Odour-causing Compounds Research Articles

Soybean oligosaccharides attenuate odour compounds in excreta by modulating the caecal microbiota in broilers

Abatement of odour emissions in poultry production is important to ensure the quality and safety in the poultry industry as well as for the benefit of the environment. This study was conducted to compare the effects of supplementation with different amounts of dietary soybean oligosaccharides (SBO) and chlortetracycline (CHL) on the major odour-causing compounds in the excreta and on the caecal microbiota in broiler chickens. One-day-old broiler chickens were subjected to a 42-day experiment involving 6 treatments with 6 replicates per treatment (10 birds/cage). The treatments were as follows: negative control (NC; basal diet), positive control (PC; basal diet supplemented with CHL) and basal diet supplemented with 0.5, 2.0, 3.5 and 5.0 g/kg SBO (0.5SBO, 2.0SBO, 3.5SBO and 5.0SBO, respectively). Fresh excreta were sampled for the analysis of odour compounds by HPLC. Caecum content was collected for the caecal microbiota analysis through 16S rRNA sequencing. Results showed that on day 42, the excreta indole concentration in the broilers fed with 2.0SBO, 3.5SBO and 5.0SBO and PC was significantly decreased (P < 0.01) compared with that in the NC-fed broilers. The excreta skatole concentration (P < 0.001) and pH (P < 0.05) were also decreased by SBO and CHL, and they were lowest in birds fed with 3.5SBO. The formate concentrations in birds fed with 3.5SBO and 5.0SBO were higher than those in birds fed with the other diets (P < 0.001). Similarly, acetate concentration (P = 0.003) was increased in birds fed with 3.5SBO. Deep sequencing of 16S rRNA revealed that the composition of the caecal microbial digesta was slightly or significantly changed by the SBO or by the CHL supplementation, respectively. The SBO supplementation decreased the abundance of Bacteroides, Bilophilaand Escherichia, which were associated with the skatole and indole concentrations in the excreta. By contrast, the CHL supplementation demonstrated a strong tendency to enrich Ruminococcus and to reduce the abundance of Rikenella. These results indicated that supplementation with dietary SBO is beneficial in attenuating the concentration of odour-causing compounds and that it modulates the composition of caecal microbiota in broiler chickens.

Development and application of an analytical method to quantify odour removal in plastic waste recycling processes

Europe is strongly committed to the recycling of plastics, especially packaging. In the development of closed loop recycling processes, recyclates must have appropriate properties, including lack of odour. The main objective of this study was to develop a technique to qualitatively and semi-quantitatively analyse the volatile contaminants in these complex plastic waste matrices before and after washing procedures. Three sampling methods were explored, SPME and purge and trap methods (activated carbon with solvent desorption and Tenax-TA with thermal desorption). All analyses were then carried out using gas chromatography – mass spectrometry. SPME was not repeatable due to the heterogeneity of the waste samples and the static character of the method. Solvent desorption with CS2 (RSD 14,5 %) and thermal desorption (RSD 13,4 %), were capable of measuring the removal efficiency of pollutants in a semi-quantitative way. A broad spectrum of chemically different, but mostly apolar volatiles can be detected. In addition, it became clear that also the analysis of the less volatile components is essential, as these are strongly adhered to the hydrophobic polymer matrix. A post-consumer film waste stream was analysed, before and after washing and pelletizing. A general decrease of 97 % and 44 %, was measured with respectively thermal and solvent desorption for the screened components. However, after reprocessing potentially odour-causing compounds are again released or formed, showing the complexity of odour removal processes in plastic recycling.

UV/chlorine control of drinking water taste and odour at pilot and full-scale

Advanced oxidation processes (AOPs) can be used to destroy taste and odour-causing compounds in drinking water. This work investigated both pilot- and full-scale performance of the novel ultraviolet (UV)/chlorine AOP for the destruction of geosmin, 2-methylisoborneol (MIB) and caffeine (as a surrogate) in two different surface waters. The efficiency of the UV/chlorine process at pH 7.5 and 8.5 was comparable to that of the UV/hydrogen peroxide (UV/H2O2) process under parallel conditions, and was superior at pH 6.5. Caffeine was found to be a suitable surrogate for geosmin and MIB, and could be used as a more economical alternative to geosmin or MIB spiking for site-specific full-scale testing.

&lt;i&gt;Arthrospira&lt;/i&gt; (Spirulina) in tannery wastewaters Part 1: The microbial ecology of tannery waste stabilisation ponds and the management of noxious odour emissions using microalgal capping

We investigated the problem of noxious gas and odour emissions in zero-discharge evaporative tannery waste stabilisation ponds. These have been little-studied systems although they present one of few options for the management of tannery wastewaters in highly water-stressed areas. A three-year study of the microbial ecology of an evaporative waste stabilisation ponding cascade was undertaken and a descriptive account of the biology and the physico-chemical parameters related to odiferous gas release is reported. Large populations of Arthrospira (Spirulina) dominated the latter facultative ponds in the cascade where odour emission was substantially reduced compared to initial anaerobic ponds. Photosynthetic productivity maxima of up to 9 000 mg∙m-2∙day-1 carbon fixation were measured in bloom conditions. Arthrospira production was associated with an oxygenated, alkaline layer established on the surface of facultative ponds (0.35 m in depth) in which oxidation of sulphide and ammonia, and the trapping of other odour-causing compounds was observed. An attempt was made to achieve comparable odour control in the anaerobic ponds by capping with recirculated microalgae-enriched effluent from facultative ponds. While this was shown to be effective in establishing an Arthrospira-dominant surface layer and an associated control of odour emissions in anaerobic ponds, large recirculation volumes (2:1) were required to maintain the Arthrospira population. Elevated salinity of recirculated facultative pond waters also negatively impacted the evaporative function in the low-salinity initial ponds in the cascade. An alternative method of Arthrospira capping was investigated which involved the construction of a free-standing high rate pond alongside the waste stabilisation pond system, and using a controlled feed of raw tannery effluent for optimising the cultivation of Arthrospira biomass. High biomass productivity was achieved in this unit (12.87 g∙m-2∙day-1), using a low feed to effluent loading volume ratio (0.21:1) and subsequent capping of anaerobic ponds from this source achieved odour control comparable to facultative ponds. This study has shown that management of the odour problem in waste stabilisation ponds is possible and that leather production using the zero-discharge evaporative disposal operation may be compatible with a level of both environmental and social acceptability of these systems. Odour problems, alone, should thus not constrain tanning as one of the few industrial agricultural activities available in rural economies.Keywords: tannery, wastewater, waste stabilisation ponds, odour, noxious gas, Spirulina, Arthrospira, microalgal biomass

Odour‐causing compounds in air samples: Gas–liquid partition coefficients and determination using solid‐phase microextraction and GC with mass spectrometric detection

A quantification method based on solid-phase microextraction followed by GC coupled to MS was developed for the determination of gas-liquid partition coefficients and for the air monitoring of a group of odour-causing compounds that had previously been found in wastewater samples including dimethyl disulphide, phenol, indole, skatole, octanal, nonanal, benzothiazole and some terpenes. Using a divinylbenzene/carboxen/polydimethylsiloxane fibre, adsorption kinetics have been studied to define an extraction time that would avoid coating saturation. It was found that for an extraction time of 10 min, external calibration could be performed in the range of 0.4-100 μg/m(3), with detection limits between 0.1 and 20 μg/m(3). Inter-day precision of the developed method was evaluated (n = 5) and RSD values between 12 and 24% were obtained for all compounds. The proposed method has been applied to the analysis of air samples surrounding a wastewater treatment plant in Catalonia (Spain). In all air samples evaluated, dimethyl disulphide, limonene and phenol were detected, and the first two were the compounds that showed the highest partition coefficients.

Effects of water washing on removing organic residues in bottom ashes of municipal solid waste incinerators

Due to their potential toxicity and odourous nature, the residual organics in municipal solid waste incinerators are recently gaining attention as an important issue of resources recovery apart from their complex mixture of organic counterpart. Studies of the organic fractions in municipal solid waste incinerator residues have been limited. In this study, extended solid-phase extraction of the water-washed bottom ash and liquid-phase extraction of the washing water were carried out with regard to bottom ash samples from three mass-burning incinerators in Taipei County (Taiwan) during four consecutive seasons of year 2008–2009. Supercritical fluid extraction and Soxtec extraction techniques along with GC–MS were successfully used to characterize the residual organics in weathered and washed bottom ashes. Supercritical fluid extraction provided the quantification of aliphatics and aromatic compounds such as hexanoic acid and benzaldehyde, respectively. Soxtec extraction was useful for qualitative analysis of aromatic and aliphatic groups in the ashes and many of which were odourous and toxic compounds. By mixing one unit weight (g) bottom ash with two unit volume (mL) water for 15 min, total organic carbon in the bottom ash was greatly reduced (e.g., from 4.1 to 1.8 wt.%). Among the removed were foul odour-causing compounds such as pyridine and quinoline derivatives, while some aromatic compounds such as 4-hydroxybenzaldehyde and low-molecular-weight aliphatics such as hexanoic acid remained. The results here suggest that washing with water can be an effective pre-treatment step for removing odour-causing and environmental concerned organics.

Removal of geosmin and 2-methylisorboneol (2-MIB) in water from Zuikerbosch Treatment Plant (Rand Water) using â-cyclodextrin polyurethanes

Geosmin and 2-methylisorboneol (2-MIB) are major organic pollutants responsible for undesirable taste and odour in water. These compounds impact greatly on the aesthetic quality and general consumer acceptability of drinking water. The use of granular activated carbon (GAC) in the removal of geosmin and 2-MIB is generally ineffective since these compounds are present at very low concentrations (ngE.-1). Water treatment technologies that can remove geosmin and 2-MIB from water below human detection threshold (&lt;10 ngE.-1) are highly sought by drinking water supplies, e.g. Rand Water. The removal of these odour-causing compounds from water samples using cyclodextrin- based nanoporous polyurethanes was investigated in our laboratory. Geosmin and 2-MIB were extracted from water samples by solid phase micro-extraction (SPME) and analysis was carried out using gas chromatography-mass spectrometry (GC-MS). Results from the analysis demonstrated that thesepolymers were highly effective in removing geosmin and 2-MIB.

Occurrence of odour-causing compounds in different source waters of China

In this study, occurrence of the main odorous compounds in different types of source water in China, including rivers, lakes and reservoirs, were investigated by integrating the methods of flavour profile analysis (FPA) and sensory-GC/MS analysis. Simultaneous distillation extraction (SDE) was chosen as the preconcentration technique while the odour-causing compounds were identified with sensory-GC/MS. It was found that MIB, which is mainly produced by some cyanobacteria and actinomycetes, was one of the most widely distributed odour-causing compounds, regardless of source type. A peak MIB concentration of approximately 170 ng l(-1) was recorded in MY Reservoir in October 2005. Among the nine investigated sites, YH Reservoir in Hebei Province was the only site showing geosmin production. A peak geosmin concentration exceeding 7,000 ng l(-1) was detected in July 2007. In June 2007, a serious taste/odour (T/O) event occurred in Wuxi City, and the offensive flavour was a strong septic or marshy odour caused by dimethyl trisulfide (431 ng l(-1) in finished water). Septic/swampy and earthy/musty odours occurred in source waters of Shanghai and Guangzhou. It was found that dimethyl trisulfide was mainly responsible for the septic/swampy odour and MIB for the earthy/musty one. Dimethyl trisulfide might be an important T/O-causing compound in China.

Supplementing coagulation with powdered activated carbon as a control strategy for trihalomethanes: application to an existing utility

To support a water treatment plant in meeting trihalomethanes (THM) legislation, different THM control strategies using existing treatment processes were investigated. The effectiveness of optimised coagulation and of powdered activated carbon (PAC) (0–25 mg/L) as a mean of supplementing natural organic matter (NOM) removal was assessed. Simultaneous full-scale and bench-scale trials were performed to document THM reductions. At the plant, source and treated water total organic carbon (TOC) was monitored online. At full scale, optimised acidified alum coagulation (3.2 mg/L Al) achieved the maximum NOM removal and the lowest THMFP concentration. Although PAC (11 mg/L) showed a small reduction in TOC (7%) and taste- and odour-causing compounds, results indicated no significant THM reductions. Coagulation and PAC adsorption trials showed a good agreement between bench-scale and plant results.

Removal of odour-causing compounds using carbonaceous adsorbents/catalysts prepared from sewage sludge

This paper discusses H(2)S, NH(3) and VOCs removal by sewage-sludge-derived materials with outstanding chemical and textural properties. These materials were obtained from different precursors using different chemical and thermal treatments. Results show that the H(2)S removal process entailed a catalytic conversion of H(2)S to S or SO(4) (2-) species. On the other hand, adsorption is the main mechanism governing the performance of sludge-based materials for NH(3) and VOCs. Retention capacities (x/M values) obtained for some of the sludge-based adsorbents/catalysts are similar to those obtained with commercial activated carbons selected as reference materials.

The effect of white or grey PVC pipe and its joint solvents (primer and cement) on odour problems in drinking water distribution systems

A study of the production of odour-causing compounds was conducted from the leaching of polyvinylchloride (PVC) pipe and its joints, primer and cement, into drinking water distribution systems. Flavour Profile Analysis (FPA), closed-loop stripping analysis--gas chromatography/mass spectrometry (CLSA-GC/MS) and sensory-GC analysis of white or grey PVC alone found no odour-causing compounds produced during the leaching experiments. FPA analysis of the PVC's primer and cement leached alone and/or when applied to grey or white PVC pipes produced a glue/varnish odour. A sweet/phenolic odour replaced the glue/varnish odour after the leached media were diluted with Milli-Q water to threshold odour intensity. Three compounds were responsible for the sweet/phenolic odour and were observed by sensoryGC analysis. The leaching study of the PVC pipe with its joint solvents (primer and cement) concluded that the original solvent compounds, and their reaction products that formed during the bonding process on the PVC pipe, were a primary source of the glue/varnish odour. The original compounds of the PVC primer and cement were not detected by CLSA-GC/MS, due to their high volatility during the CLSA extraction method and/or these compounds appeared in a solvent peak of the GC/MS analysis. However, the original primer and cement chemicals (acetone, tetrahydrofuran, methyl ethyl ketone, and cyclohexanone) had a glue/varnish odour. A total of nine odorous GC peaks were produced as reaction products from leaching of primer in water and white or grey PVC pipe with primer and cement, and white or grey PVC with primer only. None of these compounds were among the chemical ingredients in the original primer or cement. Four GC peaks with a sweet/phenolic odour were present due to the reaction products of the cement leached with white or grey PVC. None of these compounds were positively identified.

Needs and perspectives of odour research in the aquatic sciences

Over more than four decades odour research in the aquatic sciences has increasingly focused on cyanobacteria and the common odour-causing compounds, geosmin and 2-methylisoborneol. Success in future research requires a long-term perspective. Key areas for investigation are secondary metabolites and cyanobacteria, regulatory mechanisms for geosmin and other compounds' synthesis; understanding their spatial and temporal distribution (particularly relating to the food web in a habitat); and molecular mechanisms for liberation of geosmin by microorganisms.

UV and UV/H2O2 treatment of methylisoborneol (MIB) and geosmin in water

The presence of taste and odour-causing compounds in water can lead consumers to perceive the water as unsafe and thus is a great concern for water utilities. This study examined the effectiveness of direct ultraviolet (UV) photolysis and the UV/hydrogen peroxide (H 2 O 2 ) advanced oxidation process (AOP) for removing methylisoborneol (MIB) and geosmin from raw source water and treated water. Low Pressure (LP) and Medium Pressure (MP) direct UV photolysis removed 10% and 25–50% of the compounds by 1000 mJ cm −2 UV fluence, respectively. The addition of H 2 O 2 created advanced oxidation conditions, and oxidized greater than 70% of these compounds at a UV fluence of 1000 mJ cm −2 . MP UV + H 2 O 2 was consistently faster than LP UV + H 2 O 2 for MIB oxidation, but water quality affected both of the UV + H 2 O 2 AOPs. The UV + H 2 O 2 AOP oxidation of these taste and odour contaminants in natural waters was effectively modelled using the steady state OH radical concentration model. Finally, electrical energy per order (E EO ) values for oxidation of MIB and geosmin were determined for a model UV reactor, and indicated that the UV + H 2 O 2 AOP requires less than 5 kWh of UV energy to oxidize 90% of MIB or geosmin in 1,000 gallons (3,785 liters) of clearwell or raw blend water, corresponding to a cost of less than US$0.35 per 1000 US gallons (3,785 liters).

Odour from animal production facilities: its relationship to diet

Though bad odour has always been associated with animal production, it did not attract much research attention until in many countries the odour production and emission from intensified animal production caused serious nuisance and was implicated in the health problems of individuals living near animal farms. Odour from pig production facilities is generated by the microbial conversion of feed in the large intestine of pigs and by the microbial conversion of pig excreta under anaerobic conditions and in manure stores. Assuming that primary odour-causing compounds arise from an excess of degradable protein and a lack of specific fermentable carbohydrates during microbial fermentation, the main dietary components that can be altered to reduce odour are protein and fermentable carbohydrates. In the present paper we aim to give an up-to-date review of studies on the relationship between diet composition and odour production, with the emphasis on protein and fermentable carbohydrates. We hypothesise how odour might be changed and/or reduced by altering the diet of pigs. Research so far has mainly focused on the single effects of different levels of crude protein and fermentable carbohydrates on odour production. However, also important for odour formation are the sources of protein and fermentable carbohydrates. In addition, it is not only the amount and source of these compounds that is important, but also the balance between them. On the basis of our review of the literature, we hypothesise that odour nuisance from pig production facilities might be reduced significantly if there is an optimum balance between protein and fermentable carbohydrates in the diet of pigs.

Electronic sensory systems for taste and odour monitoring in water – Developments and limitations

Taste and odour causingchemicals in drinking water supplies can bedetected and identified using a variety ofanalytical techniques and sensory methods.Currently limitations exist in applying thesetechniques and methods to the continuousmonitoring of taste and odour episodes.Electronic sensory systems so called``electronic noses'' using non-specific gassensors could offer a rapid and relative simpletechnique for continuous monitoring of waterquality. Laboratory and field-based continuouswater monitoring showed that introducedpollutants such as 2-chlorophenol and geosmincould be detected by a sensor array, howeverthe detection limits were significant higherthan the odour threshold concentrations (OTC)for the respective compounds. The conditioningof the monitoring system in a temperaturecontrolled environment for on-line headspacegeneration and transfer reduced the impact ofenvironmental fluctuations on the sensorresponse profiles. At present, a sensor arraybased monitoring system could be applied to theintake protection of taste and odour causingcompounds in water supplies with a minimum OTCof 10 ppm.

Assessment of membrane processes for taste and odour removal

The occurrence of tastes and odours (T&amp;O) in potable water is considered one of the main problems by the drinking water companies. Thus, several treatment processes have been developed over the years to control T&amp;O, including air stripping, activated carbon and oxidation using ozone. However, little information is available in the literature on the use of membranes for T&amp;O removal. Therefore, the objective of this paper is to present potential of membrane processes for the removal of taste and odour-causing compounds. Several membranes were tested including ultrafiltration (UF), UF combined with powdered activated carbon (PAC), nanofiltration (NF) and low pressure reverse osmosis (LP RO) membranes. Combination of UF with PAC was found to be effective for T&amp;O control. The use of NF or LP RO is still unclear in the objective of T&amp;O control.

Odorous Substances and Cyanobacterial Toxins in Prairie Drinking Water Sources

Algal blooms in eutrophic lakes have been regarded by some as primarily an aesthetic nuisance for recreational and drinking water uses despite well documented incidents of livestock and wildlife poisoning attributed to cyanobacterial toxins. A survey was conducted of three eutrophic, water supply lakes and eight rural dugouts experiencing cyanobacterial blooms. Biomass was characterized for dominant cyanobacterial genera and analyses were conducted for the hepatotoxins, microcystin LR and RR and the neurotoxin, anatoxin-a. Some water samples collected simultaneously were screened for geosmin, 2-methylisoborneol and β-cyclocitral. Results showed that microcystin LR (LD50 of 50 µg/kg in mice) was present in concentrations up to 500 µg/g of algal biomass and microcystin LR levels were generally related to the proportion of Microcystis in the collected algal biomass. There was no relationship between the presence of microcystin LR and the presence of any of the odour compounds. Consequently, cyanobacterial odour-causing compounds in water did not provide reliable warning of the presence of the microcystin LR in these cyanobacterial blooms.