Department of Health, Animal Science and Food Safety, Faculty of Veterinary Medicine, University of Milan, via Celoria, 10, 20133, Milan, Italy.
Department of Veterinary Medicine, Faculty of Veterinary Medicine, University of Milan, via Celoria, 10, 20133, Milan, Italy.
Environ Sci Pollut Res Int. 2017 Nov;24(31):24135-24146. doi: 10.1007/s11356-017-0011-5. Epub 2017 Sep 7.
The aim of this experimental study was to evaluate the influence of anaerobic digestion and storage on indicator microorganisms in swine and dairy excreta. Samples were collected every 90 days for 15 months at eight farms, four pig, and four dairy farms, four of them having a biogas plant. Moreover, to evaluate storage effects on samples, 20 l of manure and slurry taken at each farm (digested manure only in farms with a biogas plant) were stored in a controlled climatic chamber at 18 °C, for 6 months. The bacterial load and the chemical-physical characteristics of excreta were evaluated at each sampling time, stored slurry, and manure were sampled and analyzed every 2 months. A high variability of the concentration of bacteria in the different excreta types was observed during the experiment, mainly depending on the type and time of treatment. No sample revealed either the presence of Escherichia coli O157:H7 or of Salmonella, usually linked to the temporary rearing of infected animals in facilities. Anaerobic digestion and storage affected in a significant way the reduction of indicator bacteria like lactobacilli, coliforms, and streptococci. Anaerobic digestion lowered coliforms in pig slurry (- 2.80 log, P < 0.05), streptococci in dairy manure (- 2.44 log, P < 0.001) and in pig slurry (- 1.43 log, P < 0.05), and lactobacilli in pig slurry (- 3.03 log, P < 0.05). Storage lowered coliforms and the other indicators counts, in particular in fresh wastes, while clostridia did not show a reduction in concentration.
本实验研究旨在评估厌氧消化和储存对猪和奶牛粪便中指示微生物的影响。在 15 个月内，每隔 90 天从 8 个农场（4 个养猪场和 4 个奶牛场）收集样本，其中 4 个农场有沼气厂。此外，为了评估储存对样本的影响，每个农场取 20 升粪肥和泥浆（仅在有沼气厂的农场中取消化后的粪肥），在 18°C 的控温控湿室中储存 6 个月。在每次采样时评估粪便的细菌负荷和理化特性，每隔 2 个月对储存的泥浆和粪肥进行采样和分析。在实验过程中，不同粪便类型中的细菌浓度表现出高度的可变性，主要取决于处理的类型和时间。没有样本显示大肠杆菌 O157:H7 或沙门氏菌的存在，这些细菌通常与设施中感染动物的临时饲养有关。厌氧消化和储存显著影响了指示菌如乳酸菌、大肠菌群和链球菌的减少。厌氧消化降低了猪粪浆中的大肠菌群（-2.80 对数，P<0.05）、奶牛粪便中的链球菌（-2.44 对数，P<0.001）和猪粪浆中的链球菌（-1.43 对数，P<0.05），以及猪粪浆中的乳酸菌（-3.03 对数，P<0.05）。储存降低了大肠菌群和其他指示菌的数量，特别是在新鲜废物中，而梭状芽孢杆菌的浓度没有降低。
