Purification of a reactive dyes mixture solution by means of pre-hydrolysed coagulants in the standard tests and coagulating flow system

[Display omitted] •An innovative approach to optimizing coagulation using an automated flow system.•The pH pre-adjustment and Al-salts enables achieving high effective coagulation.•Combining dye baths can enhance of treating textile-dye wastewater.•Fast final filtration is an effective method of separating post-coagulation sludge. Reactive dyes, widely used in textiles, often leach into sewage due to incomplete bonding with fibers. Coagulation offers an effective solution, yet standard lab tests for coagulation efficiency lack realism and are significantly labour and time-consuming. To address this, a novel approach is proposed: optimizing coagulation through a prototype lab flow. This system automates solution flow, reagent dosing, coagulation, and sludge separation via sedimentation and filtration. Tests reveal effective coagulation of various reactive dyes with pre-polymerized Al coagulants, but limited efficacy with Fe(III) coagulant. The flow system demonstrates mostly better purification results than jar tests, achieving around 95% colour removal with Al coagulants. This study highlights the efficacy of coagulation and filtration in jar tests, offering a simplified yet efficient method for assessing coagulation performance.