Treatability of kraft pulp bleaching wastewater by biochemical and photocatalytic oxidation
In this study the biological treatability and TiO sub(2) photocatalyzed oxidation characteristics of sulfate pulp bleaching effluents were investigated. The original wastes had a low biodegradability as determined by BOD sub(5)/COD ratios. Biological treatment was conducted in a batch activated slud...
Gespeichert in:
Veröffentlicht in: | Water science and technology 1999, Vol.40 (1), p.281-288 |
---|---|
Hauptverfasser: | , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | In this study the biological treatability and TiO sub(2) photocatalyzed oxidation characteristics of sulfate pulp bleaching effluents were investigated. The original wastes had a low biodegradability as determined by BOD sub(5)/COD ratios. Biological treatment was conducted in a batch activated sludge reactor. The nonbiodegradable fraction amounted to 60% of the initial COD and compounds specific to these wastes were not removed during biotreatment. In order to enhance the biodegradability of these wastes, mixed raw effluent, C/E-H stage effluent, D/E-D stage effluent and biologically pretreated wastes were subjected to TiO sub(2) photocatalyzed oxidation. Photocatalytic oxidation led to an increase in the BOD sub(5)/COD ratio of D/E-H stage raw and biologically treated wastewater, while chloride formation was observed in both cases in a five-hour reaction period in the presence of 1g l super(-1) TiO sub(2) and 15x10 super(-3) M H sub(2)O sub(2) at pH=6.5. The specific absorption values (A sub(272nm)/COD sub(s), A sub(254nm)/COD sub(s), A sub(346nm)/COD sub(s), A sub(436nm)/COD sub(s)) exhibited parallel decreases during photocatalytic oxidation which indicate that oxidation reactions were nonspecific with respect to the organics present in these wastes. As a conclusion it can be suggested that biological treatment should be placed before the photocatalytic oxidation method. Even in this scheme, the application of photocatalytic oxidation could only then be favored when the COD and chloride concentrations in the wastewater were below certain values or when wastewater was diluted. |
---|---|
ISSN: | 0273-1223 1996-9732 |
DOI: | 10.1016/S0273-1223(99)00396-0 |