Initial Chemical Oxygen Demand Concentration Research Articles

Wet Air Oxidation of Toxic Industrial Effluents

The disposal of process wastewater from a wood carbonization factory was studied in a laboratory batch reactor. Chemical oxygen demand (COD) reduction of 92 - 96% was achieved for samples with initial COD concentrations of more than 100 g/l. The samples subjected to wet air oxidation showed no toxic effects in toxicology tests and were readily biodegradable. Effluent containing cyanide was also subjected to wet air oxidation, and a COD reduction of 75% and cyanide removal of 99.99997% was attained. The reaction rate and activation energy of cyanide hydrolysis were determined.

Aerobic biodegradation of organic matter of swine waste

Degradation of organic matter of swine waste is dependent on the metabolic activity of the indigenous microorganisms. Although the composition of the centrifuged wastes varied, a reduction of about 80% of the chemical oxygen demand (COD) was obtained in each case when incubated at 37°C and 250 rpm without pH control. However, the time required by the indigenous mesophilic microflora for such stabilization of the waste was a function of the initial COD concentration. The agitation speed influenced the rate of organic matter degradation, while pH control between 7 and 8 and lowering the temperature to 22°C had no effect. The inoculation of selected strains isolated from treated waste or activated sludge to swine waste did not accelerate the degradation of organic matter. An adapted strain of Chaetomium cellulolyticum when inoculated in stabilized waste, reduced by a factor of two the remaining COD after 4 days of incubation. Samples from different environments were inoculated in stabilized waste and after incubation of these cultures dominant bacterial strains were isolated. When inoculated in stabilized waste these strains reduced only slightly the remaining COD. Optimization of degradation of organic matter of swine waste supernatant is possible but appears to be limited by the presence of substances of low degradability.