Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
Waste Manag. 2016 Apr;50:300-8. doi: 10.1016/j.wasman.2016.02.031. Epub 2016 Mar 2.
A leachbed is a relatively simple anaerobic digester suitable for high-solids residues and on-farm applications. However, performance characteristics and optimal configuration of leachbeds are not well-understood. In this study, two 200 L pilot-scale leachbeds fed with spent straw bedding from pigs/swine (methane potential, B0 = 195-218 L CH4 kg(-1) VS fed) were used to assess the effects of leachate recirculation mode (trickling vs. flood-and-drain) on the digestion performance. Results showed comparable substrate solubilisation extents (30-45% of total chemical oxygen demand fed) and methane conversion (50% of the B0) for the trickling and flood-and-drain modes, indicating that digestion performance was insensitive to the mode of leachate flow. However, the flood-and-drain leachbed mobilised more particulates into the leachate than the trickling leachbed, an undesirable outcome, because these particulates were mostly non-biodegradable. Inoculation with solid residues from a previous leachbed (inoculum-to-substrate ratio of 0.22 on a VS basis) hastened the leachbed start-up, but methane recovery remained at 50% of the B0 regardless of the leachate recirculation mode. Post-digestion testing indicated that the leachbeds may have been limited by microbial activity/inhibition. The high residual methane potential of leachate from the trickling (residual Bo = 732 ± 7 L CH4 kg(-1) VS fed) and flood-and-drain leachbeds (582 ± 8 L CH4 kg(-1) VS fed) indicated an opportunity for further processing of leachate via a separate methanogenic step. Overall, a trickling leachbed appeared to be more favourable than the flood-and-drain leachbed for treating spent bedding at farm-scale due to easier operation.
渗滤床是一种相对简单的厌氧消化器，适用于高固体残留物和农场应用。然而，渗滤床的性能特点和最佳配置还不是很清楚。在这项研究中，使用两个 200 升的中试规模渗滤床，分别用猪/猪粪的废垫料（甲烷潜能，B0 = 195-218 L CH4 kg(-1) VS 进料）进料，以评估渗滤液循环模式（滴滤与渗滤）对消化性能的影响。结果表明，滴滤和渗滤模式的底物溶解程度（总化学需氧量进料的 30-45%）和甲烷转化率（B0 的 50%）相当，这表明消化性能对渗滤液流动模式不敏感。然而，与滴滤渗滤床相比，渗滤床中的更多颗粒物质被转移到渗滤液中，这是一个不理想的结果，因为这些颗粒物质大多是不可生物降解的。用之前渗滤床的固体残留物接种（VS 基础上接种物与底物的比例为 0.22）加速了渗滤床的启动，但无论渗滤液循环模式如何，甲烷回收率仍保持在 B0 的 50%。消化后测试表明，渗滤床可能受到微生物活性/抑制的限制。滴滤和渗滤渗滤床渗滤液的剩余甲烷潜能较高（滴滤渗滤床的剩余 Bo = 732 ± 7 L CH4 kg(-1) VS 进料；渗滤渗滤床的剩余 Bo = 582 ± 8 L CH4 kg(-1) VS 进料），这表明可以通过单独的产甲烷步骤进一步处理渗滤液。总的来说，由于操作更简单，滴滤渗滤床似乎比渗滤渗滤床更适合在农场规模上处理废垫料。
