Odor Abatement Research Articles

Characterisation of odour masking agents often used in the solid waste industry for odour abatement

Odours from waste management facilities, wastewater treatment plants and composting areas have become a major nuisance issue for operators. In addition to facing regulations which tend to become more stringent, operators are also facing increased public pressure due to complaints from neighbours resulting in the temporary shutdown of such plants, therefore the elimination of atmospheric odours is becoming a major industrial objective. Many commercial odour control products are available on the market, however, very little is known concerning their real efficiency and mechanism of action. This paper will present the results from the study of 19 agents collected in various countries. The products were first characterised both in terms of their chemical composition and sensory properties. Selected products with different modes of application were then submitted to a study of their efficiency at the pilot-scale level. The results from one product test showed no significant difference in their odour removal efficiency as determined by olfactory and chemical analysis of the emission before and after application of the odour control product.

Odour emissions from MSW composting process steps

This study brought to the definition and the calculation of Odour Emission Factors (OEFs), which enable the estimation of odour emissions from a composting plant by relating the quantity of odour emitted to the atmosphere to a given associated activity. The results show that the aerobic biological treatment has the highest odour impact, with an OEF of 1.4 ? 108 ouE t−1. Moreover, the efficiency values that were measured on the odour abatement systems adopted in the monitored plants are presented: Biofilters have an average efficiency value of 93.88%, whereas scrubbers have very variable efficiencies, with an average value of 44.12%.

The role of surface acidity and pore size distribution in the adsorption of 2-methylisoborneol via powdered activated carbon

Powdered activated carbon (PAC) is a common answer to water utilities’ taste and odor problems. However, these utilities are often uncertain as the characteristics of PAC are critical for optimum taste and odor abatement. In order to separate the effects, if any, that pore structure and surface chemistry have on the adsorption of the odorant 2-methylisoborneol (MIB), two sets of carbons were created: five physically activated (PA)-PACs, with different pore size distributions and similar surface chemistries, and four chemically treated (CT)-PACs with similar pore structures and different surface chemistries. Nitrogen adsorption, reverse mass titrations, and Boehm titrations were used to characterize the physical and chemical attributes of the carbons. Batch tests utilized 14C-MIB and contact times resembling those found at water utilities. The pore size distributions and the percent removal of MIB for the PA-PACs indicated that a range of micro- and meso-pores (12–100 Å) were necessary regardless of natural organic matter (NOM) concentration. The performance of the CT-PACs indicated that surface chemistry did affect MIB removal, but differently depending on the concentration of NOM. In DI water, surface acidity had a strong inverse relationship with MIB removal, but increasing NOM levels lowered the impact of the acidic functional groups. In fact, in a Florida raw water, surface chemistry demonstrated no effects on adsorption as all CT-PACs performed equally.

Odour emission factors for assessment and prediction of Italian rendering plants odour impact

Among the industrial activities that may cause odour nuisance problems, rendering plants represent one of the most critical sources of smelly gaseous emissions and consequently of odour complaint. In this work, the odour emission factors (OEFs) for the rendering industry are determined based on experimental data obtained by means of dynamic olfactometry. An OEF is a representative value that relates the quantity of odour released to the atmosphere to a given associated activity. The odour emission factors were calculated to be equal to 4.52 × 10 8 ouE t −1 for process air, to 8.02 × 10 7 ouE t −1 for a mixture of process air and ambient air, and to 3.53 × 10 3 ouE t −1 for wastewater treatment tanks. Furthermore, the efficiencies of different odour abatement systems used for the treatment of different gaseous emissions from this kind of facility are evaluated and compared. The abatement efficiencies of the monitored odour reduction systems decrease passing from combustors (efficiencies over 99%) to biofilters (efficiencies between 73 and 80%) and scrubbers (efficiencies between 41 and 60%).

An Industrial Streamer Corona Plasma System for Gas Cleaning

For pulsed corona plasma applications, it becomes important to develop pilot systems with large average power and high-energy conversion efficiency. Since the beginning of 2000, we have been working on an industrial corona plasma system with tasks of 10-30 kW in average power and higher than 90% of total energy conversion efficiency. The pulsed-power source should have the following specifications: rise time of 10-25 ns, pulsewidth of 50-150 ns, pulse repetition rate of up to 1000 pulses per second, peak voltage pulse of 70 kV, peak current of 3.5 kA, dc bias voltage of 10-35 kV, and energy per pulse of up to 30 J. Sixteen parallel wire cylinder reactors are used to match the source. Gas and reactor temperatures can be controlled individually with water flow around the outside of those cylinders. The system is designed for gaseous oxidation and electrostatic dust precipitation. The system has been used for up to 17 kW in average power. This paper reports the system in detail, discusses issues related to the matching between the source and the reactor, and presents an example of industrial demonstrations on odor abatement at 1000 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> /h. Finally, this paper also gives a general guideline for design of corona plasma systems

Solid-Phase Microextraction as a Novel Air Sampling Technology for Improved, GC--Olfactometry-Based Assessment of Livestock Odors

Air sampling and characterization of odorous livestock gases is one of the most challenging analytical tasks. This is because of low concentrations, physicochemical properties, and problems with sample recoveries for typical odorants. Livestock operations emit a very complex mixture of volatile organic compounds (VOCs) and other gases. Many of these gases are odorous. Relatively little is known about the link between characteristic VOCs/gases and, specifically, about the impact of characteristic odorants downwind from sources. In this research, solid-phase microextraction (SPME) is used for field air sampling of odors downwind from swine and beef cattle operations. Sampling time ranges from 20 min to 1 h. Samples are analyzed using a commercial gas chromatography-mass spectrometry-olfactometry system. Odor profiling efforts are directed at odorant prioritization, with respect to distance from the source. The results indicate the odor downwind is increasingly defined by a smaller number of high-priority odorants. These "character defining" odorants appear to be dominated by compounds of relatively low volatility, high molecular weight, and high polarity. In particular, p-cresol alone appears to carry much of the overall odor impact for swine and beef cattle operations. Of particular interest is the character-defining odor impact of p-cresol as far as 16 km downwind of the nearest beef cattle feedlot. The findings are highly relevant to scientists and engineers working on improved air sampling and analysis protocols and on improved technologies for odor abatement. More research evaluating the use of p-cresol and a few other key odorants as a surrogate for overall odor dispersion modeling is warranted.

EVALUATION OF SIMPLIFIED COVERING SYSTEMS TO REDUCE GASEOUS EMISSIONS FROM LIVESTOCK MANURE STORAGE

Ammonia, methane, and carbon dioxide are the primary atmospheric emissions from cattle and pig farms. Asignificant part of these emissions is produced by the decomposition of slurry organic matter during manure storage andtreatment phases. Present solutions to contain emissions from storage lagoons generally involve reducing the free surface ofthe slurry by covering it either with permanent fixed structures or temporary floating ones. This study investigated theeffectiveness of five simple floating covers in reducing emissions from pig and cattle slurry. The coverings included vegetableoil (a mixture of rapeseed and soybean oil), expanded clay, chopped maize stalks, chopped wheat straw, and chopped woodchips. All were tested at two different thicknesses: 70 and 140 mm for solid coverings, and 3 and 9 mm for liquid. Slurrysamples covered with the above-mentioned materials were placed in nine stainless steel airtight cylinders measuring 190 dm3.Gaseous and odor concentrations in the headspace were monitored using a Bruel & Kjaer 1302 multi-gas monitor and a T07olfactometer. The flotation aptitude of the different coverings was also tested. Results revealed substantial differences inammonia emission reduction efficiency (1% to 100%) and odor abatement (0% to 90%), and high levels of reduction efficiencywere achieved by all the tested covers at the higher thickness. However, equally valid results were not obtained for methaneemissions reduction. In regard to flotation aptitude and cover deterioration on slurry, expanded clay and wood chipsdemonstrated long-term resistance to both deterioration and sinking.

Literature review of air pollution control biofilters and biotrickling filters for odor and volatile organic compound removal

AbstractA literature study was conducted to compare the feasibility of biofilters and biotrickling filters for the treatment of complex odorous waste air containing hydrogen sulfide (H2S), organic reduced sulfur compounds, and chlorinated and nonchlorinated volatile organic compounds (VOCs). About 40 pilot‐plant studies and full‐scale applications at wastewater treatment plants and other facilities were reviewed. Reactor design and pollutant removal efficiencies were summarized in tables for easy reference and for a perspective on the current state of the art, and to allow comparison between different projects. The survey indicated that both biofilters and biotrickling filters are capable of combining a high H2S and odor removal efficiency with VOC removal. Apart from odor abatement, biological treatment therefore holds promise for reducing the overall toxicity and potential carcinogenicity of VOC‐containing odorous waste air from wastewater treatment plants and other facilities. VOC removal efficiencies were in general lower than those of H2S and odor, although concentrations of individual VOC species were relatively low. This indicates that for effective treatment of VOC‐containing odorous waste air, the design and operation should emphasize VOC removal as the rate‐limiting parameter. © 2005 American Institute of Chemical Engineers Environ Prog, 2005

An Economic Evaluation of Livestock Odor Regulation Distances

Setback regulations-legislated distances that livestock production facilities must be removed from surrounding properties-are meant to mitigate odor impacts. If the setback length is too short, then there is evidence that surrounding properties and people suffer uncompensated damages. If, on the other hand, setback lengths are too long, then livestock producers may be paying more than that required to compensate for odor-related environmental damages. The purpose of this study is to assess the impact of Kentucky's livestock production facility setbacks on the value of surrounding properties and farm financial management decisions. This paper develops a model of the benefits of livestock odor reduction and the livestock odor abatement cost associated with setback lengths paid by producers. The results of this investigation indicate that the mandated setback lengths for Kentucky are too short. Livestock production firms are worse off under longer setback lengths, but the losses to surrounding home owners far exceed the firm gains at the mandated setbacks. A finding of this study is that the firm has no incentive to completely protect the legislated setback length. Livestock producers in compliance with the relevant setback length may feel protected from odor lawsuits despite damage being done to surrounding property. This suggests that the perceived threat of lawsuit is currently low in the state of Kentucky. Both industry and public goals could be met from further research including location and economic impact of livestock production.

Odour abatement in the integrated reactor concept for simultaneous treatment of liquid and solid pig manure fractions

New technologies are needed for manure treatment that can capture nutrients, reduce emissions of ammonia and nuisance odours, and kill harmful pathogens. A reactor concept was developed for simultaneous treatment of separately collected liquid and solid fractions of pig manure. The liquid fraction is concentrated by evaporating the water using energy from the composting system and at the same time scrubbing ammonia from the composting off-gas by acidifying the urine to pH 4 with nitric acid. This results in two marketable products, a concentrated liquid nitrogen fertiliser (NH4NO3) without phosphorus, and a stabilised, solid organic fertiliser, which is free of pathogens and weeds. By connecting the two reactor systems, emissions of ammonia and odours are abated as ammonia emitted from the composting is trapped in the liquid fraction and odorous compounds emitted from the liquid are degraded in the composting reactor. The concept was physically simulated by coupling a 80-L compost reactor to a 10-L bubble column. Operation of the bench-scale system showed that the concept is very promising. All nutrients were captured, and emissions of ammonia and odours were almost completely abated.

Activated sludge biotreatment of sulphurous waste emissions

Odours from wastewater treatment plants are comprised of a mixture of various gases, of which hydrogen sulphide (H2S) is the main constituent. Sulphurous compounds can be degraded by microorganisms commonly found in wastewater. The use of activated sludge (AS) diffusion as a dual-role system, for the treatment of wastewater and for odour control, offers an alternative to traditional sulphurous waste gas treatment processes, such as biofilters, bioscrubbers and biotrickling filters, both in practical terms (use of existing facilities) and economically (minimal capital cost). Activated sludge diffusion avoids the common problems associated with these processes such as media plugging, excess biomass accumulation, gas short-circuiting, and moisture control and maintaining the correct biofilm thickness. The design issues to be considered when using AS diffusion for odour abatement, comprise odourous air pre-treatment,blowers and diffuser types, corrosion protection and increase in odour emission intensity. Nitrification inhibition depends on the composition and acclimation of the biomass, the concentration of H2S and other components of the wastewater. Hydrogen sulphide removal rates of >98% were consistently achieved for loads of 3–34 mg H2S/g MLSS/h, in two case studies, which also showed that sludge type has an impact on the ability of the sludge to degrade H2S. Wastewater process performance measured as five-day biological oxygen demand (BOD5), chemical oxygen demand (COD) and effluent suspended solids removal was not affected by H2S diffusionat 5 ppm. A change in the microorganism population dynamics of anactivated sludge was observed when it was exposed to H2S for aperiod of more than 21 days.

Assessing the environmental impact of WWTP expansion: odour nuisance and its minimization

As part of the effort to provide proper wastewater disposal for the City of Milan, the expansion of the WWTP located in Peschiera Borromeo has been planned and is currently under completion. The plant, sized for a population of less than 300,000, will soon treat the wastes from the south-east areas of Milan for a total capacity of over 500,000 p.e. The paper describes the approach to find a satisfactory solution of an alleged odour problem that is slowing down the completion of the plant restructuring. This included a survey of the existing plant and analysis of its final design, identification of odour emission sources and their quantification, and the examination of different alternatives for odour abatement. These were carried out using air quality modelling techniques consisting of dynamic, continuous "puff" models capable of reproducing diffusion even at very low pollutant concentrations. Several intervention hypotheses were tested and compared with the few existing regulatory norms and guidelines for odour pollution. In all but the minimum and the no-action hypotheses, proposed actions would results in a drastic reduction of nuisance effects at the receptors. Under the strongest intervention hypothesis (the one adopted by the WWTP agency), odour impact would be virtually eliminated.

Livestock manure odor abatement with plant-derived oils and nitrogen conservation with urease inhibitors: A review1

Confined animal feeding operations are under environmental scrutiny for production of large quantitiesofwasteinasmallarea.Thewastecanresult in odor,global warminggases, andthe transferof nutri- ents and pathogens to water and food sources. An in- complete anaerobic degradation of the carbohydrate, protein, and lipid components in waste is the primary cause of odor emissions. This incomplete degradation results in the formation of short-chain volatile fatty acids (VFA), amines and other nitrogenous compounds, and sulfur-containing compounds. Our objectives are to provide simple, cost-effective, and environmentally sound solutions to control odor and pathogens in live- stock waste, with nutrient management a top priority. Previous studies have indicated that a urease inhibitor, N-(n-butyl) thiophosphoric triamide, can be used to re- duce urea hydrolysis in beef cattle feedlot pens, con- serve nitrogen, and inhibit ammonia emissions that contribute to odor. Our laboratory studies with antimi- crobial plant-derived oils, thymol and carvacrol, at 2 g/

ODOR FLUX MEASUREMENTS AT A FACULTATIVE SWINE LAGOON STRATIFIED BY SURFACE AERATION

Odorrelated complaints are a major concern of pork producers. Open manure storage and treatment facilitiessuch as uncovered anaerobic treatment lagoons are a major contributor to odor nuisance. Repeatable and valid fieldmeasurement techniques are needed for evaluating baseline odor emissions from existing livestock facilities and theeffectiveness of odor abatement technologies. A buoyant convective flux chamber (BCFC) for measuring odor flux from liquidsurfaces of dilute wastewaters was designed, constructed, and tested. Odor flux from a surfaceaerated stratified facultativelagoon at a 6000head swine finishing facility was measured with the BCFC. The swine buildings at this facility containedrecirculation flush pits initially charged with about 0.5m depth of effluent from the second cell of a twostage lagoon systemand discharged weekly to the first cell. The first cell was overloaded by 23% as an anaerobic lagoon with an estimated dailyloading rate of about 118 g of volatile solids per m3 of lagoon volume. To mitigate odor nuisance in the surroundingneighborhood, a statictube aeration system was installed in the first cell in an attempt to create an oxygenated surface layeron an otherwise anaerobic lagoon. Odor flux measurements with the new BCFC appeared to exhibit good repeatability basedon a limited number of tests. Odor flux of the stratified lagoon measured using a simulated wind speed of 1.1 m/s in the BCFCaveraged 1.72 odor units per s per m2 of lagoon surface area. The results are preliminary in terms of representing annual odoremission rates because odor flux is affected by wind and weather characteristics, results were based on only one constantwind speed that was simulated in the BCFC, and there were relatively few data points. The data was compared with odor fluxmeasured at two unaerated anaerobic lagoons.

Biofilter Efficiency In Odor Abatement At Composting Plants

In the present work, five composting facilities have been examined for odor abatement efficiency of the gaseous emissions control devices, mainly scrubbers and biofilters. A correlation between olfactory nuisance and chemical composition was tried, using for the chemical analysis the same samples collected for the olfactometric experiments. The odor units were determined by the dynamic method (olfactometer). For the chemical analysis, the volatile organic compounds were first enriched by gas-solid adsorption and analyzed by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. The results evidenced the role of limonene as masking agent and the discontinuous performance of the biofilters. The formation of sesquiterpenes as by-products of limonene biodegradation was highlighted.

Biofiltration as an odour abatement strategy

The chemical, physical and biological processes occurring in biofiltration are reviewed. A survey of operating biofilter performances is also presented and includes some novel comparative methods. It is concluded that biofiltration is a simple and cost-effective technology for odour removal and that an understanding of the many interactions occuring within the biofilter is essential for the optimal performance of the biofilter.

Northumbrian Water coastal programme: nine scrubbers for the price of eight!

Under the EU Urban Wastewater Treatment Directive, Northumbrian Water have to provide full sewage treatment at eight coastal sites for 1999/2000 deadlines. As part of the consequent standardisation programme, NWL appointed Entec to co-ordinate odour containment, ventilation and abatement at all eight sites. Following trials and a review of options, NWL specified the ICI “Odorgard” catalytic single stage scrubber as the standard abatement method. Tenders were sought using ECC Option A (activity schedules) conditions of contract from the three licensees. Costs were identified for anticipated odour loads/installation programmes to maximise “bulk discount” opportunities, culminating in simultaneous contracts being let to ERG for all eight sites. This represents the largest known multi-site odour abatement award in the water industry to date effectively giving discounts equivalent to the cost of the ninth scrubber. Further advantages of the bulk purchase included common operational procedures/spares and the ability to apply lessons being learnt from commissioning of prior scrubber installations.

Odour emission estimates and control strategies using models and sampling for East Bay Municipal Utility District's collection sewage system and wastewater treatment plant

For several years, public complaints regarding odours generated by East Bay Municipal Utility District's (EBMUD's) wastewater treatment plant and sewage collection system (SCS) have been increasing. In response, an Odor Control Master Plan was completed to develop near- and long-term odour abatement strategies for their wastewater system. The plan's strategies include using an advisory committee to assist in setting odour threshold levels, prioritizingodour sources, issuing an odour-status newsletter, and reviewing odour control options. The objective is to provide an odour-free community environment at least 99 percent of the year. This paper provides innovative approaches to estimate odour emissions and identify viable odour control options for SCSs through complete wastewater treatment. This paper also presents a CH2M HILL SCS odour model comparison to a comprehensive EBMUD sewage system corrosion study, illustrating that areas having high predicted odours also have high corrosion rates.

New Directions : Novel separation techniques in VOC analysis pose new challenges to atmospheric chemistry

Odorous emissions from sewers and wastewater treatment plants are a complex mixture of volatile chemicals that can cause annoyance to local populations, resulting in complaints to wastewater operators. Due to the variability in hedonic tone and chemical character of odorous emissions, no analytical technique can be applied universally for the assessment of odour abatement performance. Recent developments in analytical methodologies, specifically gas chromatography, odour assessment approaches (odour wheels, the odour profile method and dynamic olfactometry), and more recently combined gas chromatography-sensory analysis, have contributed to improvements in our ability to assesses odorous emissions in terms of odorant concentration and composition. This review collates existing knowledge with the aim of providing new insight into the effectiveness of sensorial and characterisation approaches to improve our understanding of the fate of odorous emissions during odour abatement. While research in non-specific sensor array (e-nose) technology has resulted in progress in the field of continuous odour monitoring, more successful long term case-studies are still needed to overcome the early overoptimistic performance expectations. Knowledge gaps still remain with regards to the decomposition of thermally unstable volatile compounds (especially sulfur compounds), the inability to predict synergistic, antagonistic, or additive interactions among odorants in combined chemical/sensorial analysis techniques, and the long term stability of chemical sensors due to sensor drift, aging, temperature/relative humidity effects, and temporal variations. Future odour abatement monitoring will require the identification of key odorants to facilitate improved process selection, design and management.

Field survey of reduced-sulfur emissions from a modern finnish pulp mill

Substantial advances in air emission control technology during the last decade have brought about a decrease in reduced-sulfur emissions from pulp mills. Un fortunately, these reduced-sulfur compounds still cause subjective odor problems at very low concentrations. As a result pulp mills, even with efficient odor abatement systems, may produce a foul odor in the surrounding area. On the other hand, it will not be easy to further reduce the malodorous sulfur emissions at modern pulp mills because all the major emission sources have already been eliminated. This paper presents the results of a field survey made at one of the major Finnish pulp mills. In the study, all the main emission sources we re analyzed, and the ambient air concentrations of reduced-sulfur compounds in the area surrounding the mill we re measured. Emission rates from the current sources and measured ambient air concentrations are presented. The effects of the main continuous emission sources on ground level concentrations are estimated by means of a Gaussian model of emission dispersion. In addition, the emission sources are ranked on the basis of the estimated ground level concentrations and the momentary emission rates. Finally, means of reducing the current continuous and occasional emissions of reduced-sulfur are recommended.