Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 319220
Title Mesophilic and thermophilic activated sludge post-treatment of paper mill process water
Author(s) Vogelaar, J.C.T.; Bouwhuis, E.; Klapwijk, A.; Spanjers, H.; Lier, J.B. van
Source Water Research 36 (2002). - ISSN 0043-1354 - p. 1869 - 1879.
Department(s) Sub-department of Environmental Technology
Publication type Refereed Article in a scientific journal
Publication year 2002
Abstract Increasing system closure in paper mills and higher process water temperatures make the applicability of thermophilic treatment systems increasingly important. The use of activated sludge as a suitable thermophilic post-treatment system for anaerobically pre-treated paper process water from a paper mill using recycled wastepaper was studied. Two lab-scale plug flow activated sludge reactors were run in parallel for 6 months; a thermophilic reactor at 55°C and a reference reactor at 30°C. Both reactors were operated simultaneously at 20, 15 and 10 days SRT. The effects of temperature and SRT on sludge settleability and chemical oxygen demand (COD) removal efficiencies of different fractions were studied. Total COD removal percentages over the whole experimental period were 58±5 t 30°C and 48±10 t 55°C. The effect of the SRT on the total COD removal was negligible. Differences in total COD removal between both systems were due to a lesser removal of soluble and colloidal COD at 55°C compared to the reference system. At 30°C, colloidal COD removal percentages were 65±25°75±17 nd 86±22 t 20, 15 and 10 days SRT, respectively. At 55°C, these percentages were 48±34°40±28 nd 70±25°respectively. The effluent concentrations of colloidal COD in both systems were related to the influent concentration of colloidal material. The thermophilic sludge was not able to retain influent colloidal material as well as the mesophilic sludge causing a higher thermophilic effluent turbidity. Sludge settling properties were excellent in both reactor systems. These were neither temperature nor SRT dependent but were rather caused by extensive calcium precipitation in the aeration tanks creating a very dense sludge. For application in the board industry, a thermophilic in line treatment system seems feasible. The higher effluent turbidity is most likely offset by the energy gains of treatment under thermophilic conditions.
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