Application of Nanofiltration and Reverse Osmosis Membranes for Tannery Wastewater Reuse

Abstract

Tanneries produce large amounts of wastewater with high concentrations of suspended solids, organic matter, and salts. Treatment and reuse of these effluents are of great importance to preserve water resources and save costs. Although suspended solids and high percentages of organic matter can be eliminated by physico-chemical and biological processes, refractory chemical oxygen demand (COD) and salts will remain in the wastewater after these processes. In particular, chloride and sulphate ion concentrations may hinder the treated wastewater from being reused or even discharged according to legal standards. In this work, two nanofiltration membranes and two reverse osmosis membranes are tested to assess these technologies as regeneration processes for biologically treated tannery wastewater. Permeate flux and rejection of organic matter and ions were measured at different operating conditions (transmembrane pressure and cross-flow velocities) at both total recycle and concentration modes. Results showed that the difference between permeate fluxes of nanofiltration (NF) membranes and reverse osmosis (RO) membranes was very high. Thus, at 20 bar and 1.77 m·s−1, the permeate flux of the two tested NF membranes in the total recycle mode experiments were 106 and 67 L·m−2·h−1, while the obtained permeate fluxes for the RO membranes were 25 and 18 L·m−2·h−1. Concerning rejections, RO membranes rejected almost 100% of the salts, whereas NF membranes reduced their rejection when faced with increasing concentration factors (salt rejection between 50–60% at the highest concentration factor). In addition, the fouling of RO membranes was lower than that of NF membranes, recovering more than 90% of initial permeability by only water rinsing. In contrast, chemical cleaning was necessary to increase the permeability recovery of the NF membranes above 90%. The considerably lower rejections and the higher membrane fouling of the NF membranes lead us to conclude that reverse osmosis could be the most feasible technique for water reuse in the tannery industry, though the permeate fluxes are lower than those achieved with NF membranes.

Highly Efficient Biosorption of Cationic Dyes via Biopolymeric Adsorbent-Material-Based Pectin Extract Polysaccharide and Carrageenan Grafted to Cellulosic Nonwoven Textile

“…Different condition parameters affecting the adsorption performance were studied, including the pH (varied from 3 to 9), time (ranged from 0 to 120 min. ), concentration of the MB dye (varying from 25 to 1000 mg/L), and contact temperature (22,40, and 60 • C). Following each experiment, the residual concentration was measured using a Shimadzu (UV-2600) UV-visible spectrophotometer.…”

“…These technologies have revealed deficiencies and limitations given their high investment and operating costs. The processes based on reverse osmosis and ion exchange have proved to be more interesting given their ability to recover pollutant products during their elimination from the effluents [ 22 , 23 , 24 ]. However, these processes as well as those of advanced oxidation are not economically feasible due to their investment and relatively high operating cost.…”

Membranes and Integrated Membrane Operations as Clean Technologies in the Leather Industry

“…Recently, NF and RO membranes were tested to treat biologically treated tannery wastewater in order to eliminate refractory COD and salts [95]. Salt compounds were completely rejected by RO membranes.…”

Enhancing Physiochemical Substrate Properties of Thin-Film Composite Membranes for Water and Wastewater Treatment via Engineered Osmosis Process

“…The major drivers for the significant market growth are rising awareness about wastewater recycling and rapid industrialization coupled with a growing population. A promising separation efficiency could be achieved by employing suitable membrane properties [ 8 , 9 ]. The microporous ultrafiltration (UF) membrane was found to be able to produce a high water flux while treating aerobically treated palm oil mill effluent (AT-POME), but the nano-sized pigments were not effectively rejected, as they still presented in the permeate [ 10 ].…”