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The wastewaters generated from wood pulping and paper production processes are traditionally treated by biological and physicochemical processes. In order to reduce chemical oxygen demand (COD) and color to meet increasingly strict discharge standards, advanced oxidation processes (AOPs) are being adapted as polishing treatment units. Various ozone-based processes were used in this study to treat simulated wastewaters prepared from black liquor from a hardwood Kraft pulp mill in Taiwan. The experimental results showed that the COD and color were primarily removed by direct ozone oxidation and activated carbon adsorption. While the addition of activated carbon could enhance the COD and color removal during ozonation, the addition of hydrogen peroxide improved the color removal only. For the various ozone-based treatment processes, kinetic models were developed to satisfactorily predict the COD and color removal rates. According to the kinetic parameters obtained from the various ozone-based processes, the enhanced COD and color removal of ozonation in the presence of activated carbon was attributed to the regeneration of the activated carbon by ozonation. These kinetic models can be used for reactor design and process design to treat pulping wastewater using ozone-based processes.

Metaldehyde, a cyclic tetramer of acetaldehyde, is a widely used molluscicide. Although cases with acute metaldehyde poisoning have been reported, the occurrence of severe poisoning is uncommon. To provide more information on human metaldehyde poisoning, we reviewed 15 cases of metaldehyde exposure reported to the Taiwan National Poison Control Center at the Taipei Veterans General Hospital between 1991 and 2002. While 7 patients were asymptomatic, the other 8 patients, including 4 who coingested alcohol or other poisons, exhibited toxic manifestations of abdominal pain, dizziness, nausea, irritation of oral mucosa, and seizures after oral exposure. One patient died after ingesting 12 g (or 258.6 mg/kg) of metaldehyde. Although the toxicity from metaldehyde is largely mild, the clinical course of metaldehyde poisoning may be rapidly deteriorating and fatal on rare occasions. Physicians should therefore be cautious in managing patients with metaldehyde poisoning, and vigorous supportive measures should be promptly instituted in patients who manifest severe toxicity.