Table 1.

Typical solids, effluent and bacterial cell concentrations in OECD recommended RBTs (modified from OECD 1992a, b)

OECD test designation	301 A	301 B	301 C	301 D	301 E	301 F
Name	DOC die away	CO2 evolution	MITI (I)	Closed bottle	Modified OECD screening	Manometric respirometry
mg/l SS	≤30	≤30	30	n/a	n/a	≤30
ml effluent added/l	≤1	≤1	n/a	≤0.05	0.05	≤1
Approx. cells/ml	104–105	104–105	104–105	101–103	102	104–105
Source of inoculum
1. Activated sludge	✓	✓	✓			✓
2. Secondary effluent	✓	✓	✓	✓	✓	✓
3. Surface water	✓	✓	✓	✓	✓	✓
4. Soil	✓	✓	✓
5. Mixture of above	✓	✓	✓			✓
Pretreatment options
1. Settling for 30 min or 1 h	✓	✓	✓	✓	✓	✓
2. Filtering through fine sieve	✓	✓				✓
3. Filter through a coarse filter paper	✓	✓		✓	✓	✓
4. Preconditiona	✓	✓		✓	✓	✓
5. Preculture with glucose/peptone			✓

n/a not applicable

^aPre-conditioning consists of aerating the inoculum (in mineral medium) for 5–7 days at the test temperature but does not allow pre-adaptation to the test substance