Water reuse is an important consideration for water-intensive industries, including textile manufacturing. In denim production, washing processes require substantial amounts of water. Treating wastewater for reuse can help reduce freshwater demand, provided the treated water meets the requirements of its intended application.
But does wastewater reuse always require a complex treatment system? A study from Istanbul Technical University in Türkiye suggests that the answer depends on the required water quality.
Different Reuse Goals, Different Treatment Requirements
Published in the International Journal of Environmental Science and Technology in October 2026, the study examined membrane-based treatment strategies for denim wastewater. Researchers compared configurations involving coagulation, ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO).
The systems were evaluated against two reuse scenarios: literature-based washing-water criteria and the actual water quality requirements of a final washing tank in a modified reverse-washing process.
For the stricter, literature-based criteria, configurations combining coagulation pretreatment with NF or RO achieved 97 to 100 percent removal of chemical oxygen demand, suspended solids and color. Electrical conductivity and total dissolved solids were reduced by 96 to 97 percent.
By comparison, a standalone UF system operating at 5 bar met the requirements of the second reuse scenario, achieving an overall water recovery rate of 81 percent. Meeting the stricter, literature-based criteria required a more complex coagulation plus NF/RO configuration, which achieved a total water recovery rate of 69 percent.
The study also reported an 80 to 85 percent reduction in total treatment costs when reuse criteria were based on actual operational needs rather than the literature-based washing criteria. This finding applies to the specific scenarios evaluated and should not be interpreted as a universal cost reduction for textile wastewater treatment.
Source: Koroglu et al., 2026. International Journal of Environmental Science and Technology, Volume 23, Issue 10, Article 640. Read the original study.
Choosing the Right Membrane Process
These findings highlight the importance of matching treatment technology to the intended reuse application.
UF is generally effective for removing suspended solids, colloidal particles and some larger organic matter. NF and RO can provide greater removal of dissolved substances, including salts, depending on membrane characteristics, feedwater composition and operating conditions.
Where dissolved salt reduction is essential, RO can play an important role in achieving the required water quality. Appropriate pretreatment can also help control membrane fouling and support stable system operation, although its effectiveness depends on the wastewater composition and overall process design.
The objective is not simply to maximize contaminant removal. Water quality requirements, recovery rate, operating conditions and treatment costs must be considered together when selecting a treatment configuration.
What This Means for Industrial RO Applications
For textile wastewater reuse and other industrial applications, RO membrane selection should consider feedwater quality, required salt rejection, permeate flow and operating pressure. These factors need to be evaluated together within the complete treatment system.
HJC develops industrial RO membrane solutions for water-treatment applications where dissolved-salt reduction is required. Understanding the intended reuse conditions and pretreatment requirements helps engineers determine whether RO is appropriate for a particular application.
The key lesson is that effective wastewater reuse depends on choosing a treatment configuration that meets the required water quality while balancing recovery, operating requirements and cost. The most complex system is not necessarily the most appropriate one.
Research Reference
Koroglu, E. O., et al. (2026). Membrane-based treatment strategies for textile wastewater reuse: Assessing reuse criteria with operational needs. International Journal of Environmental Science and Technology, 23(10), Article 640.