Discharges from urban waste-water treatment plants
In addition to the obligation imposed on Member States by Article 4 for adequate treatment and that under Article 5 for more stringent treatment in anticipation of a discharge in vulnerable areas, such discharges must comply with the requirements of Annex I-B. For instance, discharges from urban waste water treatment plants shall meet quantified requirements as to biochemical oxygen demand, chemical oxygen demand, and total suspended solids (Annex I, Table 1).
The CJEU recently ruled that the obligation imposed on Member States by Article 4 that concerned agglomerations submit waste-water to an adequate treatment (Case C-398/14 Commission v Portugal, para. 45), as well as their obligation under Article 5 that those waters be subjected to more stringent treatment than that described in Article 4 prior to being discharged into vulnerable areas (Case C-38/15 Commission v Spain, para. 24 (available only in French)) and, in both situations, that such discharges comply with the requirements of Annex I-B, does not imply that samples be taken over a full year.
Urban waste-water treatment plants built to comply with those requirements must be “designed, constructed, operated and maintained to ensure sufficient performance under all normal climatic conditions” taking into account seasonal variations of the load (Article 10).