Charged polymers can be used for a further intensification. This process reduces

The residual of recalcitrant compounds such as high molecular-weight degradation

Products of lignin. The resultant sludges may be rather difficult to dewater and

Are rich in inorganic material; thus, their combustion without additional fuel is

Difficult. The tertiary treatment is mainly used to remove excess nutrients such as

phosphorus [2], but it can also reduce higher levels of COD and AOX. In the Tasmanian

guidelines, the tertiary treatment is not considered to be AMT [3].

For the production of kraft pulp, the European Commission describes the BAT

For the discharge of water, with the emission data summarized in Tab. 10.2.

The biological degradation of the organic material – carbon – requires in addition

Trace elements and ammonia, as well as phosphate. These nutrients are typically

Not available in a suitable ratio in pulp mill effluents, and must be added.

Likewise, their levels must be controlled in order to avoid eutropic conditions in

The receiving waters.

Tab. 10.2 Best available technology (BAT) emission levels to the

aquatic environment for bleached kraft pulp [2].

Water flow

[m3 adt–1]

COD

[kg adt–1]

BOD

[kg adt–1]

TSS

[kg adt–1]

AOX

[kg adt–1]

Total N

[kg adt–1]

Total P

[kg adt–1]

30–50 8–23 0.3–1.5 0.6–1.5 <0.25 0.1–0.25 0.01–0.03

TSS = total suspended solids.

BOD5 = biological oxygen demand (5 days).

COD = chemical oxygen demand.

AOX = absorbable halogenated compounds.

Environmental Aspects of Pulp Production

The Tasmanian mill guidelines exclude any discharge of effluent to a river. It is

Obviously assumed that rapid dilution of the effluent with sea water reduces the

Environmental impact. This limits the potential sites for a pulp mill to the coastline.

The data listed in Tab. 10.3 show the comparability of the emission limits

With the values described by the European Commission.

Tab. 10.3 Selected emission limits to the marine environment

Described in 2004 for a potential pulp mill in Tasmania using

“accepted modern technology” (AMT) [3].

Parameter Unit Monthly average maximum Daily maximum

TSS kg adt–1 2.6 4.5

BOD5 kg adt–1 2.1 3.6

COD kg adt–1 20 34

AOX kg adt–1 0.2 0.4

In North America, effluent color is a parameter which must be monitored.

Color is more of aesthetic value than a parameter of toxicity. The presence of small

Amounts of humic acids represent a natural source for the brown color of water.

However, in the past black liquor spills and the extraction stage effluent following

A chlorination stage may have been responsible for the dark brown color of a pulp

mill’s effluent. Therefore, color still can be an effluent control parameter, and is

Analyzed in color units (CU) using different dilutions of a mixture of a platinum

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