Small wastewater treatment plants in Flanders (Belgium): standard approach and experiences with constructed reed beds
2000; Pergamon Press; Volume: 41; Issue: 1 Linguagem: Inglês
10.2166/wst.2000.0010
ISSN1996-9732
AutoresS. Vandaele, C. Thoeye, B. Van Eygen, G. De Gueldre,
Tópico(s)Wastewater Treatment and Nitrogen Removal
ResumoIn Flanders (Belgium) an estimated 15% of the population will never be connected to a central wastewater treatment plant (WWTP). Small WWTPs can be a valuable option. Aquafin bases the decision to build SWWTPs on a drainage area study. To realise an accelerated construction the process choice is made accordingly to a standard matrix, which represents the different technologies in function of the size and the effluent consents. A pilot scale constructed two-stage reed bed is used to optimise the concept of the reed beds. The concept consists of a primary clarifier, two parallel vertical flow reed beds followed by a sub-surface flow reed bed. The removal efficiency of organic pollutants is high (COD: 89%, BOD: 98%). Phosphorus removal is high at the start-up but diminishes throughout the testing period (from 100% to 71% retention after 7 months). Nitrogen removal amounts to 53% on average. Nitrification is complete in summer. Denitrification appears to be the limiting factor. In autumn leakage of nitrogen is assumed. Removal efficiency of pathogens amounts to almost 99%. Clogging forms a substantial constraint of the vertical flow reed bed. Problems appear to be related with presettlement, feed interval and geotextile.
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