Beijing Forestry University, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing, 100083, People's Republic of China.
School of Environment, Tsinghua University, Beijing, 100084, People's Republic of China.
Environ Geochem Health. 2019 Aug;41(4):1767-1776. doi: 10.1007/s10653-017-9986-6. Epub 2017 May 26.
The recovery of phosphate from human urine has been considered as one of the most attractive benefits of urine source separation because P is an essential but limited macronutrient. This study investigated the approach to modify wood waste biochar via metal oxides aiming to recover phosphate from human urine to produce a value-added biochar. Results showed the phosphate removal ability was enhanced for the modified biochar pre-treated in modification solutions of MgCl, AlCl, CaCl and FeCl, respectively, while natural biochar released phosphate to urine. Among the tested biochar, Mg-biochar presented the best capacity for phosphate removal from the hydrolyzed urine, reaching 118 mg g at a MgCl concentration of 2.3 M. However, higher MgCl concentration would not further increase the adsorption capacity. Fitting of the adsorption kinetics and isotherms indicated that the phosphate removal process was probably controlled by multiple mechanisms. Both the experimental and fitting results confirmed that the content of Mg oxides was the key factor determining the adsorption rate and capacity of phosphate on Mg-biochar. pH ranges of 7-9 and the ammonium concentration higher than 108 mg L enhanced the phosphate adsorption capacity. As such, the Mg-biochar was more favored for the treatment of hydrolyzed urine rather than fresh urine with acidic pH and lower concentration of ammonium. Further calculations were carried out using the Langmuir model to evaluate the removal of phosphate and the product. Results indicate that it is an effective technique to use Mg-biochar for phosphate removal from hydrolyzed urine and it yields phosphate-enriched biochar products.
从人类尿液中回收磷酸盐被认为是尿液源分离最具吸引力的好处之一，因为磷是一种必需但有限的大量营养素。本研究通过金属氧化物来改性木屑生物炭，旨在从人类尿液中回收磷酸盐以生产具有附加值的生物炭，从而研究了这种方法。结果表明，用 MgCl、AlCl、CaCl 和 FeCl 分别预处理改性溶液的改性生物炭具有增强的磷酸盐去除能力，而天然生物炭则向尿液中释放磷酸盐。在所测试的生物炭中，Mg-生物炭在 2.3 M 的 MgCl 浓度下对水解尿液中磷酸盐的去除能力最强，达到 118 mg/g。然而，更高的 MgCl 浓度不会进一步增加吸附能力。吸附动力学和等温线的拟合表明，磷酸盐去除过程可能受多种机制控制。实验和拟合结果均证实，Mg 氧化物的含量是决定 Mg-生物炭对磷酸盐吸附速率和吸附容量的关键因素。pH 值范围为 7-9 以及铵浓度高于 108 mg/L 可增强磷酸盐的吸附能力。因此，Mg-生物炭更有利于处理水解尿液，而不是 pH 值较低且铵浓度较低的新鲜尿液。进一步使用 Langmuir 模型进行计算，以评估磷酸盐的去除和产物。结果表明，用 Mg-生物炭从水解尿液中去除磷酸盐是一种有效的技术，可得到富含磷酸盐的生物炭产品。
