Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK.
J Environ Manage. 2023 Jul 15;338:117782. doi: 10.1016/j.jenvman.2023.117782. Epub 2023 Apr 2.
More people globally are now using on-site sanitation technologies than sewered connections. The management of faecal sludge generated by on-site facilities is still challenging and requires an understanding of all sanitation service chain components and their interactions; from source conditions to treatment and resource recovery. This study aimed to improve the current lack of knowledge regarding these interactions, by establishing a quantifiable relationship between human excreta source separation and resource recovery via pyrolysis. The effects of source separation of faeces and urine on biochar quality were investigated for different pyrolysis temperatures (450 °C, 550 °C, 650 °C) and this information was used to assess energy and nutrient recovery. Results quantify the benefits of urine diversion for nitrogen recovery (70% of total N losses during thermal treatment avoided) and show an increase in the liming potential of the produced faecal-based biochars. The quality of produced solid fuels is also improved when source-separated faeces (SSF) are used as a feedstock for pyrolysis, including a 50% increase in char calorific value. On the other hand, biochars from mixed urine and faeces (MUF) are more rich in phosphorus and potassium, and surface morphology investigation indicates higher porosity compared to SSF biochars. The high salinity of MUF biochars should be considered before agricultural applications. For both biochar types (SSF, MUF), the presence of phosphate compounds of high fertiliser value was confirmed by X-ray diffraction analysis, and temperatures around 500 °C are recommended to optimise nutrient and carbon behaviour when pyrolysing human excreta. These findings can be used for the design of circular faecal sludge management systems, linking resource recovery objectives to source conditions, and vice-versa. Ultimately, achieving consistent resource recovery from human excreta can act as an incentive for universal access to safe and sustainable sanitation.
现在，全球有更多的人在使用现场卫生技术，而不是污水连接。现场设施产生的粪便污泥管理仍然具有挑战性，需要了解所有卫生服务链组件及其相互作用；从源头条件到处理和资源回收。本研究旨在通过建立人类排泄物源分离与热解资源回收之间可量化的关系，改善当前对这些相互作用缺乏了解的状况。研究考察了粪便和尿液源分离对不同热解温度（450°C、550°C、650°C）下生物炭质量的影响，并利用这些信息评估了能源和养分回收。结果量化了尿液分流对氮回收的好处（避免了热处理过程中总氮损失的 70%），并表明所产生的基于粪便的生物炭的石灰化潜力增加。当使用源分离粪便（SSF）作为热解的原料时，所产生的固体燃料的质量也得到了改善，包括.Char 热值增加 50%。另一方面，混合尿液和粪便（MUF）的生物炭富含磷和钾，表面形态研究表明，与 SSF 生物炭相比，其具有更高的孔隙率。在农业应用之前，应考虑 MUF 生物炭的高盐度。对于这两种生物炭类型（SSF、MUF），通过 X 射线衍射分析证实了具有高肥料价值的磷酸盐化合物的存在，并且推荐在 500°C 左右的温度下进行热解，以优化营养物质和碳的行为。这些发现可用于设计循环粪便污泥管理系统，将资源回收目标与源条件联系起来，反之亦然。最终，从人类排泄物中实现一致的资源回收可以激励普遍获得安全和可持续的卫生设施。
