Zero Liquid Discharge installation for purifying and reusing up to 95% of textile wastewater at key Bangladesh suppliers

Bangladesh is a major global producer of ready-made garments (RMG), with annual exports exceeding USD 42 billion. However, the majority of RMG/textile producers utilise linear water treatment systems which depend heavily on freshwater extraction from groundwater sources/aquifers. These systems often only provide minimal wastewater treatment before discharging the water into rivers or stormwater systems. At the same time there are very few economic incentives (if any) for textile producers to adopt circular principles and treat their wastewater for reuse which consequently discourages investments in more advanced Zero Liquid Discharge (ZLD) water treatment solutions.

To address this issue, Solidaridad Network Asia Limited have partnered with QStone Capital B.V to co-lead a pilot project which aims to develop a comprehensive business case for the adoption of sustainability measures by RMG/textile factories in Bangladesh. This initiative will highlight innovative technologies through the implementation of a modular ZLD system to demonstrate its technical robustness, and develop a supporting business case based on collecting capital via a 1% surcharge on consumer purchases. The funds raised will be managed separately and independently through an auditable structure and be used to finance ongoing sustainability and social initiatives, thereby ensuring long-term environmental and economic benefits being fully aligned.

ZLD water treatment typically involves 6-7 steps to process wastewater into reusable water within the same production process, promoting a circular production model. During the crucial first step, pre-treatment, electro-coagulation is introduced to eliminate compounds harmful to subsequent purification steps. This approach reduces costs in terms of chemical usage and greenhouse gas (GHG) emissions related to it, and enhances the efficiency of later, more expensive treatment stages. The project will construct a pilot installation to demonstrate a ZLD system capable of recovering and treating textile dyeing and washing wastewater for reuse within the production process. The proposed ZLD installation aims to achieve up to 95% water savings and reuse rates while eliminating any treated water discharge.

The installation incorporates innovative techniques at two key wastewater treatment stages:

1. Electro-coagulation 2.0: An advanced innovation at the pre-treatment stage that reduces total treatment costs per cubic meter.
2. ⁠Evaporation and Crystallisation: A critical, often costly step, that converts brine (concentrated liquid salts) into dry matter following membrane treatment.

These innovations can collectively reduce total ZLD costs per cubic meter by up to 50%, enabling textile producers to recycle and reuse their wastewater. This approach offers significant environmental benefits by eliminating polluted wastewater discharge and reducing freshwater extraction from the soil, thereby promoting resource efficiency and circularity.