Fate of micropollutants in a lab-scale urban wastewater system: Impact of iron-rich drinking water treatment sludge

Abstract

Iron rich drinking water treatment sludge (Fe-DWTS) could be a potential alternative for Fe salts in controlling sulfide in the sewer network. This study investigated the impact of in-sewer dosed Fe-DWTS on the fate of 26 different intrinsic organic micropollutants in wastewater by using a lab-scale integrated system consisting of sewer reactors and a sequential batch reactor (SBR) to simulate urban wastewater collection and treatment. The batch results revealed that seven among these 26 compounds had higher removal in the Fe-DWTS dosed sewer reactor compared to the control sewer reactor. In contrast, the removal of 7 out of the 26 investigated compounds were reduced, along with the biofilm methanogenic activity due to the long-term Fe-DWTS dosing. Cycle experiments in the SBR showed that the removal of acesulfame was enhanced and the formation of carbamazepine, desvenlafaxine, tramadol and hydrochlorothiazide were reduced, compared to their behaviour in the control SBR. However, the long-term experiments showed no adverse or beneficial effect of in-sewer dosed Fe-DWTS on the removal of most micropollutants in the SBR. Codeine, trimethoprim and gabapentin were exceptions with slightly higher concentrations in the experimental SBR effluent, possibly due to change in microbial composition.