Acta hydrochim. hydrobiol. 32 (2004) 4�5 275

Editorial

Risk Assessment of Sewage from Leaking Sewers for Soil and Groundwater

In 1842, the city of Hamburg/Germany started to build the

first comprehensive sewer network. Other German cities

followed until the turn of the century. At present, more than

92 % of the population equivalents of Germany are

connected to underground sewers for wastewater and

rainwater drainage. Some of the sewer systems are almost

100 years old and require rehabilitation. Leaks of sewers

are caused by aging of materials, corrosion, breaks,

missing seals, etc., and up to 25% of sewage were

estimated to be lost in the underground. This might cause

permanent soil and groundwater pollution.

This scenario was the background of an interdisciplinary

research unit at the University of Karlsruhe (TH) on “Risk

Assessment of Sewage from Leaking Sewers for Soil and

Groundwater”, funded by the Deutsche Forschungsgemein-

schaft (FOR 350). Aspects that have been investigated in

the past 4�5 years included:

1) Temporal changes of sewage losses through leaky

sewers as influenced by colmation caused by suspended

solids of sewage or biofilm formation on soil minerals.

In memoriam Dr. rer. nat. habil. Matthias Eiswirth († 31.12.2003)

Dr. Matthias Eiswirth, to whom this issue is dedicated, was one of the leading young scientists of our research team,

whose engagement for science was extraordinary. His brilliant ideas and his excellent attitude to motivate diploma

and PhD students were outstanding.

At the turn of the year 2003/2004 his career was abruptly ended. During a mountain tour in the Alps, he and his little

son died in an avalanche. We lost a respected colleague and an overall pleasant friend.

Josef Winter

Coordinator of the Research Unit

© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

2) Metabolic activity of the microbial flora of sewage and

soil in the underground in the vicinity of sewer leaks.

3) Characterization of poorly biodegradable, recalcitrant

organic components of sewage in the non-saturated

underground and in groundwater.

4) Geochemical and microbiological precipitation and re-

solubilisation reactions in soil contaminated with sewage.

5) Modelling of the trickling behaviour of sewage and of

the microbial metabolism of sewage compounds in the

unsaturated soil.

6) Assessment and modelling of distribution of non-

degraded pollutants of sewage in groundwater.

In this special issue of Acta hydrochimica et hydrobiologica

results that were obtained with sand-filled laboratory

columns of different sizes, a 3 m � 2 m � 2 m “model

sewer” in the sewage treatment plant of the city of Karls-

ruhe, and of in-situ sewer field studies in the city of Rastatt

are reported.

Karlsruhe, October 2004