Bleach effluents stage

Elforts have been made to characterize the nature and content of individual components that are present in the low-molecular-mass fraction of the total mill effluents, which include the spent chlorination and alkali extraction stage liquors [2,4]. Approximately 456 types of compounds have been detected in the conventional bleach effluents, of which 330 are chlorinated organic compounds [22]. The compounds may be lumped into three main groups, namely, acidic, phenolic, and neutral (Table 2). Acidic compounds are further divided into the five categories of acids fatty, resin, hydroxy, dibasic, and aromatic acids. The most important fatty acids are formic and acetic acids. The dominant resin acids are abietic and dehydroabietic acids. Among the hydroxy acids identified, glyceric acid predominates. Dibasic acids such as oxalic, malonic, succinic, and mafic acids are derived from the lignin and carbohydrate fraction... 

Ullrafiltration processes have proved successful for the treatment of effluents, the treatment of black liquor, bleaching effluents and paper machine wash waters. They have also found use in the treatment of Kraft process effluents and there is increasing use of ultrafiltration to recover lignosulphonate and alkali lignin from the spent Uquors to produce other products. Reverse osmosis is used in the pulp and paper industry for concentration of sulphate liquor, using plate and frame modules and cellulose acetate membranes. Reverse osmosis is also used in the treatment of bleach effluents after various pretreatment stages. 

Opportunities for reducing effluent flows and water use are also present in the bleaching plant. Acid filtrates from hypochlorite or chlorine dioxide stages can be used as dilution and wash water for the first bleaching stage. Similarly, second extraction stage filtrates can be used as dilution and... 

Prasad, D.Y. Joyce, T.W. Sequential treatment of Ej stage Kraft bleach plant effluent. Biores. 

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),... 

---