Separation of silkworm proteins in cocoon cooking wastewaters via nanofiltration: Effect of solution pH on enrichment of sericin

Cocoon cooking wastewater contains waste silkworm proteins including sericin, which is a valuable raw material for many industries including cosmetics and pharmaceuticals. Sericin can be recovered via nanofiltration (NF) with high efficiency; however the process conditions need to be optimized to maximize separation. In this study, the effect of solution pH on NF performance was investigated for separation of silkworm proteins towards sericin enrichment. Solution pH (3.5-9.0) slightly influenced sericin rejection, which was higher than 80% in all cases. On the other hand, solution pH significantly influenced transmission of contaminant proteins, which was highest (0.52) at pH 3.5 and lowest (0.06) at pH 9.0. Increased transmission of contaminant proteins at acidic pH was attributed to possible effects of concentration polarization and increased ionic strength. Although acidic conditions (pH 4.5) favored sericin enrichment, the instantaneous purity of sericin in the retentate remained at 0.48-0.52 at pH 3.5-9.0. Furthermore, working at acidic pH caused severe fouling problems; more than threefold increase occurred in flux decline; with an increase of flux decline from 20% to 69% and fouling resistance from 3.8 x 10(13) m(-1) to 15.5 x 10(13) m(-1) (almost fourfold) when pH was reduced from 6.4 to 4.5. The contribution of fouling resistance to total resistance increased from 32-40% (pH 6.4) to 70% and 53% in acidic and alkaline conditions, respectively. Concentrating the wastewater at pH 4.5 had adverse impacts on rejection performance of NF membrane; rejection of sericin and contaminant proteins decreased from 78% to 52% and from 33% to 9%, respectively, as volume reduction factor increased from 1.00 to 1.70. Correspondingly, sericin purity in the retentate decreased from 0.59 to 0.55. The pH adjustment had no benefit for separation of sericin from contaminant proteins, and hence it was decided not to apply pH adjustment in NF stage. Instead, a two-stage process, NF (at original pH of 6.4) plus ethanol-induced precipitation were adopted, which enabled enrichment of sericin 1 from 80.0% to 92.9%. The product was considered to be of high quality as it contained greater than 90% sericin

Tekstil atıksularından su geri kazanımı için membran esaslı bir arıtma süreci geliştirilmesi.

A membrane based treatment scheme was developed for the recovery of the print dyeing wastewaters (PDWs) and the acid dye bath wastewaters (ADBWs) of carpet manufacturing industry. The treatment schemes were developed by selecting the best pre-treatment and treatment processes among the alternatives of chemical precipitation (CP), microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF). The best process train for PDW was CP+NF, where organic matter, color, turbidity and total hardness were removed at >95%. The alternative process train CP+UF also removed color and turbidity almost completely, however organic matter rejection was low, being 25% at highest. The quality of NF permeates were suitable for dyeing of light colors whereas UF permeates were suggested for washing of the printed carpets or dyeing of the dark colors. The best process train for ADBW was MF (1.0 mm)+NF, where organic matter rejection increased from 65% to 97% due to pH neutralization. Alternatively, sequential NF was required up to three stages in order to achieve similarly high rejections at the acidic pH of ADBW. Therefore, pH neutralization was realized to be a very important operational parameter affecting the treatment scheme. Although pH neutralization increased the flux declines by almost 5%, chemical cleaning was very effective to restore the original fluxes. Finally, ADBW was mixed with PDW, which already had a pH around neutral, so that the pH of ADBW would rise towards neutral without chemical consumption. The results suggested that these wastewaters could be treated together as long as they were mixed up to equal volumes at pH around neutral. Therefore, a final treatment scheme, which involved single NF for the mixture of PDW and ADBW, following their individual pre-treatment stages, was proposed as the most efficient process train.Ph.D. - Doctoral Progra

Development of a national set of environmental performance indicators

Purpose: This study was conducted as part of an EU funded project; “EuropeAid/125541/D/SER/T Technical Assistance for the Establishment of a Turkish Environmental Information Exchange Network (TEIEN)”. The purpose of the study is to develop a set of national environment indicators for Turkey. Methods: The national set of environmental performance indicators was based on DPSIR (Driving forcePressure-State-Impact-Response) model. The selection of indicators was performed based on international indicator sets used by OECD, EEA, EUROSTAT, World Bank, UN and other countries. Five criteria were considered in selecting the indicators; a) national requirements, b) policy compatibility, c) international standards, d) covering the environmental sectors, e) data availability. Results: A total of 76 indicators were included in the national set of indicators for Turkey under the themes of climate change, air quality, waste, water, land use, biodiversity, agriculture, energy, industry, tourism and transportation. Currently, a part of these indicators are in use due to inadequate data availability. Conclusions: Turkey needs to improve in-situ monitoring and collection of data to better implement the environmental performance indicators included in the national set of indicators