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Journal Article

ZBL.BAKT.REIHE B

1975/

161

3

248

265

Unknown(0)

The comparative examination of numerous ion exchange resin filter systems for discontinuous water softening on the market revealed that apparative and processing characteristics are of great influence upon the aftergrowth of bacteria in the water of ion exchange resin systems. Within the examination it was taken into consideration that on the end delivery tube of the water pipe the conditions of the colony count were more unfavorable during the long standstill over a weekend than during the week. The less favorable conditions have therefore been examined separately. The work has been divided into six test series. In the first, 5 ion exchange resin systems of types A E are simultaneously tested for colony count in the water at the inflow to the apparatus and after its passage; regeneration was accomplished twice a week with sodium chloride. The data ascertained in the course of several weeks (without first data on mondays) and the separated monday data are examined according to logarithmic transformation with the assistance of variance analysis and the Newman Keuls test for differences. The results show that apparative parameters and those relevant to the technical process have an influence upon the bacterial aftergrowth in the water. The most favorable ion exchange resin filter is type E because it shows more favorable values than all other systems and the tapwater. In the second test series the systems A E were regenerated with 1% Chloramin T containing sodium chloride. The results show again the type E as the statistically significantly most favorable system in comparison with the others and the tapwater. In the third test series it has been examined whether the long period of standstill of the brine in the resin (which has probably been responsible for the good results of the type E) would lead to values just as favorable if transferred to another type of apparatus. Systems of type D were used which are substantially different to type E in various ways. The time of brine contact and the time of backwashing was varied. The results show differences. After statistical evaluation, however, it was found that they are not significant. In order to prove whether the period of standstill in a test apparatus N constructed according to the essential characteristics of type E has influence upon the bacterial growth within the system, two softeners of this kind were examined during the regeneration process with 15 and 30 min standstill of the brine after rising brining. The results demonstrate a significant difference between the weekly average colony count between 15 and 30 min of standstill. This proves that the favorable results of type E are due to the rising brining and a period of standstill of the brine at a minimum of 30 min in the resin bed. In the fifth test series it has been examined with two systems of type E whether a significant difference exists between system E1 with regeneration with 1% Chloramin T containing sodium chloride and system E2 with regeneration with normal sodium chloride. The results demonstrate an obvious difference which can also be proved statistically. This proves that under these apparative conditions with the rising brining an efficacious disinfection can be carried out. For clarification of the question of disinfection in the sixth test series it was found that by higher concentration of sodium chloride the bactericidal action of disinfectants is intensified.

drinking water, disinfection, methodology, microorganism, water supply

ZUR FRAGE DER NACHVERKEIMUNG VON TRINK- UND BRAUCHWASSER. II. APPARATIVE UND VERFAHRENSTECHNISCHE EINFLUSSE AUD DIE VERKEIMUNG UND DIE MOGLICHKEIT ZUR DESINFEKTION VON IONENAUSTAUSCHERANLAGEN

Embase; MEDLINE

Embase

Schubert,R. H. W.