Nitrification of high total ammonia nitrogen-strength wastewaters is challenging due to free ammonia (FA) inhibition of nitrification. FA inhibition can potentially be alleviated by temporarily adsorbing ammonium (NH₄⁺) to natural zeolite, such as chabazite, followed by direct zeolite bioregeneration via nitrification. In this research, the effectiveness of chabazite addition for reducing nitrification inhibition during treatment of centrate from anaerobic digestion of swine waste was quantified. A mathematical model was developed that accounts for ion exchange of NH₄⁺ and sodium at the chabazite surface, surface diffusion of adsorbed NH₄⁺ within the chabazite grains, sequential nitrification of aqueous NH₄⁺ to nitrite and nitrate, and inhibition of nitritation and nitratation rates by NH₄⁺. The model was calibrated using results of abiotic ion exchange and nitrification studies. Subsequently, nitrification tests were carried out with synthetic wastewater with a NH₄⁺-N concentration of 1000 mg L^–1, with and without chabazite. A chabazite dose of 150 g L^–1 decreased the FA concentration to below the inhibitory level and increased the nitrification rate from 0.16 to 0.36 mg-N (g-VSS)⁻¹ h^–1. Following calibration, the model could predict the experimental data with no additional fitting parameters or parameter adjustment, in both the presence and absence of chabazite. The results suggest that the mathematical model provides a theoretically sound conceptual understanding of ion exchange assisted nitrification.

中文翻译：

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厌氧消化的畜禽粪便中硝酸盐硝化过程中菱沸石的生物再生：实验和模型研究

由于游离氨（FA）抑制硝化作用，因此高总氨氮强度废水的硝化具有挑战性。通过将铵（NH ₄ ⁺）暂时吸附到天然沸石（菱沸石）上，然后通过硝化作用直接进行沸石生物再生，可以潜在地缓解FA抑制作用。在这项研究中，量化了菱沸石的添加对减少猪粪厌氧消化浓缩液处理中硝化抑制的有效性。的数学模型的开发，占NH的离子交换₄ ⁺在菱沸石表面和钠，吸附NH表面扩散₄ ⁺中的菱沸石颗粒，NH水性的连续硝化₄⁺生成亚硝酸盐和硝酸盐，并被NH ₄ ⁺抑制硝化和硝化速率。使用非生物离子交换和硝化研究的结果对模型进行了校准。随后，对有和没有菱沸石的NH ₄ ⁺ -N浓度为1000 mg L ^–1的合成废水进行了硝化试验。150 g L ^–1的菱沸石使FA浓度降至抑制水平以下，硝化速率从0.16 mg-N（g-VSS）^-1 h ^–1增加。校准后，无论菱沸石的存在与否，该模型都可以预测实验数据而无需额外的拟合参数或参数调整。结果表明，该数学模型为离子交换辅助硝化提供了理论上合理的概念理解。