Life Cycle Assessment of evaporative recovery of mercerization wastewater


Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Çevre Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2015

Öğrenci: EDA BAYAR

Danışman: ÜLKÜ YETİŞ

Özet:

The products of textile industry are irrevocable part of our lives: clothes, carpets, towels etc. However, textile industry is known to be having impact on the environment, especially for its high levels of water consumption and waste generation. The European Union’s Industrial Emissions Directive (former IPPC Directive) requires industrial establishments to apply best available techniques (BAT) both in the production processes and in the waste treatment and disposal. The European IPPC Bureau (EIPPCB) produces sectorial best available techniques reference documents (BREFs) to co-ordinate the exchange of information between Member States concerned on BAT. The BREF prepared for textile industry recommends the application of hundreds of different techniques in the manufacture of textiles and also in the management of textile effluents. Recovery of highly alkaline wastewater formed during mercerization process by the technique of evaporation is among the BAT suggested for the textile industry. In the context of this study, three scenarios are established based on fuels used for steam production which is used in evaporative recovery (heavy fuel oil, light fuel oil and natural gas). Evaporation process is evaluated in terms of its impacts on the environment by using a life cycle assessment (LCA) tool and the environmental burdens of this process is compared to those of conventional end-of-pipe treatment option. By the aid of the SimaPro software, three scenarios of evaporation and the base-line scenario of end-of-pipe treatment (neutralization and activated sludge process) is evaluated selecting- one kg of mercerization wastewater as functional unit and setting boundary conditions as “cradle to grave”. The well-known IMPACT2002+ method is used for environmental impact analysis. The processing of 1 kg of alkaline weak lye from mercerization process by evaporation (which is using natural gas for steam production) is found to be the most environmentally friendly for the recovery of caustic caused the following major environmental impact potentials: global warming potential of 9.89E-05 kg CO2 eq; respiratory inorganics release of 7.44E-05 kg PM2.5 into air-eq; and non-renewable energy use of 0.000127 MJ. However, application of evaporative recovery was not found to improve the environmental performance of mercerization process for all impact categories in comparison with the baseline scenario of end-op-pipe treatment. In particular, impacts due to non-renewable energy and global warming potential were found to be increased to the largest extent with 1.2% and 1.24%, respectively. An economical comparison of evaporative recovery and end-of-pipe treatment of weak lye was also carried out and profitability was analyzed to assess the evaporative recovery option’s potential return on investment using Net Present Value (NPV) analysis. The results indicated that the application of evaporative recovery of weak lye is profitable and therefore it complies with economical standards.