Inorganic ion accumulation model in wastewater recycling systems: Printing and dyeing case

To solve the problem of inorganic ion accumulation in the recycling process of printing and dyeing wastewater, a mathematical model based on cycle-index and removal efficiency was proposed. The model's capacity to describe the ion accumulation was essentially confirmed through simulation and pilot tests. Results indicated that this model can better predict total dissolved solids (TDS), although the prediction results for specific ions require further refinement. With fewer than 60 cycles, TDS in the pilot system could be reliably predicted. Sensitivity analysis revealed that, when TDS, SO₄²⁻, Fe, and Mn in the effluent were considered control targets, the number of cycles, water flow, total inorganic salts added, and the recycling efficiency of printing and dyeing wastewater significantly influenced the prediction equation.