Feasibility of recovering nitrogen (N)-fertilizers from sewage has gained attention recently due to concerns about the sustainability of the Haber-Bosch process in producing N-fertilizers and of the nitrification–denitrification processes in removing N from wastewaters. This study proposes a non-pressurized gas permeable membrane reactor (GPMR) with the potential to recover high-purity N-fertilizer at lower energy demand than current technologies. Performance of the GPMR in recovering N-fertilizer from the following two waste streams of sewage-origin is demonstrated: 1) centrate generated by anaerobic digestion of primary and secondary sludge; and 2) aqueous phase generated by hydrothermal liquefaction of sewage-grown algal biomass. A process model developed for the GPMR was calibrated using test results on a synthetic feed, and validated using results from the tests on the above two waste streams. Temporal ammoniacal-N concentrations predicted by the model agreed well with the measured values (r² = 0.82; n = 70). Tests conducted on the two wastes at 24–25 °C indicated that feed-side pH of 10 and mild mixing of the feed maximized N-fertilizer recovery. The GPMR was able to recover 80–100% of ammoniacal-nitrogen from both waste streams, yielding 2–86 g of ammonium sulfate from 1 L of the feed. Energy dispersive X-ray analysis and heavy metal analysis of ammonium sulfate recovered from both feeds confirmed compliance with the US Environmental Protection Agency limits for use as fertilizer. Confocal microscopic images of virgin and used membrane surfaces were examined to assess membrane fouling. A process intensification analysis was performed to relate the physical parameters to the performance of the GPMR and to identify areas for further studies.

由于人们对生产氮肥的哈伯-博世过程的可持续性以及从废水中去除氮的硝化-硝化过程的可持续性的关注，最近从污水中回收氮（N）肥料的可行性引起了人们的关注。这项研究提出了一种非加压气体渗透膜反​​应器（GPMR），它有潜力以比当前技术更低的能源需求来回收高纯度氮肥。证明了GPMR从以下两种污水来源的废液中回收氮肥的性能：1）厌氧消化一级和二级污泥产生的浓缩液；2）污水生长的藻类生物质水热液化产生的水相。使用合成饲料上的测试结果对为GPMR开发的过程模型进行了校准，并使用以上两种废物流的测试结果进行了验证。模型预测的时间氨氮浓度与测量值非常吻合（r²  = 0.82；n = 70）。在24–25°C下对这两种废物进行的测试表明，进料侧的pH值为10，并且进料的适度混合可以最大程度地提高氮肥的回收率。GPMR能够从两种废物流中回收80-100％的氨氮，从1 L的进料中产生2-86 g的硫酸铵。从两种进料中回收的硫酸铵的能量色散X射线分析和重金属分析证实符合美国环境保护局用作肥料的限制。检查原始膜和用过的膜表面的共聚焦显微图像，以评估膜污染。进行了过程强化分析，以将物理参数与GPMR的性能相关联，并确定需要进一步研究的领域。