Steady-state and transient-state performance of a biotrickling filter treating chlorobenzene-containing waste gas

Biotrickling filter (BTF) technology was applied for the treatment of waste gas containing a mixture of chlorobenzene and 1,2-dichlorobenzene. An adapted microbial community was immobilised on a structured packing material. The strategy followed was to reach high removal efficiencies at initially low mass loading rates followed by an increase of the latter. This procedure was successful and resulted in a short start-up period of only 2weeks. A 3-month operation under steady-state conditions showed good performance, with >95% removal efficiency at a mass loading rate of 1,800gm−3day−1. Dimensionless concentration profiles showed that the chlorobenzenes were simultaneously degraded. Low dissolved organic carbon of 15mgl−1 and stoichiometric chloride concentrations in the trickling liquid indicated complete mineralisation of the pollutant. Transient-state experiments with five times higher mass loading rates caused a decrease in the removal efficiency that recovered rapidly once the mass loading rate returned to its original steady-state level. A progressive increase of the mass loading rate in a long-term performance experiment showed that the removal efficiency could be kept stable between 95 and 99% at loads of up to 5,200gm−3day−1 over several days. Above this mass loading rate, the elimination capacity did not increase any further. These results demonstrated that with a well-adapted inoculum and optimal operation parameters, a BTF system with excellent performance and stability that efficiently removes a mixture of cholorobenzene vapours from air can be obtaine

A new rockfall hazard assessment methodology for open-pit coal mines

Rockfalls represent a serious hazard in open pit-mines, threatening human lives, machinery and portal structures located at the toe of highwalls. This hazard can have signiicant inancial consequences should the production be temporarily stopped for safety issues. Results from the ACARP C19026 rockfall netting project and field observations suggest that a more effective approach to rockfall hazard management is required for safe mining operations. In this paper, a new qualitative rockfall hazard procedure speciically designed for coal mining environments developed within the current ACARP project C23026 is presented. The methodology intends to be a simple and quick tool for identifying the most dangerous highwall sections. The use of this methodology provides practitioners with a more rigorous guidance on rockfall management strategies, and the industry with the ability to generate hazard zoning maps that can be updated on a regular basis. The methodology uses in situ observations (and records of past rockfall events when available) for the deinition of three hazard levels (i.e. low, medium and high) deined on the basis of the expected rockfall energy at the base of a highwall and the rockfall frequency, evaluated through the state of activity of the highwall. As a result, the sections with a high level of hazard, which require a further strict quantitative assessment, are quickly identiied. The methodology will provide greater conidence in locating personnel, machineries, and structures over the working areas at the toe of highwalls

Steady-state and transient-state performance of a biotrickling filter treating chlorobenzene-containing waste gas

Biotrickling filter (BTF) technology was applied for the treatment of waste gas containing a mixture of chlorobenzene and 1,2-dichlorobenzene. An adapted microbial community was immobilised on a structured packing material. The strategy followed was to reach high removal efficiencies at initially low mass loading rates followed by an increase of the latter. This procedure was successful and resulted in a short start-up period of only 2 weeks. A 3-month operation under steady-state conditions showed good performance, with >95% removal efficiency at a mass loading rate of 1,800 g m(-3) day(-1). Dimensionless concentration profiles showed that the chlorobenzenes were simultaneously degraded. Low dissolved organic carbon of 15 mg l(-1) and stoichiometric chloride concentrations in the trickling liquid indicated complete mineralisation of the pollutant. Transient-state experiments with five times higher mass loading rates caused a decrease in the removal efficiency that recovered rapidly once the mass loading rate returned to its original steady-state level. A progressive increase of the mass loading rate in a long-term performance experiment showed that the removal efficiency could be kept stable between 95 and 99% at loads of up to 5,200 g m(-3) day(-1) over several days. Above this mass loading rate, the elimination capacity did not increase any further. These results demonstrated that with a well-adapted inoculum and optimal operation parameters, a BTF system with excellent performance and stability that efficiently removes a mixture of cholorobenzene vapours from air can be obtained

Pneumatosis intestinalis versus pseudo-pneumatosis: review of CT findings and differentiation

Pneumatosis intestinalis is defined as the presence of gas within the wall of the gastrointestinal tract. Originally described on plain abdominal radiographs, it is an imaging sign rather than a specific diagnosis and it is associated with both benign and life-threatening clinical conditions. The most common life-threatening cause of pneumatosis intestinalis is bowel ischaemia. Computed tomography (CT) is usually requested to detect underlying disease. The presence of pneumatosis intestinalis often leads physicians to make a diagnosis of serious disease. However, an erroneous diagnosis of pneumatosis intestinalis may be made (i.e. pseudo-pneumatosis) when intraluminal beads of gas are trapped within or between faeces and adjacent mucosal folds. The purpose of this pictorial essay is to review and describe the CT imaging findings of pneumatosis and pseudo-pneumatosis intestinalis and to discuss key discriminatory imaging features

Long-term radiographic follow-up of the Nissen fundoplication in children

This study examined 46 children 5–9 years (mean 6.7) after Nissen fundoplication surgery for gastroesophageal reflux (GER). Eleven were deceased and ten of the 35 families declined objective evaluation. The remaining 25 children (71%) had a barium swallow examination. In 16 of the 25 patients the fundoplication was intact. In 2 patients a small portion of the fundoplication was displaced above the diaphragm. In 5 patients there was residual esophageal disease. In 3 patients (one with esophageal disease), with a hiatus hernia prior to surgery, despite immediate postoperative reduction, the barium swallow examination done for this study revealed recurrent hiatus hernia but no GER. Long-term results of the Nissen fundoplication reveal success in eliminating clinically significant gastroesophageal reflux. Those patients with esophageal disease prior to the surgery need close interval follow-up to monitor continuing problems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46689/1/247_2006_Article_BF02389563.pd

Local staging of rectal cancer: the current role of MRI

With the advent of powerful gradient coil systems and high-resolution surface coils, magnetic resonance imaging (MRI) has recently extended its role in the staging of rectal cancer. MRI is superior to endorectal ultrasound, the most widely used staging modality in patients with rectal tumors, in that it visualizes not only the intestinal wall but also the surrounding pelvic anatomy. The crucial advantage of MRI is not that it enables exact T-staging but precise evaluation of the topographic relationship of a tumor to the mesorectal fascia. This fascia is the most important anatomic landmark for the feasibility of total mesorectal excision, which has evolved into the standard operative procedure for the resection of cancer located in the middle or lower third of the rectum. MRI is currently the only imaging modality that is highly accurate in predicting whether or not it is likely that a tumor-free margin can be achieved and thus provides important information for planning of an effective therapeutic strategy, especially in patients with advanced rectal cancer