Report and presentations are now online for the ESPP workshop Pharmaceuticals in sewage biosolids (27/10/2016). The main workshop conclusions are:

  • Incineration of sewage sludge can be an appropriate solution depending on local conditions (e.g. contaminated sludge, lack of agricultural space for spreading …) but is lower down the recycling hierarchy (energy “recovery” not recycling). Even if phosphorus is recovered from ash (to produce fertiliser or for industry applications), organic carbon, nitrogen, potassium, sulphur and micro-nutrients are lost.
  • Concerns about sludge contaminants must be taken seriously and addressed both by developing data and information to support risk assessments, and by taking upstream actions wherever possible to reduce contamination of sewage sludge. For industrial chemicals and consumer chemicals, this is possible by actions targeting users and households (reduce discharge to sewers), but for pharmaceuticals it is much more difficult.
  • Public exposure risk to organic contaminants via sewage sludge should be put into context of exposure from other routes (both the same and other organic contaminants via direct contact and in household dust, air, water). However, this does not absolve the need to address sewage sludge use in agriculture in order to inform farmers, the food industry, consumers and decision makers.
  • Veterinary pharmaceuticals and hormones are also present at significant levels in manures, and this should also be addressed, both by reductions at source where possible, and by monitoring and treatment where manure nutrients are recycled.
  • There still a need for more data regarding fate of organic contaminants, including pharmaceuticals in sewage sludge. There is more data on heavy metals, and more data on organic contaminants in water (sewage works discharge, rivers, drinking water) than in biosolids. The question is multi-faceted: contaminants in biosolids, fate in sewage treatment and in sludge treatment processes, in soils, in crops, both short and medium term presence and impacts.
  • Pharmaceuticals and other organic chemicals in sewage sludge are varied and complex, and cannot be considered as a single issue. Of the wide number of molecules, new pharmaceuticals and chemicals, breakdown products, which to monitor? Further data and understanding is needed to try to identify different families of substances which have similar behaviour, but without over-simplifying.
  • Pharmaceuticals and hormones are important challenges, because of the inherent obstacles to upstream reductions, both in sewage sludge and in animal manures.
  • More immediately however, industrial and household chemicals require monitoring and action, in particular:
    • PFOS (perfluorooctane sulfonate) and other perfluorinated chemicals, e.g. from Teflon
    • triclosan and triclocarban
    • brominated flame retardants and substitute chemicals
    • dioxins
    • PAH (poly aromatic hydrocarbons)
  • Composting is generally effective for removing many, but not all pharmaceuticals. Female hormones however are largely not degraded.
  • Removal of organic contaminants in sewage treatment systems is very variable and difficult to predict, depending on contaminant molecule chemistry, sludge properties, dewatering, treatment conditions.
  • Anaerobic digestion can break down some pharmaceuticals, but further work is needed to better understand how to improve this, including looking at sludge disintegration upstream of digesters (e.g. Cambi, Haarslev, Biothely). Further work is needed on degradation metabolites to verify if these pose issues.
  • There is potential to develop new sludge treatment process chains in order to improve pharmaceuticals removal, e.g. treatments upstream of anaerobic digestion, or modification of conditions in digesters and in the sewage works biological treatment cycles
  • Female hormones are often not degraded in sludge treatment, but this may be not of environmental or health significance. Manures either spread or going directly to soils from animals in the field often contains significant levels of such hormones.
  • Antibiotic resistance is a globally important health issue, and should be better studied for sewage biosolids application. Knowledge shows that soils can naturally adapt, because soil organisms naturally release antibiotics, so that antibiotic resistance appearing after sludge application seems to be only temporary.
  • Several studies confirm that movement of organic contaminants to groundwater is very low from sewage sludge land application. This is unsurprising, as the contaminants found in sludges are those which tend to partition to solids, and not to water.
  • Data is needed to develop robust risk assessments of agricultural use of sewage biosolids, and also of manures, taking into account fate of and possible impacts of pharmaceuticals in sewage treatment processes, sludge treatment, in soil and possibly in crops and for grazing livestock. This cannot be feasibly done for the large number of pharmaceutical molecules and other organic contaminants, so screening is needed to identify priority substances.

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