TECHNOLOGY FOCUS - BIOLOGY - Preferred Process: Treatment is under anaerobic conditions at 10-37, preferably 30 degreesC and pH 5.5-8.5, preferably 6.9, for at least 15, particularly 15-21, days, and the system is either illuminated or an electron acceptor, e.g. trimethylamine-N-oxide is added. The waste contains TBP at 0.01 mM to 1 M and bacteria are inoculated at 104-1010 per ml. An additional carbon source may also be added, particularly a buffered solution containing 0.1-10 g/l yeast extract or a succinate, glutamate, benzoate, malate or fumarate salt at 2-10, best 10, mM; optionally also growth factors, at least biotin and p-aminobenzoic acid, each at 2-40 mug/l. The content of residual TBP is particularly measured by HLPC, with refractive index detection.Preferred Device: The decantation tank is 0.5-1 m deep, with surface area depending on the flow rate of effluent. It also includes lines for supplying waste and bacteria; for discharge of processed effluent and systems for recovering bacteria for recycle, particularly a filter of diatomaceous earth or a continuously operating centrifuge.Preferred Bacteria: These are R. palustris and R. rubrum, particularly a mixture of at least one of these and at least one of R. capsulatus or R. sphaeroides. Specified strains are R. rubrum S1 (ATCC 11170); R. capsulatus Saint Louis (ATCC 23782); R. sphaeroides 2.4.1 (ATCC 17023) and ten strains of R. palustris e.g. GCA009 (ATCC BAA-98), ATCC 17002; ATCC 17007; DSM 8283 and DSM 126. (A) are preselected on a medium containing at least 12 microM, preferably 1 mM, TBP. The most preferred strain, ATCC BAA-98 contains a gene for cytochrome P450 under control of the LHapproximatelyzapproximatelyBe promoter. EXAMPLE - Rhodopseudomonas palustris CGA009 (ATCC BAA98) was grown under photosynthetic conditions in Hutner culture medium in presence of 2 mM TBP. After 21 days, the content of TBP had been reduced to 25% of its original value. After 21 days, bacterial growth (assessed for optical density) was nearly the same for cells grown in presence or absence of TBP.