Wastewater monitoring by means of e-nose, VE-tongue, TD-GC-MS, and SPME-GC-MS
Graphical abstract
Introduction
Over the past few decades, pollution has increasingly become a crucial factor affecting the quality of life and health status of urban populations. Indeed, very harmful pollutants from industries and households can be drained by wastewater, leading to a deterioration of water quality and causing serious damage to human health, aquatic ecosystems, animals, and the environment [[1], [2], [3], [4], [5], [6]]. Moreover, one of the irritating factors in wastewater is the presence of an unpleasant odor that comes from volatile compounds in wastewater passing into the air by evaporating and is transmitted by the wind and contaminates nearby areas [7]. That's why air and water pollution are reported to be the main cause of several diseases, such as cardiovascular dysfunction, inflammation, respiratory infections, and cancer leading to millions of deaths around the world every year [[8], [9], [10], [11], [12]].
The aim of wastewater analysis is to curb polluting elements. This will reduce or eliminate complaints from the population affected. In order to detect ultra-trace amounts of organic compounds in air and wastewater, different approaches, such as Gas Chromatography-Mass Spectrometry (GC-MS) [13], TD-GC-MS [14], SPME-GC-MS [15], Headspace Solid-Phase Micro-Extraction Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) [16], Gas Chromatography-Flame Ionization Detector (GC-FID) [17], Gas Chromatography-Tandem Mass Spectrometry (GC-MS-MS) [18], and High Performance Liquid Chromatography-Fluorescence Detection (HPLC-FLD) [19] have been performed. These techniques provide very detailed information on the nature and concentration of the samples. However, they allow analysis of single compounds in odors. This is not enough sufficient to adequately characterize wastewater odors [20,21]. Indeed, they are relatively expensive, not transportable, often require samples pre-treatment, long measurement times, and qualified personnel [22].
Besides, for wastewater analysis, several devices have been devised including e-nose [23,24], e-tongue [[25], [26], [27]], e-nose correlated with olfactometry analysis [20,28], a portable and commercial e-nose (PEN3) in conjunction with GC-MS [29], voltammetric electronic tongue combined with HPLC as reference method [30]. Despite the advantages and potential of these instruments, complete wastewater analysis has not been fully explored because the reported studies only analyze odorous air or liquid wastewater samples individually. In the literature, it is difficult to find a study reporting the use of e-nose, VE-tongue, TD-GC-MS, SPME-GC-MS, and physic-chemical analysis for quasi-complete analysis of odorous air, headspace, and liquid samples from water and wastewater sites. To fill this gap, the devices mentioned above are used in this study.
For this purpose, Fez, an imperial and touristic city of Morocco, is selected for this investigation because it has a fast-growing urban workforce and is understudied for its outdoor air and water's quality. The city is crossed by two rivers “Oued Fez” and “Sebou”. The “Sebou” river (496 Km) flows to Fez and discharges into the atlantic sea (near to Kenitra city). It is widely used for different purposes like city water supply, industry, and agriculture [31]. The polluted “Oued Fez” river discharges into the “Sebou” river that makes it contaminated. They are affected by different types of untreated water discharges from industrial activities, tanneries, petrol stations, metallurgy, and pottery [32]. Wastewater pollution has a negative impact on the agricultural and economic area of Fez. It also has the same impact on the quality of water [33].
Due to the health problems caused by some Volatile Organic Compounds (VOCs) following volatilization processes in wastewater, e-nose and VE-tongue systems could be helpful because of their significant advantages for wastewater analysis. To easily interpret multidimensional data from the complex responses generated by the sensor arrays, pattern recognition methods have been used, including PCA, HCA, and SVMs.
The present research highlights the ability of an e-nose and VE-tongue technology in conjunction with pattern recognition methods to characterize and discriminate water and wastewater samples. In addition, analytical technics such as TD-GC-MS and SPME-GC-MS methods have been used to determine compounds of the water and wastewater samples.
The novelty is to carry out an almost complete analysis of different wastewaters by exploiting their odorous air, liquid, and their headspace samples using e-nose and VE-tongue systems. The obtained results are explained by TD-GC-MS, SPME-GC-MS, and physico-chemical analysis techniques. The both systems have the advantages of being easy to handle, fast, no qualified personnel required, and allow on-site measurements.
Thus, the carried tasks are summarized in three main points:
- -
A home-developed e-nose, in combination with chemometric tools, is used to analyze odorous air samples from water and wastewater sites. The obtained results are explained by TD-GC-MS technique, which allows the identification of compounds in these odorous air samples.
- -
The same e-nose is also utilized to analyze the liquid headspace samples from the seven sites. Compounds in these headspace samples are identified using the SPME-GC-MS technique, which helps explaining the VE-tongue results.
- -
Another multi-sensor system (VE-tongue) is operated for the analysis of the liquid samples. The results of this analysis are elucidated by physico-chemical analysis.
Section snippets
Methods of sampling
In general, every sample of unpleasant emissions from a pollutant source is affected by climatic conditions such as the collection period, temperature, humidity, rain, and wind. Some difficulties may arise in collecting and analyzing samples which can be represented in the results. Thus, in order to identify appropriate instruments, equipment and sampling methods, it is important to know the nature and characteristics of the emission source [34]. The purpose of sampling is to obtain
E-nose results
Fig. 1A and B shows the normalized conductance of the MQ-9 sensor exposed to odorous air samples collected above sites and the corresponding headspace of liquid samples, respectively. In both cases, the normalized conductance increases with exposure time. This can be explained by the presence of oxidizing chemicals on the sensing surface of n-type solid-state gas sensors. These responses of MQ-9 sensor reach a steady state after 120 s of sample exposure. In Fig. 1A, the smallest response
Conclusion
Wastewater has been shown to be the object of many human health problems and discomfort.
Detection systems that are simple to handle, on-site, affordable, and capable of analyzing both odorous air and liquid samples from wastewater are rare to find in the literature.
In the present study, the use of detection systems (e-nose and VE-tongue) fulfilling these criteria was highlighted. Their potential to distinguish between clean water and wastewater samples was the main focus of this study. They
Credit author statement
Mohamed Moufid: Investigation, Formal analysis, Methodology, Software, Experimentation, Writing. Nezha El Bari: Writing Reviewing, Funding acquisition, Carlos Tiebe, Michael Hofmann, Matthias Bartholmai: Writing Reviewing. Benachir Bouchikhi: Conceptualization, Supervision, Validation, Project administration, Ressources, Funding acquisition, Writing Reviewing.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
We would like to thank Moulay Ismaïl University of Meknes for financial support of the project “Research support”. This work is funded by the federal Ministry of Education and Research (Germany) and Ministry of Higher Education, Scientific Research and Executives training (Morocco) under the Framework program of Moroccan-German scientific research cooperation, project PMARS III N°2015–87. Additionally we have to thank Mr. Richter, Mrs. Brödner, Mr. Lindemann and Mr. Jörg of BAM for carrying out
References (45)
- et al.
Emission characteristics and associated health risk assessment of volatile organic compounds from a typical coking wastewater treatment plant
Sci. Total Environ.
(2019) - et al.
Human health risk from heavy metal via food crops consumption with wastewater irrigation practices in Pakistan
Chemosphere
(2013) - et al.
Environmental pollution and health hazards from distillery wastewater and treatment approaches to combat the environmental threats: a review
Chemosphere
(2018) - et al.
In search of key: protecting human health and the ecosystem from water pollution in China
J. Clean. Prod.
(2019) - et al.
Water and health: from environmental pressures to integrated responses
Acta Trop.
(2019) - et al.
Simple and accurate quantification of BTEX in ambient air by SPME and GC–MS
Talanta
(2016) - et al.
Development of an electronic nose to characterize odours emitted from different stages in a wastewater treatment plant
Water Res.
(2018) - et al.
Characterization of odor released during handling of swine slurry: Part I. Relationship between odorants and perceived odor concentrations
Atmos. Environ.
(2009) - et al.
Electronic noses for the continuous monitoring of odours from a wastewater treatment plant at specific receptors: focus on training methods
Sensor. Actuator. B Chem.
(2008) - et al.
Monitoring dissolved orthophosphate in a struvite precipitation reactor with a voltammetric electronic tongue
Talanta
(2016)
Evaluation of an electronic nose for odorant and process monitoring of alkaline-stabilized biosolids production
Chemosphere
Determination of detergents in washing machine wastewater with a voltammetric electronic tongue
Talanta
Assessment of water quality and toxicity of polluted rivers Fez and Sebou in the region of Fez (Morocco)
Environ. Pollut.
Genotoxicity evaluation of effluents from textile industries of the region Fez-Boulmane, Morocco: a case study
Ecotoxicol. Environ. Saf.
Voltammetric electronic tongue combined with chemometric techniques for direct identification of creatinine level in human urine
Measurement
Exhaled breath analysis using electronic nose and gas chromatography–mass spectrometry for non-invasive diagnosis of chronic kidney disease, diabetes mellitus and healthy subjects
Sensor. Actuator. B Chem.
Physicochemical and microbial assessment of spring water quality for drinking supply in piedmont of Béni-Mellal Atlas (Morocco)
Physics. Chemistry. Earth. A-B-C.
Outdoor in situ monitoring of volatile emissions from wastewater treatment plants with two portable technologies of electronic noses
Sensor. Actuator. B Chem.
Removal of volatile organic compounds (VOCs) emitted from a textile dyeing wastewater treatment plant and the attenuation of respiratory health risks using a pilot-scale biofilter
J. Clean. Prod.
Emerging concerns of VOCs and SVOCs in coking wastewater treatment processes: distribution profile, emission characteristics, and health risk assessment
Environ. Pollut.
Probabilistic health risk assessment of heavy metals at wastewater discharge points within the Vaal River Basin, South Africa
Int. J. Hyg Environ. Health
The identification, health risks and olfactory effects assessment of VOCs released from the wastewater storage tank in a pesticide plant
Ecotoxicol. Environ. Saf.
Cited by (24)
A review of the state-of-the-art wastewater quality characterization and measurement technologies. Is the shift to real-time monitoring nowadays feasible?
2024, Journal of Water Process EngineeringVolatile organic compounds (VOCs) in wastewater: Recent advances in detection and quantification
2023, Microchemical JournalSynergetic application of an E-tongue, E-nose and E-eye combined with CNN models and an attention mechanism to detect the origin of black pepper
2023, Sensors and Actuators A: PhysicalQuality assessment of royal jelly based on physicochemical properties and flavor profiles using HS-SPME-GC/MS combined with electronic nose and electronic tongue analyses
2023, Food ChemistryCitation Excerpt :Therefore, the E-nose/tongue have been expected to be a promising alternative to the time-consuming and expensive classic analytical techniques. Currently, the E-nose/tongue have been widely applied in pharmaceutical, environment and safety, agricultural, and food industries due to their rapid, simple, non-destructive, and non-pollution features (Moufid et al., 2021). Therefore, the multi-function feature of the E-nose/tongue devices is essential in the early detection of food quality, mainly for human consumption and food control (Mohd Ali et al., 2020).
Chemical characterization of odorous emissions: A comparative performance study of different sampling methods
2023, TalantaCitation Excerpt :An increasing number of industrial/waste management activities are subject to odour emission monitoring. Therefore, at the regulatory level, often it is necessary not only to quantify the olfactory nuisance, using sensorial analysis (e.g. dynamic olfactometry), but also to chemically characterise these emissions, to evaluate, by knowing the chemicals present in odours and their concentrations, the molecules responsible for the odour harassment and their potential impact on citizens' and workers’ health [9–13]. Indeed, odour can be correlated with odour-related symptoms, such as irritation, pain, headaches, eyes irritation and unusual tiredness [14,15], or health effects related to the odorous and hazardous compounds potentially contained in the odorous emissions [16]: so knowing the chemical composition is fundamental to investigate the potential health effects associated with odorous emissions.
Development of a wide-range soft sensor for predicting wastewater BOD<inf>5</inf> using an eXtreme gradient boosting (XGBoost) machine
2022, Environmental ResearchCitation Excerpt :Specifically, the objective function used in determining the optimal parameters of an SVM model seeks to maximize generalizability (Liu and Xie, 2020; Jiang et al., 2020). Because of this, SVM can be used even with relatively small datasets, which can be important when analysing novel processes and technologies (Hosseinzadeh et al., 2022; Moufid et al., 2021). The disadvantage of SVM is that its generalizability objective may lead the model to overfit to the dominant condition in the dataset (Jaramillo et al., 2018).