Characterization of natural Yemeni zeolites as powder sorbents for ammonium valorization from domestic waste water streams using high rate activated sludge processes

Abstract

BACKGROUND In this study three natural Yemeni zeolites (NZ1, NZ2 and NZ3) having major minerals such as clinoptilolite and mordenite, were evaluated as low cost sorbents for the removal and recovery of ammonium ions. RESULTS The zeolite samples, with pHPZC = 9.1 ± 0.2, 7.9 ± 0.2 and 7.4 ± 0.2 for NZ1, NZ2 and NZ3, respectively, showed high ammonium sorption capacities. At pH 8, for treated waste waters: (i) with low NH4+ levels (from 25 to 100 mgNH4/L); and (ii) for concentrated NH4+ side streams generated from the anaerobic digestion of sewage sludge (from 400 up to 1500 mg L‐1), maximum loading capacities of 27 to 51 mgNH4 g‐1 were measured for the studied zeolites. Measured sorption isotherms, in the concentration range 0.05 to 5 g L‐1, were well described by the Langmuir isotherm. The ammonium sorption kinetics was controlled by particle diffusion and was well described by both the homogeneous diffusion (HPDM) and shell progressive (SPM) models. CONCLUSION Comparison of the equilibrium data with results for natural and synthetic zeolites demonstrate the higher performance of the studied zeolites providing low residual ammonium values <1 mgNH4 g‐1 and <10 mgNH4 g‐1 when treating both diluted and concentrated‐NH4+ streams, respectively. © 2017 Society of Chemical Industry

Physical and mineral characterisation of natural zeolites from Taiz, South-western Yemen

“…Comparatively, the geochemical composition of zeolite in this research were found to be comparable with previous reports (Alshameri et al, 2019;JMayai et al, 2018;Shaban and Abu Khadra, 2017). The mean ratio of SiO :Al O for representative 2 2 3 zeolite sample from the studied area is in the range of 6.34-6.98.…”

Zeolites for Nitrogen Recovery from the Anaerobic Membrane Bioreactor Permeate: Zeolite Characterization

“…As can be seen in Table 4, the Langmuir model fits better with the experimental data, as has been found by many other authors [12,13,18] who emphasise the fact that both models fit correctly when working with low ammonium values, but for higher concentrations, only the Langmuir model allows a good fit. This is because the Freundlich model does not consider an intrinsic limit to the zeolite capacity while the Langmuir model considers that all the adsorbent material has a limited number of exchange points.…”

“…Furthermore, the procedure employed in this research based on adjusting the pH after activation by means of CO 2 stripping allows the decrease of the amount of washing water in 90% compared adjusting the pH of the zeolite by successive washings. As can be seen in Table 4, the Langmuir model fits better with the experimental d as has been found by many other authors [12,13,18] who emphasise the fact models fit correctly when working with low ammonium values, but for higher concen tions, only the Langmuir model allows a good fit. This is because the Freundlich m does not consider an intrinsic limit to the zeolite capacity while the Langmuir model siders that all the adsorbent material has a limited number of exchange points.…”

“…The ammonium sorption kinetic data for N-Z are similar to those of the conventional zeolite behaviour described in other studies (Figure 1). In the first 20 min, ammonium adsorption reached 50%; after that fast step, the ammonium removal rate dropped, indicating that particle diffusion controls the sorption rate process, as has been observed in previous studies [12][13][14]. An amount of 90% ammonium adsorption was reached after 3 h, and after 4 h, the increase in ammonium removal was negligible, indicating equilibrium has been reached.…”

“…Figure 4 shows the fitting of the Na-Z experimental data with the Langmuir and Freundlich isothermal models. It should be noted that unlike other works that studied maximum adsorption capacity of the zeolite working with high ammonium concentrations [12,24], in this work, the ammonium concentration, obtained from AnMBR permeate, was significantly low.…”