- “urban waste water”: domestic waste water or a mixture of domestic waste water and/or industrial waste water and/or run-off rain water;

- “collection system”: a system of conduits which collects and conducts urban waste water

- “primary treatment”: the treatment of waste water by a physical and/or chemical process involving settlement of suspended solids, or other processes which the biochemical oxygen consumption of the incoming waste water before discharging is reduced in 5 days at 20C by at least 20%, and the total suspended solids in the incoming waste water are reduced by at least 50%;

- “secondary treatment”: treatment of waste water by a process generally involving biological treatment with secondary settlement, or another process whereby the values of the sectoral emission limit values for effluent water established in these regulations are respected;

- “appropriate treatment”: treatment of waste water by any process and/or disposal system, which after discharge allows the receiving waters to meet the relevant quality objectives and the relevant provisions of these regulations;;

- “sludge”: residual sludge whether treated or untreated from water treatment plants;

- “agglomeration”: an area where the population and/or the economic activities are sufficiently concentrated for urban waste water to be collected and conducted to an urban waste treatment plant or to a final discharge point;

- “vulnerable areas”: in accordance with Directive 91/271/EEC concerning the treatment of urban waste water, for the application of Section 2.3.6. and 5.3.1, vulnerable areas are considered to be a water mass included in the following groups:


natural freshwater lakes, other freshwater masses, estuaries and coastal waters which are eutrophic or may be eutrophic in the near future if protective measures are not taken;


surface waters intended for the catchment of drinking water, which could contain a higher nitrate concentration than is established in accordance with the immission standards in question if no measures are taken;


areas where further treatment to that specified in Section 5.3.1. is needed to comply with Directive 91/271/EEC.

With regard to group sub 1, the following elements can be taken into consideration when it is determined which nutrients must be reduced by further treatment:


lakes and rivers flowing into lakes, reservoirs or closed bays in which low water replenishment is established so accumulation can occur; in these areas phosphorous must also be removed from the waste water unless it can be demonstrated that its removal has no effect on the level of eutrophication; where discharges from large agglomerations take place, the removal of nitrogen can also be considered;


estuaries, bays and other coastal waters in which low water replenishment is established, or which contain large quantities of nutrients; discharges from small agglomerations in these areas are usually of less importance, but for large agglomerations phosphorous and/or nitrogen must also be removed unless it can be demonstrated that their removal has no effect on the level of eutrophication.

- “Population equivalent (P.E.): the organic biodegradable load having a five-day biochemical oxygen demand at 20C (BOC520) of 60 g oxygen per day.