Septic Odors Research Articles

Implications for emergency response to the severe odor incident occurred in source water: Potential odorants and control strategy.

Sudden odor incidents occurring in the source water have been a severe problem for water suppliers. In order to apply emergency control measures effectively, it is necessary to identify the target compounds responsible for odor incidents rapidly. The present work identified the odorants and explored emergency disposal mechanisms for sudden and severe odors in the QT River's drinking water source (HZ city, China). Medicinal, chemical, septic, and musty odors with strong intensities were detected in the source water. The effect of conventional treatments of drinking water treatment plant (DWTP) on odors' removal was limited, which was evident by the presence of medicinal, chemical, and musty odors with moderate intensities in the effluent of DWTP. Total seventeen odorants were identified successfully in the source water of QT River and the effluent of DWTP. The measured OAVs and reconstituting the identified odorants explained 87, 87, 89, and 94% of medicinal, chemical, septic, and musty odors, respectively, in the source water of the QT River and 90, 87, and 88% of medicinal, chemical, and musty odors in the effluent. Styrene, phenol, 2-chlorophenol, 2-tert-butylphenol, and 2-methylphenol were associated with the medicinal odor, while propyl sulfide, diethyl disulfide, propyl disulfide, and indole were related to the septic odor. Geosmin and 2-methylisoborneol (2-MIB) were responsible for the musty odor, and cyclohexanone, 1,4-dichlorobenzene, and nitrobenzene were involved with the chemical odor. Based on the characteristics of identified odorants, powdered activated carbon (PAC) was applied to control the odors in the QT River. The results indicated that the medicinal, chemical, septic, and musty odors could be removed entirely after adding 15 mg/L PAC, which effectively controlled emergency odor problems. Overall, the study would offer a scientific basis and operational reference for emergency odor management and control in DWTP with similar complicated odor incidents.

Treatment performance comparison between regular O3\u2013BAC and O3\u2013BAC with rear sand filtration: verification in a full-scale study

BackgroundTo improve the microbial safety of drinking water, an arrangement of O3–BAC with rear sand filtration (O3–BAC–sand) has been proposed. In this study, efforts were devoted to evaluate the benefits and drawbacks of O3–BAC–sand in a full-scale water treatment plant. The performance of the two configurations was compared in terms of particles, turbidity, CODMn and typical odorants and pesticides.ResultsThe O3–BAC–sand yielded lower turbidity but higher CODMn (by approximately 7%) in the finished water than regular O3–BAC (sand–O3–BAC). Both systems removed odors in raw water; however, sand–O3–BAC was more effective on septic and musty odorants. The total pesticide removals by sand–O3–BAC and O3–BAC–sand were 78% and 72%, respectively; though the latter had shorter activated carbon durable years.ConclusionThe re-location of the sand filter would sacrifice the BAC efficiency in removals of organic matter and micropollutants. This tradeoff is a result of the loss of the particulate organic matter removal by sand filters, because locating the sand filter behind BAC causes particle load increase on BAC; some measures of enhanced coagulation should be suggested to improve the turbidity and particle removal. The study will be helpful for improvement of the O3–BAC process in drinking water treatment.

Synergistic effect of musty odorants on septic odor: Verification in Huangpu River source water

Revealing the main contributors to septic odor is a challenge since diverse compounds are responsible for this odor, and there might exist synergistic effects among different odorants. In this study, based on a reconstitution evaluation, the contribution of eighteen odorants identified in Huangpu River source water to the septic odor was explored. The reconstitution test result showed that the three typical odorants, including bis(2‑chloroisopropyl) ether (BCIE), diethyl disulfide (DEDS) and dimethyl disulfide (DMDS), with respective average odor activity values (OAVs) of 2.35, 1.65 and 0.78, only contributed 61 ± 3% of the FPA intensity for septic odor in Huangpu source water. At a BCIE concentration of 50 ng/L, synergistic effect for the septic odor occurred at 10 ng/L for geosmin and 20 ng/L for 2‑methylisoborneol (MIB), showing that coexisting musty odorants could enhance the septic odor intensity caused by some typical odorants. When both geosmin and MIB, with an average OAV of 4.54 and 1.38, were further included in addition to the three typical odorants, 88 ± 4% of the septic odor in Huangpu River source water could be explained. With addition of the remaining odorants with much lower OAVs (<0.23), 94 ± 2% of the septic odor could be explained. The musty odor was not affected by the presence of the co-existing odorants at the concentration levels of the present study. This study indicated that the overall odor of water contaminated with musty and septic odorants is a combination of both concentrations of individual contaminants and their synergistic effects. This is the first study to reveal the synergistic effects of typical musty odorants on septic odor, and the results of this study demonstrated that the synergistic effects of other odorants should be considered when dealing with the septic odor in drinking water.

Simultaneous removal of multiple odorants from source water suffering from septic and musty odors: Verification in a full-scale water treatment plant with ozonation

Ozonation is known to be very effective in the removal of odorants from source water. However, it is not known if ozonation is effective in the removal of multiple odorants causing different types of odors. In this study, the removal performance for odors and odorants were evaluated in a Water Treatment Plant (WTP), which was equipped with coagulation, sedimentation, ozonation, biological activated carbon (BAC) filtration, sand filtration, and chlorination in succession and located in the downstream of the Huangpu (HP) River, over the period from April, 2014 to April, 2015. Flavor profile analysis (FPA) results showed that the source water was constantly associated with septic and musty odors. Geosmin and 2-MIB, with an average OAV of 4.54 and 1.38, respectively, were the major odorants for musty odor, while bis(2-chloroisopropyl) ether, DEDS and DMDS with an average OAV of 2.35, 1.65 and 0.78, respectively, might be responsible for the septic odor. While the musty odor could be removed effectively through the combination of ozonation and BAC, the septic odor and associated odorants required further treatment with sand filtration and chlorination for complete removal. It is clear that the advanced treatment process was effective for the treatment of source water containing complicated odorants. It should be noted that the sedimentation process needs careful management because release of odorants may occur during the treatment. The result of this study will be helpful for the mitigation of odors in WTP using source waters suffering from complicated odor problems.

Identification of complex septic odorants in Huangpu River source water by combining the data from gas chromatography-olfactometry and comprehensive two-dimensional gas chromatography using retention indices

Identification of the trace odorants causing the septic odors in source waters with complex matrixes has long been a big challenge. The Huangpu (HP) River, an important source water for Shanghai, has long been suffering from septic and musty odors, although major odorants have not been identified. In this study, combining the data from gas chromatography-olfactometry with mass spectrometry (GC-O/MS) and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) using retention indices (RIs) was used for the identification of odorants in HP source water. Olfactometry peaks detected in water extracts by GC-O/MS were combined with the chromatography peaks detected by GC×GC-TOFMS based on the RIs determined using the retention times (RTs) of alkanes C7–C30. A total of thirteen olfactometry peaks were obtained though GC-O/MS analysis, and potential odorants corresponding to each of the olfactometry peaks were screened based on the odor characteristics and match similarity using GC×GC-TOFMS. Finally, fourteen odorants (one odorant was detected in GC×GC-TOFMS without an olfactometry peak), including three septic odorants (bis(2-chloroisopropyl) ether, diethyl disulfide and dimethyl disulfide) and two musty ones (geosmin and 2-MIB), were confirmed by using authentic standards. The septic and musty odorants in six source water samples taken over a period of six months were quantified. Bis(2-chloroisopropyl) ether, with an odor activity value (OAV) of 1.84–3.2, was found to be a major septic odorant in HP source water, followed by diethyl disulfide (OAV 1.56–1.96) and dimethyl disulfide (OAV 0.37–2.42), while geosmin (OAV 4.37–11.44) was the major musty odorant, followed by 2-MIB (OAV 1.13–1.89). This is the first comprehensive study focusing on the identification of odorants in a complex source water. The integrated approach used in this study could be applied for the identification of odorants in other complex source waters suffering similar odor problems.

Sensory GC analysis of decaying vegetation and septic odors

GC–MS is combined with sensory GC analysis to identify chemicals responsible for decaying vegetation and septic odors in drinking water supplies.A study was undertaken to identify the chemicals responsible for septic and decaying vegetation odors, not only in odor reference standards but also in natural waters. Two complementary extraction methods—closed‐loop stripping analysis and simultaneous distillation extraction—were used. Chemical identification was performed by gas chromatography (GC) with mass spectrometry, and sensory identification was accomplished by flavor profile analysis and sensory GC. Dimethyl disulfide, dimethyl trisulfide, and 2‐isobutyl‐3‐methoxypyrazine were the principal contributors to decaying vegetation odors, whereas dimethyl trisulfide and indole were strongly associated with septic odors. In addition, the study confirmed the presence of these chemicals as well as 2‐isopropyl‐3‐methoxypyrazine (associated with decaying vegetation) in water supplies.

The use of reference materials in sensory analysis

In descriptive sensory techniques, reference materials are used to establish a common vocabulary for various aromas and flavors. A reference standard can be any chemical or natural material that adequately represents the particular characteristic described. This paper evaluates the utility of various reference materials that have been proposed as odor standards. The odor reference library used included odors commonly attributable to microbiological and industrial sources. The results of utilizing reference standards demonstrated that some materials were very good; that is, they yielded a distinctive odor that transcended cultural and language differences, as well as different levels of experience. Other aromas required several standards to distinguish among subtle but important differences, e.g., geosmin and 2-methylisoborneol to differentiate earthy/musty odors. These standards also included natural materials prepared in various states to reference different types of common odors in water - for example, grass clippings (in water) that had been freshly cut to represent a grassy odor, or had been held for a week to represent a septic odor, as well as dried grass for a hay odor. Other reference materials yielded bimodal distributions in which, primarily, two groups centered around different descriptors; these kinds of materials would not make good reference standards.

The use of reference materials in sensory analysis

In descriptive sensory techniques, reference materials are used to establish a common vocabulary for various aromas and flavors. A reference standard can be any chemical or natural material that adequately represents the particular characteristic described. This paper evaluates the utility of various reference materials that have been proposed as odor standards. The odor reference library used included odors commonly attributable to microbiological and industrial sources. The results of utilizing reference standards demonstrated that some materials were very good; that is, they yielded a distinctive odor that transcended cultural and language differences, as well as different levels of experience. Other aromas required several standards to distinguish among subtle but important differences, e.g., geosmin and 2-methylisoborneol to differentiate earthy/musty odors. These standards also included natural materials prepared in various states to reference different types of common odors in water - for example, grass clippings (in water) that had been freshly cut to represent a grassy odor, or had been held for a week to represent a septic odor, as well as dried grass for a bay odor. Other reference materials yielded btmodal distributions in which, primarily, two groups centered around different descriptors; these kinds of materials would not make good reference standards.

Just When You Think You Have It Under Control

The Des Moines Water Works, in Des Moines (Iowa), survived the severe drought of 1988 without any water supply problems. However, in early 1989 the utility began experiencing some strange phenomena including an increase in the organic loading of raw water and a septic odor on filters that had been backwashed and placed on standby that could only be attributed to the drought. The article describes the actions taken by the utility to discover the cause of the odor, the solution: filter super chlorination, and the final analysis that it could not be determined what caused the odor.

Coal for water purification

In descriptive sensory techniques, reference materials are used to establish a common vocabulary for various aromas and flavors. A reference standard can be any chemical or natural material that adequately represents the particular characteristic described. This paper evaluates the utility of various reference materials that have been proposed as odor standards. The odor reference library used included odors commonly attributable to microbiological and industrial sources. The results of utilizing reference standards demonstrated that some materials were very good; that is, they yielded a distinctive odor that transcended cultural and language differences, as well as different levels of experience. Other aromas required several standards to distinguish among subtle but important differences, e.g., geosmin and 2-methylisoborneol to differentiate earthy/musty odors. These standards also included natural materials prepared in various states to reference different types of common odors in water - for example, grass clippings (in water) that had been freshly cut to represent a grassy odor, or had been held for a week to represent a septic odor, as well as dried grass for a bay odor. Other reference materials yielded btmodal distributions in which, primarily, two groups centered around different descriptors; these kinds of materials would not make good reference standards.