waste water treatment has not sufficiently reduced problems of heavy metals,nitrogen, and phosphorus in Bulgaria (Halcrow 1999; Ecoglasnost 1999). Thecontrol of wastewater in urban areas is further hampered by the discharge ofuntreated wastewater from industrial enterprises. Consequently, duringextensive dry periods, increased control and application of specific measuresare necessary for wastewater treatment plants and septic pits of small humansettlements located in the area of sanitary protection zones of potable watersources.
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