrogen concentrations in the incoming water, likely due to dilution. Similarly, a strong negative correlation (r = \(-\)0.69, \(p\) = 0.004) was observed between the rainfall and nitrogen levels in the outgoing water (Average N-Total Out), again indicating that rainfall leads to a reduction in the nitrogen concentrations in the effluent, most likely due to dilution effects.  
Finally, rainfall showed a moderate negative correlation (r = \(-\)0.569, \(p\) = 0.015) with the ammonium concentrations in the incoming water (Average NH\({}_{4}\) In), indicating that higher rainfall may reduce the ammonium concentrations in the incoming water.