Effluent-free papermaking: industrial experiences and latest developments in the German paper industry.

Thanks to multiple recirculation of process water, the German paper industry has succeeded in decreasing the specific fresh water demand from an average of 50 m3/t thirty years ago to 13 m3/t today. Although the increasing closure of white water loops creates many problems, it is bound to be part of the German paper industry's ongoing development. For a few years, in the production of packaging paper, two paper mills have been running with a totally closed water system including different process water treatment plants as 'kidneys'. This paper presents a comprehensive survey of the pros and cons of closed process water systems followed by significant examples of effluent-free production of corrugating medium and test liner. Additionally, operation experiences and economic aspects are discussed.

Comparison of the endocrine effects of treated wastewaters from different paper mills by use of an in-vitro test with modified yeast cells.

As opposed to effluents from chemical pulp production, very little is known about the endocrine potential of papermaking effluents. To evaluate the endocrine potential of biologically treated effluents from the main grades produced in Germany (fine, graphic and packaging papers), 16 samples were studied by means of the Recombinant Yeast Estrogen Assay (R-YEA). 10 samples were tested positive; seven of them were effluents from recovered paper processing mills. Possible sources of endocrine disruptors in addition to wood components include papermaking chemicals, paper converting chemicals, if recovered paper is used, and/or detrimental substances introduced by impurities in these chemicals. Six of the above samples were subjected to individual substance analyses to detect endocrinologically active or potentially endocrinologically active substances. Even though phthalate compounds were detected in concentrations between 0.46 and 2.36 microg/L, only two of the six samples were tested positive in the R-YEA, because the test fails to adequately detect this compound's class. Despite this drawback, the R-YEA will be used for further studies because of the great variety of potential endocrine substances present in paper mill effluents. In particular, mechanical and recycled fibre pulps as well as the constituents of chemical additives must be investigated in more detail.

Participation of pterins in the control of lymphocyte stimulation and lymphoblast proliferation.

Biopterin accumulation had been demonstrated as the result of normal and, especially, of malignant hemopoietic cell proliferation (Ziegler, I. et al. Blut, 44: 231-240, and 261-270, 1982). Among 13 major intermediates of pterin metabolism and two lumazines, xanthopterin (but not dihydroxanthopterin) was found to inhibit cell proliferation (half-maximum inhibition at 1.8 X 10(-5) M) during concanavalin A-induced lymphocyte activation in pre-stimulated lymphocytes and in a lymphoid cell line grown in continuous culture (LS-2). LS-2 cells exposed to maximum inhibitor concentrations largely maintained the initial thymidine incorporation rate for about 40 hr but failed to enter logarithmic growth. Isoxanthopterin inhibition was found only in serum-free medium, since it is trapped by the alpha-acid glycoprotein present in the serum. The reduced biopterin derivatives, sepiapterin, dihydrobiopterin, and tetrahydrobiopterin, are costimulators during concanavalin A-induced lymphocyte activation. Their costimulatory effect follows an optimum curve and peaks at 1.5 to 3 X 10(-5) M. It is highest at the suboptimal and supraoptimal concanavalin A concentration. The D-erythro isomer dihydroneopterin was inactive. The results indicate that the anabolic-reduced biopterin derivatives are not simply lymphocytic products, but, in combination with the catabolites xanthopterin and isoxanthopterin, they also participate in the regulation of lymphocyte activation. Hence, they fulfill the criteria for lymphokines.

Radiation-induced cell killing is highly dependent upon buffer treatment (filtration compared to autoclaving) due to metal-catalyzed formation of hypochlorite: a cautionary note.

Buffer solutions used in experiments in radiation biology may be sterilized by either autoclaving or filtration. We show here that for phosphate-buffered saline such differences in buffer treatment may result in widely differing dose-effect curves for cell killing. The temperature-dependent transformation of monophosphate ions into di- or polyphosphate evidently proceeds to an appreciable extent upon autoclaving the buffers at 120 degrees C for 10 to 20 min. This increases the capability of the buffer to chelate spurious metal contaminations and, as a consequence, to reduce the amount of cytotoxic hypochlorite being produced. Depending on conditions of buffer treatment we have observed dose modification factors for the colony-forming ability of yeast cells up to the order of 3. Thus effects due to buffer treatment might easily outweigh the effect which the experiment was originally designed to determine. We strongly advise, therefore, that results of parallel sets of experiments in which different methods of buffer sterilization have been used should not be compared directly.

Mechanism of inhibition of cyclo-oxygenase in human blood platelets by carbamate insecticides.

Carbamates are a widely used class of insecticides and herbicides. They were tested for their ability to affect human blood platelet aggregation and arachidonic acid metabolism in platelets. (1) The herbicides of the carbamate type have no, or only little, influence up to a concentration of 100 microM; the carbamate insecticides, however, inhibit both aggregation and arachidonic acid metabolism in a dose- and time-dependent manner. (2) Carbaryl, the most effective compound, inhibits platelet aggregation and cyclo-oxygenase activity completely at 10 microM. The liberation of arachidonic acid from phospholipids and the lipoxygenase pathway are not affected, whereas the products of the cyclo-oxygenase pathway are drastically decreased. (3) By using [14C]carbaryl labelled in the carbamyl or in the ring moiety, it could be proved that the carbamyl residue binds covalently to platelet proteins. In contrast with acetylsalicylic acid, which acetylates only one protein, carbaryl carbamylates a multitude of platelet proteins. (4) One of the carbamylated proteins was found to be the platelet cyclo-oxygenase, indicating that carbaryl resembles in this respect acetylsalicylic acid, which is known to inhibit this enzyme specifically by acetylation.

Temperature sensitive events between photoreceptor and circadian clock?

The phase shifting action of low temperature pulses of 6 degrees C and 2 h duration administered to the various phases of the Drosophila pseudoobscura circadian rhythm and the action of light pulses given 30 min after the beginning of these low temperature pulses have been investigated. The phase response curve obtained from experiments with light pulses during low temperature cannot be explained on the basis of a straightforward and sequential phase shifting of the oscillation by the various transitions in the pulses. The response curve, after the slight phase shifting action of the temperature pulses is corrected for, resembles the standard phase response curve4 for light pulses (at 20 degrees C) in its wave form but not in its time course. Our curve is shifted in time in a manner that indicates that the light pulses accompanying the low temperature pulses arrived at phase points 1.5 h later than the actual phases at which they were given. We attribute this delay to a slowing down of the information that is apparently transmitted by a process that is temperature dependent.