Emission Characteristics and Factors of Selected Odorous Compounds at a Wastewater Treatment Plant

This study was initiated to explore the emission characteristics of Reduced Sulfur Compounds (RSCs: hydrogen sulfide, methyl mercaptan, dimethyl sulfide, dimethyl disulfide), ammonia and trimethylamine from a Wastewater Treatment Plant (WWTP) located at Sun-Cheon, Chonlanam-Do in South Korea. The study also evaluates flux profiles of the six selected odorous compounds and their flux rates (μg/m2/min) and compares their emission characteristics. A Dynamic Flux Chamber DFC was used to measure fluxes of pollutants from the treatment plant. Quality control of odor samples using a non-reactive sulfur dioxide gas determined the time taken for DFC concentration to reach equilibrium. The reduced sulfur compounds were analyzed by interfacing gas chromatography with a Pulsed Flame Photometric Detector (PFPD). Air samples were collected in the morning and afternoon on one day during summer (August) and two days in winter (December and January). Their emission rates were determined and it was observed that during summer relatively higher amounts of the selected odorous compounds were emitted compared to winter. Air samples from primary settling basin, aeration basin, and final settling basin were tested and the total amount of selected odorous compounds emitted per wastewater ton was found to be 1344 μg/m3 from the selected treatment processes. It was also observed that, in this study, the dominant odor intensity contribution was caused by dimethyl disulfide (69.1%)

Conversion of chemical scrubbers to biotrickling filters for VOCs and H2S treatment at low contact times

The purpose of this work was to evaluate the technical and economical feasibility of converting three chemical scrubbers in series to biotrickling filters (BTFs) for the simultaneous removal of H2S and volatile organic compounds (VOCs). The conversion of the full-scale scrubbers was based on previous conversion protocols. Conversion mainly required replacing the original carrier material and recycle pumps as well as modifying the controls and operation of the reactors. Complete removal of H2S and VOCs on a routine basis was reached at neutral pH in a longer period of time compared to previous conversions reported. Biotrickling filters operated at a gas contact time of about 1.4 s per reactor and at pH controlled between 6.5 and 6.8. Inlet average concentrations below 10 ppmv of H2S and below 5 ppmv for VOCs were often completely removed. The first and second bioreactors played a primary role in H2S removal. Year-round operation of the biotrickling filters proved the ability of the system to handle progressive load increases of H2S and VOCs. However, fast, sudden load changes often lead to reduced removal efficiencies. Odor analyses showed average removal efficiencies above 80 %. Gas chromatography-mass spectrometry of selected samples showed that outlet odor concentration was due to limited removal of VOCs. The conversion showed was economically viable taking into account the theoretical consumption of chemicals needed for the absorption and oxidation of both H2S and VOCs.Peer ReviewedPostprint (published version

Preliminary Hydrogen Sulfide Emission Factors and Emission Models for Wastewater Treatment Plant Headworks

Generation of hydrogen sulfide (H2S) is a common phenomenon from wastewater collection, transport, and treatment processes. Impacts of H2S emissions from wastewater include corrosion and reduction in the service life of wastewater infrastructure, odor nuisance in the community, and health impacts on wastewater operations and maintenance personnel (Neilsen, et al. WEFTEC 2006). Conventional odor control studies performed by municipalities to design their individual odor/corrosion control strategies largely depend on establishing a dilution to detection threshold (D/T) ratio and ascertaining the recognition threshold (R/T) for air samples collected from the study area. These conventional odor studies based on grab samples using R/T and D/T technique using a few days of data have a number of limitations and potentially lead to inaccurate conclusions. However, H2S emission studies using continuous air monitoring is expensive and time consuming. The objective of this research is to understand the feasibility of utilizing emission factors as a tool to predict hydrogen sulfide emissions from headworks of four different Jefferson Parish, Louisiana wastewater treatment plants (WWTP). Proposed model(s) developed for predicting H2S emission factors that depend on wastewater parameters should be convenient for the municipalities to use as the data required is monitored routinely. Use of H2S emission models should assist rapid identification of H2S emission hot spots, optimize H2S control strategies, predict potential health risks, prevent community odor nuisance, and ascertain infrastructure corrosion. This dissertation attempts to; i) develop a research methodology, ii) identify instruments required, iii) generate emission factor ranges and compare their sensitivity to wastewater parameters, iv) generate preliminary empirical emission models based on flow treated, population serviced and area served by a treatment plant for each sampling location and v) provide a roadmap for future research opportunities to refine the models generated as part of this dissertation. Key words: emission model, emission factor, emission ranges, hydrogen sulfide, odor control, air quality, wastewater treatment

Development of innovative system to contain the odourous impact of industrial plants

Il seguente progetto di dottorato si occupa dello sviluppo di sistemi innovativi per l'abbattimento delle emissioni odorose degli impianti industriali, concentrandosi su due settori industriali sviluppati nella Regione Marche: l'industria del legno e il riciclaggio dei rifiuti vegetali. L'impatto odorigeno delle attività industriali è un grave problema per le attività produttive stesse; anzi, spesso le autorità competenti per il controllo sono costrette ad agire. La causa principale di tali impatti non è sempre dovuta al superamento delle concentrazioni imposte dai limiti di legge; anzi, una pianificazione urbanistica inefficace in passato ha portato all'insediamento di stabilimenti industriali in prossimità di zone residenziali: le molestie olfattive diventano motivo di denuncia dei cittadini, che ostacolano lo svolgimento del lavoro delle aziende. In questo contesto è fondamentale lo sviluppo di sistemi innovativi efficaci, finalizzati al contenimento degli odori provenienti dai processi produttivi. Il presente progetto di ricerca di dottorato è stato cofinanziato da una società (Pan Eco srl), la cui missione è quella di supportare le diverse industrie presenti sul campo nel rispetto delle normative ambientali; in questo settore ottiene autorizzazioni e sviluppa progetti volti al rispetto di tutti i vincoli ambientali. Considerando lo scenario appena descritto e la mission aziendale, l'obiettivo generale del programma di ricerca è stato lo sviluppo di sistemi innovativi per il contenimento delle emissioni odorose in atmosfera da parte di diversi impianti industriali. L'obiettivo generale del progetto è stato raggiunto attraverso obiettivi e attività specifici: - definizione dello stato dell'arte dei sistemi attualmente applicati per l'abbattimento delle emissioni in atmosfera di composti organici, compreso il contesto legislativo. Attraverso la ricerca bibliografica è stata realizzata una sintesi delle principali tecniche di campionamento, analisi e abbattimento delle emissioni odorigene, anche facendo riferimento alle principali normative a livello nazionale ed europeo; - individuazione delle aziende marchigiane (almeno due) con problematiche legate all'impatto olfattivo della produzione industriale. Sono state individuate due società, una operante nel settore del legno e l'altra operante nel riciclaggio dei rifiuti organici; - progettazione e realizzazione di un sistema innovativo di abbattimento delle emissioni. In entrambi i settori presi in considerazione è stato individuato e implementato un innovativo sistema di abbattimento odori: verniciatura UV per il settore legno e vermicomposting per il riciclo dei rifiuti organici; - campionamento, caratterizzazione delle emissioni e valutazione degli eventuali miglioramenti. In entrambe le società è stato effettuato il campionamento delle emissioni utilizzando tecniche consolidate ed è stato valutato l'effettivo abbattimento delle emissioni odorigene con l'introduzione dei sistemi innovativi.This PhD project deals with the development of innovative systems for the abatement of odorous emissions from industrial plants, focusing on two industrial sectors developed in Marche Region: the wood industry and vegetable waste recycling. The odor impact of industrial activities is a serious problem for the production activities themselves; indeed, the competent authorities for control are often forced to take action. The main cause of such impacts is not always due to an overcoming of the concentrations imposed by the legal limits; indeed, an ineffective urban planning in the past has led to industrial plants located near residential areas: olfactory harassment becomes reason for citizens reports, that hinder the correct operation of companies. The problem of odorous emissions mainly concerns the following companies (Bertoni, 1993): - Companies in the industrial sector (wood industry, chemical industry, oil and gas refineries, foundries, plastic and paint production); - Agri-food companies (meat processing); - Companies that deal with waste and wastewater treatment (landfills and composting companies). In particular, the main odorous compounds are (Bertoni, 1993): - VOCs (Volatile Organic Compounds): aliphatic and aromatic hydrocarbons, phenols, aldehydes and ketons; - VSCs (Volatile Sulfur Compounds): hydrogen sulfide (H2S) and mercaptans (SH); - Nitrogen compounds: ammonia (NH3) and amines. The odorous emission from industrial facilities can be the cause of annoyance to the people living in the surrounding area. A long-term exposure may bring up serious damage to human health such as nausea, headaches and other related respiratory problems (Lebrero et al., 2011; Zarra et al., 2009b). In this context, the development of effective innovative systems is fundamental, aimed at containing odors from the production processes. The present PhD research project has been cofunded by a company (Pan Eco srl), whose mission is to support the various industries in the field compliance with environmental regulations; in this sector, it obtains authorizations and develops projects aimed at respecting all environmental constraints. Considering the scenario just described and the company mission, the general goal of the research program was the development of innovative systems for the containment of odorous emissions into the atmosphere by various industrial plants. The general goal of the project has been achieved through specific objectives and activities: - definition of the state of the art of the systems currently applied for the abatement of atmospheric emissions of organics compounds, including the legislative context. Through bibliographic research, a summary was made regarding the main techniques for sampling, analysis and abatement of odor emissions, also referring to the main laws at national and European level; - identification of companies in the Marche region (at least two) with problems associated with the odor impact of industrial production. Two companies have been identified, one operating in the wood industry and the other operating in the recycling of organic waste; - design and implementation of innovative emissions abatement system. In both sectors taken into consideration, an innovative odor abatement system was identified and implemented: UV painting for wood sector and vermicomposting for the recycling of organic waste; - sampling, characterization of emissions and assessment of the performance. In both companies, the sampling of emissions using consolidated techniques was carried out and the effective abatement of odor emissions was assessed

Comparative Evaluation of Conventional and Innovative Biotechnologies for Odour Abatement in Wastewater Treatment Plants

Como resultado de una legislación ambiental cada vez más estricta, del acercamiento de las zonas residenciales a las Estaciones Depuradoras de Aguas Residuales (EDARs) y del aumento de las expectativas ciudadanas con respecto a los estándares de calidad ambiental exigidos a las compañías que explotan estas EDARS, el número de quejas por contaminación odorífera ha crecido de manera substancial en los últimos años. En la presente tesis se realiza una comparación sistemática de la eficacia de diferentes sistemas biológicos (tanto convencionales como innovadores: biofiltros, biofiltros percoladores, sistemas de difusión en lodos activos, bioreactores de membrana y sistemas bifásicos) en el tratamiento de emisiones odoríferas, centrándose en la fracción más hidrofóbica de estas emisiones. Además, se evalúa la influencia de parámetros clave en el rendimiento de desodorización del proceso, la estabilidad y las dinámicas microbianasDepartamento de Ingeniería Química y Tecnología del Medio Ambient

Odour Detection Methods: Olfactometry and Chemical Sensors

The complexity of the odours issue arises from the sensory nature of smell. From the evolutionary point of view olfaction is one of the oldest senses, allowing for seeking food, recognizing danger or communication: human olfaction is a protective sense as it allows the detection of potential illnesses or infections by taking into account the odour pleasantness/unpleasantness. Odours are mixtures of light and small molecules that, coming in contact with various human sensory systems, also at very low concentrations in the inhaled air, are able to stimulate an anatomical response: the experienced perception is the odour. Odour assessment is a key point in some industrial production processes (i.e., food, beverages, etc.) and it is acquiring steady importance in unusual technological fields (i.e., indoor air quality); this issue mainly concerns the environmental impact of various industrial activities (i.e., tanneries, refineries, slaughterhouses, distilleries, civil and industrial wastewater treatment plants, landfills and composting plants) as sources of olfactory nuisances, the top air pollution complaint. Although the human olfactory system is still regarded as the most important and effective “analytical instrument” for odour evaluation, the demand for more objective analytical methods, along with the discovery of materials with chemo-electronic properties, has boosted the development of sensor-based machine olfaction potentially imitating the biological system. This review examines the state of the art of both human and instrumental sensing currently used for the detection of odours. The olfactometric techniques employing a panel of trained experts are discussed and the strong and weak points of odour assessment through human detection are highlighted. The main features and the working principles of modern electronic noses (E-Noses) are then described, focusing on their better performances for environmental analysis. Odour emission monitoring carried out through both the techniques is finally reviewed in order to show the complementary responses of human and instrumental sensing

Multipoint characterization of the emission of odour, volatile organic compounds and greenhouse gases from a full-scale membrane-based municipal WWTP

Altres ajuts: Acord transformatiu CRUE-CSICDifferent environmental and social concerns can arise due to the generation of gaseous emissions during the treatment of urban wastewater. However, there is not an extensive knowledge about which are the main potential odour and greenhouse gas (GHG) emission sources in a wastewater treatment plant (WWTP) and their variability. In this study, a multipoint characterization of the gaseous emissions generated in a full-scale municipal WWTP located in Barcelona was conducted, aiming at identifying the main odour and GHG emission sources. The WWTP under study treats an average inlet flow of 33,000 m3 d−1 using a Ludzack-Ettinger system with Membrane BioReactor (MBR) technology, and it has installed a gas caption and treatment system consisting of a biotrickling filter followed by a conventional biofilter to treat part of the off-gases produced during the wastewater treatment. For this work, gaseous emissions characterization campaigns were conducted to assess the proper performance of the gas treatment unit and to estimate the emission factors referred to odorants and GHGs for the different emission sources and to assess the proper performance of the gas treatment system. Besides, a chemical characterization of the different volatile organic compounds (VOC) present in the gaseous emissions was performed through TD-GC/MS. The main potential odour sources were the reception tank, the barscreens building and the primary settler, where odour concentrations were in the range of 1300 and 2600 ou·m−3. Moreover, GHG emissions were found during the primary treatment and in the MBR units, ranging from 2.21 to 68,217.13 mg CO2eq·m−3. Different VOCs such as aromatic hydrocarbons, alkanes and ketones were found in the gaseous emissions with a high variability among all the emission sources. The results obtained are valuable indicators that can be used to develop odour and GHG mitigation strategies in WWTPs and to estimate the environmental impact of these facilities

GIS-Based Odor Impact Assessment from Biosolids Land Application Sites

Biosolids applied to agricultural land may upset neighboring communities due to the inherent malodorous smell of biosolids. The problem of the odor becomes a major concern in the wastewater treatment industry when community responses could vary from complaints to legal action to ban or reduce biosolids recycling through land. Unlike odor at a wastewater treatment facility, which is produced from the characteristics of wastewater itself and from individual unit processes, land-applied biosolids odor depends not only on the quality of biosolids, but also on the biosolids emissions levels, unfavorable weather conditions and topographic characteristics, and variation of human perception. Those factors increase the complexity of nuisance odor at land application sites. This dissertation aims to assess biosolids emission impacts on surrounding communities by estimating the level of biosolids odor emissions, simulating odor dispersion, and quantifying human perception to biosolids odor. Odor emission rates at land-applied biosolids fields were estimated using three different approaches: assumed flow rate, statistical inference, and simulated-flux chamber. The estimated emission rates were used as an input to dispersion models. The U.S. Environmental Protection Agency Regulatory Models, both screening and refined models, were used to simulate dispersion of biosolids odor at land application sites. A Geographic Information System (GIS) was employed to support modeling steps and to create maps. Appraisal of odor perception by receptors was assessed by use of Steven's psychophysics power law. The District of Columbia Water and Sewer Authority (DCWASA) land application fields in Virginia were used as case studies. More specifically, 45 fields in Albemarle and Orange Counties were focused on. Concentration prediction maps along with probability maps were created to support visualization and provide information on potential odor impacts to communities. Possible human perceptions were expressed in Intensity maps. The methods and results described in this dissertation can support decision makers in selecting appropriate land application sites prior distributing biosolids to reduce adverse effects from land-applied biosolids

Testing, Validation and Dissemination of an Innovative Biotechnology for Air and Water Treatment.

The present study is aimed to follow the start-up in the Italian and European framework of an American biotechnology for environmental decontamination and it focused on field testing stage for air treatment application, in parallel with a bench/pilot scale application on industrial wastewater treatment. The biotechnology applied is based on immobilized cell bioreactors, where air is ventilated and water is recirculated to provide the optimal conditions for the development of a mixed bacteria consortium, growing on contaminants captured from contaminated media (i.e. air or wastewater). The technology proposed has been studied from different perspectives, i.e. emission risk, overall sustainability and remediation performance. Several pilot installations have been accomplished for air treatment application, in different areas of interest. In particular, in the healthcare sector (hemodialysis unit, operatory room, intensive care unit and anatomo-pathological laboratory), where the protection against microbial and chemical agents is perceived as a necessity, both for operators and patients, the biotechnology displayed remarkable results, particularly on VOCs and bacterial count. In order to try and address one of the most challenging issue for air treatment, i.e. odor containment, two major pilot applications have been performed, on waste and wastewater treatment plant, with promising, but still unsteady results. A new opportunity for application was envisaged in radioactivity contaminated indoor environments and a preliminary impact assessment has been outlined, based on results obtained in different fields. For wastewater treatment, a single pilot scale plant was implemented and silk manufacturing effluent was object of the experimental remediation attempted. In a cost-effective perspective, the implementation of this system appears to be suitable for several solutions, i.e. within the framework of a multi-stage treatment process or as independent and easily implementable wastewater technology for cottage-scale manufacturing or small communities

Measuring odours in the environment vs. dispersion modelling: A review

Source characterization alone is not sufficient to account for the effective impact of odours on citizens, which would require to quantify odours directly at receptors. However, despite a certain simplicity of odour measurement at the emission source, odour measurement in the field is a quite more complicated task. This is one of the main reasons for the spreading of odour impact assessment approaches based on odour dispersion modelling. Currently, just a very limited number of reports discussing the use of tracer gas dispersion experiments both in the field and in wind tunnels for model validation purposes can be found in literature. However, when dealing with odour emissions, it is not always possible to identify a limited number of tracer compounds, nor to relate analytical concentrations to odour properties, thus giving that considering single odorous compounds might be insufficient to account for effective odour perception. For these reasons, the possibility of measuring of odours in the field, both as a way for directly assessing odour annoyance or for verifying that modelled odour concentrations correspond to the effective odour perception by humans, is still an important objective. The present work has the aim to review the techniques that can be adopted for measuring odours in the field, particularly discussing how such techniques can be used in alternative or in combination with odour dispersion models for odour impact assessment purposes, and how the results of field odour measurements and model outputs can be related and compared to each other