Waste stabilization ponds (WSP) are a well-established wastewater treatment technology in Namibia. However, they are often overloaded and we still lack concepts and technologies for improvement. Therefore, this study presents the full-scale implementation of two pretreatment technologies to reduce the inflow of organic and solid loads into a facultative pond. We specifically compared the effects of anaerobic biological and mechanical pretreatment by an upstream anaerobic sludge blanket (UASB) reactor and a 250 μm micro sieve (MS). Not only in Namibia but also in most sub-Saharan countries, there is little experience with these technologies for the treatment of municipal wastewater in small and fast-growing local communities. Both technologies were tested in parallel for a period of 17 months and proved operational. While the UASB achieved better removal results with respect to chemical oxygen demand (COD) and suspended solids (TSS), the MS was more flexible in handling changing inflow patterns and had a much smaller footprint. The average total COD reductions of the MS and the UASB were 22 and 50%, respectively. TSS were removed by 45% with the MS and by 57% with the UASB reactor. Therefore, UASB and MS are viable options for the enhancement of existing WSP to reach better effluent values of the facultative pond.

废物稳定池（WSP）是纳米比亚成熟的废水处理技术。但是，它们经常超负荷运行，我们仍然缺乏改进的概念和技术。因此，本研究提出了两种预处理技术的全面实施，以减少有机物和固体物向兼性池的流入。我们专门比较了上游厌氧污泥床（UASB）反应器和250μm微筛（MS）进行厌氧生物和机械预处理的效果。不仅在纳米比亚，而且在大多数撒哈拉以南国家，在小型和快速发展的当地社区中使用这些技术处理市政废水的经验都很少。两种技术均经过了17个月的并行测试，并证明可以运行。虽然UASB在化学需氧量（COD）和悬浮固体（TSS）方面取得了更好的去除效果，但MS在处理变化的流入模式时更加灵活，占地面积更小。MS和UASB的平均总COD减少分别为22％和50％。用MS除去TSS的量为45％，而用UASB反应器除去的量为57％。因此，UASB和MS是增强现有WSP以达到兼并池更好的出水价值的可行选择。