Incineration is one of the prevailing methods of sewage sludge management worldwide. However, the pollutants of NO_X, SO₂, and heavy metals emitted severely limit this disposal method during the incineration process. By adding baking soda to the co-hydrothermal carbonization process of sewage sludge and Chlorella vulgaris, this study improved the cleanliness of hydrochar. The characteristics of hydrochar produced with 0, 4, 8, and 12 g baking soda/15 g sample were evaluated. When added 8 g baking soda/15 g sample, the content of N and S in hydrochar dropped to the lowest, 0.98% and 0.16%, respectively. Compared with the hydrochar produced with no baking soda, the contents of N and S of hydrochar with 8 g baking soda/15 g sample decreased by 66.78% and 80.72%, respectively. TG-FTIR analysis shown that NO_X and SO_X emissions from the hydrochar combustion process were reduced. As for heavy metals, they can be divided into two categories. One is easy to combine with amino acids hydrolyzed from protein to dissolve in the liquid phase; the other is easy to combine with amino acids and sedimented as a part of hydrochar. The fixation ratios of Zn, Cr, Cu, and Mn of the hydrochar produced with 12 g baking soda/15 g sample reached 74.34%, 93.53%, 79.47%, and 81.74%, respectively. The comprehensive assessment using multi-dimensional decision-making methods showed that the hydrochar produced with 12 g baking soda/15 g sample had the best environmental friendliness.

焚烧是世界范围内污水污泥管理的主要方法之一。然而，NO _X、SO _{2 等}污染物，并且排放的重金属严重限制了焚烧过程中这种处理方法。本研究通过在污水污泥和小球藻的共水热碳化过程中加入小苏打，提高了水炭的清洁度。评估了用 0、4、8 和 12 克小苏打/15 克样品生产的氢化碳的特性。当添加8g小苏打/15g样品时，氢化炭中N和S的含量分别下降到最低，分别为0.98%和0.16%。与不加小苏打的水炭相比，8克小苏打/15克样品的水炭的N和S含量分别降低了66.78%和80.72%。TG-FTIR 分析表明 NO _X和 SO _X氢碳燃烧过程的排放量减少了。至于重金属，可分为两大类。一是易与蛋白质水解的氨基酸结合溶解在液相中；另一种易与氨基酸结合而沉淀为水炭的一部分。用12 g小苏打/15 g样品生产的水焦的Zn、Cr、Cu和Mn的固定率分别达到74.34%、93.53%、79.47%和81.74%。使用多维决策方法的综合评估表明，12 g小苏打/15 g样品生产的水焦具有最佳的环保性。