The application of locally synthesized clay-based adsorbents for the removal of nutrients from brewery wastewater

Abstract

Nutrients are a major category of environmental pollutants that can cause severe environmental problems. Therefore, this study aimed to develop a promising adsorbent from local clay for removing nutrients from brewery wastewater. The study mainly focused on the removal of NH3, PO₄3⁻, NO3− and H2S from the industrial wastewater. The adsorbent was prepared using a solution containing 1 M Na2CO3, 0.5 M citrate, and 2 M NaCl to remove inorganic impurities, and H2O2 to remove organic impurities. The treated clay was dried, ground, and sieved using a sieve size between 63 µm and 1 mm. Working nutrient solutions were obtained from the stock solution through several dilution processes. The maximum adsorption capacity of local clay for NH3, PO₄3−, NO3− and H2S was found to be greater than 90% at various pH ranges of 2 to 11 under optimum operating conditions of 11 g adsorbent dose and 120 min, respectively. In a similar application of real wastewater, the results showed that local clay reduced NH3 from its initial concentration of 0.764 mg/L to 0.377 mg/L, PO₄3− from 6.834 mg/L to 2.464 mg/L, NO3− from 4 mg/L to 1.2 mg/L, and H2S from 2 mg/L to 0.23 mg/L. The adsorption process was fitted to the Freundlich isotherms, with some deviations and maximum adsorption capacities of 0.53, 0.44, 0.02, and 0.68 mg/g for NO3, PO4, NH3, and H2S, respectively. Similarly, the linear pseudo-second-order model provided an excellent fit to the experimental data, with correlation coefficients of 0.996 for NO₃⁻, 0.999 for PO₄3−, 0.997 for NH₃, and 0.999 for H₂S, indicating that the adsorption process is better defined by pseudo-second-order kinetics. Finally, it can be concluded that this clay has potential adsorptive capacity for the removal of NH3, PO₄3−, NO3−, and H2S from aqueous solutions.