The effects of nutrient limitation (nitrogen and phosphorus) on BOD removal from post-coagulated Pinus radiata sulfite pulp and paper mill wastewater in a baffled aerated stabilisation basin-laboratory pilot scale study.

The use of coagulation and flocculation for tertiary treatment of pulp and paper mill effluent was investigated, where the evaluation was based on the removal of nitrogen (N), phosphorus (P) and BOD from post-coagulated wastewater. The study was undertaken on laboratory scale aerobic stabilisation basins (ASB). Two post coagulated (alum) wastewaters were studied, where the BOD:N:P ratios were 100:1.3:0.06 and 100:1.3:0.3. These wastewaters were treated in two identical concurrent simulations (A & B). The influent ratio for 'A' was selected representing the composition of actual coagulated Pinus radiata sulfite pulp effluent mixed with paper mill effluent. The input composition for 'B' represented a typical P concentration found in existing pulp and paper mill effluents. Unmodified sludge collected from a mill-pond was added at 4% v/v to each simulation replicating the treatment conditions at full-scale. Similar high percentage removals of BOD and COD occurred after 28 days (two HRTs) which were 94 and 67% respectively for 'A', and 98 and 70% respectively for 'B', where both remained at steady state during the third HRT. A statistical analysis of the data revealed that there was no significant difference in the sample variance of the BOD and COD results.

The dissolution and microbial degradation of mobile aromatic hydrocarbons from a Pintsch gas tar DNAPL source zone.

Source zones containing tar, a dense non-aqueous phase liquid (DNAPL), can contaminate groundwater for centuries. A common occurrence of tar is at former Pintsch gas factories. Little is known about the composition and fate of contaminants dissolving from Pintsch gas tar DNAPL. In this study, we determined the composition and water-soluble characteristics of mobile aromatic hydrocarbons and their biodegradation metabolites in the DNAPL contaminated groundwater at a former Pintsch gas tar plant. We assessed the factors that determine the fate of observed groundwater contaminants. Measured values of density (1.03-1.06 kg/m3) and viscosity (18.6-39.4 cP) were found to be relatively low compared to common coal tars. Analysis showed that unlike common coal tars phenanthrene is the primary component rather than naphthalene. Moreover, it was found that Pintsch gas tar contains a relatively high amount of light molecular aromatic hydrocarbon compounds, such as benzene, toluene, ethylbenzene and xylenes (BTEX). Less commonly reported components, such as styrene, ethyltoluenes, di-ethylbenzene, 1,2,4,5-tetramethylbenzene, were also detected in water extracts from Pintsch gas tar. Moreover, 46 relatively hydrophilic metabolites were found within the tar samples. Metabolites present within the tar suggest biodegradation of mobile aromatic Pintsch gas tar compounds occurred near the DNAPL. Based on eleven detected suspect metabolites, a novel anaerobic biodegradation pathway is proposed for indene. Overall, our findings indicate that Pintsch gas tar has higher invasive and higher flux properties than most coal tars due to its relatively low density, low viscosity and, high content of water-soluble compounds. The partitioning of contaminants from multi-component DNAPL into the aqueous phase and re-dissolution of their slightly less hydrophobic metabolites back from the aqueous phase into the DNAPL is feasible and demonstrates the complexity of assessing degradation processes within a source zone.

Depletion of E. coli in permeable pavement mineral aggregate storage and reuse systems.

Permeable pavement reservoirs provide an important opportunity for the harvesting and storage of stormwater for reuse. This research aims to determine whether storage in dolomite, calcite and quartzite mineral aggregates in the base course of a permeable pavement impacts on the survival of the pathogen indicator organism Escherichia coli (E. coli) in storage. The reasons for depletion were also investigated. Twelve model permeable pavement storage reservoirs were filled, in triplicate, with dolomite, calcite and quartzite. Three reservoirs contained no aggregate. After filling with pathogen spiked rainwater, the concentration of E. coli was examined for 22 days in the reservoirs. The reservoirs were then agitated to determine if there was E. coli present which was not in aqueous suspension. The results of the experiments show that there is no significant difference in the depletion of E. coli found in reservoirs without aggregate, and those filled with dolomite or calcite. The rate of depletion was found to be significantly lower in the quartzite filled reservoirs. Agitation of the reservoirs yielded increases in the aqueous concentration of E. coli in all reservoir types, suggesting that the bacteria are adhering to the surface of the mineral aggregate and to the reservoir walls.

Associations between stomach cancer incidence and drinking water contamination with atrazine and nitrate in Ontario (Canada) agroecosystems, 1987-1991.

BACKGROUND: Nitrate and atrazine are two chemicals that are heavily used in certain sectors of agriculture. They are suspected to be associated with the development of certain types of tumours. METHODS: Existing data were obtained on the incidence of specific types of cancers, contamination of drinking water with atrazine and nitrate, and related agricultural practices for the 40 ecodistricts in the province of Ontario. The data were merged into a georelational database for geographical and statistical analyses. Weighted (by population size) least squares regression analyses were conducted while controlling for confounding socioeconomic and lifestyle factors. Maximum likelihood spatial error models were estimated when least square regression error terms were found to be spatially autocorrelated using the Moran's I statistic. RESULTS: Atrazine contamination levels (range 50-649 ng/l, maximum acceptable concentration [MAC] = 60000 ng/l) were positively associated (P < 0.05) with stomach cancer incidence and negatively associated with colon cancer incidence. Nitrate levels, (range 0-91 mg/l, MAC = 10 mg/l) were negatively associated with stomach cancer incidence. CONCLUSION: The associations found at the ecodistrict level, both positive and negative, if confirmed by other studies, raise serious questions about maximum allowable limits for atrazine, as well as possibilities of complex trade-offs among disease outcomes, and interactions of biophysical and social mechanisms which might explain them. Although the negative associations appear to have no direct biological explanations, such counter-intuitive outcomes may occur in complex systems where social and biological variables interact.

Gastropharyngeal and gastroesophageal reflux in globus and hoarseness.

BACKGROUND: The role of gastropharyngeal reflux in patients with globus pharyngeus and hoarseness remains unclear. OBJECTIVE: To evaluate patients with complaints of globus, hoarseness, or globus and hoarseness combined for the presence of gastropharyngeal and gastroesophageal reflux. DESIGN: Prospective clinical cohort study of 3 groups of patients undergoing ambulatory 24-hour double-probe pH monitoring. In patients with pathologic gastroesophageal reflux, an upper gastrointestinal endoscopy was also performed. SETTING: Tertiary care, outpatient clinic. PATIENTS: Twenty-seven patients with globus alone, 20 patients with hoarseness alone, and 25 patients with globus and hoarseness combined. RESULTS: Patients with well-defined pathologic reflux (ie, gastroesophageal reflux with or without gastropharyngeal reflux) were present mainly in the group of patients with globus combined with hoarseness: 18 (72%) of 25 patients, compared with 7 (35%) of 20 patients with hoarseness alone and 8 (30%) of 27 with globus alone. Seven (10%) of all 72 patients had prolonged acid exposure at the laryngopharyngeal junction in the presence of a normal gastroesophageal pH registration. Abnormal findings in the esophagus were found at endoscopy in 17 (65%) of 26 patients with pathologic gastroesophageal reflux (with or without gastropharyngeal reflux). CONCLUSIONS: We found a high prevalence of pathologic reflux in patients with both globus and hoarseness. Based on these findings, we strongly advise upper gastrointestinal endoscopy for symptomatic otolaryngological patients with pathologic gastroesophageal reflux.

Effect of alum treatment on the trihalomethane formation and bacterial regrowth potential of natural and synthetic waters.

Waters from five reservoirs and "synthetic waters", prepared using terrestrially derived dissolved organic matter (DOM) extracted from vegetation and reservoir catchment soils, were studied for their treatability with alum using a jar test procedure. DOM in drinking water is a precursor for the formation of trihalomethanes (THM) following chlorine disinfection and can also be a substrate for microbial growth in the drinking water distribution system. The trihalomethane formation potential (THMFP) represents an upper concentration limit on THMs formed by chlorination, while bacterial regrowth potential (BRP) is an indicator of the bioavailability of DOM. BRP and THMFP were measured before and after alum treatment and the results were related to the source of the DOM. It was found that freshly derived terrestrial DOM in synthetic water resulted in higher THMFP and BRP than DOM in reservoir waters. For the samples investigated, conventional alum treatment did not always reduce the THM precursor levels formed in laboratory tests below the NH&MRC (1996) guideline level of 250 microg/L nor produce microbially stable waters.

Effect of cigarette smoking on gastropharyngeal and gastroesophageal reflux.

Gastropharyngeal reflux appears to be associated with various otolaryngological complaints. Cigarette smoking is known to affect adversely the defense mechanisms against reflux of acid gastric contents into the esophagus. To study the relationship between gastropharyngeal, as well as gastroesophageal, reflux and cigarette smoking, 15 subjects underwent 24-hour double-probe pH monitoring while smoking their daily amount of cigarettes. The percentage of time the pH was below 4 during the smoking period was significantly higher than the percentage of time the pH was below 4 during the nonsmoking period, proximal, at the level of the upper esophageal sphincter, as well as distal, above the lower esophageal sphincter. These findings demonstrate that smoking increases gastropharyngeal and gastroesophageal reflux. Smokers with complaints and disorders caused by reflux should therefore be advised to stop smoking in order to reduce reflux.