Ispuštanje otpadnih voda sa sadržajem fosfata u prirodne prijemnike ubrzava proces eutrofikacije vodenih ekosustava. U svrhu očuvanja površinskih voda, sve se više pažnje posvećuje uklanjanju fosfata iz otpadnih voda do vrlo niskih koncentracija. Za proces biološkog uklanjanja fosfata iz otpadnih voda odgovorne su fosfat-akumulirajuće bakterije (PAB). PAB u aerobnim uvjetima rasta akumuliraju otopljene fosfate prisutne u otpadnoj vodi u obliku netopivih unutarstaničnih zrnaca polifosfata. PAB uključuju filogenetski i taksonomski različite grupe kultivabilnih i nekultivabilnih bakterija. Prosječno uklanjanje fosfata iz otpadne vode ovisiti o kapacitetu soja PAB da unutarstanično akumulira fosfate i o brojnosti toj soja u aktivnom mulju..; In the attempt to harmonize protection and monitoring of surface waters with European regulations in the fields of protection, monitoring and river basin management, the Water Framework Directive (2000/60/EC) implementation started in the Republic of Croatia several years ago. As the first implementation step in the area of transitional and coastal waters of the Adriatic river basins, their typification was carried out according to the system B, which resulted in the determination of 6 water types of transitional waters and 5 water types of coastal waters. In theses areas, which are unique river basin sub-units, 52 water bodies were determined, of which 12 were proposed as candidates for heavily modified water bodies. For purposes of surveillance monitoring and estimation of ecological status of water bodies of transitional and coastal waters, ecological status boundaries for chlorophyll a biomass and individual supporting physico-chemical parameters of water quality element phytoplankton were proposed.