Enhancement of sulfate reduction activity using granular sludge in anaerobic treatment of acid mine drainage.

Three laboratory-scale, upflow anaerobic reactors were operated for about 250 d to determine the effect of activated granular sludge with high density of sulfate reducing bacteria in the treatment of artificial acid mine drainage. Sulfate reducing bacteria in the granular sludge taken from the upflow anaerobic sludge blanket reactor were 1-2 x 10(6) c.f.u. g(-1), which is at least 10 times higher than that of organic substrates such as cow manure and oak compost. The reactors with granular sludge effectively removed over 99% of heavy metals, such as Fe, Al, Cu, and Cd during the experiment. This result suggests a feasibility of the application of granular sludge as a source of sulfate reducing bacteria for the treatment of acid mine drainage.

Anaerobic degradation of pyrrolidine and piperidine coupled with nitrate reduction.

Biodegradability of secondary amines (pyrrolidine, piperidine, piperazine, morpholine, and thiomorpholine) under anaerobic conditions was examined in microbial consortia from six different environmental sites. The consortia degraded pyrrolidine and piperidine under denitrifying conditions. Enrichment cultures were established by repeatedly sub-culturing the consortia on pyrrolidine or piperidine in the presence of nitrate. The enrichments strictly required nitrate for the anaerobic degradation and utilized pyrrolidine or piperidine as a carbon, nitrogen, and energy source for their anaerobic growths. The anaerobic degradation of pyrrolidine and piperidine reduced nitrate to nitrogen gas, indicating that these anaerobic degradations were coupled with a respiratory nitrate reduction.

Isolation and characterization of a novel Pseudomonas sp., strain YG1, capable of degrading pyrrolidine under denitrifying conditions.

A denitrifying bacterium, strain YG1, capable of degrading pyrrolidine under denitrifying conditions, was isolated. On the basis of phenotypic and phylogenetic characteristics, it was identified as a member of the genus Pseudomonas. During the anaerobic degradation of pyrrolidine, YG1 reduced a stoichiometric amount of nitrate to nitrogen gas, demonstrating that the degradation of pyrrolidine is coupled with respiratory nitrate reduction. YG1 also degraded pyrrolidine with a higher degradation rate under aerobic conditions than under denitrifying conditions.

Simultaneous degradation of p-nitrophenol and phenol by a newly isolated Nocardioides sp.

A p-nitrophenol (PNP)- and phenol-mineralizing bacterium (strain NSP41) was isolated from an industrial wastewater and identified as a member of the genus Nocardioides. PNP was degraded via a hydroquinone pathway, and phenol was degraded through a catechol pathway in strain NSP41. Both enzyme systems for the degradation of PNP and phenol were induced simultaneously in the presence of both compounds. Although both enzyme systems were induced at the same time, PNP and phenol were degraded by the hydroquinone and catechol pathway, respectively. However, during the simultaneous degradation in the low phenol concentration, after the exhaustion of phenol, some PNP was transformed by the catechol pathway and 4-nitrocatechol was transiently accumulated. Kinetically, the addition of phenol greatly enhanced the apparent PNP degradation rate, which may be due to the increased cell mass by the assimilation of phenol.