Abstract:

Gas chromatography-mass spectrometry(GC-MS) was employed for the determination of organic pollutants in recirculating water of a paper-recycling industry. Origins of the detected organics and potential pollutions on the environment and human being were discussed. Their contents in water at different production stages were compared. Water samples were first pre-treated by liquid-liquid extraction using methyl tert-butylether(MTBE) with the presence of heptadecanoic acid(C17) as the internal standard. They were then treated by bis(trimethylsilyl)trifluoroacetamide(BSTFA) and trimethylchlorosilane(TMCS) in pyridine, followed by GC-MS analysis for the detection of respective trimethylsilyl esters formed at different stages. Using this approach, nearly 50 kinds of organic chemicals, such as resin acids, fatty acids, additives and their ramifications were detected in the processed water. And the resin acids were mainly existed in pulping water, which may come from secondary fibers and sizing agents. The fatty acids, aromatic acids and their derivatives, which may come from secondary fibers, impurities and additives, such as printing ink, plastic matters, surface active agents, were mainly existed in the white water and mixed water coming out of the mill. It was found that the mixed water contained most kinds of organic chemicals while the vacuum pumping water contained the least organic chemicals. The main chemicals contained in vacuum water were aromatic acids. There are large mounts of fatty acids, aromatic acids and theirs derivations in the wastewater of each papermaking processes, most of them are brought by the adding of secondary fiber and other additives. These organics are harmful to the environment, and difficult to be eliminated by sedimentation and flocculation. Therefore, in order to reduce the pollution of the organic pollutants in effluent wastewater, it is necessary to avoid adding phthalic acid and ester of phthalic acid. The addition of additives of long chain fatty acids and aromatic compound should be minimized in the papermaking processes.

Key words: secondary fibre, waste water from paper mill, organic pollutant, GC-MS