College of Engineering, China Agricultural University, Beijing 100083, PR China.
College of Engineering, China Agricultural University, Beijing 100083, PR China.
Sci Total Environ. 2019 Feb 20;652:623-632. doi: 10.1016/j.scitotenv.2018.10.302. Epub 2018 Oct 23.
This study investigated the effects of biochar seeding (wheat straw biochar and rice husk biochar) on nutrient recovery via struvite formation, and improvements in the particle size of precipitated struvite from anaerobic digestate supernatant. Simultaneously, the influence of biochar seeding on heavy metal accumulation and elimination of pathogens (total coliforms and Escherichia coli) was evaluated under various operational factors, e.g., pH, supersaturation, reaction time, and seeding rates. Compared to the non-seeding process (maximum recovery efficiency of phosphate and ammonium 91% and 83%, respectively, with a particle size of 70 μm) and the struvite-seeding process (maximum recovery efficiency of phosphate and ammonium 97% and 94%, respectively, with a particle size of 100 μm), the process of biochar seeding improved nutrient recovery up to 7% and 11% for phosphate and ammonium, respectively, and increased struvite particle size by 43%, regardless of biochar type. XRD diffraction and FTIR analysis confirmed the prevalence of orthorhombic characteristics and an inner crystalline structure of the struvite formed by biochar seeding. About 75% of total coliforms and 70% of Escherichia coli were removed from the digestate supernatant through seeded struvite precipitation, regardless of the seeding materials. However, the biochar seeding process led to an accumulation of heavy metals in the acquired struvite product than that with non-seeded precipitation process. The concentrations of these metals were still well below permissible limits for application on agricultural land. It can be concluded that the inclusion of biochar as a seeding material might be a sustainable strategy to enhance struvite formation, intensify nutrient recovery, and yield high-quality struvite fertilizer with increased particle sizes.
本研究探讨了生物炭接种（小麦秸秆生物炭和稻壳生物炭）对鸟粪石形成过程中养分回收的影响，以及改善厌氧消化液上清液中沉淀鸟粪石的颗粒大小。同时，在不同操作因素（如 pH 值、过饱和度、反应时间和接种率）下，评估了生物炭接种对重金属积累和病原体（总大肠菌群和大肠杆菌）去除的影响。与不接种过程（磷酸盐和铵盐的最大回收效率分别为 91%和 83%，颗粒大小为 70μm）和鸟粪石接种过程（磷酸盐和铵盐的最大回收效率分别为 97%和 94%，颗粒大小为 100μm）相比，生物炭接种过程可分别提高磷酸盐和铵盐的养分回收效率 7%和 11%，并将鸟粪石颗粒大小增加 43%，而与生物炭类型无关。XRD 衍射和 FTIR 分析证实了生物炭接种形成的鸟粪石具有正交特征和内部结晶结构。通过接种的鸟粪石沉淀，从消化液上清液中去除了约 75%的总大肠菌群和 70%的大肠杆菌，而与接种材料无关。然而，与非接种沉淀过程相比，生物炭接种过程导致获得的鸟粪石产品中重金属的积累。这些金属的浓度仍然远低于农业用地应用的允许限值。可以得出结论，将生物炭作为接种材料可能是一种可持续的策略，可以增强鸟粪石的形成，强化养分回收，并产生粒径更大的高质量鸟粪石肥料。
