This report is only available in Swedish. English summary is available in the report.
At present, there are no requirements for Swedish wastewater treatment plants (WWTPs) to remove pharmaceutical residues and other emerging substances. However, it is likely that such requirements will soon be introduced in Sweden. Therefore, SYVAB has initiated a project to investigate how such an advanced treatment could be implemented at the Himmerfjärdsverket WWTP. The current report summarizes previous investigations and pilot-tests to remove pharmaceuticals from wastewater, related to Himmerfjärdsverkets future treatment process configuration. Tests have been conducted by IVL Swedish Environmental Research Institute, partly in collaboration with SYVAB, through pilot tests at Himmerfjärdsverket and the R&D-facility Hammarby Sjöstadsverk. The removal efficiency in today's process at Himmerfjärdsverket is over 85% for some pharmaceuticals while others are reduced to a much lower degree or their concentration may even be higher in outgoing water than in the inflow. Despite low removal efficiency, pharmaceutical levels in the recipient are representing low risk of adverse environmental effects for most of the studied substances. This is mainly because of a high water exchange in the receiving recipient Himmerfjärden with the outer archipelago. A performed risk analysis shows that a more advanced treatment would not be required to achieve medium risk levels in the recipient, since risk levels are already below 1 for all substances analysed. However, to achieve low-risk levels of pharmaceuticals already in outgoing water from the WWTP, i.e. without dilution, an extended treatment would be required for at least 7 of the analysed substances. The highest treatment demand would be for Oxazepam (96% reduction). After rebuilding the current WWTP into an active sludge plant with MBR technology, the removal efficiency for some pharmaceuticals is expected to increase, which, however, only affects the need for extra purification very little as the risk analysis reveals. All investigated pharmaceuticals are efficiently removed from MBR-effluent with both activated carbon filtration and ozonation at appropriate doses and load according to several pilot tests performed. Treatment of water in GAK filters provides stable low levels of pharmaceuticals until breakthrough occurs. If the extra treatment is to be dimensioned to reduce levels in outgoing water under predicted no effect concentrations (PNEC), a treatment of 96% of the total flow would be required based on Oxazepam according to the performed evaluation. Alternatively, a higher proportion of the flow can be treated but that the carbon is changed after a longer period, after the entire sorption capacity has been consumed. If the level of ambition is to reduce the levels of all pharmaceuticals to very low levels, one can expect carbon consumption of about 15-20 g/m3 of water (or 50 - 75 m3/kg of carbon). If extended treatment is based on ozonation, it should be dimensioned for an ozone dose of >9 mg O3/L for reduction of levels in outgoing water under predicted no effect concentrations (PNEC). In addition to pharmaceuticals, outgoing water from Himmerfjärdsverket also contains other organic micropollutants that are important to include in the assessment of extended treatment. Himmerfjärdsverket's emissions of PFOS contribute for example to over 90% of the limit value for fulfilling good chemical surface water status. Reduction of PFOS from wastewater has not been thoroughly tested on site, but existing results from experiments with leachate at Hammarby Sjöstadsverk and drinking water indicate that a high degree of reduction over a carbon filter can be expected and breakthrough of PFOS is expected to occur simultaneously or slightly earlier than for pharmaceuticals. However, high degrees of reduction cannot be expected in ozonation.
Coworkers: Christian Baresel
Report number: B2339
Authors: Christian Baresel, Andriy MalovanyyDownload publication