An on-line roboticized apparatus, including an optical biosensing film with an automatic flow sampling system, has been developed for biochemical oxygen demand (BOD) determination of seawater. The sensing film employed in the apparatus consisted of an organically modified silicate (ORMOSIL) film embedded with tri(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) perchlorate. Three species of microorganism cultivated from seawater were immobilized in an ORMOSIL-polyvinyl alcohol matrix. Possible factors affecting BOD determination were studied, including sampling frequency, temperature, pH and sodium chloride concentration. Based on measurements of the linear fluctuant coefficients and the reproducibility of its response to seawater, the BOD apparatus showed the advantages of high veracity and short response time. Generally, the linear fluctuant coefficient (R2) in the BOD range 0.2–40 mg l−1 was 0.9945 when using a glucose/glutamate (GGA) BOD standard solution. A reproducible response for the BOD sensing film of within ±2.8% could be obtained in the 2 mg l−1 GGA solution. The BOD apparatus was applied to the BOD determination of seawater, and the values estimated by this biosensing apparatus correlated well with those determined by the conventional 5 day BOD (BOD5) test.

The phenol-degrading efficiency of Pseudochrobactrum sp. was enhanced by ultraviolet (UV) irradiation. First, a bacterial strain, Pseudochrobactrum sp. XF1, was isolated from the activated sludge in a coking plant. It was subjected to mutation by UV radiation for 120 s and a mutant strain with higher phenol-degrading efficiency, Pseudochrobactrum sp. XF1-UV, was selected. The mutant strain XF1-UV was capable of degrading 1800 mg/L phenol completely within 48 h and had higher tolerance to hydrogen ion concentration and temperature variation than the wild type. Haldane’s kinetic model was used to fit the exponential growth data and the following kinetic parameters were obtained: μmax = 0.092 h−1, Ks = 22.517 mg/L, and Ki = 1126.725 mg/L for XF1, whereas μmax = 0.110 h−1, Ks = 23.934 mg/L, and Ki = 1579.134 mg/L for XF1-UV. Both XF1 and XF1-UV degraded phenol through the ortho-pathway; but the phenol hydroxylase activity of XF1-UV1 was higher than that of XF1, therefore, the mutant strain biodegraded phenol faster. Taken together, our results suggest that Pseudochrobactrum sp. XF1-UV could be a promising candidate for bioremediation of phenol-containing wastewaters.

An organically modified silicate (ORMOSIL) as a matrix for oxygen-sensitive sensor, in which dimethyldimethoxysilane was selected as an organic modifier in the precursor, is described. The sensing film with tris-(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) as an indicator developed in this paper was characterized by efficient quenching by oxygen. Blue light-emitting diodes (λ max ＝ 475 nm) were employed as light excitation source. The linear range of the dissolved oxygen was from 0.5 to 16 μg/mL. The measured RSD was 2%, the response time (t 95 ) was 60 s, and the determination limit was 0.2 μg/mL. A portable and inexpensive luminescence-based sensor was established and applied to the determination of dissolved oxygen in the surface water.ORMOSIL, fluorescent quenching, oxygen sensing film, ruthenium complex.