Development of a membrane based treatment scheme for water recovery from textile effluents


Tezin Türü: Doktora

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

Tezin Onay Tarihi: 2005

Öğrenci: GÖKŞEN ÇAPAR

Eş Danışman: ÜLKÜ YETİŞ, LEVENT YILMAZ

Özet:

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.