Investigation of pathogenic Escherichia coli and microbial pathogens in pulp and paper mill biosolids.

Biosolids produced from pulp and paper mill wastewater treatment have excellent properties as soil conditioners, but often contain high levels of Escherichia coli. E. coli are commonly used as indicators of fecal contamination and health hazard; therefore, their presence in biosolids causes concern and has lead to restrictions in land-spreading.

Effects of nitrogen and phosphorus limitation on the activated sludge biomass in a kraft mill biotreatment system.

Unlike wastewater, pulp and paper mill effluents are generally severely deficient in bioavailable nitrogen and phosphorus. The influence of nitrogen and phosphorus limitations on steady-state or typical pulp and paper mill activated sludge floc properties and performance was studied using a bioreactor-fed synthetic raw mill effluent and seeded with mill activated sludge. Limitation of either nitrogen or phosphorus decreased growth, five-day biochemical oxygen demand, and suspended solids removal.

Isolation of poly-3-hydroxybutyrate metabolism genes from complex microbial communities by phenotypic complementation of bacterial mutants.

The goal of this study was to initiate investigation of the genetics of bacterial poly-3-hydroxybutyrate (PHB) metabolism at the community level. We constructed metagenome libraries from activated sludge and soil microbial communities in the broad-host-range IncP cosmid pRK7813. Several unique clones were isolated from these libraries by functional heterologous complementation of a Sinorhizobium meliloti bdhA mutant, which is unable to grow on the PHB cycle intermediate D-3-hydroxybutyrate due to absence of the enzyme D-3-hydroxybutyrate dehydrogenase activity.

Common stresses affecting activated sludge health and performance--what the four-assay set can tell us.

Previously, we developed a novel biological early warning (BEW) system for directly monitoring the health and performance of activated sludge, the "four-assay set". In the present work, the four-assay set has been used to measure the effects of four common stresses on activated sludge biomass: high temperature; pH; anoxia; and starvation. The results demonstrate both the utility of the Paprican four-assay set as a biomass-evaluating and BEW tool, and the tolerances of a typical kraft mill activated sludge for these four stresses.