Gökhan Zengin

Enhanced growth and lipid accumulation by a new Ettlia texensis isolate under optimized photoheterotrophic condition

A green microalgae, named as Ettlia texensis was obtained from local freshwater in Turkey. The effects of autotrophic, photoheterotrophic and heterotrophic cultivations on biomass and lipid production were studied. Searching the preferences of the carbon and nitrogen source revealed that this strain could grow photoheterotrophically well with glucose and yeast extract. In the optimized medium, the highest biomass productivity and total lipid content achieved were 0.97 g/L d and 26% of dry weight basis, respectively. Moreover, the major fatty acid methyl esters were C16:0; C18:1; C18:2 and C18:3. In a scale-up attempt, productions were accomplished in a 3 L stirred tank bioreactor. The final biomass and lipid productivities obtained in bioreactor with 250 rpm agitation rate were 0.92 g/L d and 322 mg/L d, respectively. The biochemical compositions were monitored simultaneously by the FTIR spectroscopy during the production in bioreactor. E. texensis could be potent candidate for commercial production in the bioreactor photoheterotrophically.

Eco-Friendly Soaking Process Using Tannic Acid as an Alternative Bactericide

Abstract Eco-friendly leather processes based on the usage of natural products have become a potentially attractive issue for leather industry during the last few decades. Synthetic protective chemicals like bactericides used in most soaking process are known as hazardous substances and cause tannery effluents with high concentrations of Chemical Oxygen Demand (COD). In the present study, the effect of tannic acid on microorganisms, skin, wool and effluent were investigated in order to demonstrate the applicability of tannic acid in soaking process instead of commonly used bactericides. The bacterial load (cfu/ml), COD and Nitrogen Content (N) of the soaking effluents and Total Kjeldahl Nitrogen (TKN) content of skins and wools were investigated. Application of 0.5 and 1 wt% tannic acid concentrations was more effective than commercial bactericide, while comparable results were achieved by 0.1 and 0.3 wt% tannic acid. The application of tannic acid for soaking process resulted in lower COD and N values of effluents. The results show that tannic acid has the potential to be an alternative, eco-friendly bactericide for leather industry by reducing the pollution of leather soaking process.

Corporate carbon footprint for country Climate Change mitigation: A case study of a tannery in Turkey

Assessment of carbon emissions and environmental impact of production is indispensable to achieve a sustainable industrial production in Turkey, especially for those companies willing to compete in new international green markets. In this case study, corporate carbon footprint of a representative Turkish tanning company was analyzed. Inventory and impact data are presented to help in the environmental decision-making process. The results indicate that significant environmental impacts were caused during the landfilling of solid wastes as well as the production of the electricity and fuel required in the tannery. Turkish tannery inventory data presented here for the first time will be useful for leather tanning company managers to calculate sustainability key indicators. Improving alternatives at country level were identified (increasing the renewable sources on electricity production and promote energy recovery in landfills) which would be useful not only to decrease greenhouse gas (GHG) emissions of tanning sector but also of other industries requiring electricity and producing organic wastes. Considering the substantial contribution of industrial processes to the Turkish carbon emissions (15.7%) (TUIK, 2013), work done on those areas would provide a sound improvement in environmental profile of Turkey. The importance to promote a national strategy to reduce GHG emissions in Turkey was discussed here, as well as its relation to corporate carbon footprint assessments. One of the significant points revealed from the case study is the lack of published country specific emission factors for Turkey, which is a fundamental prerequisite to promote corporate carbon footprint assessment within the country.

Bitkisel Tabaklanmış Saraciyelik Derilerde Yağlayıcı Polimerlerin Kullanılabilirliği

The demand on the production of leathers with natural look and touch has shown an increase in recent years. Therefore, the usage of vegetable tannins in leather production has also increased accordingly. However, the leathers tanned or heavily retanned with vegetable tannins show high hydrophilic character. Besides, a light finishing is usually preferred to be applied on leathers in order to obtain the natural look and touch which hinders the resistance of leathers to external factors (water, humidity, light etc.). Lubricating acrylic syntans are well-known auxiliaries in leather industry with their fatliquoring and filling effect in retannage as well as their water-repellent properties. In this research, different percentages of a lubricating acrylic polymer was used in retanning process of vegetable tanned leathers and its effect on water absorption and vapour permeability properties of the leathers were investigated. The results showed that the water absorption properties of the leathers processed with lubricating acrylic syntans were lower than the blank samples. The increase in syntan quantities resulted in decreased water absorption values of the leathers. The water vapour permeability of the samples was also found to be increased with the offer of lubricating acrylic syntans.

Farklı Proses Aşamasındaki Derilerin Diferansiyel Taramalı Kalorimetre ile Termal Davranışlarının Belirlenmesi ve Analiz Koşullarının Değerlendirilmesi

Calismada farkli proses asamasindaki derilerin termal davranislari cesitli kosullar altinda diferansiyel taramali kalorimetre (DSC) ile incelenmis ve derilerin hidrotermal stabilitesinin DSC ile tespit edilebilirligi arastirilmistir. Bu amacla oncelikle ham deri, pikle, tabaklanmis ve mamul haldeki derilerin hidrotermal stabilitesi, buzulme sicakligi standart testi ile analiz edilerek belirlenmistir. Ardindan ayni deri ornekleri farkli kosullandirma parametreleri kullanilarak kuru ve yas formda DSC metodu ile analiz edilmistir. Elde edilen veriler; 24 saat kosullandirilmis ve basinca dayanikli kaplar icerisinde, sulu ortamda, 25-150 oC araliginda analiz edilen deri orneklerinin en iyi sonuclari verdigini gostermistir. Ayni zamanda mevcut kosullardaki DSC termogramlarindan elde edilen verilerin, derilerin standart metot ile elde edilen buzulme sicakligi (Ts) degerleri ile paralellik gosterdigi tespit edilmistir.

The Effect of Lubricating Acyrilic Polymer on Ageing of Saddlery Leathers

OZET: Bitkisel tabaklama maddeleri ayakkabilik ve saraciyelik derilerin uretimi yaninda agir, sert ve dolgun derilerin uretiminde de kullanilmaktadir. Krom ve diger inorganik tabaklama maddelerinin ekolojik ikamesi olabilen bitkisel tabaklama maddeleri; hidrofil karakterdedirler, surtmeye ve gunes isinlarina karsi hassasiyet gosterirler. Bu ozelliklerini gelistirmek icin bitkisel tabaklanmis deriler, polimerik malzemelerle muamele edilirler. Calismada, farkli oranlarda yaglayici akrilik polimerlerin kullanildigi saraciyelik derilere hizlandirilmis yaslandirma islemi uygulanmistir. Yaslandirmanin etkisi, derilerin cekme ve yirtilma mukavemeti, su buhari gecirgenligi, surtme, renk ve isik hasligi degerleri ile morfolojik ozellikleri acisindan degerlendirilmistir. Sonuc olarak, yaslanmanin olumsuz etkisinin %8 yaglayici akrilik uygulamasi ile elimine edilebilecegi belirlenmistir.