Dyestuff wastewater treatment by combined SDS-CuO/TiO₂ photocatalysis and sequencing batch reactor

Abstract

Combined technology of SDS-CuO/TiO₂ photocatalysis and sequencing batch reactor (SBR) were applied to treating dyestuff wastewater. Photocatalysis was carried out in a spiral up-flow type reactor as pre-treatment. SDS-CuO/TiO₂ photocatalyst was prepared by modification of nano-TiO₂ using CuO and sodium dodecyl sulfate (SDS). Results show that the SDS-CuO/TiO₂ photocatalyst contains two kinds of crystals, including TiO₂ and CuO. The band gap of this photocatalyst is 1.56 eV, indicating that it can be excited by visible light (λ<794.87 nm). And characterization also shows that there are alkyl groups on its surface. It takes 40 min to improve the biodegradability of dyestuff wastewater. Five-day biochemical oxygen demand (BOD₅) and dehydrogenase activity (DHA) of wastewater reach the maximum value when dissolved oxygen is higher than 2.97 mg/L. SBR reactor was used to treat this biodegradability improved wastewater. Chemical oxygen demand (COD) and colority decline to 72 mg/L and 20 times, respectively, when the sludge loading is 0.179 kg(COD)/[kg(MLSS)·d], dissolved oxygen is 4.09 mg/L and aeration time is 10 h.

Keywords

biodegradability / photocatalysis / sequencing batch reactor / dyestuff wastewater

References

[1] RobinsonT., ChandranB., NigamP.. Removal of dyes from a synthetic textile dye effluent by biosorption oon apple pomace and wheat straw [J]. Water Research, 2002, 36: 1743-1748

[2] AhnD. H., ChangW. S., YoonT. I.. Dyestuff wastewater treatment using chemical oxidation, physical adsorption and fixed bed biofilm process [J]. Process Biochemistry, 1999, 34: 429-439

[3] LiuW., ChenS.-f., ZhaoW., ZhangS.-juan.. Titanium dioxide mediated photocatalytic degradation of methamidophos in aqueous phase [J]. Journal of Hazardous Materials, 2009, 164: 154-160

[4] CrisitinaA., ArturoM. A., SixtoM., AnaB.. New insights on solar photocatalytic degradation of phenol over Fe-TiO₂ catalysts: Photo-complex mechanism of iron lixiviates [J]. Applied Catalysis B: Environmental, 2009, 93(1/2): 96-105

[5] KohtaniS., InaokaY., HayakawaK., NakagakiR.. Degradation of benzo[a]pyrene using TiO₂ and Ag-loaded BiVO₄ photocatalysts: Evaluation by the Ames mutagenicity assay [J]. Journal of Advanced Oxidation Technologies, 2007, 10(2): 381-386

[6] YamashitaH., HaradaM., MisakaJ., TakeuchiM., NeppolianB., AnpoM.. Photocatalytic degradation of organic compounds diluted in water using visible light-responsive metal ion-implanted TiO₂ catalysts: Fe ion-implanted TiO₂ [J]. Catalysis Today, 2003, 84: 191-196

[7] HuC., WangY.-zhang.. Decolorization and biodegradability of photocatalytic treated azo dyes and wool textile wastewater [J]. Chemosphere, 1999, 39(12): 2107-2215

[8] JonstrupM., WaerjerstamM., MurtoM., MattiassonB.. Immobilisation of TiO₂ for combined photocatalytic-biological azo dye degradation [J]. Water Science & Technology, 2010, 62(3): 525-531

[9] BolducL., AndersonW. A.. Enhancement of the biodegradability of model wastewater containing recalcitrant or inhibitory chemical compounds by photocatalytic pre-oxidation [J]. Biodegradation, 1997, 8(4): 237-249

[10] TurchiC. S., OllisD. F.. Photocatalytic degradation of organic water contaminants: Mechanisms involving hydroxyl radical attack [J]. Journal of Catalysis, 1990, 122(1): 178-192

[11] XuX., JiF.-y., FanZ.-hong.. Design of spiral up-flow tower-type photocatalysis reactor [J]. China Water & Wastewater, 2009, 25(23): 79-81

[12] WangJ.-f., JinW.-b., ZhaoQ.-l., LiuZ.-g., LinJ.-kan.. Peformance of treating wastewater and anti-shockloading in oxic-settling-anaerobic (OSA) process for minimization of excess sludge [J]. Environmental Science, 2007, 28(11): 2488-2493

[13] WuL., YuJ. C., FuX.-zhi.. Characterization and photocatalytic mechanism of nanosized CdS coupled TiO₂ nanocrystals under visible light irradiation [J]. Journal of Molecular Catalysis A: Chemical, 2006, 244(1/2): 25-32

[14] GopidasK. R., BohorquezM., KamatP. V.. Photophysical and photochemical aspects of coupled semiconductors: Charge-transfer processes in colloidal CdS-TiO₂ and CdS-AgI systems [J]. J Phys Chem, 1990, 94(16): 6435-6440

[15] GhijsenJ., TjengL. H., VanelpJ., EskesH., WesterinkJ., SawatzkyG. A., CzyzykM. T.. Electronic structure of Cu₂O and CuO [J]. Physical review B: Condensed Matter and Materials Physics, 1988, 38(16): 11322-11330

[16] KoffybergF. P., BenkoF. A.. A photoelectrochemical determination of the position of the conduction and valence band edges of p-type CuO [J]. Journal of Applied Physics, 1982, 53(2): 1173-1177

[17] RobertD.. Photosensitization of TiO₂ by M_xP_y and M_xS_y nanoparticles for heterogeneous photocatalysis applications [J]. Catalysis Today, 2007, 122(1/2): 20-26

[18] TianG.-l., HeH.-b., ShaoJ.-da.. Effect of Microstructure of TiO₂ thin films on optical band gap energy [J]. Chinese Physics Letters, 2005, 22(7): 1787-1789

[19] Al-aniS. K. J., HigazyA. A.. Study of optical absorption edges in MgO-P₂O₅ glasses [J]. Journal of Materials Science, 1991, 26: 3670-3674

[20] WangZ.-y., TangP.-s., JiangY.-l., FanX.-p., QianG.-d., HongZ.-lian.. Study on fluorescence and diffuse reflection spectrum of nanosized TiO₂ [J]. Rare Metal Materials and Engineering, 2004, 33(Suppl.3): 162-168

[21] FriedmanL., FishelD., ShechterH.. Oxidation of alkylarenes with aqueous sodium dichromate: A useful method for preparing mono-and polyaromatic carboxylic acids [J]. The Journal of Organic Chemistry, 1965, 30(5): 1453-1457

[22] ZhangW., WangX.-x., LinH.-x., FuX.-zhi.. Influence of magnetic field on the formation rate of hydroxyl radical in photocatalysis [J]. Acta Chimica Sinica, 2005, 63(18): 1765-1768

[23] OhY. K., KimY. J., AhnY., SongS. K., ParkS.. Color removal of real textile wastewater by sequential anaerobic and aerobic reactors [J]. Biotechnology and Bioprocess Engineering, 2004, 9(5): 419-422

[24] JinY.-z., WeiY.-y., ChenX.-ping.. Studies on treatment of printing and dying wastewater by hydrolysis and acidification-SBR technology [J]. China Environmental Science, 2004, 24(4): 489-491