## 3 Results
### Technological Process Improvement Through Polyaluminium Chloride Addition and Struvite Reduction  
The graph in Figure 7 shows the relationship between the ether extract (EE) load in raw sewage and the volume of discharged sewage. Three lines in Figure 7 represent different ranges of coagulant (polyaluminium chloride) consumption: a solid red line for polyaluminium chloride consumption between 0.89 and 2.1 kg of product/kg of EE load, a dashed blue line for polyaluminium chloride consumption between 2.1 and 2.8 kg of product/kg of EE load and a dashed green line for polyaluminium chloride consumption between 2.8 and 5.3 kg of product/kg of EE load. The flexplot shows a clear positive correlation between the ether extract load and the volume of discharged sewage.  
Figure 6: Silhouette analysis of sewage pollutants using optimal \(K\)-means clusters: (**a**) ether extract; (**b**) phenols; (**c**) chlorides; (**d**) sulfates.  
Supplementary data for the above analysis are presented in Appendix B (Table A3). In year H, the average monthly polyaluminium chloride consumption was 8950 kg of product/month, with the EE load in raw sewage being 4096 kg/day. In the following year, the average monthly coagulant consumption increased to 9540 kg of product/month, with the EE load being 3475 kg of product/day. Polyaluminium chloride consumption per kg of the EE load rose from 2.185 kg of product to 2.745 kg of product.  
The values of discharged sewage in Figure 8 vary depending on the ether extract (EE) load in raw sewage and the consumption of commercial product--Polystabil KWS for struvite reduction. The flexplot in Figure 8 shows a positive relationship between the ether extract load and the volume of discharged sewage sludge. As the ether extract load increases, so does the volume of discharged sewage. This relationship is illustrated through three lines representing different ranges of Polystabil KWS consumption: a solid red line (0.0064-0.0075 L of product/m\({}^{3}\) of discharged sewage), a dashed light blue line (0.0075-0.012 L of product/m\({}^{3}\) of discharged sewage) and a dashed green line (0.012-0.024 L of product/m\({}^{3}\) of discharged sewage).  
Additionally, in Appendix B (Table A4), the average values of Polystabil KWS addition as a struvite reduction measure are presented. The analysis yielded the following results: In year H, the average monthly volume of discharged sewage was 15,050 m\({}^{3}\)/month, the Polystabil KWS consumption was 188 L of product/month and the Polystabil KWS consumption per m\({}^{3}\) of discharged sewage was 0.0125 L of product. In year I, the average monthly volume of discharged sewage was 17,482 m\({}^{3}\)/month, the average monthly Polystabil KWS consumption was 154 L of product/month and the Polystabil KWS consumption per m\({}^{3}\) of discharged sewage was 0.0088 L of product.  
Based on Table 5, a moderate positive correlation (Spearman's correlation) was observed between the volume of discharged sewage sludge and the polyaluminium chloride consumption (\(p\)-value \(<\) 0.05). Conversely, the ether extract load showed a moderate negative correlation with polyaluminium chloride consumption and a strong negative correlation with the volume of discharged sewage sludge. Both correlations were statistically significant, with the latter being highly significant (\(p\)-value \(<\) 0.01). Additionally, Polystabil KWS consumption exhibited a strong negative correlation with the volume of discharged  
Figure 7: Dependence of the volume of discharged sewage and the ether extract (EE) load along with various levels of polyaluminium chloride consumption.