Abstract：
Covered anaerobic lagoons (CALs) are Latin America\'s main livestock waste treatment systems. Mexico has 680 CALs that present low biogas yields (0.05 m3 m-3 digester d-1) and low COD removal rates (< 60%). This work focused on diagnosing CAL´s low performance in dairy farms by determining and analyzing operational parameters. Seven CALs located in the main dairy basin of Mexico were analyzed. The sampling areas for each CAL were the supernatant, the active zone, settled sludge, and digester inlet and outlet. The variation of the process parameter values corroborated that CALs appeared stratified and not working as expected. The sludge zone, comprising 50-58% of total solids content and 1-15% of total CALs volume, showed an elemental compounds content suitable for organic fertilizer (340, 48, and 5 kg t-1 of C, N, and S, respectively). However, this zone contained, at least, 85% of the slowly hydrolysable material; the methanogenic potential was less than 87 mL CH4 g VS-1, and the C/N ratio ranged from 4.9 to 17, outside of the optimal range. The biogas produced did not exceed 60% of methane content and more than 3000 ppm of H2S. The sludge zone significantly influences the lagoon\'s dynamics since it is a nutrient sink. Furthermore, the lack of agitation is the leading cause for the low energy yield and the low removal of organic matter rate. This work provides valuable information to address the operational problems within the CALs improving our understanding that shall allow proposing reactivation alternatives.
摘要：
覆盖厌氧泻湖（CAL）是拉丁美洲主要的牲畜废物处理系统。墨西哥有680个CAL，其沼气产量低（0.05m3m-3消化器d-1）和COD去除率低（<60％）。这项工作的重点是通过确定和分析操作参数来诊断CAL在奶牛场中的低性能。分析了位于墨西哥主要乳品盆地的七个CAL。每个CAL的采样面积是上清液，活跃区,沉降污泥,和消化器入口和出口。过程参数值的变化证实了CAL出现分层且未按预期工作。污泥区,包含50-58%的总固体含量和1-15%的总CAL体积，显示出适合有机肥料的元素化合物含量（340、48和5kgt-1的C，N,S,分别)。然而,这个区域包含，至少,可缓慢水解的材料的85％；产甲烷潜力小于87mLCH4gVS-1，C/N比范围为4.9至17，超出了最佳范围。产生的沼气不超过60％的甲烷含量和超过3000ppm的H2S。污泥区显着影响泻湖的动态，因为它是一个营养池。此外，缺乏搅拌是导致能量产量低和有机物去除率低的主要原因。这项工作提供了有价值的信息，以解决CAL中的操作问题，从而提高了我们的理解，从而可以提出重新激活的替代方案。
