1
|
Silamat B, Mark O, Djordjević S, Chaiwiwatworakul P. Implementation of two-phase modeling of hydrogen sulfide in fresh market's combined sewers in Rat Burana, Bangkok. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 358:120852. [PMID: 38608577 DOI: 10.1016/j.jenvman.2024.120852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Revised: 04/01/2024] [Accepted: 04/03/2024] [Indexed: 04/14/2024]
Abstract
Hydrogen sulfide (H2S) is one of the sewer gases commonly found in wastewater collection systems. This anaerobic degradation product causes issues, ranging from odor nuisances and health hazards to pipe corrosion. Several studies have provided an understanding of H2S formation mechanism, including simulations of H2S emissions in sewers, especially in pressurized systems. However, the present models necessitate a large amount of data due to the complexity of the H2S processes and common routine-monitoring water quality parameters may not fit the requirements. This study aims to simulate the fate and transport of H2S in both air and water phases in combined sewers, with a realization of practicableness of the application. The study case is centered around a fresh market in Bangkok, where the sewers are commonly plagued with garbage-related issues. These challenges pose difficulties for site monitoring across various aspects, necessitating the application of unconventional methods. On-site hydrodynamics, wastewater quality, and H2S gas concentration data were monitored on hourly and daily bases. It was found that the sulfides in the combined sewerage were correlated with sewage quality, e.g., COD, sulfate (SO42-), and pH concentrations in particular. The model results were in an acceptable range of accuracy (R2 = 0.63; NSE = 0.52; RMSE = 1.18) after being calibrated with the measured hydrogen sulfide gas concentration. The results lead to the conclusion that the simplified model is practical and remains effective even in sewers with untraditional conditions. This could hold promise as a fundamental tool in shaping effective H2S mitigation strategies.
Collapse
Affiliation(s)
- Benyapa Silamat
- Department of Environmental Engineering, Faculty of Engineering, King Mongkut's University of Technology Thonburi, Bangkok, 10140, Thailand
| | - Ole Mark
- Innovation Urban Drainage, Krüger A/S, Gladsaxevej 363, Denmark
| | - Slobodan Djordjević
- Centre for Water Systems, University of Exeter, Exeter, EX4 4QF, United Kingdom
| | - Pichet Chaiwiwatworakul
- Department of Environmental Engineering, Faculty of Engineering, King Mongkut's University of Technology Thonburi, Bangkok, 10140, Thailand.
| |
Collapse
|
2
|
Zhang L, Qiu YY, Sharma KR, Shi T, Song Y, Sun J, Liang Z, Yuan Z, Jiang F. Hydrogen sulfide control in sewer systems: A critical review of recent progress. WATER RESEARCH 2023; 240:120046. [PMID: 37224665 DOI: 10.1016/j.watres.2023.120046] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 04/17/2023] [Accepted: 05/02/2023] [Indexed: 05/26/2023]
Abstract
In sewer systems where anaerobic conditions are present, sulfate-reducing bacteria reduce sulfate to hydrogen sulfide (H2S), leading to sewer corrosion and odor emission. Various sulfide/corrosion control strategies have been proposed, demonstrated, and optimized in the past decades. These included (1) chemical addition to sewage to reduce sulfide formation, to remove dissolved sulfide after its formation, or to reduce H2S emission from sewage to sewer air, (2) ventilation to reduce the H2S and humidity levels in sewer air, and (3) amendments of pipe materials/surfaces to retard corrosion. This work aims to comprehensively review both the commonly used sulfide control measures and the emerging technologies, and to shed light on their underlying mechanisms. The optimal use of the above-stated strategies is also analyzed and discussed in depth. The key knowledge gaps and major challenges associated with these control strategies are identified and strategies dealing with these gaps and challenges are recommended. Finally, we emphasize a holistic approach to sulfide control by managing sewer networks as an integral part of an urban water system.
Collapse
Affiliation(s)
- Liang Zhang
- Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, China
| | - Yan-Ying Qiu
- Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, China
| | - Keshab R Sharma
- Australian Centre for Water and Environmental Biotechnology (ACWEB), The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Tao Shi
- Australian Centre for Water and Environmental Biotechnology (ACWEB), The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Yarong Song
- Australian Centre for Water and Environmental Biotechnology (ACWEB), The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Jianliang Sun
- School of Environment, South China Normal University, Guangzhou, China
| | - Zhensheng Liang
- Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, China
| | - Zhiguo Yuan
- Australian Centre for Water and Environmental Biotechnology (ACWEB), The University of Queensland, St. Lucia, QLD 4072, Australia; School of Energy and Environment, City University of Hong Kong, Hong Kong, China.
| | - Feng Jiang
- Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, China.
| |
Collapse
|
3
|
Yang Z, Zhu DZ, Yu T, Edwini-Bonsu S, Shypanski A, Liu Y. Case study of H 2S release and transport in a trunk sewer with drops. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2020; 82:2271-2281. [PMID: 33339783 DOI: 10.2166/wst.2020.475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Field work was performed to investigate the release of hydrogen sulphide (H2S) and its transport in the sewer trunk with drops in the Bonnie Doon area in Edmonton, Alberta, Canada, in order to develop a proper odor control strategy. The liquid sulfide concentration in the upstream trunk was low (less than 1.0 mg/L), and no H2S gas was detected in the head space under this low concentration. However, high H2S gas concentration was detected in the middle reach of the trunk due to the stripping effect of the three drops (2.7 m, 5.2 m and 2.0 m) along the trunk. The released H2S at drops was then transported in the sewer system and emitted at various locations and caused odor concerns. These drops played an important role in H2S release, and the overall H2S mass transfer coefficient at drops was much higher than that in normal gravity sewers. The overall oxygen and H2S mass transfer coefficient (KLa) was estimated to be around 200 h-1 and 300 h-1 at the first two drops, respectively. Field sampling of biofilm indicates that Desulfomicrobium was identified as the sulfate-reducing bacteria (SRB) responsible for sulfide generation in sewer wall biofilm and Thiobacillus was the only predominant member in manhole wall biofilm contributing to sewer manhole corrosion.
Collapse
Affiliation(s)
- Zhi Yang
- Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 2W2, Canada E-mail:
| | - David Z Zhu
- Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 2W2, Canada E-mail:
| | - Tong Yu
- Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 2W2, Canada E-mail:
| | | | - Adam Shypanski
- Drainage Planning, EPCOR Drainage Services, Edmonton, AB T5 J 3A3, Canada
| | - Yanchen Liu
- International Joint Laboratory on Low Carbon Clean Energy Innovation, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| |
Collapse
|
4
|
Zobeyer H, Zhu DZ, Edwini-Bonsu S. Air flow model development and application in a complex combined sewer system. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2020; 82:1687-1700. [PMID: 33107862 DOI: 10.2166/wst.2020.430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A steady-state air flow model was developed and applied in a complex combined sewer system in the city of Edmonton, Alberta, Canada. The model solves the continuity at each junction and the momentum equation for the links coupled with dropshaft and other manholes. The dropshaft pressure gradient is computed using the dropshaft equation and air flow rate through manhole pickholes is computed considering the opening as an orifice. A leakage factor is used as a calibration parameter to represent the area through which air can leak from the manholes into the neighborhood. The model uses an iterative solution algorithm with a forward sweep for the continuity and backward sweep for the momentum equation. An underrelaxation is applied to update pressure in each iteration for model stability. The model was calibrated and validated by using the measured air flow rate and manhole pressure in the sewer network, with good results. An analysis of the air flow characteristics shows that a significant amount of air is brought into the system due to a large headspace in the upstream trunk but over 70% of this air is released into the neighborhood due to reduced headspace in the downstream trunk.
Collapse
Affiliation(s)
- Hasan Zobeyer
- Dept. of Water Resources Engineering, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh; Dept. of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, T6G 2W2, Canada E-mail:
| | - David Z Zhu
- Dept. of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, T6G 2W2, Canada E-mail:
| | - Stephen Edwini-Bonsu
- Dept. of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, T6G 2W2, Canada E-mail:
| |
Collapse
|
5
|
Zhang Q, Shao W, Zhu DZ, Xu W. Steady air flow model for large sewer networks: a theoretical framework. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2020; 82:503-512. [PMID: 32960795 DOI: 10.2166/wst.2020.353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Modelling air movement in sewer networks is needed in order to address the issues related to sewer odour complaints and sewer corrosions due to hydrogen sulphide in sewers. Most of the existing air flow models can only be applied in small sewer networks or the trunk lines of sewer systems. The purpose of this paper is therefore to propose a theoretical approach to formulate a general governing equation set for modelling steady air movement in large sewer systems. This approach decomposes the sewer system of interest into its basic physical components as pipes and nodes, and builds local topology of each pipe and each node based on geographic information system data as the fundamentals of model formulation. It avoids manually identifying each branch of the sewer system, eliminates the effect of physically closed networks in sewer systems on the governing equations, and considers key sewer components and all known driving forces. The proposed approach was applied to a real sewer system with over 500 pipes. The results show that the proposed model is applicable in modelling air movement in a large sewer system and provides a general idea of sewer gases moving through the system and their emission.
Collapse
Affiliation(s)
- Qi Zhang
- Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 2W2, Canada E-mail: ; State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China
| | - Weiyun Shao
- Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 2W2, Canada E-mail:
| | - David Z Zhu
- Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 2W2, Canada E-mail: ; College of Civil and Environmental Engineering, Ningbo University, Zhejiang 315211, China
| | - Weilin Xu
- State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China
| |
Collapse
|
6
|
Pan G, Wang B, Guo S, Zhang W, Edwini-Bonsu S. Statistical analysis of sewer odour based on 10-year complaint data. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2020; 81:1221-1230. [PMID: 32597408 DOI: 10.2166/wst.2020.217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The City of Edmonton has been suffering from sewer odour problem for many years. Ten years of odour complaints data from 2008 to 2017 were statistically analyzed to identify major factors that relate to the odour problem. Spatial and temporal distributions of odour complaints in the city were first presented. Then relationships between the complaints and physical attributes of the sewer systems were analyzed by introducing a parameter of risk index. It was found that the snowmelt and storm events could possibly reduce odour complaints. Old sewer pipes and large drop structures are statistically more linked and thus significantly contribute to the complaints. The risk index relationship for three pipe materials is clay pipe > concrete pipe > PVC pipe. Combined sewers are more problematic in terms of odour complaints than sanitary sewers. And no clear correlation has been found between the changes of sewer pipe slope or angle and the complaints.
Collapse
Affiliation(s)
- Gang Pan
- College of Intelligence and Computing, Tianjin University, Tianjin, 300350, China
| | - Bao Wang
- College of Intelligence and Computing, Tianjin University, Tianjin, 300350, China
| | - Shuai Guo
- Department of Municipal Engineering, Hefei University of Technology, Hefei, 230009, China E-mail:
| | - Wenming Zhang
- Department of Civil and Environmental Engineering, University of Alberta, Edmonton, T6G 1H9, Alberta, Canada
| | - Stephen Edwini-Bonsu
- Department of Civil and Environmental Engineering, University of Alberta, Edmonton, T6G 1H9, Alberta, Canada
| |
Collapse
|
7
|
Matos RV, Ferreira F, Gil C, Matos JS. Understanding the effect of ventilation, intermittent pumping and seasonality in hydrogen sulfide and methane concentrations in a coastal sewerage system. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:3404-3414. [PMID: 30511226 DOI: 10.1007/s11356-018-3856-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/26/2018] [Indexed: 06/09/2023]
Abstract
Gas pollutants emitted during wastewater transport contribute to atmospheric pollution, aggravated risks for utility workers, infrastructure corrosion, and odour nuisance. Field studies have shown that is difficult to effectively obtain reliable correlations between in-sewer air movement and gas pollutant concentrations. This study aimed at investigating the influence of different ventilation and operating conditions in H2S and CH4 horizontal and vertical movement in a section of a gravity sewer, downstream of a pumping station. Relevant liquid and gas phase quality parameters were monitored, and significant H2S concentrations were measured (with lower contents of CH4). Results evidenced that headspace temperature and ventilation played a key effect when analysing H2S and CH4 dynamics. Setups with a similar content of sulfide and chemical oxygen demand resulted in different H2S and CH4 headspace concentrations. It was also observed that an increase in ventilation resulted in a decrease of average headspace relative humidity of over 70%, with clear implications in corrosion potential estimates. Another interesting observation was that the wastewater drag induced by intermittent pumping, in absence of ingassing, originated pressure differences of up to 0.2 Pa m-1 between studied manholes. This differential originated a wave pattern of gas moving upstream and downstream, thus resulting in several gas peaks per pumping event, at the same sections. In addition, in confined setups, full mixing was not observed along the manholes.
Collapse
Affiliation(s)
- Rita Ventura Matos
- CERIS, Civil Engineering Research and Innovation for Sustainability, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais 1, 1049-001, Lisbon, Portugal.
| | - Filipa Ferreira
- CERIS, Civil Engineering Research and Innovation for Sustainability, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais 1, 1049-001, Lisbon, Portugal
| | - Carla Gil
- Águas do Tejo Atlântico, ETAR da Ericeira, Estrada de Ribeira de Ilhas, 2640-05, Santo Isidoro, Portugal
| | - José Saldanha Matos
- CERIS, Civil Engineering Research and Innovation for Sustainability, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais 1, 1049-001, Lisbon, Portugal
| |
Collapse
|
8
|
Yu T, Ding Q, Wang L, Zhu DZ, Shao Y. Experimental study on air pressure variation in a horizontal pipe of single-stack drainage system. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2019; 79:114-125. [PMID: 30816868 DOI: 10.2166/wst.2019.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The water trap seal under the sanitary appliances is the primary defense against the ingress of foul gases and odors. However, research on air pressure variation in a horizontal pipe of a single-stack drainage system is very limited. Thus a physical model study was conducted to investigate the air pressure variation in a horizontal pipe. Four parameters were studied that affect the pressure variation; that is, water flow rate, inlet height, ventilation condition and outlet condition. When the top of the vertical drainage stack and the outlet were fully open to the atmosphere, the flow in the horizontal pipe changed from free surface flow to slug flow at certain times. The mean values and magnitudes of pressure fluctuation at measuring points on the horizontal pipe increased with Qw but decreased along the horizontal pipe. The inlet height had relatively small influence on the pressure variation. Three ventilation conditions; that is, top fully open, half open and sealed, were tested, and a choking flow was formed in the vertical drainage stack and the pressure in the horizontal pipe decreased under the top sealed condition. Three outlet conditions; that is, outlet fully open, half submerged and fully submerged, were tested. The pressure in the horizontal pipe increased significantly under the outlet fully-submerged condition, which should be avoided in the actual operation by careful designing.
Collapse
Affiliation(s)
- Tingchao Yu
- Department of Civil Engineering, Zhejiang University, Hangzhou 310058, China E-mail:
| | - Qiang Ding
- Department of Civil Engineering, Zhejiang University, Hangzhou 310058, China E-mail: ; Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada, T6G 2W2
| | - Luwen Wang
- Department of Civil Engineering, Zhejiang University, Hangzhou 310058, China E-mail:
| | - David Z Zhu
- Department of Civil Engineering, Zhejiang University, Hangzhou 310058, China E-mail: ; Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada, T6G 2W2
| | - Yu Shao
- Department of Civil Engineering, Zhejiang University, Hangzhou 310058, China E-mail:
| |
Collapse
|
9
|
Short MD, Daikeler A, Wallis K, Peirson WL, Peters GM. Dissolved methane in the influent of three Australian wastewater treatment plants fed by gravity sewers. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 599-600:85-93. [PMID: 28472696 DOI: 10.1016/j.scitotenv.2017.04.152] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 04/19/2017] [Accepted: 04/20/2017] [Indexed: 06/07/2023]
Abstract
Methane (CH4) is an important anthropogenic greenhouse gas and a by-product of urban sewage management. In recent years and contrary to international (IPCC) consensus, pressurised (anaerobic) sewers were identified as important CH4 sources, yet relatively little remains known regarding the role of gravity sewers in CH4 production and conveyance. Here we provide the results of a nine month study assessing dissolved CH4 levels in the raw influent of three large Australian wastewater treatment plants (WWTPs) fed by gravity sewers. Similar to recent international research and contrary to IPCC guidance, results show that gravity sewered wastewater contains moderate levels of CH4 (≈1mgL-1). Dissolved CH4 concentration correlated negatively with daily sewage flow rate (i.e. inversely proportional to sewer hydraulic residence time), with daily CH4 mass loads on average some two-fold greater under low flow (dry weather) conditions. Along with sewage hydraulic residence time, sewer sediments are thought to interact with sewage flow rate and are considered to play a key role in gravity sewer CH4 production. A per capita load of 78gCH4person-1y-1 is offered for gravity sewered wastewater entering WWTPs, with a corresponding emission estimate of up to 62gCH4person-1y-1, assuming 80% water-to-air transfer of inflowing CH4 in WWTPs with combined preliminary-primary plus secondary treatment. Results here support the emerging consensus view that hydraulic operation (i.e. gravity versus pressurised, sewage flow rate) is a key factor in determining sewer CH4 production, with gravity sewer segments likely to play a dominant role in total CH4 production potential for large metropolitan sewer networks. Further work is warranted to assess the scale and temporal dynamics of CH4 production in gravity sewers elsewhere, with more work needed to adequately capture and assess the scale of diffuse sewer network CH4 emissions from sprawling urban settlements globally.
Collapse
Affiliation(s)
- Michael D Short
- School of Natural and Built Environments, University of South Australia, Mawson Lakes, South Australia 5095, Australia; Future Industries Institute, University of South Australia, Mawson Lakes, South Australia 5095, Australia; School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
| | - Alexander Daikeler
- School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia; Institute for Energy Systems and Technology, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Kirsten Wallis
- School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - William L Peirson
- School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Gregory M Peters
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| |
Collapse
|
10
|
Jiang G, Sun J, Sharma KR, Yuan Z. Corrosion and odor management in sewer systems. Curr Opin Biotechnol 2015; 33:192-7. [DOI: 10.1016/j.copbio.2015.03.007] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 03/06/2015] [Accepted: 03/11/2015] [Indexed: 10/23/2022]
|
11
|
Kim H, Lee H, Choi E, Choi I, Shin T, Im H, Ahn S. Characterization of odor emission from alternating aerobic and anoxic activated sludge systems using real-time total reduced sulfur analyzer. CHEMOSPHERE 2014; 117:394-401. [PMID: 25180483 DOI: 10.1016/j.chemosphere.2014.08.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 08/01/2014] [Accepted: 08/02/2014] [Indexed: 06/03/2023]
Abstract
Anaerobic biodegradation of sulfur-containing compounds always generates volatile sulfur compounds (VSCs) including H2S, methyl mercaptan, and dimethyl sulfide (DMS). VSC emissions from wastewater treatment plants (WWTPs) result in odor complaints from people living nearby. To control odor-causing compounds in WWTPs, it is important to know the odor emission quantity particularly with continuous monitoring. Since modified activated sludge processes always include anaerobic, anoxic and aerobic conditions for nutrient removal, odor emission from these different environmental settings is expected. In this study, continuous monitoring of VSCs from the headspace of an alternating aerobic and anoxic (AAA) activated sludge process via total reduced sulfur (TRS) analyzer was performed. There is clear pattern of the initial TRS peak immediately after the initiation of the aeration in the AAA system and TRS concentration begins to drop through the remaining air-on cycle. On the other hand, during the air-off period, TRS concentrations increase with time. In particular, a clear inflection point in the TRS profile could be observed after complete removal of nitrate during air-off, meaning more VSCs formation. Since the highest odor emission occurs after the initiation of aeration, the future control of exhausted air should only deal with air collected during the initial aeration period (e.g., 30min), a similar concept for the treatment of first flush in combined sewer overflow. In addition, application of a control scheme to initiate aeration immediately after denitrification is completed during air-off should be beneficial in reducing odor emission.
Collapse
Affiliation(s)
- Hyunook Kim
- Department of Energy and Environmental System Engineering, University of Seoul, Seoul, Republic of Korea.
| | - Hyunjoo Lee
- Department of Energy and Environmental System Engineering, University of Seoul, Seoul, Republic of Korea
| | - Eunsun Choi
- Department of Energy and Environmental System Engineering, University of Seoul, Seoul, Republic of Korea
| | - Il Choi
- Department of Energy and Environmental System Engineering, University of Seoul, Seoul, Republic of Korea
| | - Taesub Shin
- Department of Energy and Environmental System Engineering, University of Seoul, Seoul, Republic of Korea
| | - Hyungjoon Im
- Department of Energy and Environmental System Engineering, University of Seoul, Seoul, Republic of Korea
| | - Soobin Ahn
- Department of Environmental Science, University of Maryland-Baltimore County, Baltimore, MD, USA
| |
Collapse
|