One of the potential emission sources of odorous compounds from wastewater treatment plants is sludge processing. The odorous compounds released from dewatered sludge can result in odor nuisance. This study concerns the use of flux hood chamber combined with proton transfer reaction—time of flight—mass spectrometry (PTR-MS) technique for periodical monitoring of odorous compounds emitted from aged, stabilized dewatered sludge samples from 2 different wastewater treatment plants located in Pomeranian Voivodeship, Poland. Based on determined concentration of the chemical compounds and olfactory threshold values, theoretical odor concentrations (known also as “odor activity value” or “odor index”) were calculated for 17 selected odorous compounds. As a result, sulfur compounds such as diethyl sulphide, dimethyl sulphide, methanethiol, and ethanethiol were estimated as the most significant chemical compounds responsible for malodorous effect (average results, e.g., methanethiol, 178 ou/m³; diethyl sulphide, 184 ou/m³). Based on Pearson correlation coefficient, we revealed a correlation between odorous substances emitted from aged, stabilized dewatered sludge cakes. It was revealed that stabilized dewatered sludge still possessed significant amount of odorous compounds and applied measurement technique could be used for monitoring of odor concentration level of selected malodorous compounds.

Varieties of gas chromatography (GC) combined with chemical detection (CD) and sensory analysis at the odour detection port (ODP) for the evaluation of environmental odorants has steadily increased in application and sophistication; this has given rise to a plethora of techniques that cater to specific tasks. With this diversity of approaches in mind, there is a need to assess the critical points at which these approaches differ, as well as likely risks and factors that may affect them. These critical points explained within this review include sample preparation, GC separation techniques (with associated co-elution risks), how the elute is separated between CD and sensory analysis, the type of CD, the type of sensory analysis (with particular attention paid to its factors and guidelines), integrative data techniques, as well as how that data may be used. Additionally, this review provides commentary on the current state of the research space and makes recommendations based on how these analyses should be reported, the standardisation of nomenclature, as well as the impediments to the future goals of this research area. By careful consideration of the critical points of varying analytical processes and how best to communicate these findings, the quality of output within this area will improve. This review provides a benchmark for how GC-CD/sensory analysis should be undertaken and reported.

Opportunities for the beneficial re-use of biosolids are limited by nuisance odour emissions. Volatile organic compounds (VOCs) from anaerobically stabilised biosolids were measured to identify compounds that could contribute to the overall odour character of nuisance emissions. Flux hood sampling and chemical analysis were used to identify VOCs emitted from biosolids as they were stored in ambient conditions. Compounds emitted varied as the biosolid cakes were stored for a period of 50 days. VOCs detected in the biosolids are likely to occur from catchment sources as well as abiotic and biotic generation in the wastewater processing and the biosolids as they are stored. Odour activity values (OAVs) were used to compare odorants. Trimethylamine was the only VOC detected that exceeded the sulfur compounds in terms of OAVs. Other compounds such as limonene, ethyl methyl benzene and acetic acid were detected at concentrations exceeding their olfactory detection limits, however at lower OAVs than sulfur compounds.

Biosolids storage areas are a significant contributor to wastewater treatment plant (WWTPs) odour emissions which can cause sensorial impact to surrounding communities. Most odour impact regulations are based on odour concentration (COD) measurements determined by dynamic olfactometry. Understanding the relationship between odorants concentrations and COD in the biosolids emission is important to identify how the measurement and monitoring can be conducted using analytical rather than sensorial techniques. Some of the odorants are unknown in biosolid emissions, increasing the uncertainty in predicting COD. In this study, emissions from 56 biosolid samples collected from two WWTPs located in Sydney, Australia, were analysed by analytical and sensorial methods, including olfactory detection port (ODP) and dynamic olfactometry. Concentrations of 25 odorants and two ordinal variables represented odour events detected by ODP assessors were linked to COD values. Bayesian Model Averaging and Variable Selection with Bayesian Adaptive Sampling were applied to model the relation between COD and odorants concentrations. Results indicate the usability of the probabilistic methods and nonlinear transformations in modelling the odour concentrations based on odorants concentrations from biosolids emission and the accuracy of a small dataset.