将污水中的磷回收并在农田中供作物再利用是一个同时解决水体磷污染和磷肥来源紧缺难题的方法。而小球藻已经被证明了可以高度富集污水中的磷，并将富集后的磷以聚磷酸盐的形式贮存在细胞内。同时水热炭化法可以通过调节水热反应中水体pH从而促进聚磷酸盐的水解。因此本研究采用水热炭化法，通过控制反应条件制得不同的水热生物炭，并进行物理化学表征，以及水稻盆栽实验筛选出最佳的可以提高磷利用效率的水热生物炭。之后，建立根箱体系，结合核磁共振光谱分析技术揭示水热生物炭中的磷在水稻根际的释放以及被根系吸收的机理。本次研究包括水热炭化法制作富磷小球藻水热生物碳，盆栽实验筛选水稻磷利用率最高的水热生物碳，和根箱实验分析水热生物碳中的磷在水稻根际的迁移转化机理。通过这些实验研究富磷小球藻水热生物碳的稻田减磷增效应用和机制，最终希望实现磷从污水向作物－农田中的循环。

Recovering phosphorus from the wastewater and applying these phosphorus resources to the farmland can solve the issues of phosphorus pollution in water and limitation of phosphate rock, the resources of phosphorus fertilizer. The chlorella vulgaris has been demonstrated to own the capacity to enrich the phosphorus from the wastewater, and store phosphorus within cells in the form of polyphosphate. Moreover, the hydrothermal carbonization is able to promote the degradation of polyphosphate by adjusting the pH in the reaction solution. Therefore, the hydrothermal carbonization is used in this research and different varieties of hydrochar will be fabricated under different reaction conditions. The hydrochar that most increases the phosphorus utilization efficiency by rice will be screened by characterizing the hydrochar and evaluating the nutrients uptake and growth after pot experiment. Afterwards, combined application of rhizobox system and nuclear magnetic resonance spectrum will reveal the mechanism of how phosphorus is released from the hydrochar to the rhizosphere of rice and taken up by the rice. This study contains three experiments: 1) fabricating phosphorus-rich chlorella vulgaris hydrochar; 2) screening the hydrochar that most increase the phosphorus uptake rate by rice; 3) conducting rhizobox experiment to analyze the mechanism with respect to phosphorus of chlorella vulgaris hydrochar transformation and mobilization in the rhizopshere of rice. We aim to research on the mechanism of applying the phosphorus-rich chlorella vulgaris hydrochar to the paddy soil to increase the phosphorus utilization rate, and hope to achieve the recycling of phosphorus from wastewater to crop-soil system.