Hidrológiai Közlöny 1961 (41. évfolyam)

2. szám - Póta Béla: Felszíni vízkivételi művek kagylósodása

160 Hidrológiai Közlöny 1961. 2. sz. Póta B.: Felszíni vízkivételi művek kagylósodása 5. Wessenberg—Lund: Biologie der Süsswassertiere. Wien. 1939. 6. Mugele, O. F.—Wiseman, A. : Water Treatment. Mussel Contros. London. 1958. (84—86. o.) 7. Korschelt, E. : Über die Entwicklung von Dreissena polymorpha Pali. SB. Oes. naturf. Freunde Berlin. 1891. (131—146. o.). 8. Meisenheimer, J. : Die Entwicklungsgeschichte von Dreissensia polymorpha Pali. SB. Ges. Marburg. 1899/1900. (93—98. o.) 0EPA30BAHME PAKOBHH HA nOBEPXHOCTllblX B0,T103AE0PHbIX COOPy>KEHMflX E. noma Elő CTpOHTejlbCTBy npOMblUIJieHHOrO H X03flHCTBeHH0nnTbeBoro B0«0CHa6>KeHnyi co3AaroTC5i Bee öOAbme M Sojibiiie n0BepxH0CTHbix B0A03aö0pHbix coopyweHuií. MO>KHO ci<a3aTb, MTO NOMTH HHrae He 3aÖ0THTCH 06 ycTpaHeHHM öOAee 3HamiTejibHbix noTepb Ha TpeHHio H oö ycTpaHeHHH yMeHbuieHiiH nonepeMHoro ceMeHiifl Tpyö, B03HHKaiOIUHXCfl BCJieACTBHe 06pa30BaHHH paKOBHH H anbr. 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IIpeiiMyinecTBOM ero HBJIHETCH TO, MTO HCT nepepbiBa B paöore, HO iiMeeToi Mcnbine pe3yjibTaT0B, MEM y npe>KHnx ABYX CIIOCOÖOB. HMeeTCH Apyroii cnocoö, no KO'ropoMy rioBepxnocTH 'ipyőbi, conpHKacaiouuieoi c BOAOÍÍ noKpbmaioTca c KpacKoii, coflep>Kaiomeií MfcimbjiKa. HCAOCTATOK 3Toro cnocoőa GOCTOHT B TÓM, MTO B HCAOCTYRINUX ceMemiíix i<paci<a cTiipaercH ABH>i<yiueiícíi BOAOÍÍ 3a 6—8 AET H CHOBa IlOKpblTb 3T0 CCMeHIie B03MOJKHO TOAbKO nocAe pa3öopa. B npoxoAHMbix ceneHHax noBTopnoe noKpbiTHe BW3biBaer noTepn BpeMeHH. CaMbIM HOBbIM CnOCOÖOM HBAHeTCH cnocoö TepMHMecKott oőpaöOTKH. Pe3yabTaT HCCAeaoBaHHÍi Ha 15 paKOBHH H30öpa>KeH Ha 0ua. 3., r«e öyKBOft [a] 0Ö03HaHeHa 3aBHCHM0CTb MOKAV TeMnepaTypoft, a öyKBott [b] Meway KOAHMecTBOM eme >KHByiHHx 0praHH3M0B. Há (pue. 4. öyKBott [a] n0Ka3aH0 BpeMH, HeoöxoAHMoe AAH yHHMTOweHHH npn +40" U, a ÖyKBott [bj pe3yAbTaT hccacaoBaHHÍi, npoBeAeHHbix no WHByujHM opraHH3MaM. npenMymecTBO 3Toro cnocoőa ero öe30nacH0CTb Ha oöcAy>KHBaioinHH nepcoHaji, a HeAOcraTOK ero COCTOHT B TOM, MTO npHMeHHTb MOWHO TOAbKO TaM, RAE napa, HAH Tenjiaa BOAa AeaieBO MOweT öbiTb noABeACHa B ceTb. Ha (jtnrype BHAHO, MTO npn +40° U paKOBHHbi norHÖHyT 3a 15 MIIHYT. Shell Formation at Surfacc Intakes By B. Póta Corrolary to the development of industrial and domestic water supply in Hungary, surface intakes are being built in increasing numbers. However, protection measures against the formation of algae and shells, and consequently against increased head losses due to the contracted conduit cross section caused by them are omitted in the majority of installations. Yet this danger is always present in practice and gives rise frequently to serious difficulty in water supply. Protection against the formation of shells is only dealt with in this paper, the problem of algae formation being adequately covered by the literature. The oldest method used for the removal of shells is chlorination. With one process chlorine is added to water to produce a concentration of 0,5 ppm. for 7 days and chlorinated water is fed into the supply line. This process is most efficient during the summer months, since the larvae are killed in these times, which are more sensitive to chlorine than the fully developed shells. With an other process the conduit is filled with chlorine gas of 20 ppm. concentration. The essential layout of a conduit designed for this type of purification is shown in Fig. 2. Chlorine gas is introduced at the erest point [a]. The entrance of chlorine gas to filter plánt and pumping station [c] and [d], respectively, ; can be prevented by valves [6]. This is necessary, becose in closed conduits — especially if there are differences in elavation — chlorine gas becomes trapped and may cause accidents, yet it attacks the walls of the pipe as well. When gas is introduced, air must be removed from the conduit at point [e"|. After a period of 4 to 5 hours gas and shells- separated from the pipe wall aro flushed with water drawn from the elevated tank. Flushing should preferably not be directod towards the intake [/], since this may cause the clogging of the rack at times of normál operation. Recently a third chlorination process is alsó gainingpopularity, and is termed the preventive method. In this 0.5 to 1.5 ppm. chlorine is added to the water for one hour, after which chlorination is discontinued for a period of 4 to 6 hours. This cycle is continued in the summer months for several days. The advantage is, that normál operation is not interrupted by cleaning, however this is offset by the reduced efficiency. A different approach consists in applying a paint containing an arsenic compound to the surfaces coming in contact with water. The disadvant.age is, that the paint is removed by flowing water in 6 to 8 vears, and inaccessiblo conduits can be repainted only by exposing them. In the case of accessible conduits the operation must be interruptod for renewing the paint. Heat treatment is the method most recently applied. InveKtigation results obtained with 15 spqcies of shells are reproduced in Fig. 3, illustrating the relationship between the temperature f«] and the number of shells living after the treatment [6]. The time required for extermination at 40 Centigrades [a] is plotted against the number of living shells [6], on the basis of the corresponding experiments. The advantage of this method is that the personal is not endangered thereby, yet a disadvantage is that its application is restricted to systems, where steam or hot water can be introduced at low cost into the conduit. As to be aeen from the figure, 15 minutes are necessary at 40 Centrigrades to kill the shells.