From removal of organic micropollutants to municipal wastewater reuse - technological and social perspectives

In this thesis, wastewater reuse was investigated from technological and social perspectives, based on
which the thesis was divided into two parts. In the first part, the removal of chemical and microbial
contaminants by full-scale and pilot-scale granular activated carbon (GAC) filters, in different process
combinations, was examined. In the second part, the perceptions of reused wastewater were studied
through a discourse analysis and compared with those of desalinated seawater, which is another
alternative water source.

The results showed that the treatment of wastewater with a process combination of a membrane
bioreactor, GAC filtration, and disinfection with ultraviolet radiation improved its quality to a level that
approached that of drinking water. Limits on some organic micropollutants, such as pharmaceuticals, are
generally not included in drinking water legislation or legislation for irrigation with reused wastewater,
adding insecurities to the evaluation of water quality. Nevertheless, the water was treated to a high
degree and potentially constitutes a beneficial supplementary resource for irrigation or drinking water
production during drought or times of water scarcity. Whether the water criteria need to be complemented
with additional parameters merits further investigation.

Organic micropollutants are removed by GAC filters primarily through adsorption but also through
biological degradation. Measurements from a full-scale GAC filter indicated degradation of certain
pharmaceuticals, which was confirmed in laboratory experiments with granules from various GAC filters.
The degradation appeared to be affected specifically by the oxygen concentration in the filters and by
operation time.

In the second part of the thesis work, the discourses over wastewater reuse and desalination on the
Swedish islands of Öland and Gotland were examined and compared with general discourses identified
from literature. Wastewater reuse and desalination are ways of producing drinking water when
groundwater and surface water resources are not sufficient and are often compared in the literature. The
results showed that the local discourses often had similarities with the general ones and that there were
differences between the two islands. Desalination on Gotland seemed to be more controversial than
wastewater reuse and desalination on Öland, and the perceptions of wastewater reuse and desalination
were affected by many factors, such as visions and values with regard to welfare or sustainability and
other political topics—for example local industries.