[Character of the big-city municipal waste water bacterial contamination and assessment of its elimination degree as a result of biological treatment process].
The highest possible effectiveness of sewage treatment is of particular significance when the sewage is discharged into surface waters used for recreational purposes. The Gulf of Gdańsk, with its much frequented beaches along the shore, is the disposal reservoir for the wastewater from two large biological treatment plants collecting the sewage from Gdańsk and Gdynia. The purpose of this work was to perform bacteriological examination of the communal sewage from these two large agglomerations before and after their biological treatment. On that basis the degree of reduction of bacteriological contamination of sewage as a result of biological treatment was determined. The examination included determining of coliform and faecal coliform bacteria MPN (Most Probably Number), faecal streptococci index as well as Salmonella sp. and coagulase positive staphylococci. An extremely high level of bacterial contamination of raw sewage was found amounting from 9.3 x 10(18) (Gdańsk) to 1.8 x 10(20) (Gdynia) faecal coliform bacteria in 100 cm3 of sewage and respectively from 5.6 x 10(5) to 1.8 x 10(6) faecal streptococci in 100 cm3 of sewage on average. It was also observed that the effectiveness of the sewage treatment plants is so high that it assures the level of reduction of bacterial contamination within the limits of 92% for staphylococci and streptococci to 99.999% for coliform bacteria. It was also pointed out that despite a very effective work of sewage treatment stations the level of contamination of treated sewage discharged into the surface waters is often high. Hence the necessity of verification of data concerning level of sewage contamination which are usually assumed in the project documentation.
Szumilas
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Zakład Ochrony Srodowiska i Higieny Transportu Instytut Medycyny Morskiej i Tropikalnej 81-519 Gdynia.
Michalska
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Bartoszewicz
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D001419:Bacteria / Q000302:isolation & purification*; D004784:Environmental Monitoring; D006801:Humans; D011044:Poland; D014865:Waste Disposal, Fluid; D014871:Water Microbiology; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000592:standards*
D014874:Water Pollutants, Chemical