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PubMed2006

Characterization and assessment of Al Ruwais refinery wastewater.

An extensive bulk parameters and component-based analysis was carried out for Al Ruwais refinery wastewater during the period of June 2002-June 2003. The program included identification of major process and utilities wastewater streams and quantification of these streams relative to the total wastewater generated from all refinery processes. In addition to the high biochemical oxygen demand (BOD) and chemical oxygen demand (COD) reported levels, the analysis showed high concentrations of polyaromatic hydrocarbons (PAHs) and phenolic compounds in the major wastewater streams. Polychlorinated biphenyls (PCBs) were also detected in few streams. The caustic water was found to have the highest levels of the pollutants mentioned above. Dilution of the wastewater with process cooling water serves as the main treatment approach applied to the effluent wastewater before disposal into the sea. Primary as well as secondary treatment units are thought to be essential and strongly recommended to reduce the pollutants to levels below the United Arab Emirates (UAE) standards for marine discharge.

Environmental Pollutants↗
PubMed2006

Root canal irrigants.

Local wound debridement in the diseased pulp space is the main step in root canal treatment to prevent the tooth from being a source of infection. In this review article, the specifics of the pulpal microenvironment and the resulting requirements for irrigating solutions are spelled out. Sodium hypochlorite solutions are recommended as the main irrigants. This is because of their broad antimicrobial spectrum as well as their unique capacity to dissolve necrotic tissue remnants. Chemical and toxicological concerns related to their use are discussed, including different approaches to enhance local efficacy without increasing the caustic potential. In addition, chelating solutions are recommended as adjunct irrigants to prevent the formation of a smear layer and/or remove it before filling the root canal system. Based on the actions and interactions of currently available solutions, a clinical irrigating regimen is proposed. Furthermore, some technical aspects of irrigating the root canal system are discussed, and recent trends are critically inspected.

Anti-Infective Agents, Local↗
PubMed2003

Endoscopic balloon dilatation of esophageal strictures in infants and children: 17 years' experience and a literature review.

PURPOSE: Whereas endoscopic balloon dilatation (EBD) of benign esophageal strictures is an established mode of therapy in adults, this has not been accepted universally in the pediatric population. The aim of this study is to report the safety, efficacy, and long-term results of EBD for children in the authors' center. METHODS: Between 1986 and 2002, a total of 77 children (median age, 1.8 years; range, 2 months to 20 years) were treated by EBD for various causes: 2 had achalasia, and 75 had esophageal strictures (postesophageal atresia repair, 63; reflux esophagitis, 7; postfundoplication, 2; caustic injury, 3). Dilatations were performed using flexible endoscopy and fluoroscopic screening under general anesthesia. RESULTS: A total of 260 dilatations were carried out with the mean number of EBD per patient being 3.4 (range, 1 to 19). A mean period of 5 months (maximum, 28 months) for each patient was required. Four complications of esophageal perforations (1.5%) were observed, but only one required surgical repair because of persistent leakage. The remaining patients have undergone long-term follow-up (median follow-up, 6.6 years), and all are asymptomatic. CONCLUSIONS: This large series has shown that EBD can provide a safe and effective mean of relieving esophageal strictures with good long-term results.

Adolescent↗
PubMed2005

Reflux in esophageal atresia, tracheoesophageal cleft, and esophagocoloplasty: Bianchi's procedure as an alternative approach.

PURPOSE: Fundoplication has been used successfully to treat gastroesophageal reflux (GER) in the pediatric population. Although successful in many patients, there is a significant risk of complications and failure, especially in high-risk patients such as those with certain types of associated anomalies, diffuse motility disorders, chronic pulmonary disease, neurological impairment, and young infants. However, the results are poorer with children with severe pathologic lesion associated to reflux: tracheoesophageal cleft, esophagocoloplasty, and esophageal atresia (EA) with severe dysmotricity. In neurologically impaired children with neuromuscular incoordination and GER, Bianchi has proposed total esophagogastric dissociation (TED). The authors report the use of esophagogastric or esocologastric dissociation to control reflux in children with severe GER in other situations, such as EA, burn esophageal lesions having led to coloplasty and severe esotracheal cleft. METHODS: The authors reviewed the patients operated on for an esogastric or cologastric disconnection between 1997 and 2002. It is a single center retrospective study. The initial diagnosis, previous surgical procedure, postoperative course, and follow-up results were studied. RESULTS: Between September 1999 and June 2003, 13 TEDs were performed in 6 boys and 7 girls. The mean age for TED procedure was 35 months (range 14 days to 218 months). Indication for TED was severe persistent reflux in, respectively, 9 cases of EA (7 with coloplasty and 2 with preservation of the native esophagus after atresia repair, associated in 1 case with an esotracheal cleft), 2 cases of esotracheal cleft type III, and 2 cases of esophagocoloplasty for caustic burns. Six patients had undergone previous fundoplications (1-4 procedures) that failed, whereas the remaining patients underwent TED as the primary antireflux procedure. The average follow-up was 26 months (range 1 month to 4 years). There were no complication during the immediate postoperative course. Three children died at 3, 4, and 12 months after the procedure from acute respiratory failure. Respiratory status was improved in 8 children, and recurrent bronchitis was noted in 1 child. Regarding the digestive status, gastrostomy was closed at 18 and 24 months in 2 children, and partial nocturnal enteral nutrition (200 to 900 mL/d) through the gastrostomy remains necessary in the other children. CONCLUSION: Total esophagogastric dissociation procedure improves the respiratory consequences of severe GER, particularly in children for whom other surgical treatments have failed. The long-term safety of this operation remains to be determined especially regarding the consequences of a gastrointestinal Roux-en-Y loop procedure.

Adolescent↗
PubMed2005

Ethanol induction of complete heart block in swine.

OBJECTIVES: A method for the induction of complete heart block (CHB) by ethanol injection and its success rate in a pig model of acute right ventricular failure is reported. Additionally, a review of the literature for the induction of CHB in laboratory animals is detailed. The literature review was undertaken to both compare our rate of success with other methods and provide insight into our technique and refine its implementation. BACKGROUND: Animal models of CHB have facilitated the understanding of therapeutics for various cardiac pathologies in humans. In our laboratory, CHB in pigs is used for complete control of heart rhythm in studies of biventricular pacing. MATERIALS AND METHODS: Experiments carried out on pigs in our laboratory that required the induction of CHB were reviewed retrospectively. In addition, review of the literature for creating CHB in animals was undertaken. Our success rate was compared to that of other groups. RESULTS: Our success rate (93%) is similar to other models of CHB, in general, and to those models that used the injection of caustic substances with thoracotomy. CONCLUSIONS: Review of the literature indicates that our success rate is comparable to other groups and that, although many approaches have been described in both open- and closed-chest models, success is likely dependent on the practice and skill of the experimenter. In addition, review of the literature has afforded us new perspectives on the experimental induction of CHB.

Animals↗
PubMed2004

Characterization and availability of cyanide in solid mine tailings from gold extraction plants.

The aim of this study was to investigate the availability and fate of cyanide in gold mill solid tailings. For this purpose, aged (6-9 years) and recently discharged (3 months) tailings were sampled at various depths from two gold mining sites in Quebec (Canada). A physicochemical characterization of the tailings along with a bacterial enumeration was performed and batch-leaching tests with water and caustic solution were conducted to assess the soluble cyanide fraction. Following the standard acid reflux/distillation method, the total cyanide concentration (CN(T)) in fresh tailings was higher (average of 19.5 +/- 2.0 compared to 3.2 +/- 0.7 mg/kg) and the pH more alkaline (10.6 +/- 0.1 compared to 7.6 +/- 0.2) compared to aged ones. In aged tailings, the enumeration of total heterotrophic (10(4)-10(6) cfu/g) and cyanide-resistant bacteria (10(2)-10(5) cfu/g) showed a significant indigenous microflora, but no growth on agar plates was detected in fresh tailings, suggesting an evolution and a gradual acclimatization of bacterial populations with weathering. Elevated concentrations of CN(T), weak acid dissociable cyanide (CN(WAD)), cyanate (CNO-), and thiocyanate (SCN-) were measured in the supernatant solution of the fresh tailings samples collected in-situ, highlighting their reactivity, whereas these species were not detectable in aged tailings. Accordingly, when batch-leaching tests were performed with fresh samples, 68-72% of the total cyanide was released into aqueous solution with more than 20% being CN(WAD). Again, CN(T) and CN(WAD) were not detectable during leaching of aged tailings. In fresh tailings, approximately 50% of the cyanides were quantifiable with the standard acid reflux/distillation method (readily soluble cyanides, and weak to moderately strong complexes), whereas in aged tailings only 15 to 33% of the actual total cyanide content was measured by the standard method. These results stress the necessity of performing a preliminary alkaline extraction prior to total cyanide determination. In summary, this study revealed a difference in physicochemical properties, cyanide concentration and speciation, viable bacterial populations and cyanide leaching behavior between aged and fresh solid mine tailings. The findings indicate that the more reactive cyanide species initially associated with the solid tailings have naturally degraded within the mine tailings impoundment area, resulting primarily from volatilization (decrease in pH), leaching, and bacterial degradation.

Bacteria↗
PubMed2005

Microbially mediated phosphine emission.

There is still a lot of controversy in literature concerning the question whether a biochemical system exists enabling micro-organisms to reduce phosphate to phosphine gas. The search for so-called 'de novo synthesised' phosphine is complicated by the fact that soils, slurries, sludges, etc., which are often used as inocula, usually contain matrix bound phosphine (MBP). Matrix bound phosphine is a general term used to indicate non-gaseous reduced phosphorus compounds that are transformed into phosphine gas upon reaction with bases or acids. A study was carried out to compare the different digestion methods, used to transform matrix bound phosphine into phosphine gas. It was demonstrated that caustic and acidic digestion methods should be used to measure the matrix bound phosphine of the inoculum prior to inoculation to avoid false positive results concerning de novo synthesis. This is especially true if anthropogenically influenced inocula possibly containing minute steel or aluminium particles are used. The comparative study on different digestion methods also revealed that the fraction of phosphorus in mild steel, converted to phosphine during acid corrosion depended on the temperature. Following these preliminary studies, anaerobic growth experiments were set up using different inocula and media to study the emission of phosphine gas. Phosphine was detected in the headspace gases and its quantity and timeframe of emission depended on the medium composition, suggesting microbially mediated formation of the gas. The amount of phosphine emitted during the growth experiments never exceeded the bound phosphine present in inocula, prior to inoculation. Hence, de novo synthesis of phosphine from phosphate could not be demonstrated. Yet, microbially mediated conversion to phosphine of hitherto unknown reduced phosphorus compounds in the inoculum was evidenced.

Bacteria, Anaerobic↗
PubMed2006

A case study of waste management at the Northern Finnish pulp and paper mill complex of Stora Enso Veitsiluoto Mills.

This work presents the current waste management system at the pulp and paper mill complex of Stora Enso Oyj Veitsiluoto Mills at Kemi, Northern Finland. This paper covers examples of case studies carried out at the mill and describes how the wastes and by-products are utilized as a neutralizing agent for acidic wastewaters (i.e., green liquor dregs from the causticizing process), as a hardener in filling mine cavities (i.e., ash from the fluidized bed boiler), as a landscaping agent (i.e., ash as well as the fibre clay from chemical wastewater treatment plant), as a hydraulic barrier material for landfills (i.e., fibre clay), and as a soil enrichment agent (i.e., calcium carbonate from the precipitated calcium carbonate plant). In addition, the wood waste from the wood-handling plant, sawmill, packaging pallet plant and from the groundwood mill, as well as the biosludge from the biological wastewater treatment plant, are all incinerated in the fluidized bed boiler for energy production. Due to effective utilization of the solid wastes generated at the mills, the annual amount of waste to be disposed of in the landfill has decreased between 1994 and 2004 from 42,990 to 6083 tonn (expressed as wet weight). The paper also gives an overview of the relevant European Union legislation on the forest industry and on waste management, as well as of the pulping process and of the generation of major solid wastes in the pulp and paper mills.

Finland↗
PubMed2004

Toxicity to Daphnia magna and Vibrio fischeri of Kraft bleach plant effluents treated by catalytic wet-air oxidation.

Two Kraft-pulp bleaching effluents from a sequence of treatments which include chlorine dioxide and caustic soda were treated by catalytic wet-air oxidation (CWAO) at T=463 K in trickle-bed and batch-recycle reactors packed with either TiO2 extrudates or Ru(3 wt%)/TiO2 catalyst. Chemical analyses (TOC removal, color, HPLC) and bioassays (48-h and 30-min acute toxicity tests using Daphnia magna and Vibrio fischeri, respectively) were used to get information about the toxicity impact of the starting effluents and of the treated solutions. Under the operating conditions, complex organic compounds are mostly oxidized into carbon dioxide and water, along with short-chain carboxylic acids. Bioassays were found as a complement to chemical analyses for ensuring the toxicological impact on the ecosystem. In spite of a large decrease of TOC, the solutions of end products were all more toxic to Daphnia magna than the starting effluents by factors ranging from 2 to 33. This observation is attributed to the synergistic effects of acetic acid and salts present in the solutions. On the other hand, toxicity reduction with respect to Vibrio fischeri was achieved: detoxification factors greater than unity were measured for end-product solutions treated in the presence of the Ru(3 wt%)/TiO2 catalyst, suggesting the absence of cumulative effect for this bacteria, or a lower sensitivity to the organic acids and salts. Bleach plant effluents treated by the CWAO process over the Ru/TiO2 catalyst were completely biodegradable.

Animals↗
PubMed2005

Synthesis of ettringite: a way to deal with the acid wastewaters of aluminium anodising industry.

Synthesis of ettringite from acid wastewaters of the aluminium anodising industry has been studied as a possible route of reducing the emissions to the environment, recovering at the same time resource materials as a useful marketable mineral. Wastewaters of different concentrations have been subjected to the process of synthesis suspending calcium oxide and calcium aluminate powders at different time and pH conditions. High caustic alkalinity (pH approximately 12) and low sulphate concentrations (<0.1 M) are the most suitable conditions to synthesise ettringite. The mineral characterisation has been performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA), proving the high purity of the pursued solid product when hydrated in the appropriate sodium hydroxide concentrations. In such conditions, around 90% of the aluminium initially present in the wastewater solutions is recovered in the form of ettringite.

Aluminum↗
PubMed2005

Well-head arsenic removal units in remote villages of Indian subcontinent: field results and performance evaluation.

Since 1997, over 135 well-head arsenic removal units have been installed in remote villages in the Indian state of West Bengal bordering Bangladesh. Every component of the arsenic removal treatment system including activated alumina sorbent is procured indigenously. Each unit serves approximately 200-300 households and contains about 100 L of activated alumina. No chemical addition, pH adjustment or electricity is required for operating these units. The arsenic concentration in the influent varies from around 100 microg/L to greater than 500 microg/L. In the treated water, arsenic concentration is consistently below 50 microg/L. The units are capable of removing both arsenites and arsenates from the contaminated groundwater for several months, often exceeding 10,000 bed volumes. In the top portion of the column, the dissolved iron present in ground water is oxidized by atmospheric oxygen into hydrated Fe(III) oxides or HFO particles which in turn selectively bind both As(III) and As(V). Upon exhaustion, these units are regenerated by caustic soda solution followed by acid wash. The arsenic-laden spent regenerant is converted into a small volume sludge (less than 500 g) and contained over a coarse sand filter in the same premise requiring no disposal. Many units have been operating for several years without any significant operational difficulty. The treated water is used for drinking and cooking. Most importantly, the villagers are responsible for the day to day operation and the upkeep of the units.

Adsorption↗
PubMed2007

Reaction pathways and kinetics of butylated hydroxyanisole with UV, ozonation, and UV/O(3) processes.

The chemical degradation of the endocrine disrupting chemical, butylated hydroxyanisole (BHA), was investigated by different treatment processes including ultraviolet (UV) irradiation, ozonation (O(3)), and UV/O(3). O demethylation, dimerization, and oxidation have been found to be the main degradation mechanisms. A systematic decay pathway was proposed based on ten identified intermediates in the studied processes, including a unique pathway leading to the formation of precipitates in the ozonation process. An unconventional minimum-type variation of BHA decay rate constants from acidic to caustic range has been found for both ozonation and UV/O(3) processes. The precipitates formed during ozonation can be removed during the process to optimize the treatment, while the UV/O(3) process can offer a relatively fast and clean process to degrade BHA and its associated intermediates.

Antioxidants↗
PubMed1977

Transcervical tubal occlusion with a steerable hysteroscope: implantation of devices into extirpated human uteri.

A new steerable fiberoptic hysteroscope particularly useful in visualizing the tubal ostia has been evaluated in 61 extirpated uteri. The efficacy and safety of this hysteroscope were shown. The feasibility of deploying occlusive devices into the intramural portion of the tubes with the steerable hysteroscope was demonstrated. Whether these devices or modifications thereof will prove to be superior to other currently tested methods of occlusion, e.g., caustics, plastics, or cautery under in vivo conditions, remains to be established. The steerability of the hysteroscope has advantage irrespective of the method to achieve transcervical tubal occlusion as it allows coaxial alignment of the delivery.

Adult↗
PubMed2000

Epithelial ingrowth after laser in situ keratomileusis.

PURPOSE: To report the incidence and risk factors for clinically significant epithelial ingrowth after laser in situ keratomileusis as well as the recurrence rate and visual outcomes after its treatment. METHODS: We defined clinically significant epithelial ingrowth as that which required surgical removal. From a cohort of 3, 786 eyes that underwent primary laser in situ keratomileusis from February 1996 to August 1998 and its derivative of 480 eyes that later underwent enhancement laser in situ keratomileusis by one surgeon (R.K.M.), we identified all eyes with clinically significant epithelial ingrowth. RESULTS: The incidence of significant epithelial ingrowth after primary treatment was 35 (0.92%) of 3,786 eyes. The incidence after enhancement treatment was eight (1.7%) of 480 eyes (p = NS). Fourteen of 43 eyes had a postoperative epithelial defect associated with subsequent development of epithelial ingrowth. Six of 43 eyes had loose epithelium intraoperatively, suggesting epithelial basement membrane dystrophy. Epithelial ingrowth was treated by lifting the flap, scraping the bed and the posterior surface of the flap, and replacing the flap without the use of caustic agents. In 42 of 43 eyes, the epithelial ingrowth under the flap was continuous with the surface epithelium. Clinically significant ingrowth recurred in 10 of 43 eyes after the initial surgical removal. CONCLUSIONS: Clinically significant epithelial ingrowth is an infrequent complication of laser in situ keratomileusis. We hypothesize that epithelial ingrowth is secondary to postoperative invasion under the flap by surface epithelial cells rather than intraoperative implantation of epithelial cells. Treatment should consist of complete mechanical removal of epithelium from the posterior surface of the corneal flap and keratectomy bed and ensuring tight apposition of the flap with the bed.

Corneal Diseases↗
PubMed2004

Descemet membrane detachment with hemorrhage after alkali burn to the cornea.

PURPOSE: To report two cases of Descemet membrane detachment associated with hemorrhage after alkali burn to the cornea. DESIGN: Observational case reports. METHODS: We describe two patients with detachment of Descemet membrane associated with hemorrhage after alkali burns to the cornea. RESULTS: Patient 1 received a splash of caustic soda to the face. Descemet membrane detachment with hemorrhage was present. An attempt at reattachment using intraocular gases failed. Patient 2 sustained a chemical burn secondary to an airbag injury. A thickened, detached Descemet membrane associated with a hyphema was evident. CONCLUSIONS: Detachments of Descemet membrane associated with alkali burns are often accompanied by irreversible endothelial cell damage.

Burns, Chemical↗
PubMed1985

Late sequelae of gastric acid injury.

The late sequelae of gastric acid injury follow a predictable pattern and often require operative correction. Pyloric and antral stenoses are the most commonly cited late complications of acid ingestion. Other late sequelae include intractable pain, achlorhydria, protein-losing gastroenteropathy, duodenal atonicity, radiographic abnormalities, mucosal metaplasia, and gastric carcinoma. Resection of the injured gastric segment appears to provide the most favorable long-term result. Diligent patient follow-up is required to ensure adequate restoration of gastrointestinal function and to correct late-appearing complications. The distinction between the expected sites of gastrointestinal injury in acid versus alkali ingestion has become less clear with the recent introduction of readily available concentrated liquid household alkaline products, and the incidence of late gastric sequelae of caustic injuries has increased accordingly.

Adult↗
PubMed2003

Challenges in reversing esophageal discontinuity operations.

BACKGROUND: After catastrophic esophageal or gastric disruption results in esophageal discontinuity, operations to restore swallowing are surgical challenges. METHODS: A retrospective review and assessment of functional results was performed in 40 patients (average age 59.9 years) who had 42 operations to reverse esophageal discontinuity between 1973 and 2002. RESULTS: Esophageal discontinuity resulted from gastric necrosis after esophagectomy and esophagogastrostomy (n = 10) or hiatal hernia repair (n = 4), esophageal perforation complicating dilatation (n = 5), failed colonic or jejunal interpositions (n = 5), caustic ingestion (n = 4), Boerhaave syndrome (n = 4), esophagogastric anastomotic leak (n = 3), and other causes (n = 6). Eighteen patients (43.9%) required prolonged mechanical ventilation. Thirty-one (75.6%) had an end cervical esophagostomy; 6, an anterior thoracic esophagostomy; 2, lateral esophagostomy and in situ native esophagus stapled and divided distally; and 1 each, a stapled, divided esophagus without esophagostomy and a stapled undivided esophagus without esophagostomy. Twenty-six patients (63.4%) had undergone partial or total gastrectomy. Ten (24.4%) had vocal cord paralysis. Operations reestablishing continuity included colonic interposition in 23 (56.1%), substernal gastric interposition in 7 (17.1%), esophagectomy and cervical anastomosis in 6, esophageal reanastomosis in 3, staged jejunal interposition in 1, and Roux-en-Y esophagojejunostomy in 1. There were no hospital deaths. Twenty-eight patients (68.3%) had postoperative complications. Length of stay averaged 20.6 days. Follow-up for 40 patients averaged 54.5 months. Functional results (39 patients) were excellent in 12 (30.8%), good in 15 (38.5%), fair in 10 (25.6%), and poor in 2 (5.1%). CONCLUSIONS: Successful reversal of esophageal discontinuity requires individualized assessment and ingenuity. Despite appreciable morbidity, the ultimate result is generally gratifying.

Adult↗
PubMed1983

Esophageal replacement with colon in children: functional results and long-term growth.

Twenty-three children consecutively undergoing colon interposition for esophageal replacement were evaluated with barium swallows, clinical interviews, and questionnaires. Fourteen patients underwent colon interposition because of caustic burns of the esophagus only or of the hypopharynx and esophagus. Nine children had long-segment esophageal atresia or esophageal atresia with tracheoesophageal fistula and are included in our operative group. The mean follow-up was 12.8 years for all patients. Strictures, leaks, and colon ischemia at the proximal anastomosis represent the major morbidity for the operative procedure. Analysis of growth charts reveals that patients who ingest lye tend to remain in the 50th percentile after colon transplant, while patients with esophageal atresia or tracheoesophageal fistula who had been in the 12th percentile preoperatively improved to the 33rd percentile after successful transplantation. Radiographic examinations, functional results, and growth curves demonstrated excellent results in 20 patients. Although the choice of a conduit for esophageal replacement is controversial, the surgeon can expect good long-term function and growth with the use of colon in children.

Burns, Chemical↗