Department of Biological Systems Engineering, Washington State University, Pullman, Washington, USA.
Department of Animal Sciences, Washington State University, Pullman, Washington, USA.
J Environ Qual. 2024 Nov-Dec;53(6):1176-1187. doi: 10.1002/jeq2.20626. Epub 2024 Sep 10.
The dairy industry has seen notable changes in the last couple of decades, including increased size of farms and regional concentrations of dairies. This has resulted in substantial manure production in small geographical areas, raising environmental concerns. Vermifiltration, an emerging low cost and eco-friendly technology for treating wastewater, was evaluated to assess the influence of earthworm population density on the performance of a laboratory-scale vermifilter treating liquid dairy manure. We monitored the reduction efficiencies of various components, including total nitrogen (TN), ammonium-nitrogen (NH -N), nitrate-nitrogen (NO -N), total phosphorus (TP), orthophosphate (ortho-P), chemical oxygen demand (COD), total solids (TS), and total suspended solids (TSS), in treated dairy wastewater. This evaluation was conducted at 0; 5000; 10,000; and 15,000 earthworm densities per cubic meter (m) of bedding. Reduction efficiencies of 41%-89% (TN), 46%-86% (NH -N), 34%-74% (NO -N), 3%-17% (TP), 18%-38% (ortho-P), 35%-66% (COD), 24%-54% (TS), and 50%-87% (TSS) were observed with higher earthworm densities exhibiting greater reduction efficiencies. Notably, the densities of Eisenia fetida at 10,000 and 15,000 earthworms m showed no significant difference in vermifilter performance. This suggests that increasing the Eisenia fetida density beyond 10,000 earthworms m may not further improve the vermifilter's performance in treating dairy wastewater. This study's findings indicate that using vermifiltration with an earthworm population density of 10,000 earthworms m could effectively mitigate the negative environmental impact of liquid dairy wastewater at a low cost and sustainably.
在过去的几十年里，乳制品行业发生了显著的变化，包括农场规模的扩大和奶牛场的区域集中。这导致了大量粪便在小地理区域内产生，引发了环境问题。蚯蚓过滤是一种新兴的低成本、环保型废水处理技术，用于评估蚯蚓种群密度对实验室规模蚯蚓过滤器处理液态奶牛粪肥性能的影响。我们监测了各种成分的去除效率，包括总氮（TN）、铵态氮（NH₋N）、硝酸盐氮（NO₋N）、总磷（TP）、正磷酸盐（ortho-P）、化学需氧量（COD）、总固体（TS）和总悬浮固体（TSS）在处理后的奶牛废水中。这项评估是在 0、5000、10000 和 15000 条/立方米（m）的垫料密度下进行的。TN 的去除效率为 41%-89%，NH₋N 为 46%-86%，NO₋N 为 34%-74%，TP 为 3%-17%，ortho-P 为 18%-38%，COD 为 35%-66%，TS 为 24%-54%，TSS 为 50%-87%，随着蚯蚓密度的增加，去除效率也随之提高。值得注意的是，Eisenia fetida 的密度在 10000 和 15000 条/立方米时，蚯蚓过滤器的性能没有显著差异。这表明，将 Eisenia fetida 的密度增加到 10000 条/立方米以上可能不会进一步提高蚯蚓过滤器处理奶牛废水的性能。本研究结果表明，使用蚯蚓过滤技术，蚯蚓种群密度为 10000 条/立方米，可以以低成本、可持续的方式有效减轻液态奶牛废水的负面环境影响。
