# Behaviour of PPCP Substances in a Fluvial Aquifer after Infiltration of Treated Wastewater
## 4 Results
### Generalization of PPCP Substance Behaviour  
The results of the infiltration experiment at the Kojetin site enable PPCP substances to be divided into four groups  
* Substances with random occurrence in very low concentrations and therefore with an undetectable origin.  
Figure 5: Measured and modelled content of Sucralose in 2022, relative values.  
At the WWTP outlet, the substances of this group often had concentrations below the detection limit, so the infiltration experiment could not affect the concentrations of these substances in the monitoring wells PZ1, CP1 and PZ5. Nevertheless, they were analyzed in low concentrations at irregular intervals in some samples. An example of this group of substances is caffeine, which was detected in well PZ1 in the sample from 20 November and in well CP1 in the sample from 30 November. However, during the entire experiment, caffeine was not detected in the WWTP water samples. A similar result can be observed with other substances such as Bisphenol S, Methylparaben, Paracetamol, Paraxanthin, Propylparaben, and Saccharin. The problem with these substances is their general presence in various components of the environment, including practically all watercourses, so their origin is difficult to unambiguously detect.
* Substances, the contents of which increased in the Quaternary aquifer after the infiltration experiment. Substances of this group are characterized by a high concentration in treated wastewater, which was later manifested in the occurrence in wells PZ1 and CP1. It is important that these substances were not present in the wells before the start of the experiment. The resulting content of these substances in the wells remain lower than at the WWTP outlet. Characteristic representatives of this group are oxypurnol, Sucralose, Hydrochlorothiazzide, Diclofenac-4-hydroxy, and Benzotriazole. But all the substances which systematically occurred during the infiltration experiment should be included (Table 2). Absence of these substances at the beginning of the experiment reveals that they are degrading at some rate in the groundwater.
* Substances persistent, apparently without significant WWTP influence Substances in this group are characterized by a higher concentration in wells than in treated wastewater. They usually occurred in the groundwater from the beginning of the infiltration experiment. The water in the observed wells was therefore more similar to water from the Morava River than to the WWTP. A typical representative is Acesulfame, whose concentrations in the river exceeded twice the average values of the water leaving the WWTP. This group also includes DEET and Sulfamethazine, which are all persistent substances that are not subject to degradation either in the Morava River or in the rock environment of the gravel sands of the experimental site.
* Substances with a high natural attenuation capacity. Substances in this group are characterized by concentrations above the detection limit in the water leaving the WWTP, possibly also in the Morava River. Nevertheless, these substances were not detected in the observation wells. It can be assumed that these substances have a good sorption/degradation capability in the rock environment. This is a relatively large group of substances that includes Acebuttol, Atenolol, Azithromycin, Benzotriazole 1-methyl, Bisoprolol, Celiprolol, Cetriazine, Citalopram, Clarithromycin, Climbazole, Clindamycin, Cyclophosphamide, Erythromycin, Fexofenadine, Fluconazole, Irbesartan, Carbamazepine-2-hydr., Carbamazepine-DHH, Carbamazepine-E, Lamotrigine, Iosartan, Metoprolol, Mirtazapine, Naproxen, Naproxen-O-desmeth, Oxcarbazepine, PROS, Sertraline, Sitagliptin, Sotalol, Sulfamethoxazole, Telmisartan, Tramadol, Trimethoprim, Venlafaxine, Venlafaxine O-desmet, Verapamil, and Warfarin.