Figure 8 Diagrammatic representation of anaerobic filter process from

Anaerobic Filter
Figure 9 Diagrammatic representation of fluidized and expanded bed reactor process (from Ref. 77).

Anaerobic Technologies Suppliers and Anaerobic Plants in the Pulp and Paper Industry. Table 13 shows the major suppliers of full-scale anaerobic treatment plants for industrial wastewater and the corresponding technologies. It may be noted from this table that a significant number of installations for pulp and paper mill wastewater treatment are performed by Paques BV, The Netherlands, and Bioethane Systems International, Canada. In total, 89 installations were performed in the year 1998, of which 69 UASB, 15 anaerobic contact, and 3 fluidized bed reactors were chosen [6]. Table 14 summarizes the performance of selected fullscale applications of anaerobic technologies in the pulp and paper industry. The UASB reactor configuration is distinctively the best choice, followed by the anaerobic contact process. There are limited applications of the other anaerobic reactor configurations such as fluidized bed and anaerobic filter. Agro-pulping black liquors have a high content of nonbiodegradable lignin that contributes to 50% of the COD; subsequently, there is a need to develop viable solutions to handle such wastewaters.

Thermophilic Anaerobic Reactor Applications. Pulp and paper industries typically discharge warm (50°C) effluents, and conventional reactors operating under mesophilic conditions require cooling of such wastewaters. Attempts have been made periodically by various groups to investigate the possibility of applying thermophilic anaerobic processes to pulp and paper discharges, but to date there is no conclusive evidence to prove the superior performances of thermophilic reactors as compared to their mesophilic counterparts.

Lepisto and Rintala [87] used four different types of thermophilic (55°C) anaerobic processes, namely an upflow anaerobic sludge blanket (UASB) digester, UASB enriched with sulfate, UASB with recirculation, and fixed-bed digester with recirculation for investigating the

Table 13 Commercial Suppliers of Full-Scale Anaerobic Treatment Plants for Industrial Wastewaters

Process Technology supplier/Trade name. Number of plants: pulp and configuration__paper/total number of industries_

Table 13 Commercial Suppliers of Full-Scale Anaerobic Treatment Plants for Industrial Wastewaters

Process Technology supplier/Trade name. Number of plants: pulp and configuration__paper/total number of industries_

UASB

ADIa

Biothaneb Biothane UASB 17/189

Degremontc Anapulse 3/44

Paquesd Biopaq 49/266

Purace

Contact process

ADI-BVF 1/67

Biobulk 0/4

Analift 1/22

-

Anamet 13/63

IC reactor

-

-

-

Biopaq-IC 1/40

Anaerobic filter

-

-

Anafiz 1/8

-

-

Fluidized bed

-

-

Anaflux 3/13

-

-

reactor

aADI Systems Inc., USA; bBiothane Systems International, Canada; cDegremont, France; dPaques BV, The Netherlands; ePurac AB, Sweden. Courtesy of UNDP India website, Ref. 6.

aADI Systems Inc., USA; bBiothane Systems International, Canada; cDegremont, France; dPaques BV, The Netherlands; ePurac AB, Sweden. Courtesy of UNDP India website, Ref. 6.

removal of chlorinated phenolics from soft wood bleaching effluents. All four processes eliminated/reduced chlorinated phenols, catechols, guiacols, and hydroquinones from bleach mill effluents. The ranges of COD and AOX removal were 30-70% and 25-41%, respectively, in the four reactors. Jahren et al. [88] treated TMP whitewaters using three different types of thermophilic anaerobic reactor configurations. The anaerobic hybrid reactor consisted of a UASB and a filter that degraded 10 kg COD/m3/day. The anaerobic multistage reactor, composed of granular sludge and carrier elements, gave a degradation rate of 9 kg COD/m3/day at loading rates of 15-16 kg COD/m3/day and HRT of 2.6 hours. The anaerobic moving bed biofilm digester handled loading rates of up to 1.4 kg COD/m3/day.

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