Table 2. Overview of the results of the mutagenicity test.

Mutagenicity at the WWTPs Mörfelden–Walldorf and Bickenbach in the Ames fluctuation test with Salmonella typhimurium strains YG1041 and YG1042 with and without S9 mix. Mutagenic samples (>20.8% revertant colonies) are labelled with (+), non-mutagenic samples with (-). n.a., not analyzed due to high cytotoxicity.

Season	WWTP	Sample site	Test response	Revertant percentage mean (%)
YG1041-S9 mix
Spring	Mörfelden Walldorf	US	–	12.9
		MT	–	10.8
		BT	–	14.0
		DS	–	16.1
	Bickenbach	US	–	8.7
		MT	–	15.1
		BT	–	20.2
		DS	–	11.9
Fall	Mörfelden Walldorf	BT-L	–	10.8
		US	–	12.9
		MT	–	14.4
		BT	–	14.0
		DS	–	16.1
	Bickenbach	US	–	8.8
		MT	–	12.2
		BT	–	20.2
		DS	–	11.9
YG1041+S9 mix
Spring	Mörfelden Walldorf	US	+	39.3
		MT	n.a.	n.a.
		BT	+	49.7
		DS	+	56.5
	Bickenbach	US	–	4.8
		MT	n.a.	n.a.
		BT	+	49.2
		DS	+	52.3
Fall	Mörfelden Walldorf	BT-L	+	52.8
		US	+	22.1
		MT	n.a.	n.a.
		BT	+	57.5
		DS	+	54.4
	Bickenbach	US	–	15.3
		MT	n.a.	n.a.
		BT	+	47.1
		DS	+	53.3
YG1042-S9 mix
Spring	Mörfelden Walldorf	US	–	17.8
		MT	n.a	n.a
		BT	–	19.1
		DS	–	17.8
	Bickenbach	US	–	10.9
		MT	–	5.8
		BT	–	17.3
		DS	–	13.7
Fall	Mörfelden Walldorf	BT-L	n.a	n.a
		US	–	17.8
		MT	n.a	n.a
		BT	–	9.5
		DS	–	17.9
	Bickenbach	US	–	10.9
		MT	–	5.8
		BT	–	17.3
		DS	–	13.7
YG1042+S9 mix
Spring	Mörfelden Walldorf	US	+	41.9
		MT	n.a.	n.a.
		BT	+	47.1
		DS	+	41.4
	Bickenbach	US	–	20.5
		MT	n.a.	n.a.
		BT	+	45.0
		DS	+	42.4
Fall	Mörfelden Walldorf	BT-L	+	54.9
		US	+	32.5
		MT	n.a.	n.a.
		BT	+	52.8
		DS	+	51.3
	Bickenbach	US	+	36.2
		MT	n.a.	n.a.
		BT	+	51.8
		DS	+	56.0