Utilization of rain tree (Samanea saman) residue as modified adsorbent to treat oil and grease in canteen wastewater

Abstract

The utilization of waste materials as adsorbent precursors is gaining intention to treat fats, oils, and greases (FOG), especially in wastewater treatment. Tree residue, an abundant waste, provides a potential feedstock to be converted into valuable materials. This research aimed to develop modified adsorbent prepared from rain tree (Samanea saman) residue for FOG treatment. The synthesis process of modified adsorbent was conducted by chemical pretreatment using different chemical agents (i.e., NaOH, ZnCl2, and H3PO4­). The pre-treated twigs and leaves (1:4 ratio) were continued by pyrolysis process at different temperatures (i.e., 350, 550, and 750oC) using a heating rate of 10oC min-1 for 2 h. A batch sorption screening test was initially conducted for removing FOG from synthetic oily wastewater, and the ANOVA was employed to define the best-modified adsorbent among treatments. The result confirmed that modified adsorbent by H3PO4-treated and produced at 350oC had the highest net efficiency of FOG removal, with a yield and removal percentage of 55.87±1.40 and 79.77±1.17%, respectively. The adsorption studies of the best-modified indicated that the pseudo-second-order kinetic and Langmuir isotherm models were well-fitted to the experiment data. The maximum adsorption capacity of FOG was found to be 6.89 mg g-1. Fourier transform infrared spectroscopy (FTIR) result exhibits the present carbonyls, hydroxyls, and aliphatic groups. Scanning Electron Microscope (SEM) image showed the porous structure on the surface. The subsequent identification of the best-modified adsorbent was carried out by fixed-bed column test and performed optimum condition for canteen wastewater treatment by setting 10 cm bed height and flow rate 5 ml min-1. However, the breakthrough point could not be identified due to the column clogging (12 h). Overall, modified adsorbents produced had the ability to remove FOG, which indicated that rain tree residue could be utilized as an alternative adsorbent precursor for FOG treatment.