Sažetak
Textile industry is rated as the most polluting sector though there are serious efforts to mitigate the environmental effects. Mercerization is the first stage of textile treatment: highly caustic alkaline solution of sodium hydroxide and auxiliary chemicals are used at high temperature to improve the textile fibre strength and dye efficiency by rearranging the cellulose molecules in the fibres. With ultrafiltration (UF) separation processes suspended solids can be removed from wastewater generated after rinsing the treated cotton and the alkaline solution of surfactants may be reused. Since wastewater from mercerization process has high temperature and is extremely alkaline, ceramic membranes could be appropriate choice for its treatment. Experiments were carried out on laboratory cross flow membrane set‐up using mercerization wastewater without any changes or additions. Laboratory filtration experiments were conducted with two ceramic membranes 1 and 500 kDa in cross‐flow filtration mode with complete retentate recycling at the cross‐flow velocity (CFV) of 1 – 3 m s–1. During separation tests, permeate flux decline and transmembrane pressures (TMP) were measured and these results were used to investigate the fouling mechanisms. The membrane performances were measured in terms of parameters such as pH, alkalinity, conductivity, total suspended solids (TSS), turbidity, and total organic carbon (TOC). Hermia has developed four empirical models that correspond to four basic types of fouling: complete blocking, intermediate blocking, standard blocking and cake layer formation. In this work Hermia’s models are used to investigate the fouling mechanisms involved in crossflow ultrafiltration using tubular multichannel ceramic membranes of 1 and 500 kDa MWCO. For the smaller MWCO the main drive for fouling was found to be intermediate blocking while for the larger pore size clogging appeared mostly due to gel layer formation.
Ključne riječi
ultrafiltration pore blocking model ceramic membrane textile wastewater
