School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), City Campus, Broadway, NSW 2007, Australia; City Water Technology, 2072 Sydney, Australia.
Department of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology, 283 Goyang-Daero, Ilsanseo-Gu, Goyang-Si,Gyeonggi-Do, 10223, Republic of Korea.
Water Res. 2020 Nov 1;186:116320. doi: 10.1016/j.watres.2020.116320. Epub 2020 Aug 19.
Urine dilution is often performed to avoid clogging or scaling of pipes, which occurs due to urine's Ca and Mg precipitating at the alkaline conditions created by ureolysis. The large salinity gradient between urine and flushing water is, theoretically, a source of potential energy which is currently unexploited. As such, this work explored the use of a compact reverse electrodialysis (RED) system to convert the chemical potential energy of urine dilution into electric energy. Urine' composition and ureolysis state as well as solution pumping costs were all taken into account. Despite having almost double its electric conductivity, real hydrolysed urine obtained net energy recoveries E of 0.053-0.039 kWh/m, which is similar to energy recovered from real fresh urine. The reduced performances of hydrolysed urine were linked to its higher organic fouling potential and possible volatilisation of NH due to its high pH. However, the higher-than-expected performance achieved by fresh urine is possibly due to the fast diffusion of uncharged urea to the freshwater side. Real urine was also tested as a novel electrolyte solution and its performance compared with a conventional KFe(CN)/KFe(CN) couple. While KFe(CN)/KFe(CN) outperformed urine in terms of power densities and energy recoveries, net chemical reactions seemed to have occurred in urine when used as an electrolyte solution, leading to TOC, ammonia and urea removal of up to 13%, 6% and 4.4%, respectively. Finally, due to the migration of K, NH and PO, the low concentration solution could be utilised for fertigation. Overall, this process has the potential of providing off-grid urine treatment or energy production at a household or building level.
尿液稀释通常用于避免管道堵塞或结垢，这是由于尿液中的 Ca 和 Mg 在尿解产生的碱性条件下沉淀所致。尿液和冲洗水之间的大盐度梯度理论上是一种潜在能量源，但目前尚未得到利用。因此，本工作探索了使用紧凑型反渗透（RED）系统将尿液稀释的化学势能转化为电能。考虑了尿液的组成和尿解状态以及溶液泵送成本。尽管实际水解尿液的电导率几乎是其两倍，但仍获得了 0.053-0.039 kWh/m 的净能量回收率 E，与从实际新鲜尿液中回收的能量相似。水解尿液的性能降低与其较高的有机污染潜力以及由于其较高的 pH 值而可能导致 NH 的挥发有关。然而，由于未带电的尿素向淡水侧快速扩散，新鲜尿液的性能高于预期。还将实际尿液用作新型电解质溶液，并将其性能与传统的 KFe(CN)/KFe(CN) 对进行了比较。虽然 KFe(CN)/KFe(CN) 在功率密度和能量回收方面优于尿液，但当用作电解质溶液时，尿液似乎发生了净化学反应，导致 TOC、氨和尿素的去除率分别高达 13%、6%和 4.4%。最后，由于 K、NH 和 PO 的迁移，低浓度溶液可用于施肥。总的来说，该工艺有可能在家庭或建筑物层面提供非联网的尿液处理或能源生产。
