Effluent extraction pipes

Clarified water is removed by effluent extraction pipes that are attached to the moving center section. The clarified water that normally contains <30 mg/L of suspended solids can be recycled in the process and/or sewered. 

FIGURE 27.6 Spiral scoop (top) and effluent extraction pipes. 

In the case of low temperature tar, the aqueous Hquor that accompanies the cmde tar contains between 1 and 1.5% by weight of soluble tar acids, eg, phenol, cresols, and dihydroxybenzenes. Both for the sake of economics and effluent purification, it is necessary to recover these, usually by the Lurgi Phenosolvan process based on the selective extraction of the tar acids with butyl or isobutyl acetate. The recovered phenols are separated by fractional distillation into monohydroxybenzenes, mainly phenol and cresols, and dihydroxybenzenes, mainly (9-dihydroxybenzene (catechol), methyl (9-dihydtoxybenzene, (methyl catechol), and y -dihydroxybenzene (resorcinol). The monohydric phenol fraction is added to the cmde tar acids extracted from the tar for further refining, whereas the dihydric phenol fraction is incorporated in wood-preservation creosote or sold to adhesive manufacturers. Naphthalene Oils. Naphthalene is the principal component of coke-oven tats and the only component that can be concentrated to a reasonably high content on primary distillation. Naphthalene oils from coke-oven tars distilled in a modem pipe stiU generally contain 60—65% of naphthalene. They are further upgraded by a number of methods. 

End-of pipe effluent source. Effluent samples were taken from the El (first extraction stage) sewer of the bleach plant while the mill was processing Pinus radiata. Samples were stored at 4 °C. Treatment trials were carried out on filtered wastewater samples (25 mL) which had been adjusted to pH 11. The Fe-TAML catalyst (0.5 - 10 pM) was added simultaneously with H2O2 (2 - 30 mM) and stirred at 50 °C for a prescribed amount of time 30 - 300 minutes 34),... 

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