The influence of Fez03, pyruvate and a sealing putty on microbiologically induced corrosion in part of a copper cold-water plumbing system in a large building was investigated. For this purpose, these three substances were injected into the pipe lumen of a non-disinfected and a thermally disinfected section of a tap line affected by microbiologically induced corrosion. It was shown that these substances stimulate, in varying degrees, the microbiological corrosion of copper pipes.Untersucht wurde der EinfluR von FezOs, Pyruvat und einem Dichtkitt auf die mikrobiologisch beeinfluRte Korrosion in einem Teilbereich eines Kaltwasser-Hausinstallationssystems aus Kupferrohren.Dazu wurden diese drei Substanzen jeweils ins Rohrlumen des undesinfizierten und des thermisch desinfizierten Kupferrohres des unter mikrobiologischer Beteiligung korrodierenden Trinkwasser-Installationssystems injiziert. Es konnte gezeigt werden, daB diese Substanzen in unterschiedlichem Ausmal3 die mikrobiologische Korrosion von Kupferrohren fordern.

On the basis of a standardized in vitro irrigation model, the incrustation behavior of catheters was investigated using collected urine with controlled contamination (Proteus mirabilis). Irrigation treatment with a NaCl solution did not effectively reduce incrustation compared to the control experiment. On the other hand, incrustations were definitively prevented or existing crystal deposits were largely dissolved with a citrate solution of pH 4.0 (Suby G). Analytical investigations (infrared spectroscopy, scanning electron microscopy) of the deposits on the catheter revealed the presence of struvite (MgNH₄PO₄ × 6H₂O), brushite (CaHPO₄ × 2H₂O) and carbonate apatite (Ca₁₀[PO₄] [CO₃OH]₆[OH]₂).

Encrustations are the most frequent complications occurring with indwelling catheters and urine drainage systems. The conditions for bacterial infections, using synthetic urine and controlled contamination by Proteus vulgaris, were standardised by using an in vitro model. Crystal deposits on catheters were analysed by infra-red spectroscopy and scanning electron microscopy. The main components of deposits in all investigations were struvite (MgNH4PO4.6H2O) 60-70% and carbonate apatite (Ca10(PO4,CO3)6 (OH,CO3)2) 30-40%. Investigations as to the quality and quantity of encrustations confirmed the analysis. Irrigation treatment was carried out with physiological saline solution and citric acid solution (Suby G) to study and quantify the dissolution of crystal deposits. Regular irrigation with citric solution resulted in a 70% dissolution of encrustations and ensured free flow as ascertained by measuring flow rates.