Behaviour of emerging contaminants in sewage sludge after anaerobic digestion

Abstract

Nowadays, there is an increasing concern over the presence of contaminants in the aquatic environment, where they can be introduced from wastewater after their incomplete removal in the treatment plants. In this work, degradation of selected emerging pollutants in the aqueous and solid phases of sewage sludge has been investigated after anaerobic digestion using two different digesters: mesophilic and thermophilic. Initially, sludge samples were screened by ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS) for identification of emerging contaminants in the samples. In a second step, a target quantitative method based on LC coupled to tandem MS was applied for selected pollutants identified in the previous screening. The behaviour of the compounds under anaerobic conditions was studied estimating the degradation efficiency and distribution of compounds between both sludge phases. Irbesartan and benzoylecgonine seemed to be notably degraded in both phases of the sludge. Venlafaxine showed a significant concentration decrease in the aqueous phase in parallel to an increase in the solid phase. The majority of the compounds showed an increase of their concentrations in both phases after the digestion. Concentrations in the solid phase were commonly higher than in the aqueous for most contaminants, indicating that they were preferentially adsorbed onto the solid particles. KeywordsEmerging contaminants; sewage sludge; anaerobic digestion; time-of-flight mass spectrometry; triple quadrupole mass spectrometry.3/28

Identification of Aquifer Recharge Sources as the Origin of Emerging Contaminants in Intensive Agricultural Areas. La Plana de Castellón, Spain

“…Even valsartan, with a maximum EWW concentration of more than 23,000 ng/L, has only been detected in one GW sample with a concentration of 9.5 ng/L. This low rate of detection is due to the fact that this compound can transform into its TP [63] and, to a small extent, to be retained in the vadose zone, which in this case has an average depth of 20 m.…”

“…Several studies have revealed that this compound is considered to be highly stable in water/sediment [59], and, therefore, its presence in GW has been reported by a number of researchers [17,[60][61][62]. Concerning venlafaxine, recent studies have indicated that it is not a compound that degrades easily and rapidly into its TP [63]. Therefore, this behavior might help to preserve the compound in the EWW during the process of irrigation and subsequent storage in the aquifer saturated zone.…”

“…Carbamazepine may be a good indicator for soil with little organic matter and clayey characteristics, and it has been reported to also be appropriate for soils with high organic matter content [59]. Concerning venlafaxine, recent studies have reported that it is not easily and rapidly degraded into its TP [63]; this characteristic helps to preserve the compound in the EWW during the process of irrigation and subsequent storage in the aquifer saturated zone.…”

Analytical methodologies for the determination of pharmaceuticals and personal care products (PPCPs) in sewage sludge: A critical review

“…For instance, Gago-Ferrero et al [34] achieved LOQs of 4.1 ng/g for diclofenac and 9.8 ng/g for salicylic acid by applying a method based on UAE and UHPLC-MS/MS. In contrast, Boix et al [38] reported lower limits (eg., 63 ng/g for diclofenac and ng/g for salicylic acid) using a similar method but with HPLC as the chromatographic stage. Regardless of these factors, through the use of quantification approaches such as internal standard with isotope dilution, standard addition or matrix-matched techniques most technical deficiencies during extraction, clean-up, instrumental analysis, etc.…”

Sustainable Management of Sewage Sludge for the Production of Organo-Mineral Fertilizers

“…Because of a large number of emerging organic contaminants there is a need for future monitoring programmes and technological changes in sewage sludge management in order to reduce the concentration of organic contaminants to a level acceptable for sewage sludge application [27].…”