Anaerobic Toxicity of Fines in Chemi-Thermomechanical Pulp Wastewaters: A Batch Assay-Reactor Study Comparison

Abstract

Toxicity of chemi-thermomechanical pulping (CTMP) wastewaters was tested in batch assays and in anaerobic sludge blanket reactors. In batch serum bottle tests particulate constituents were responsible for 80-90% of the inhibition of acetoclastic activity, and the soluble (fines-free) fraction accounted for 10-20%. Performance of two 2-stage anaerobic sludge blanket reactor systems was compared, one receiving fines-free (NF) and the other unaltered (F) CTMP waste for 140 days. Both reactors became acclimatized to CTMP and developed a tolerance to resin acid concentrations as high as 300-1500 mg·1−1 in the sludge bed. The fines-free reactor was superior throughout, but the differences in performance did not reflect the batch test results. At the organic loading rate of 17-22 g soluble COD.g VSS−1·d−1 NF treated 100% CTMP waste with 42% and F with 38% removal efficiency. Fines accumulation in the sludge bed of F reactor caused a 70% increase in bed volume, resulted in deterioration of sludge settleability, and led to an increased likelihood of biomass loss.

Anaerobic Digestion of Wastewaters from Pulp and Paper Mills : A Substantial Source for Biomethane Production in Sweden

“…Compared to AD processes of kraft bleaching wastewaters, more emphasis was given to biomethane production. However, the potential challenges in applying the AD process due to presence of wood resin, sulphuric compounds and residual bleaching chemicals (H2O2 and DTPA; Pichon et al, 1987;Pichon et al, 1988;Welander, 1989;Habets and de Vegt, 1991;Richardson et al, 1991) have been the main focus together with COD reduction.…”

“…removal of fibres Richardson et al 1991), removal of H2O2 (Welander, 1989;Habets and de Vegt, 1991) and detoxification by precipitation of presumably resin acids and LCFA; Welander (1989).…”

“…COD reductions for high-rate AD of CTMP wastewater range 30-60% (anaerobic fixed film/bed reactor, Pichon et al, 1987;Pichon et al, 1988;UASB, Welander, 1989;Richardson et al, 1991;Habets and de Vegt, 1991), with the lowest reduction for wastewaters from the production of unbleached pulp (Richardson et al, 1991). The corresponding biomethane production was varying in the range of 100-300 NmL g COD 1 reduced, with the lowest production for wastewaters rich in sulphuric compounds (Pichon et al (1987).…”

“…The corresponding biomethane production was varying in the range of 100-300 NmL g COD 1 reduced, with the lowest production for wastewaters rich in sulphuric compounds (Pichon et al (1987). Habets and de Vegt (1991) and Richardson et al (1991) concluded that a stable AD-process could be maintained when shifting between wastewater from the production of TMP and CTMP implying differences in OLR and wastewater composition. However, as for the kraft process there seem to be no studies addressing the possible impact of shifts between raw materials for the pulp production within TMP and CTMP mills.…”

Detoxification d un effluent de pate chimico-thermomecanique par voie anaerobie

“…Les mêmes remarques tiennent pour le traitement réalisé avec les boues de Lors des passages 2, 3, 4 et 6, l'acide déshydroabiétique n'est présent qu'au temps initial (figures 7A et 8). Ceci est surprenant, compte tenu de l'abondance des travaux rapportant la recalcitrance de cet acide lors de dégradations anaérobies (Bisaillon et al, 1991;McFarlane et Clark 1988;Richardson et al 1991;). …”