Odorous Vocs Identification from Ageing Dewatered Anaerobically Stabilised Biosolids from Polish Wwtp by Two-dimensional Gas Chromatography Couple with Time-of-flight Mass Spectrometry

Abstract

Odour from biosolids emission is a complicated matrix. Still a little is known about chemical composition of odours from biosolids and which compounds are responsible for overall odour. Apart from well-known odorants such as sulfur compounds and ammonia, participation of volatile organic compounds (VOCs) in overall odour may be of importance. Especially, if those chemicals have a low or unknown odour threshold, exist in low concentrations and their identification possesses an analytical challenge. In this work two anaerobically stabilised dewatered biosolids samples from wastewater treatment plant in Poland were stored over 21 days under ambient conditions. Emissions from biosolids samples were collected in triplicate onto Tenax TA sorbent tubes using a U.S. EPA flux hood method on days 1, 7, 10, 14 and 21. The 55 VOCs coming from different chemical compounds categories such as aliphatic and aromatic hydrocarbons, alcohols, aldehydes, ketones, sulphides and esters were identified by two-dimensional gas chromatography couple with time-of-flight mass spectrometry. The results for both biosolids samples vary. For example, during the first day of the biosolids storage 2-methylthiophene and 2-methylheptane were detected in both biosolids cakes whilst methanethiol and methyl ethyl sulphide in the biosolids cake no. 1 only. Only a few compounds were presented during the entire storage period: toluene, styrene, dimethyl sulphide (apart from the first day from biosolids cake no 1) and hexadecanal (apart from the seventh day from biosolids cake no 2). Most of the compounds were detected on an irregular basis across the whole measurement period.