Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n, 47011 Valladolid, Spain; Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina s/n, 47011 Valladolid, Spain.
Department of Civil and Environmental Engineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
Sci Total Environ. 2024 Jan 10;907:168083. doi: 10.1016/j.scitotenv.2023.168083. Epub 2023 Oct 24.
Piggery wastewater has become a large source of pollution with high concentrations of nutrients, that must be managed and properly treated to increase its environmental viability. Currently, the use of microalgae for treating this type of wastewater has emerged as a sustainable process with several benefits, including nutrient recovery to produce valuable products such as biostimulants, and CO capture from flue gases. However, the biostimulant production from biomass grown on piggery wastewater also has environmental impacts that need to be studied to identify possible hotspots. This work presents the life cycle assessment by IMPACT 2002+ method of the production of microalgae-based biostimulants, comparing two different harvesting technologies (membrane in scenario 1 and centrifuge in scenario 2) and two different technologies for on-site CO capture from flue gases (chemical absorption and membrane separation). The use of membranes for harvesting (scenario 1) reduced the environmental impact in all categories (human health, ecosystem quality, climate change, and resources) by 30 % on average, compared to centrifuge (scenario 2). Also, membranes for CO capture allowed to decrease environmental impacts by 16 %, with the largest reduction in the resource category (∼33 %). Thus, the process with the best environmental viability was achieved in scenario 1 using membranes for CO capture, with a value of 217 kg CO eq/FU. In scenario 2 with centrifugation, the high contribution of the cultivation sub-unit in all impacts was highlighted (>75 %), while in scenario 1 the production sub-unit also had moderate contribution in the human health (∼35 %) and climate change (∼30 %) categories due to the lower concentration and high flow rates. These results were obtained under a worst-case situation with pilot scale optimized parameters, with limited data which would have to be further optimized at industrial-scale implementation. The sensitivity analysis showed a little influence of the parameters that contribute the most to the impacts, except for the transportation of the piggery wastewater to the processing plant in scenario 2. Because of the relevant impact of biostimulant transportation in scenario 1, centrifugation becomes more favourable when transportation distance is longer than 321 km.
养猪废水已成为高浓度营养物的主要污染源，必须加以管理和适当处理，以提高其环境可持续性。目前，利用微藻处理这种废水已成为一种具有多种益处的可持续工艺，包括回收营养物以生产有价值的产品，如生物刺激素，以及从烟道气中捕获 CO。然而，从养猪废水中生长的生物质生产生物刺激素也会对环境产生影响，需要加以研究，以确定可能的热点。本工作采用 IMPACT 2002+方法对基于微藻的生物刺激素生产进行了生命周期评估，比较了两种不同的收获技术（方案 1 中的膜和方案 2 中的离心）和两种不同的烟道气 CO 就地捕获技术（化学吸收和膜分离）。与离心（方案 2）相比，膜用于收获（方案 1）可使所有类别（人类健康、生态质量、气候变化和资源）的环境影响平均降低 30%。此外，膜用于 CO 捕获可使环境影响降低 16%，其中资源类别（约 33%）的降幅最大。因此，在方案 1 中使用膜进行 CO 捕获的过程具有最佳的环境可行性，其 CO eq/FU 值为 217kg。在方案 2 中采用离心法时，在所有影响中，培养子单元的高贡献尤为突出（>75%），而在方案 1 中，由于浓度较低且流量较高，生产子单元在人类健康（约 35%）和气候变化（约 30%）类别中也有中等贡献。这些结果是在使用优化后的中试规模参数的最坏情况下得出的，使用的数据有限，在工业规模实施时需要进一步优化。敏感性分析表明，除了方案 2 中养猪废水输送到加工厂的情况外，对影响贡献最大的参数的影响不大。由于方案 1 中生物刺激素输送的相关影响，当输送距离超过 321km 时，离心法更为有利。
