The use of efficient green cleaning agents, such as biosurfactants, is important in oil sludge treatment.Enhanced oil recovery from oily sludge by different rhamnolipids was comparatively evaluated. Using crude glycerol, the wild-type strain Pseudomonas aeruginosa SG and the recombinant strains P.aeruginosa PrhlAB and P. stutzeri Rhl produced 1.98 g L À1 , 2.87 g L À1 and 0.87 g L À1 of rhamnolipids, respectively. The three bacterial strains produced different rhamnolipid mixtures under the same conditions. The proportions of mono-rhamnolipids in the three rhamnolipid products were 55.92%, 94.92% and 100%, respectively. These rhamnolipid products also possessed different bioactivities.Emulsifying activity became higher as the proportion of mono-rhamnolipids increased. The three rhamnolipid products were stable at temperatures lower than 121 C, pH values from 5-11 and NaCl concentrations from 0-15%. All three rhamnolipid products could recover oil from oily sludge, but oil recovery efficiency was positively related to the proportion of mono-rhamnolipids. Mono-rhamnolipids produced by the recombinant strain Rhl exhibited the best oil recovery efficiency (53.81%). The results reveal that mono-rhamnolipids are the most promising for oil recovery from oily sludge.

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Abstract. At present, phase measurement method of power frequency three-phase power signal containing multiple harmonic, is generally based on the Hanning window FFT correction measurement methods. But their accuracy limited by the conventional FFT features is very difficult to guarantee. When the measured instantaneous phase is very small, the phase difference accuracy measured will be reduced; when the measured signal contains a large number of harmonic components, a larger measurement error will be made; when the cycle of the detected signal is instable, non-synchronous sampling will be produced so that the measurement accuracy will be affected. To solve the problems above, this paper analyzes the characteristic advantages of all phase FFT algorithm in the application of three-phase power phase measurement. The algorithm is an important electronic technology algorithm, which makes the measurement of small phase difference still maintaining high accuracy and makes the measurement results not affected by the harmonic component and non-synchronous sampling.

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