Anaerobic digestion dung filtrate recycling

This experiment investigated whether the water demand of low-tech anaerobic digestion (AD) systems in rural areas of sub-Saharan Africa could be reduced by continuous recycling of filtered digestate. We used 2 different concentrations of cow dung and filtrate, with 3 replicates and ran a semi-continuous system over 79 days with a reactor retention time of 25 days. We found that a higher chemical oxygen demand (COD) removal efficiency was achieved with dung and undiluted filtrate than with dung and diluted filtrate, indicating that AD could potentially be implemented more widely than is currently practiced, as labour could be saved for water collection activities. We regularly measured the COD, total solids (TS) and volatile solids (VS) content of the digestate and present the mean values with standard deviation here.

本实验探究了撒哈拉以南非洲农村地区的低技术厌氧消化（anaerobic digestion, AD）系统能否通过持续循环利用过滤后的消化液降低其需水量。本研究采用两种不同浓度的牛粪与滤液，设置3组平行实验，并以25天的反应器停留时间运行半连续式厌氧消化系统共计79天。结果表明，相较于添加牛粪与稀释滤液的实验组，添加牛粪与未稀释滤液的实验组可获得更高的化学需氧量（chemical oxygen demand, COD）去除率，这意味着厌氧消化技术的推广应用潜力较当前实际应用更广，可节省集水环节的人力成本。本研究定期测定了消化液的化学需氧量、总固体（total solids, TS）与挥发性固体（volatile solids, VS）含量，并在此呈现其平均值与标准差。