Efficiency of Coagulation/Flocculation for the Removal of Complex Mixture of Textile Fibers from Water

Abstract

Synthetic fibers enter wastewater treatment plants together with natural fibers, which may affect treatment efficiency, a fact not considered in previous studies. Therefore, the aim of the present study was to evaluate the efficiency of the coagulation/flocculation process for the removal of a mixture of textile fibers from different water matrices. Natural and synthetic fibers (100 mg/L; cotton, polyacrylonitrile, and polyamide) were added to a synthetic matrix, surface water and laundry wastewater and subjected to coagulation/flocculation experiments with ferric chloride (FeCl3) and polyaluminum chloride (PACl) under laboratory conditions. In the synthetic matrix, both coagulants were found to be effective, with FeCl3 having a lesser advantage, removing textile fibers almost completely from the water (up to 99% at a concentration of 3.94 mM). In surface water, all dosages had approximately similar high values, with the coagulant resulting in complete removal. In laundry effluent, the presence of surfactants is thought to affect coagulation efficiency. PACl was found to be effective in removing textile fibers from laundry wastewater, with the lowest removal efficiency being 89% and all dosages having similar removal efficiencies. Natural organic matter and bicarbonates showed a positive effect on the efficiency of FeCl3 in removing textile fibers from surface water. PACl showed better performance in coagulating laundry wastewater while surfactants had a negative effect on FeCl3 coagulation efficiency.

A Feasible and Efficient Monitoring Method of Synthetic Fibers Released during Textile Washing

“…Simultaneously, technologies to filter and remove fibers from sludge are developed. For instance, under laboratory conditions, an experiment by Vasiljevic et al [16] was conducted on removing microfibers with FeCl 3 and polyaluminum chloride (PACl). Using FeCl 3 showed up to 99% effectiveness in removing MFs from a water mixture of cotton and synthetic polymers.…”

“…The main source of microfibers that later enter the water-circulating system is related to washing machines' wastewater [17]. Many studies were conducted to explore the factors that enhance MFs emission-washing condition (water volume [17], presence of detergent, temperature [18], washing load [19]), age of garments [17], textiles parameters (finishing, hairiness, yarn twist, composition) [20,21], type of washing machine (top-or front load) [16]. The main conclusions are that aged materials, increased water volume, and high temperature increase the release of microfibers, while the greater mass of the washing load and more compact structure of the fibers decrease the emission.…”

“…MFs from aged materials have greater mass and are more often recoverable than MFs from new textiles. Moreover, the greater the filter size, the broader the range of recovered microfibers [16]. According to the literature, the most common method used in the experiments to obtain the samples was the filtration of after-wash water.…”