What is it about?
Post-treatment of anaerobic reactor effluent with maturation ponds is a good option for small to medium-sized communities in tropical climates. The treatment line investigated, operating in Brazil, with an equivalent capacity to treat domestic sewage from 250 inhabitants, comprised a upflow anaerobic sludge blanket reactor followed by two shallow maturation ponds (unbaffled and baffled) and a granular rock filter (decreasing grain size) in series, requiring an area of only 1.5 m2 inhabitant−1. With an overall hydraulic retention time of only 6.7 days, the performance was excellent for a natural treatment system. Based on over two years of continuous monitoring, median removal efficiencies were: biochemical oxygen demand = 93%, chemical oxygen demand = 79%, total suspended solids = 87%, ammonia = 43% and Escherichia coli = 6.1 log units. The final effluent complied with European discharge standards and WHO guidelines for some forms of irrigation, and appeared to be a suitable alternative for treating domestic sewage for small communities in warm areas, especially in developing countries. KEYWORDS: Sewage, granular rock filter, shallow maturation ponds, baffled pond, UASB reactor.
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Why is it important?
Wastewater treatment concepts and technology have come a long way, with considerable advances, where not so long ago (more or less 100 years) raw sewage (RS) was directly dumped in water courses or oceans. Unfortunately, this is still a reality in many small to medium-sized communities, especially in developing countries. Low-cost, easy maintenance and simple to implement wastewater treatment plants (WWTPs) can help to resolve this problem and natural treatment systems are considered an attractive alternative when compared to more expensive and resource-consuming treatment lines, such as activated sludge, aerated biofilters and biodiscs. Waste stabilisation ponds (WSPs) are used around the world in temperate and warm climate countries to treat domestic sewage for millions of people and are recommended by WHO.
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This page is a summary of: Performance evaluation of a natural treatment system for small communities, composed of a UASB reactor, maturation ponds (baffled and unbaffled) and a granular rock filter in series, Environmental Technology, March 2017, Taylor & Francis,
DOI: 10.1080/09593330.2017.1304456.
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