Phosphorus and Arsenic Removal Characteristics of FMBO-S Adsorbent and Its Field Applicability to Arsenic-Contaminated Groundwater in Punjab, Pakistan

This study evaluated the phosphorus and arsenic removal characteristics of starch-stabilized ferromanganese binary oxide (FMBO-S) and examined its applicability to actual arsenic-contaminated groundwater in Punjab, Pakistan. In the field water-quality investigation, 954 groundwater samples were collected from 117 sites, and arsenic contamination exceeding both the Pakistani drinking-water standard of 50 μg/L and the World Health Organization (WHO) guideline value of 10 μg/L was identified in some samples. Microbial contamination, total dissolved solids (TDS), and nitrate nitrogen were also observed in the study area, indicating the need to evaluate treatment technologies under actual groundwater conditions. FMBO-S showed an increased average pore diameter and mesopore fraction compared with ferromanganese binary oxide (FMBO), and its Langmuir maximum adsorption capacity in the adsorption isotherm test was 61.24 mg/g. In the continuous-flow test using actual groundwater, FMBO-S showed arsenic removal of 352–463 μg/g per unit mass of adsorbent, which was higher than those of magnetite and basalt. In the arsenic batch test, the adsorption behavior of FMBO-S was well described by the pseudo-second-order kinetic model. Therefore, FMBO-S was evaluated as a candidate adsorbent whose follow-up applicability could be expanded after further verification of mass production, coexisting ion effects, long-term breakthrough performance, and unit treatment cost.