Steering a course on sewage pharmaceutical removal in Sweden

Micropollutants

Issue: 

Sweden has started to implement improvements in sewage treatment for pharmaceutical and other micropollutant removal but is focused mainly on developing its policy for future action. Keith Hayward spoke with Christian Baresel of research institute IVL, which has been providing input on wastewater treatment needs and options, and contributed one of the reports supporting the recent recommendation by the Swedish Environmental Protection Agency for action on pharmaceuticals.

There are two important messages contained in the recent report by the Swedish Environmental Protection Agency to the country’s government on advanced wastewater treatment for removal of pharmaceuticals and other micropollutants. The first is that the agency sees the issue of being of sufficient concern that it recommends action be taken. The second is that action in the form of the addition of more advanced treatment at sewage works is viable.

Input to the report on the treatment options has come in particular from Swedish research institute IVL, especially through a key report it prepared specifically for the latest EPA report. Dr Christian Baresel was part of the team that prepared the IVL report. The work included setting out costs associated with different advanced treatment options. ‘[The costs] are based on our experiences in Sweden. We also used information from more than 40 installations in Germany, for example,’ he explains. ‘I think the costs are really viable.’

 

Assessing advanced options

This message of viability is important given what lies behind the statement. In particular, the report looked at pharmaceuticals. It also looked at another key current concern for the government – microplastics. More than this, it looked more widely at other pollutants. ‘We have done screening for many, many years – not only in Swedish treatment plants, but also in others,’ says Baresel. Other contaminants are likely to require action, so he says it does not make sense to target them separately with individual treatment steps. ‘That’s just not really resource efficient,’ he adds.

The report therefore includes an assessment of how well different technologies are able to tackle a wide range of contaminants of concern, explains Baresel. These include, for example, the issue of antibiotic-resistant bacteria.

The assessment is focused in terms of the number of substances actually considered. In the case of pharmaceuticals, for example, Baresel puts the total number of medical substances entering Swedish treatment plants at more than 2000. There is therefore a focus on the most important indicator substances, including ones found in high concentrations and others that may have a chronic effect at low concentrations over a long period of time. Baresel sees this can provide a basis for assessing treatment performance. ‘We have to analyse only a few in order to see if the treatment plant works or not,’ he says.

There is extra focus on Swedish conditions given, for example, that most wastewater sludge in the country goes to agricultural land. This contrasts with Germany, where there is more of a focus on use of sludge in incineration or thermal processing. Baresel explains that powdered activated carbon is one option for removing pollutants. ‘It’s the preferred option in Germany,’ he says. However, it ends up in the sludge, which would count against use of the sludge on land. ‘That is quite an important aspect for Sweden,’ he adds.

The overall findings in terms of technology options are summed up in figure x. This highlights technologies that are currently available, as well as emerging options.

 

Cost questions

There are questions around the cost of adding advanced treatment. ‘The actual cost of installing and operating the techniques are quite easy [to judge],’ says Baresel. More complex are the planning and permitting costs. ‘That is still a big issue in Sweden,’ he adds.

Sweden has just taken a big step forward with its first full-scale installation opening at Linköping, for which IVL carried out the pilot testing. For such early plants, the additional costs will be relatively high, but Baresel sees that over time this will reduce. ‘We can use all the experience on the other ones, so the cost for planning and everything else will be much lower,’ he says.

 

The way ahead

The message in terms of treatment technologies is that there are viable options. But this does not simply mean that there is a one-size-fits all solution for all treatment plants.

To begin with, Baresel underlines the importance of aligning the treatment with the requirements of the local receiving waters. This point comes through in the EPA’s recommendations to government.

‘The recipient determines what pollutants you have to remove,’ says Baresel. ‘The recipient is really important.’ This can mean, for example, that even though compounds are only present in very low concentrations, a receiving water with a very low dilution rate may still require treatment. Equally, local conditions could mean that treatment does not need to be provided for certain substances, even if it is feasible to remove them.

It also means considering what treatment is already in place at a treatment plant. By way of example, Baresel cites the Linköping wastewater treatment plant. Ozonation provides one means for removing pharmaceuticals, but he says there are concerns around the creation of by-products. ‘You need some kind of polishing,’ he notes, pointing out that this therefore adds to costs. The option identified for Linköping was to put the ozonation between the two biological stages at the plant, allowing by-products to be removed in the second biological stage. In this option, ozonation was also identified as a means of increasing the release to organically-bound phosphorus and nitrogen, improving treatment for these compounds also.

Such an approach adds to the complexity of any regulatory framework, since it is not simply a case of setting fixed discharge limits for each substance, even if only indicator substances are used as the basis for regulation. Baresel sees this as a key area for progress. ‘The main issue is that setting of the actual goal of the treatment,’ he says.

Another area requiring progress is the testing that is used, including testing for any by-products formed. ‘We have seen many projects that have used analyses that are not viable for pharmaceuticals, for example,’ says Baresel. Test results can mean the difference between indicating a plant is likely to remove or that additional treatment is needed.

Baresel sees the opportunity to use a relatively small number of indicator substances covering pharmaceuticals – 15 or 16 based on the testing programme that has been developed in the country. Assessment of concentrations and dilution factors combined with data on toxicity can be used to identify compounds that representing an unacceptable risk, and then for treatment at a plant to focus on these compounds. This approach is similar to the way nutrient controls are already assessed in relation to sensitive waters.

 

Broad treatment options

The message is that each location needs its own specific approach. Baresel does explain however that there are some broad scenarios about likely options to pursue.

One of these is in fact that in many cases any action on pharmaceuticals should not run ahead of dealing with other issues. ‘In Sweden, we have many treatment plants. The majority are below 20,000 population equivalents,’ says Baresel. ‘There the recommendation is [to do] nothing on the advanced treatment because you need to first upgrade them to really remove nutrients to a good level.’ Tackling pharmaceuticals before this would add to the expense of doing so and would not be an efficient use of resources, he explains.

Treatment plants based on membrane bioreactors, meanwhile, already include a process able to remove microplastics, as well as antibiotic-resistant bacteria and any substances attached to the particulate material removed. In this case, Baresel says the recommendation would be to add a small polishing step based on a biological active filter with activated carbon. ‘That’s more or less the easiest installation,’ he says, adding: ‘Of course, not many treatment plants have an MBR process installed.

Another more general option is to use ozonation followed by a biological activated treatment step, with ozonation removing some of the contaminants and activated carbon removing the rest, explains Baresel. ‘You need to complement the different technologies,’ he says. ‘That’s the main recommendation.’

 

More information:

IVL Report C 235, April 2017

Keywords: 

  • Sweden, IVL, pharmaceuticals, micropollutants, microplastics