Degradation of carbamazepine and triclosan in sewage sludge mixtures used for fertilizing agricultural soils

Global deficit of fertilizers is evident and as a result of the war in Ukraine the situation is worsening. At the same time, not all the possible major resources of nutrients have found appropriate application in agriculture, as for example sewage and its sludge, which are among the most promising sources of P, N and organic matter. Sewage sludge (SS) usage as an agricultural fertilizer has a number of limitations. Amongst them persistent organic pollutants (POPs) have a special role due to their ability to affect living organisms. Ongoing work directed to eliminating POPs present in SS is widely reported, but due to the complexity of these compounds no universal success has been achieved. In the case of several undesired residual compounds promising results have been gained using SS composting with different bulking agents. The current study was concentrated on the degradation of some widely used persistent POPs that are present in SS, namely carbamazepine (CBZ) and triclosan (TCS). Peat alone as a bulking agent widely used in the mixture with sewage sludge in Estonia is not suitable for initiating the process of composting. Additions of carbon-rich matter, as for example draff, might provide the relevant conditions needed for launching this process.