The fate of pharmaceuticals and personal care products during composting of sewage sludge

Abstract

Pharmaceutical and personal care products (PPCPs) are eliminated from wastewater on wastewater treatment plants, and can enter sludge treatment areas along with sludge that is often composted and subsequently used as fertilizer. The objective of this study was: i) to compare the concentrations of PPCPs before and after composting of sewage sludge (SS) that is important for producers of composts and policy makers, ii) to quantify an effect of composting process on decomposition of PPCPs, iii) to find out relationship between PPCPs, selected chemical properties and microorganisms . The experiment was conducted over a duration of four months with sewage sludge mixed with straw pellets (SPs) in various proportions. The concentrations of PPCPs in the input materials were measured before the composting began, and in the compost at the end of the trial. Of all 12 monitored PPCPs, telmisartan showed the highest concentrations (up to two orders of magnitude). Composting has a positive effect on the breakdown of caffeine, citalopram , diclofenac, mirtazapine , venlafaxine and partially sulfapyridine . Conversely, the decomposition of amitriptyline , carbamazepine , cetirizine , ibuprofen , telmisartan , and triclosan was not influenced by the composting process. All analyzed PPCPs had significant ( p < 0.001) positive correlations with pH, electrical conductivity, total nitrogen, fungi and Gram-negative bacteria. However, a significant ( p < 0.001) negative correlation was seen with PPCPs and total carbon, the carbon-to-nitrogen ratio, bacteria, actinobacteria , Gram-positive bacteria and total microbial biomass . Composting technology should be further investigated and optimized for its potential to reduce the concentration of PPCPs in sewage sludge. • Dewatered sewage sludge was composted with straw pellets. • The fate of selected pharmaceuticals in composted sewage sludge was investigated. • Concentrations of caffeine, diclofenac, citalopram, and mirtazapine decreased. • Concentrations of some pharmaceuticals increased due to loss of organic matter.