BIOLOGICAL AND CHEMICAL CHARACTERIZATION OF AN EFFLUENT FROM PRODUCTION OF DEINKED PULP AND TISSUE

The effluent from deinking of high-yield pulp-based newsprint and tiss ue production exhibited slight toxicity to bioluminescent bacteria, a green alga and fish. The toxicities are expressed in toxic units (TU) that are in the range of 1.1 to 2. These values are also applicable to chronic toxicity for fish and sublethal effects such as the sensitivi ty of offsprings from parent fish preexposed for the effluent. The org anic content of the effluent was biologically degradable to ca. 70% ba sed on COD and TOC. The biologically stabilised effluent was non-toxic to the organisms assayed. The residual organic matter of the stabilis ed effluent contained mostly fatty acids in concentrations comparable to those in the raw water used in production. The daily discharge of p otentially bioaccumulative organic matter from the production amounted to about 6.2 kg, while the river water from which the raw water is ta ken and which enters the same recipient as the effluent, transports ab out 1,700 kg per day.