Pollutants derived from real textile wastewater present a high environmental risk. This work involves the study of the removal of chemical oxygen demand (COD), color, and turbidity from Tunisian real textile wastewater by two different water treatment technologies: chemical coagulation (CC) and electrocoagulation (EC). A comparative study between these two methods was conducted based on the separation performance and operating cost (OC). The effects of different operational parameters including electrolysis time (t), voltage, and pH for EC and the coagulant concentration, initial pH, and time of slow mixing (t _sm) for CC were studied using response surface methodology. The developed quadratic models for the responses were in good agreement with the experimental data. The experiments proved the efficiency of both chemical and electrochemical techniques for the treatment of textile effluent. Indeed, by using EC, the reduction efficiencies of COD, color, and turbidity were 63.05, 99.07, and 96.31%, respectively, under optimal conditions (pH 9, t = 36.26 min, and voltage 4 V). For CC treatment, the achieved removal efficiencies of COD, color, and turbidity were 54.02, 96.21, and 93.7%, respectively, at pH 8.57, a coagulant concentration of 204.75 mg/L, and a t _sm of 28.41 min as optimal operating conditions. The OC obtained for EC and CC was about 0.47 and 0.2 USD/m³, respectively. Even if the OC of the EC process was higher as compared to the CC process, the treated water obtained by EC meets the Tunisian Standards (NT 106.03 and NT 09-14) for textile wastewater discharge into the environment and demonstrates a high potential for its reuse in various industrial activities. EC technology can be integrated into a wastewater management system that ensures a zero liquid discharge of wastewater into the environment.

Purpose: The main purpose of this study resides essentially in the development of a new tool to quantify the biomass in the bioreactor operating under steady state conditions.Design/methodology/approach: Modeling is the most relevant tool for understanding the functioning of some complex processes such as biological wastewater treatment. A steady state model equation of activated sludge model 1 (ASM1) was developed, especially for autotrophic biomass (XBA) and for oxygen uptake rate (OUR). Furthermore, a respirometric measurement, under steady state and endogenous conditions, was used as a new tool for quantifying the viable biomass concentration in the bioreactor.Findings: The developed steady state equations simplified the sensitivity analysis and allowed the autotrophic biomass (XBA) quantification. Indeed, the XBA concentration was approximately 212 mg COD/L and 454 mgCOD/L for SRT, equal to 20 and 40 d, respectively. Under the steady state condition, monitoring of endogenous OUR permitted biomass quantification in the bioreactor. Comparing XBA obtained by the steady state equation and respirometric tool indicated a percentage deviation of about 3 to 13%. Modeling bioreactor using GPS-X showed an excellent agreement between simulation and experimental measurements concerning the XBA evolution.Originality/value: These results confirmed the importance of respirometric measurements as a simple and available tool for quantifying biomass.

Membrane bioreactor (MBR) is widely regarded as an effective tool for wastewater treatment to the conventional activated sludge process thanks to its various advantages. In this paper, we study the influence of chemical oxygen demand to nitrogen ratio (ratio COD/N) on MBR fouling propensity. Therefore, two runs (I and II) were conducted with different low ratio COD/N equal to 2.3 and 0 to promote autotrophic bacteria development. The organic loading rates (OLR) were equal to 0.3 and 0kg COD.m³d^-1 for runs I and II, respectively and the nitrogen loading rate (NLR) was equal to 0.12 and 0.2kgNm³d^-1 for both runs. The results showed that the fouling rate decreased from 0.064E+12 to 0.015E+12 (m^-1d^-1) with the decrease of COD/N ratio. The two runs are conducted without membrane cleaning during all the experimental periods equal to 51 for the first run and 54 days for the second. The results also point out that the fouling resistance was mainly reversible for both runs such as the contribution of the resistance due to suspended solids (Rg) to the total resistance was equal to 60 and 74% for run I and II, respectively. Moreover, the contribution of adsorption resistance (Rads), decreased from 12.7 to 7.19 %. This leads to a great reduction in the cost of membrane chemical cleaning.

This research aims to study the removal of Cobalt (Co) using chitin. The optimum conditions for removing Co were ascertained through batch experiments. This study involves the determination of chitin metal-binding efficiency by using a polymer enhanced diafiltration setup that utilizes a membrane process (ultrafiltration) to keep the Chitin. The effects of several parameters on sorption like pH, the concentrations of chitin, and Co were examined. The best efficiency was reached if the setup was run at pH < 6.3 (i.e., chitin pK_a). At acidic conditions and by employing 6 g/L of chitin, Co level (20 mg/L) was decreased at 95%. To further investigate the kinetics of sorption for each gram of chitin, equilibrium experiments were carried out. For 1–100 mM Co, the performed rheological measurements show that chitin was observed to be moderately shear thickening at relatively lower levels (4 and 6 g/L); further, it was moderately shear thinning at slightly more important levels (12 and 20 g/L). Some improvement of the raw polymer will be necessary to enhance sorption to a sustainable limit and make this scheme an economically viable process.

Zero liquid discharge (ZLD) is increasingly promoted to reduce freshwater use and eliminate wastewater discharge in the textile sector, one of the most water-intensive and pollutant-generating industries. Although ZLD literature is growing rapidly, it remains unclear whether feasibility-related aspects (economic viability, energy demand, and environmental performance) are integrated into textile ZLD research or are primarily addressed in technology-focused studies. To examine this, a two-phase bibliometric framework is applied to map global textile ZLD research from 2000 to 2026 using publications retrieved from the Web of Science Core Collection and Scopus. Phase 1 assessed the full textile ZLD landscape ( n = 99 after screening) to identify dominant technological themes and the field’s intellectual structure. Phase 2 refined the dataset using economic, environmental, and energy-related terms ( n = 36 after screening) to test whether a sustainability-focused subset restructured the dataset. Keyword co-occurrence networks and thematic mapping show that textile ZLD research is consistently structured around membrane-based separation, desalination, dye removal, and water recovery. Sustainability concepts (e.g., economic analysis, energy use, and life-cycle assessment [LCA]) remain loosely connected and peripheral, highlighting a maturity gap between technological development and feasibility-driven evaluation. Based on these findings, a sustainability agenda is urgently needed, including: (i) standardized reporting of recovery and reclaimed-water quality; (ii) harmonized energy indicators (kWh·m ^–3 ) with clearly defined system boundaries; (iii) comparable CC/OC (capital/operating costs) reporting under consistent assumptions; and (iv) transparent LCA inputs and scenarios. These measures would strengthen benchmarking across studies and support more decision-oriented design and implementation of textile ZLD systems.