Industrial wastewater recovery and reuse: strategies for sustainable water management

Why reuse industrial wastewater today: turning a cost into a resource

Industrial wastewater reuse means treating process effluent to a quality level compatible with a non-potable application and reintroducing it into the facility, reducing both freshwater withdrawals and discharge volumes. This strategy is especially effective in water-intensive industries and, more broadly, in contexts where water availability is critical or discharge costs are high.

In this scenario, Idro Group designs and delivers industrial wastewater treatment plants with the goal of recovering and reusing water within the production cycle, while also ensuring compliance with legal discharge limits when the treated water is released to the environment.

Industrial water reuse and wastewater minimization: strategy comes before technology

Before selecting a treatment technology, the most effective approach to industrial wastewater reuse starts with a phased management strategy: reduce, segregate, treat and reuse.

In practice, the best results are achieved when a company builds an accurate water balance, identifying where water enters the site, which departments consume it, and at what points it becomes wastewater. From there, it becomes easier to segregate different wastewater streams—for example, separating relatively less contaminated rinse water from more concentrated process discharges. Segregation improves treatment efficiency and produces a more stable, predictable reclaimed water quality.

At that stage, it becomes possible to define a truly fit-for-purpose reuse strategy, calibrated to real operational needs: the water quality required for cooling, washing, dust suppression, or other non-potable processes is not always the same and these differences drive both treatment train selection and cost structure.

In a context of increasing water scarcity, the European Union recognizes reuse as a lever to reduce pressure on water bodies and enhance climate resilience—provided that treatment is appropriate and management is correctly implemented.

Most common treatment trains for industrial wastewater recycling

Industrial wastewater reuse requires a treatment train designed around the specific wastewater matrix (industry sector, chemicals used, variability of loads) and the final intended reuse application. Unlike municipal wastewater, industrial effluents may contain oils and emulsions, fine suspended solids, surfactants, metals, process chemicals, and concentration peaks, making a customized approach essential.

In general, the most effective scheme follows the logic: reduce – segregate – treat – reuse, including:

• Flow reduction and stream segregation: separating more concentrated streams (e.g., baths, regenerations, critical wash water) from those more “reusable” (e.g., rinses) improves stability and reduces treatment costs.

• Physico-chemical pretreatment: equalization, pH adjustment, coagulation/flocculation, flotation/sedimentation are used to remove suspended solids, colloids, oils, and part of the non-biodegradable contaminant load.

• Biological treatment (when applicable): useful for reducing biodegradable organic load and improving downstream treatability.

• Polishing for reuse:advanced filtration and, when required by target quality, membrane processes (UF/NF/RO) and disinfection, to produce water suitable for specific non-potable plant applications.

Within this framework, Idro Group approaches industrial wastewater treatment as a set of engineered solutions designed around discharge characteristics and end goals (discharge compliance and/or recovery where applicable), using treatment logics aligned with sector requirements and regulatory context.

Reuse applications and savings metrics: how to estimate ROI

The most common applications for industrial wastewater reuse are those where reclaimed water does not need to meet drinking-water standards and does not come into contact with the product. In practice, treated water is often reused for:

• Cooling systems (make-up for cooling towers and auxiliary circuits), with careful verification of chemical quality and risk of scaling, corrosion, and biofouling.
   
• Industrial washing and utility services (yards, pre-wash, technical cleaning), where required quality depends on the type of soil and internal requirements.
   
• Support processes (e.g., dust suppression, equipment washing, and other non-potable uses), depending on department specifications.
   

To determine whether the investment is economically justified, it helps to define a short set of clear indicators (KPIs) and compare “before vs. after” implementation:

• m³/year of freshwater avoided and the corresponding % reduction in withdrawals.
   
• m³/year of discharge avoided and the reduction in related costs (transportation, disposal, external treatment, or discharge fees).
   
• kWh and chemicals per m³ treated, to assess overall efficiency and avoid situations where water savings are offset by excessive energy consumption.
   

Overall, industrial wastewater reuse can significantly reduce both freshwater withdrawals and discharge volumes, delivering economic and environmental benefits. Results depend on influent wastewater quality and variability, required reclaimed water quality for the final use, and the continuity of process loads. For this reason, initial assessment and wastewater characterization are essential to set realistic goals and select the most suitable treatment train.

If you want to evaluate industrial wastewater recovery and reuse at your facility in practical terms, contact us. Idro Group can support you with initial analysis and wastewater characterization, define realistic reuse objectives and savings KPIs, and design a treatment plant aligned with your wastewater matrix and regulatory requirements.