Department of Civil Engineering, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil.
Department of Civil Engineering, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil.
Sci Total Environ. 2021 Oct 1;789:147861. doi: 10.1016/j.scitotenv.2021.147861. Epub 2021 May 21.
To optimize the swine wastewater (SWW) treatment, this study investigated different hydraulic retention times (HRTs) for microalgae cultivation. For this purpose, five pilot-scale reactors operated in semi-continuous flow, with HRTs equal to 9, 12, 15, 18, 21 days were evaluated in terms of SWW polishing and biomass production. The effluent treatment was discussed accompanied by principal component analysis, which allowed identification of causes of variance in the data set, ideal for studies with real effluent and influenced by environmental conditions. All reactors show satisfactory removals of N-NH (91.6-95.3%), COD (15.8-39.9%), DO increment (in average 7.5 mg O/L) and, only the longest HRT (21 days) was able to remove Ps (21%). The results obtained indicated that a consortium of microalgae and bacteria was developed for all the tested HRTs. On the other hand, HRT = 12 days provided a healthier culture of photosynthesizing organisms (chl-a/VSS = 3.04%). Carbohydrates (20.8-31.3%) and proteins (2.7-16.2%) were the compounds of commercial interest in the highest proportion in the biomass of all reactors, with contents comparable to that of terrestrial crops. Thus, it was suggested a valorization route of these compounds of high added value to return to pig farming, where the nutrients were intended to supplement the swine feed and clarified water for cleaning the pig stalls. Thus, in the circular economy context, this research contributes to water footprint reduction and the sustainability of the pig farming production chain. The economic and environmental analysis of the route is suggested to enable its implementation on a large scale, as well as further technical feasibility research (reactor types, exposure to external environment, evaluation of pathogen removal and animal feed supplementation from SWW microalgae biomass).
为了优化猪废水（SWW）处理，本研究考察了不同水力停留时间（HRT）对微藻培养的影响。为此，评价了五个以半连续流方式运行的中试规模反应器，HRT 分别为 9、12、15、18 和 21 天，以评估 SWW 抛光和生物量生产。伴随主成分分析讨论了出水处理，该分析允许识别数据集的方差原因，非常适合具有实际废水且受环境条件影响的研究。所有反应器均显示出对 N-NH（91.6-95.3%）、COD（15.8-39.9%）、DO 增量（平均 7.5 mg O/L）的去除效果令人满意，只有最长的 HRT（21 天）能够去除 Ps（21%）。结果表明，对于所有测试的 HRT，微藻和细菌的共生体得到了发展。另一方面，HRT = 12 天为光合生物提供了更健康的培养（chl-a/VSS = 3.04%）。在所有反应器的生物质中，碳水化合物（20.8-31.3%）和蛋白质（2.7-16.2%）以最高比例是具有商业价值的化合物，其含量与陆生作物相当。因此，建议采用这些高附加值化合物的增值途径，将其返回养猪业，在养猪业中，养分旨在补充猪饲料和清洁猪圈用水。因此，在循环经济背景下，本研究有助于减少水足迹并提高养猪生产链的可持续性。建议对该途径进行经济和环境分析，以使其能够大规模实施，并进一步进行技术可行性研究（反应器类型、暴露于外部环境、评估病原体去除和从 SWW 微藻生物质中补充动物饲料）。
