Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK.
Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK.
Water Res. 2020 Feb 1;169:115253. doi: 10.1016/j.watres.2019.115253. Epub 2019 Nov 1.
Unsafe disposal of faecal sludge from onsite sanitation in low-income countries has detrimental effects on public health and the environment. The production of biochar from faecal sludge offers complete destruction of pathogens and a value-added treatment product. To date, research has been limited to the laboratory. This study evaluates the biochars produced from the co-treatment of faecal sludge from septic tanks and agricultural waste at two full-scale treatment plants in India by determining their physical and chemical properties to establish their potential applications. The process yielded macroporous, powdery biochars that can be utilised for soil amendment or energy recovery. Average calorific values reaching 14.9 MJ/kg suggest use as solid fuel, but are limited by a high ash content. Phosphorus and potassium are enriched in the biochar but their concentrations are restricted by the nutrient-depleted nature of septic tank faecal sludge. High concentrations of calcium and magnesium led to a liming potential of up to 20.1% calcium carbonate equivalents, indicating suitability for use on acidic soils. Heavy metals present in faecal sludge were concentrated in the biochar and compliance for soil application will depend on local regulations. Nevertheless, heavy metal mobility was considerably reduced, especially for Cu and Zn, by 51.2-65.2% and 48.6-59.6% respectively. Co-treatment of faecal sludge with other carbon-rich waste streams can be used to influence desired biochar properties. In this case, the addition of agricultural waste increased nutrient and fixed carbon concentrations, as well as providing an additional source of energy. This study is a proof of concept for biochar production achieving full-scale faecal sludge treatment. The findings will help inform appropriate use of the treatment products as this technology becomes more commonly applied.
在低收入国家，现场卫生设施产生的粪便污泥如果处理不当，会对公共卫生和环境造成有害影响。从粪便污泥中生产生物炭可以完全破坏病原体，并提供增值处理产品。迄今为止，研究仅限于实验室。本研究通过确定来自印度两个全规模处理厂的化粪池粪便和农业废物共处理产生的生物炭的物理和化学性质，评估了从粪便污泥中生产生物炭的潜力及其应用。该工艺产生了大孔、粉末状的生物炭，可用于土壤改良或能源回收。平均热值达到 14.9 MJ/kg 表明可作为固体燃料使用，但由于灰分含量高而受到限制。磷和钾在生物炭中得到了富集，但由于化粪池粪便的营养物质匮乏，其浓度受到限制。高浓度的钙和镁导致石灰化潜力高达 20.1%的碳酸钙当量，表明适用于酸性土壤。粪便污泥中存在的重金属在生物炭中浓缩，其土壤应用的合规性将取决于当地法规。尽管如此，重金属的迁移性通过 51.2-65.2%和 48.6-59.6%分别降低了 Cu 和 Zn 的重金属的迁移性，特别是 Cu 和 Zn。与其他富碳废物流共处理粪便污泥可以用来影响所需的生物炭特性。在这种情况下，添加农业废物增加了养分和固定碳的浓度，并提供了额外的能源来源。本研究是生物炭生产实现全规模粪便污泥处理的概念验证。这些发现将有助于为这项技术的广泛应用提供适当的处理产品使用信息。
