Screening and monitoring microbial xenobiotics’ biodegradation by rapid, inexpensive and easy to perform microplate UV-absorbance measurements

Table 4 Biodegradation and time needed for absorbance decrease in the different activated sludge community setups using different media, biomass concentration and initial xenobiotics’ concentrations

Xenobiotic	Concentration[mg L^-1]	Initial MLSS [g L^-1]	Decrease of absorbance values¹			Lowest absorbance value achieved after [d]²			Biodegradation confirmed by LC /GC
			R2A-UV	MSM-CN	MSM	R2A-UV	MSM-CN	MSM
BTri	1	0.5	✓	✓	✓	10	12	13	Yes
		2.0	n.d.	n.d.	n.d.	n.a.	n.a.	n.a.	No
		3.5	n.d.	n.d.	n.d.	n.a.	n.a.	n.a.	Yes
	10	0.5	✓	✓	✓	15	16	18	Yes
		2.0	✓	✓	✓	14	12	13	Yes
		3.5	n.d.	n.d.	n.d.	n.a.	n.a.	n.a.	Yes
5-TTri	1	0.5	✓	✓	✓	10	8	7	Yes
		2.0	n.d.	n.d.	n.d.	n.a.	n.a.	n.a.	No
		3.5	n.d.	n.d.	n.d.	n.a.	n.a.	n.a.	Yes
	10	0.5	✓	✓	✓	10	9	9	Yes
		2.0	✓	✓	✓	8	8	8	Yes
		3.5	n.d.	n.d.	n.d.	n.a.	n.a.	n.a.	Yes
SMX	1	0.5	✓	✓	✓	4	3	4	Yes
		2.0	n.d.	n.d.	n.d.	n.a.	n.a.	n.a.	No
		3.5	n.d.	n.d.	n.d.	n.a.	n.a.	n.a.	No
	10	0.5	✓	✓	✓	6	5	8	Yes
	10	2.0	✓	✓	✓	3	8	8	Yes
		3.5	✓	✓	✓	4	8	8	Yes

Shown are BTri, 5-TTri and SMX. 4-TTri was not biodegraded and is therefore not shown.
n.d. – biodegradation determination not possible, background due to biomass concentration too high.
n.a. – not applicable as no biodegradation could be detected by UV-AM.
¹Change in UV-AM indicates biodegradation.
²Time needed to achieve a stable value in UV-AM after a change in absorbance.

ISSN: 1756-0500