Removal of heavy metal ions from its low concentrated lake water via LiBr/PES hollow fiber membrane module system

The treatment of river or lake water for heavy metal removal is of special concern due to their persistence and recalcitrance in the environment. In the current study, an ultrafiltration (UF) system consisting of polyethersulfone (PES) UF hollow fiber (HF) membranes spun from Liberia doped solutions was used for the removal of most critical, heavy metals (Mg²⁺, K⁺, Ca²⁺, Mo²⁺, Cr²⁺, Mn²⁺, Ni²⁺, Cu²⁺, Pb²⁺, Zn²⁺, As³⁺, Na¹⁺, Fe²⁺, Cd²⁺, and Co²⁺) and Cl¹⁻ ions from lake water at high-flux rate filtration through the commercial grade filtration setup. The 300 UF HF having potted length of 1.07 m with 0.95 m² of total permeation surface area was positioned on the final stage in a commercial grade module consisting of multimedia filter, iron filter, active carbon filter, and water softener filter. In addition, the performance of formulated HF membranes was characterized in terms of raw lake water flux, turbidity, total dissolved solids, water hardness, chemical oxygen demand (COD), and biochemical oxygen demand (BOD) experiments. The results revealed that the UF filtration system cleaned the water at a high flux rate (417 L/h) with a reduction of 58% water hardness, 77.4% turbidity, 73.7% BOD, and 67.76% COD. Moreover, PES/LiBr HF showed electrostatic repulsion on most of the dissolved heavy metals and 74% of total tested heavy metals demonstrated 44–99% rejection rate of passing through the membranes.