Cryptanaerobacter phenolicus gen. nov., sp. nov., an anaerobe that transforms phenol into benzoate via 4-hydroxybenzoate.

An anaerobic bacterium that transforms phenol and 4-hydroxybenzoate (4-OHB) into benzoate, strain LR7.2T, was isolated from a culture originating from a mixture of swamp water, sewage sludge, swine waste and soil. Cells of strain LR7.2T are Gram-positive short rods (1 x 2 microm) that are electron-dense when observed by electron microscopy. The optimum pH and temperature for growth and transformation activity of 4-OHB are 7.5-8.0 and 30-37 degrees C, respectively. The bacterium does not use sulphate, thiosulphate, nitrate, nitrite, FeCl3, fumarate or arsenate as an electron acceptor. It does not normally use sulphite, although stimulation of growth and 4-OHB transformation activity at a low concentration (up to 2 mM) has been reported previously under different culture conditions. The presence of 4-OHB or phenol is essential for growth; transformation of 4-OHB or phenol into benzoate is used to produce energy for growth. Using [6D]-phenol, 4-OHB was shown to be an intermediate in the transformation of phenol into benzoate. No spore was observed. The bacterium has a DNA G+C content of 51 mol% and its major membrane fatty acid is anteiso-C(15 : 0). The 16S rRNA gene sequence of strain LR7.2T shows only 90 % similarity to its closest relative (Pelotomaculum thermopropionicum). From these results, a new taxon is proposed: Cryptanaerobacter phenolicus gen. nov., sp. nov. The type strain is LR7.2T (=ATCC BAA-820T=DSM 15808T).

Swine waste treatment by self-heating aerobic thermophilic bioreactors.

Pig manure represents a very high-strength wastewater that is well suited for a self-heating aerobic thermophilic treatment. Here we report the use of 59-L Aerobic Thermophilic Sequencing Batch Reactors (AT-SBR) to study the treatment of pig manure with a HRT of 6 days. Temperatures up to 75 degrees C were reached without external heating by using Venturi-type aerators but these conditions were detrimental for the respiratory activity of the microflora. For COD removal, better performances were achieved when the temperature was limited to 50 degrees C. However, higher temperatures increased the rate of phosphorus crystallisation and the volatilisation of ammonia. A temperature of 50 degrees C was enough to eliminate faecal coliforms and Campylobacter spp., but 60 degrees C was needed for the efficient destruction of Clostridium perfringens. Consequently, an operating temperature of 60 degrees C appears to be a good compromise. Under these conditions, the BOD(5) decreases from 50.5 to 1.0 g L(-1), yielding a 98% removal.

Improving the biotreatment of hydrocarbons-contaminated soils by addition of activated sludge taken from the wastewater treatment facilities of an oil refinery.

Addition of activated sludge taken from the wastewater treatment facilities of an oil refinery to a soil contaminated with oily sludge stimulated hydrocarbon biodegradation in microcosms, bioreactors and biopile. Microcosms containing 50 g of soil to which 0.07% (w/w) of activated sludge was added presented a higher degradation of alkanes (80% vs 24%) and polycyclic aromatic hydrocarbons (PAHs) (77% vs 49%) as compared to the one receiving only water, after 30 days of incubation at room temperature. Addition of ammonium nitrate or sterile sludge filtrate instead of activated sludge resulted in a similar removal of PAHs but not of alkanes suggesting that the nitrogen contained in the activated sludge plays a major role in the degradation of PAHs while microorganisms of the sludge are active against alkanes. Addition of sludge also stimulated hydrocarbon biodegradation in 10-kg bioreactors operated during 60 days and in a 50-m3 biopile operated during 126 days. This biopile treatment allowed the use of the soil for industrial purpose based on provincial regulation ("C" criteria). In contrast, the soil of the control biopile that received only water still exceeded C criteria for C10-C50 hydrocarbons, total PAHs, chrysene and benzo[a]anthracene. The stimulation effect of sludge was stronger on the 4-rings than on 2-rings PAHs. The soil of the biopile that received sludge was 4-5 times less toxic than the control. These results suggest that this particular type of activated sludge could be used to increase the efficiency of the treatment of hydrocarbon-contaminated soils in a biopile.