Trace elements enhance biofilm formation in UASB reactor for solo simple molecule wastewater treatment.

In this paper, trace elements (TE) adding was investigated in one bench-scale UASB reactor treating solo simple molecule wastewater with the aim of evaluating its effect on enhancing biofilm formation. After adding sufficient TE (3 mL/L) in the influent, during 3 days, COD removal efficiency increased from 74% to 90% comparing to no adding TE. Over 55 days of operation, the organic loading rate (OLR) reached 11 g/L/day with COD removal efficiencies greater than 90%. While in the steady running period no effect even improvement on treatment performance was observed without any TE adding. The results illuminated that TE accounted for quick start-up of the UASB biofilm system rather than ever known biocatalyst.

Bench-scale study using PVA gel as a biocarrier in a UASB reactor treating corn steep liquor wastewater.

PVA-gel beads were used as a biocarrier for treatment of corn steep liquor wastewater containing high levels of volatile fatty acids (VFA), where retention of biomass could be either solely in the porous microstructure of the gel or by granule formation using a gel bead as a nucleus. With stable COD removal efficiencies of 90% or greater, continuous treatment was demonstrated over a four month period, with organic loading rates being increased stepwise from 2.5 to 22.5 kg COD/m3 d. In addition, VFA in the effluent were, with few exceptions maintained close to zero. Gas production increased over the course of the study and reached a level of 0.38 m3/kg COD consisting of 65% methane with the remainder being mostly carbon dioxide. Biomass granules containing methane producing bacteria progressively formed around the PVA-gel beads during the study. In contrast, very few small natural granules developed apart from PVA-gel nuclei indicating that PVA gel may serve well as a seeding material to enhance granulation when natural occurrence is lacking.

A pilot-plant study of a moving-bed biofilm reactor system using PVA gel as a biocarrier for removals of organic carbon and nitrogen.

A pilot-plant study was conducted to evaluate the performance of a moving-bed biofilm reactor process using PVA-gel beads as a biocarrier. Real primary-settled wastewater was fed to the pre-denitrification system and removals of nitrogenous and organic contaminants were evaluated over a 1-year period. The results demonstrated that at a total nitrogen (TN) loading of 18 mg/L.h, a TN removal efficiency in keeping with and even exceeding the theoretical maximum efficiency based on the level of internal recycle, was possible and a nitrification rate of 15 mg/L.h was sustained with a HRT of only 2.5 h at 15 degrees C. Furthermore, soluble COD and BOD5 in the effluent of the pilot plant were reduced to levels well below most regulatory discharge limits. In addition, the possibility of using this biocarrier in a system, including the elimination of waste organic sludge, was discussed.

Polychlorinated biphenyls and organochlorine pesticides in plasma and the embryonic development in Lake Erie water snakes (Nerodia sipedon insularum) from Pelee Island, Ontario, Canada (1999).

From three locations along a 34-km shoreline of Pelee Island, Ontario, 30 gravid female Lake Erie water snakes (Nerodia sipedon insularum) were sampled to determine the organochlorine (OC) contaminant levels in plasma and the number of live and dead embryos present in the body cavity. Plasma was analyzed for 59 polychlorinated biphenyl (PCB) congeners and 14 organochlorine pesticides. Concentrations of pesticides were low (< or =0.1 ng/g wet wt) in all snakes, but there was significant variation in mean PCB concentrations in plasma from among the sampling locations on Pelee Island. Snakes (n = 5) from the West shore and dock area of the island had significantly higher PCB concentrations (90.4 +/- 15.0 ng/g wet wt) in plasma than those from Lighthouse Point (n = 5; 34.4 +/- 13 ng/g wet wt) and the south shore of the island (n = 5; 29.4 +/- 16.3 ng/g wet wt). Body mass of the female snakes ranged from 252 to 880 g, and mean masses were not significantly different among sample sites. The number of live embryos found ranged from 13 to 46 female snakes and no dead embryos were detected. There were significant positive correlations among body mass, snout-vent length, and number of young per female. There were no significant correlations among body mass, snout-vent length, number of young per female, or per-gram body mass of female snakes and contaminant concentrations in plasma. It was concluded that an interim estimate of a no-effect level on embryonic survival in N. sipedon insularum may be a maximum average concentration of 90.4 ng/g wet wt PCBs and a maximum average concentration of 3.6 ng/g wet wt p,p'-dichloro-diphenyl-dichloroethylene in plasma.

Characterization of denitrifying granular sludge treating soft groundwater in an upflow sludge-blanket reactor.

Nitrate removal from soft groundwater using ethanol as a carbon source in an upflow sludge-blanket reactor containing denitrifying granular sludge was investigated. At a hydraulic retention time of 0.83 h, influent nitrate was increased stepwise from 20 to 145 mg N/l (volumetric loading rates (VLRs), 0.60 to 4.2 g N/l/d, respectively) and sludge was periodically wasted to maintain a sludge bed of about 2 3 the liquid volume. Complete nitrate removal was achieved at influent nitrate concentrations up to 75 mg N/l(2.1 g N/l/d). MLSS increased from 20 g/l at a VLR of 0.6 g N/l/d to 51 g/l at a VLR of 1.9 g N/l/d, above which it decreased. VSS increased from 11 g/l to a maximum of 25 g/l at a VLR of 2.1 g N/l/d. Settling velocities showed the same trend with maximum values in a VLR range of 1.5 to 2.1 g N/l/d. However, granule size, calcium and magnesium contents of the granular sludge and protein, carbohydrate and nucleic acid contents of extracellular polymers decreased steadily with an increase in VLR throughout the range of testing. Within the VLR range of 0.6 to 2.1 g N/l/d, corresponding to complete nitrate removal and efficient sludge retention, the granular sludge had a high calcium content of 24 to 22%, magnesium ranged from only 0.7 to 0.1%, proteins from 3.2 to 1.3%, carbohydrates from 4.2 to 1.4%, and nucleic acids from 0.34 to 0.05% of the sludge dry weight. These results suggest an optimum operational VLR in terms of nitrate removal and sludge retention of about 2 g N/l/d.

Chlorinated hydrocarbon concentrations in plasma of the Lake Erie water snake (Nerodia sipedon insularum) and northern water snake (Nerodia sipedon sipedon) from the Great Lakes basin in 1998.

From the Great Lakes basin, concentrations of 59 congener-specific polychlorinated biphenyls (PCBs) and 14 organochlorine pesticides were measured in blood plasma of northern water snake (Nerodia sipedon sipedon) and Lake Erie water snake (Nerodia sipedon insularum), which is endangered in Canada. In 1998, four male adult Lake Erie water snakes were sampled from Pelee Island, western Lake Erie; four male northern water snakes were sampled at Little Lake, about 20 km north of Parry Sound in central Ontario; and four adult gravid female northern water snakes were sampled from Garden Island, eastern Lake Ontario. The blood plasma was pooled by site for a total of three samples analyzed. The Pelee Island sample from male Lake Erie water snakes contained less than half the lipid concentration (0.349%) than samples from the other sites, but it was the most contaminated with PCBs, even on a wet weight basis. Summed concentration of individual PCBs in the Pelee Island sample was 167 ng/g (wet weight), which was 14-fold higher than the next most contaminated sample, which was from Little Lake. The plasma sample from Little Lake contained 12 ng/g (WW) and was four times more contaminated with PCBs than the sample from female snakes from Garden Island, Lake Ontario. Organochlorine pesticide concentrations in plasma were relatively similar among sites. None of the pesticides was found above trace concentrations (0.1-0.9 ng/g) except pp'-DDE, which occurred at 2-5 ng/g among sites. PCB congener patterns in the Lake Erie water snakes were compared to PCB patterns in plasma of common snapping turtle (Chelydra serpentina serpentina) from Lake Ontario, herring gull eggs (Larus argentatus) from western Lake Erie, and mudpuppy eggs (Necturus maculosus) from the Detroit River. The PCB patterns in water snake and herring gull sample were most similar, followed by the pattern in snapping turtle plasma. The presence of more lower-chlorinated chlorobiphenyls in the mudpuppy eggs relative to the other species made this sample distinct from the water snake, gull, and turtle.

Nitrogen pollution: an assessment of its threat to amphibian survival.

The potential for nitrate to affect amphibian survival was evaluated by examining the areas in North America where concentrations of nitrate in water occur above amphibian toxicity thresholds. Nitrogen pollution from anthropogenic sources enters bodies of water through agricultural runoff or percolation associated with nitrogen fertilization, livestock, precipitation, and effluents from industrial and human wastes. Environmental concentrations of nitrate in watersheds throughout North America range from < 1 to > 100 mg/L. Of the 8,545 water quality samples collected from states and provinces bordering the Great Lakes, 19.8% contained nitrate concentrations exceeding those which can cause sublethal effects in amphibians. In the laboratory lethal and sublethal effects in amphibians are detected at nitrate concentrations between 2.5 and 100 mg/L. Furthermore, amphibian prey such as insects and predators of amphibians such as fish are also sensitive to these elevated levels of nitrate. From this we conclude that nitrate concentrations in some watersheds in North America are high enough to cause death and developmental anomalies in amphibians and impact other animals in aquatic ecosystems. In some situations, the use of vegetated buffer strips adjacent to water courses can reduce nitrogen contamination of surface waters. Ultimately, there is a need to reduce runoff, sewage effluent discharge, and the use of fertilizers, and to establish and enforce water quality guidelines for nitrate for the protection of aquatic organisms.

Etiology of summer diarrhea among the Navajo.

The etiology of diarrhea in children and adults on the Navajo Indian Reservation was investigated in August 1975. Fifty-six ill individuals and 37 controls were included in the study. Shigella was most commonly associated with diarrhea, and was isolated from 32% of ill children and adults. Fifty percent of Shigella isolates tested were resistant to ampicillin. Heat-stable enterotoxin-(ST)-producing organisms were associated with noninflammatory diarrhea in adults (27% of these cases had ST-producing strains) but not in children. Heat-labile enterotoxin-producing organisms were found among controls as well as individuals with diarrhea. No children had evidence of rotavirus infection. These findings suggest that ST-producing organisms are important causes of sporadic cases of noninflammatory summer diarrhea among Navajo adults and confirm the importance of Shigella in inflammatory diarrhea among adults and children in this setting.

Value of examination for fecal leukocytes in the early diagnosis of shigellosis.

Fecal specimens from 101 patients with diarrhea were cultured and also examined with methylene blue for leukocytes. Thirty-six patients had leukocytes in their stools and 29 had culture-proven shigellosis. The sensitivity of fecal leukocytes in shigellosis was 95% (19/20) when cup specimens were obtained, and 44% (4/9) when swab or diaper specimens were examined. Only 45% of the patients with shigellosis who provided cup specimens had grossly bloody dysentery. Twelve other patients had fecal leukocytes but no demonstrable invasive bacterial pathogens. Methylene blue examination was useful in identifying motile trophozoites of Giardia lamblia and eggs or larvae of other heavy intestinal paraistic infections. Among patients with naturally-acquired acute diarrhea, methylene blue examination of stools for leukocytes is much more sensitive than examination for blood in predicting a positive culture for Shigella spp. It is also of value in detecting parasites.