Textile industry generates a high volume of wastewater containing various type of pollutants. Although high color and chemical oxygen demand (COD) removals are achieved with the combination of ...biological and chemical treatment processes, reverse osmosis (RO) process is generally needed for water recovery due to high conductivity of the textile wastewater. In this study, a pilot scale RO process containing one spiral wound membrane element was operated under three different operational modes, i.e. concentrated, complete recycle and continuous, to collect more information for the prediction of a real-scale RO process performance. It was claimed that complete recycle mode of operation enabled mimicking the operational conditions exerted on the first membrane, whereas continuous mode of operation created conditions very similar to the ones exerted on the last membrane element in a real scale RO process train. In the concentrated and continuous mode of operation, water recovery and flux were around 70% and 19 L/m2/h (LMH). Permeate produced in the RO process can be safely reused in the dyeing process as the feed and permeate conductivities were around 5500 μS/cm and 150 μS/cm, respectively, at 70% water recovery. However, color concentration in the concentrate exceeded the discharge limits and would need further treatment. The RO performance was accurately predicted by ROSA simulations.
•Pilot scale RO process was operated for water recovery from textile wastewater.•RO process operated at different operational modes.•Around 70% water recovery at around 19 LMH was obtained.•Feed and permeate conductivities were 5500 μS/cm and 150 μS/cm, respectively.
Industrial wastewater reuse together with zero or near zero liquid discharges have been a growing trend due to the requirement of sustainable water management mandated by water scarcity and ...tightening discharge regulations. Studies have been conducted on the reclamation of textile industry wastewater using RO processes. However a lot of scientific attention has been drawn upon limiting the amount of concentrate generated from RO processes, which depends on the concentrations of scale forming ions in the concentrate stream. Hence, this study aims at investigating the applicability of an ultra-filtration (UF) membrane integrated pellet reactor to remove scale forming ions, i.e. Ca2+, Mg2+ and Si from the concentrate of a pilot-scale textile industry RO process, for the first time in the literature. The resulting effluent was further tested in a secondary RO process to decrease concentrate volume and increase total water recovery. The pellet reactor operated at an extremely low hydraulic retention time of 0.1 h removed scale forming ions, i.e. Ca2+, Mg2+, with 90–95% efficiency, which improved the secondary RO process performance up to 92–94% overall water recovery, i.e. near zero liquid discharge was reached. Ozonation of the concentrate partially removed COD and color, which further improved the secondary RO filtration performance.
•Pellet reactor may precipitate membrane scaling cations.•Hardness removal was 93% at HRT 0.1 h and pH 11.5.•After pellet reactor treatment, water recovery in the secondary RO was 85%.•Overall water recovery improved to 94% in the process.•Near-zero liquid discharge may be possible with the suggested process.
The aim of this study was to investigate the usefulness of a membrane hybrid process for the treatment of real textile wastewater (TWW) and its potential reuse in the dyeing of cotton knitted fabric ...(DCF) process. To determine a suitable pretreatment, sand filtration, coagulation, and UF hollow fiber (UF–HF) were compared on a laboratory scale in terms of turbidity, color, and total organic carbon (TOC). Here, UF-HF provided the best removal results of 93.6%, 99.0%, and 29.0%, respectively. The second stage involves the study of UF flat sheet membranes (5, 10, 20, and 50 kDa). The 5 kDa membrane provided the best permeate quality according to the chemical oxygen demand (COD), turbidity, TOC, conductivity, and color by 54.5%, 83.9%, 94.2%, and 45.7–83.3%, respectively. The final step was treatment with nanofiltration (NF) and reverse osmosis (RO) and these effluents were reused for dyeing. Finally, the effluents from UF-HF/5 kDa UF/RO (Scenario 1) and UF-HF/5 kDa UF/NF (Scenario 2) were analyzed for turbidity, COD, TOC, biological oxygen demand, conductivity, hardness, anions and cations, and color. Both scenarios provided high removal results of 76.3–83.5%, 94.6–97.7%, 88.5–99%, 95.4–98.0%, 59.2–99.0%, 88.7–98.7%, 60.7–99.1%, and 80.0–100%, respectively. They also satisfied the DCF tests compared to the standard DCF samples. The innovative aspect of this research is as follows: 1) the complete analysis of hybrid membrane separation processes for the purpose of reuse of treated textile wastewater and 2) the proposal of a new criterion for reuse for DCF.
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•Usefulness of hybrid membrane process for reuse in textile dyeing was established.•ZW-1/5 kDa UF/NF–RO showed removal efficiencies of monitored parameters of 59–100%.•High color fastness of dyed textile with ZW-1/5 kDa UF/NF permeate was achieved.•New reuse criteria for dyeing cotton knitted fabric were proposed.•Treatment ZW-1/5 kDa UF/NF shows the better economic efficiency of 395.656,00 €.
Small and medium‐sized enterprises (SME) in the textile sector need to take the necessary steps for the reuse of wastewater in a shorter time and at low cost. The Taguchi experimental design method ...with an L9 (34) array was used to determine the optimum operating conditions and the important factors in the reuse of biologically treated textile wastewater using nanofiltration (NF). The signal‐to‐noise ratios showed that Desal 5DL, 16 bar, 1.5, and 2 L min−1 were the optimum conditions for the factors of NF membrane type, transmembrane pressure, volume reduction factor, and cross‐flow rate, respectively. The NF composite meets the water quality for the purposes of use in the dyeing process, the finishing process, and for general use in the production processes.
The Taguchi experimental design method was used to determine the optimum nanofiltration conditions for the reuse of treated textile wastewater, in a short time and with less cost. With this approach, small and medium‐sized enterprises will be able to integrate their facilities into the circular economy model, by the reuse of wastewater in their facilities.
Purpose
The aim of this research was to assess the health risk of textile wastewater reuse as irrigation water on leafy vegetable (
Basella alba
) by comparing variable growth rate in different ...ration of wastewater and freshwater irrigation and assess their soil-to-plant transfer factor (TF) and health risk index (HRI).
Methods
Pot experiments were laid out with five treatments including control with three replications with different irrigation schemes with textile wastewater collected from the untreated point source. The irrigation scheme was, 100 % groundwater as control with four treatments as 75 % groundwater: 25 % wastewater, 50 % groundwater: 50 % wastewater, 25 % groundwater: 75 % wastewater and 100 % wastewater.
Results
Soil-to-plant TF in different treatments including control were in the order of Pb (1.0–1.7) > Cu (1.3–1.5) > Cd (0.8–1.0) > Zn (0.1–1.1). TF values of Pb and Cu in the range from 1 to 1.7 indicating their accumulation in
B. alba
plants and their potential health risk by dietary exposure. The HRI for individual metal as well as cumulative HRI of the metals was less than unity (0.33) which indicated the consumption of the vegetables was considered to be safe for one harvest.
Conclusion
Over many seasons of irrigation with wastewater, level of salinity and heavy metals can accumulate on the agriculture land and their long term consumption may link to a chronic health risk. Hence, consumption of these vegetables on regular basis should be avoided.
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