Recovery of sericin protein from silk processing wastewaters by membrane technology

Aygün, Saniye Seylan
Cocoon cooking wastewaters (CW) and silk degumming wastewaters (SDW) of silk processing industry were treated by membrane processes for sericin recovery. CW contains only sericin while SDW contains both sericin and soap. Sericin in CW had four molecular weight (MW) fractions; 175-200 kDa (Sericin-1), 70-90 kDa (Sericin-2), 30-40 kDa (Sericin-3) and 10-25 kDa (Sericin-4). Two alternative process trains were developed for CW; 1. centrifugation + microfiltration + nanofiltration + precipitation, 2. centrifugation + microfiltration + nanofiltration + dialysis + precipitation. In the first process, a sericin/silkworm protein mixture was obtained with a sericin content of 39-46%. In the second one, however, a pure sericin product was obtained. The sericin recovery efficiency of the developed process train was found as 76%. Severe flux declines of 70-75% were observed in NF stage in both process trains. However, cleaning with 0.5 M NaOH and 190-200 mg/L free chlorine restored the fluxes by 83-127%. The MW of sericin in SDW was 110-120 kDa. The soap and sericin were separated in the pre-treatment stage consisting of centrifugation (pH 3.5, 10 min) and gravity settling (4 oC, 24 h). The ultrafiltration membrane with molecular weight cut-off of 5 kDa achieved 59% sericin recovery at pH 3.5, accompanied by severe flux decline of 88%. Furthermore, clean water flux was restored by only 31% via chemical cleaning.


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YİĞİT, Nevzat Özgü; Uzal, N.; KÖSEOĞLU, Hasan; Harman, I.; Yukseler, H.; Yetiş, Ülkü; CİVELEKOĞLU, Gökhan; KİTİŞ, Mehmet (Elsevier BV, 2009-05-15)
The objective of this study was to investigate the performance of a pilot-scale membrane bioreactor (MBR) system for the treatment of a highly concentrated mixed wastewater from wet processes (dyeing, finishing, and sizing) of a denim producing textile industry. The MBR system, containing a Submerged hollow fiber membrane module in the aeration tank, was operated aerobically for about 3 months on-site at a continuous flow mode. The system was operated at two different operation stages: (1) 110 Sludge wastag...
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Discharge of colored effluents without decoloration originated from textile industries may cause serious problems in the receiving environments. In this study, natural materials that are basaltic tephra and clinoptilolite were used to remove various dyestuffs used in the textile industry. Those materials are cheap and available in large quantities in Turkey. The investigation of adsorption of basic, acidic and reactive dyes on these materials is the objective of this study. During preliminary experiments it...
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Natural zeolites, especially clinoptilolite, have the ability of removing certain cations from wastewater by utilizing ion exchange and adsorption. In this study, clinoptilolite originated from Bigadiç, Balıkesir deposit was investigated in its natural and conditioned form for its effectiveness in removing Zn2+ and Pb2+ ions from aqueous solutions. In addition, relevant mechanisms involved in heavy metal removal by clinoptilolite were examined in this study. Throughout this work, equilibrium and kinetic stu...
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Settling properties of activated sludge typically establish the performance and the cost of biological wastewater treatment plants, and they are considerably affected by the solids concentration of the sludge and the mean cell residence time of the system. In this work, effects of mean cell residence time of the system and solids concentration of sludge on the settling properties of activated sludge were studied. By statistical analysis of the laboratory data, mathematical expressions were suggested to e...
Citation Formats
S. S. Aygün, “Recovery of sericin protein from silk processing wastewaters by membrane technology,” M.S. - Master of Science, Middle East Technical University, 2008.