Individual wastewater treatment in Flanders (Belgium)

In Flanders, it is not possible to centralise the infrastructure for handling all wastewater. Decentralised treatment should be considered an essential part of an overall regional policy. Decentralised wastewater treatment can be small-scale (20 to 2,200 Inhabitant Equivalent (IE)) or individual (less than 20 IE). This paper deals with the operation, performances, technological aspects and costs of Individual Wastewater Treatment Plants (IWTPs) in Flanders. Different treatment systems are described and tentatively evaluated. The total costs (capital and operation) can be of the same order of those of centralised systems, i.e. 100 EURO/IE.year. In terms of overall performance, most of the systems tested in Flanders, i.e. aerobic biological filter, activated sludge system, submerged aerated filter, biorotor and percolation reed bed, appear capable to perform well in principle. However, there remain problems to be solved. The effluent quality differs 'in situ' considerably, depending on the care and attention given by the owner. Hence, the legislator should not only focus on certification of installations as such, but foremost give attention to regular validation of the performance at the household. In this respect, there is an urgent need for the design and the logistic management of proper performance control systems.