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Ibangha IAI, Madueke SN, Akachukwu SO, Onyeiwu SC, Enemuor SC, Chigor VN. Physicochemical and bacteriological assessment of Wupa wastewater treatment plant effluent and the effluent-receiving Wupa River in Abuja, Nigeria. Environ Monit Assess 2023; 196:30. [PMID: 38072841 DOI: 10.1007/s10661-023-12209-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 11/30/2023] [Indexed: 12/18/2023]
Abstract
The occurrence of pathogens in discharged wastewater effluent may constitute potential public health risks. This study assessed the physicochemical and bacteriological characteristics of water samples taken from the Wupa River in Abuja, Nigeria, which receives the final effluent of the Wupa Wastewater Treatment Plant. Sixty sewage/water samples were collected over 12 months from five sampling points. Coliform bacteria and Escherichia coli were simultaneously enumerated using the membrane filtration technique and Chromocult Coliform Agar. HANNA multiparameter metre was used to measure the physicochemical parameters including temperature, pH, electrical conductivity (EC), dissolved oxygen (DO) and total dissolved solids (TDS). Results of the bacteriological analysis showed that impermissible high mean counts of E. coli (≥ 1.2 × 104 CFU/100 ml) and total coliforms (≥ 5.4 × 104 CFU/100 ml) were detected in 95% and 100% of the water samples respectively. These values exceed the acceptable standard limits. The mean values of physicochemical parameters ranged from 6.3 to 8.7, 20.9 to 27.3 °C, 116 to 325.0 µS/cm, 1.3 to 11.4 mg/l and 98.0 to 180.0 mg/l for pH, temperature, EC, DO and TDS respectively, with all conforming to international and national standards. Wupa River seems to have a minor negative environmental impact, per the physicochemical data obtained in this study. However, the high counts of faecal indicator bacteria demonstrated in the effluent samples were higher than those of the river at both upstream and downstream sites, implying that the river microbial load may increase to constitute an unchecked environmental hazard. Adequate disinfection of the Wupa plant effluent before discharge into the Wupa River is imperative.
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Affiliation(s)
- Ini-Abasi I Ibangha
- Water and Public Health Research Group (WPHRG), University of Nigeria, Nsukka, Enugu State, Nigeria
- Department of Microbiology, Faculty of Biological Sciences, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Stella N Madueke
- Water and Public Health Research Group (WPHRG), University of Nigeria, Nsukka, Enugu State, Nigeria
- Department of Microbiology, Faculty of Biological Sciences, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Sunday O Akachukwu
- Water and Public Health Research Group (WPHRG), University of Nigeria, Nsukka, Enugu State, Nigeria
- Department of Microbiology, Faculty of Biological Sciences, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Stella C Onyeiwu
- Department of Food Technology, Kaduna Polytechnic, Kaduna, Kaduna State, Nigeria
| | - Simeon C Enemuor
- Water and Public Health Research Group (WPHRG), University of Nigeria, Nsukka, Enugu State, Nigeria
- Department of Microbiology, Faculty of Biological Sciences, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Vincent N Chigor
- Water and Public Health Research Group (WPHRG), University of Nigeria, Nsukka, Enugu State, Nigeria.
- Department of Microbiology, Faculty of Biological Sciences, University of Nigeria, Nsukka, Enugu State, Nigeria.
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Li J, Tang WZ, Gu L. Energy efficiency assessment of China wastewater treatment plants by unit energy consumption per kg COD removed. Environ Technol 2023; 44:278-292. [PMID: 34397318 DOI: 10.1080/09593330.2021.1969596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 08/09/2021] [Indexed: 06/13/2023]
Abstract
Unit energy consumption per kg pollutant removed (kWh/kgCODremoved) is used for the first time in assessing and ranking the sustainability of main treatment technologies of 1215 wastewater treatment plants (WWTPs) in China. The metric better measures the sustainability of main treatment technologies in WWTPs than unit energy consumption per cubic meter treated (kWh/m3). The energy consumption data of these WWTPs were selected from the database of 1399 WWTPs to evaluate the energy efficiency of different treatment technologies. 80.3% of the WWTPs applied anaerobic-oxic plus anaerobic-anoxic-oxic, oxidation ditch, and sequencing batch reactor as main technologies. Statistical analysis shows that the unit energy consumption of WWTPs decreases with increasing design flow rate, operation loading rate, and influent COD concentration. For example, the average unit energy consumption of SBR decreases from 2.76 kWh/kgCODremoved to 0.83 kWh/kgCODremoved when the design flow rate increases from less than 10,000 m3/d to 100,000-200,000 m3/d. The mean unit energy consumption of SBR decreases from 1.71 kWh/kgCODremoved to 1.32 kWh/ kgCODremoved and 2.85 kWh/ kgCODremoved to 0.63 kWh/kgCODremoved as the operation loading rate and COD removal increase from 40% to 100% and from less than 150 mg/L to over 450 mg/L, respectively. SBR has the lowest unit energy consumption among all the technologies. Therefore, SBR might be the most appropriate technology in small and medium-scale WWTPs in China. Regression equations were developed to predict the unit energy consumption for sustainable design treatment trains by input variables such as design flow rate, operation loading rate, and influent COD concentration.
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Affiliation(s)
- Jinze Li
- Department of Civil and Environmental Engineering, Florida International University, Miami, FL, USA
| | - Walter Z Tang
- Department of Civil and Environmental Engineering, Florida International University, Miami, FL, USA
| | - Li Gu
- Key laboratory of the Three Gorges Reservoir Region's Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, Chongqing, People's Republic of China
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Liao G, Bin L, Tang B, Li P, Qiu B, Huang Z, Huang S, Fu F. Insights into the fouling layer of flat-sheet membrane and its development in an integrated oxidation ditch-membrane bioreactor. Bioresour Technol 2022; 345:126466. [PMID: 34864179 DOI: 10.1016/j.biortech.2021.126466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/22/2021] [Accepted: 11/27/2021] [Indexed: 06/13/2023]
Abstract
This work revealed the characteristics of fouling layer on the flat-sheet membranes and its development in an integrated oxidation-ditch membrane bioreactor. During the operation period (130 days), the reactor performed very well in removing pollutants. As the operation proceeded, membrane fouling occurred on the flat-sheet membranes and trans-membrane pressure showed a cyclical variation. The experimental results showed that the process of membrane fouling appeared successively in two different structures: biofilm (BF) and sludge fouling (SF). The substances causing membrane fouling were mainly organic foulants and a small amount of inorganic metal compounds, especially the protein-like and fulvic acid-like substances in loosely bound extracellular polymeric substances (LB-EPS). The analysis of microbial communities revealed that SF and BF had very different microbial properties. Although most membrane foulants could be removed by physical and chemical cleaning methods, the protein-like and fulvic acid-like substances in BF were contribute much to causing irreversible membrane fouling.
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Affiliation(s)
- Guohao Liao
- School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Liying Bin
- School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Bing Tang
- School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China.
| | - Ping Li
- School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Bangqiao Qiu
- School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Zhaole Huang
- School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Shaosong Huang
- School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Fenglian Fu
- School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
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Peng L, Wang F, Zhang D, Fang C, van der Hoek JP, Chu W. Effect of oxidation ditch and anaerobic-anoxic-oxic processes on CX 3R-type disinfection by-product formation during wastewater treatment. Sci Total Environ 2021; 770:145344. [PMID: 33515881 DOI: 10.1016/j.scitotenv.2021.145344] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/27/2020] [Accepted: 01/17/2021] [Indexed: 06/12/2023]
Abstract
The high chlorine dosages in wastewater treatment plants during the COVID-19 pandemic may result in increased formation of disinfection by-products (DBPs), posing great threat to the aquatic ecosystem of the receiving water body and the public health in the downstream area. However, limited information is available on the effect of biological wastewater treatment processes on the formation of CX3R-type DBPs. This study investigated the effect of oxidation ditch (OD) and anaerobic-anoxic-oxic (AAO), two widely used biological wastewater treatment processes, on the formation of five classes of CX3R-type DBPs, including trihalomethanes (THMs), haloacetic acids (HAAs), haloacetaldehydes (HALs), haloacetonitriles (HANs) and halonitromethanes (HNMs), during chlorination. Experimental results showed that biological treatment effectively reduced the dissolved organic carbon (DOC) and UV254, while it increased the dissolved organic nitrogen (DON), and therefore the ratio of DON/DOC. In addition, increases in the contents of soluble microbial product- and humic acid-like matters, and the transformation of high molecular weight (MW) fractions in the dissolved organic matter into low MW fractions were observed after OD and AAO processes. Although biological treatment effectively decreased the formation of Cl-THMs, Cl-HAAs, Cl-HANs and Cl-HNMs, the formation of DBCM, DBAA, BDCAA, DBCAA, DCAL, TCAL and DBAN (where C = chloro, B = bromo, D = di, T = tri) all increased significantly, due to the increased formation reactivity. Moreover, biological treatment increased the ratio of bromide/DOC and bromine incorporation into THMs, HAAs and DHANs except for HALs and THANs. Different from previous studies, this study revealed that biological treatment increased the formation of some DBPs, especially brominated DBPs, despite the efficient removal of organic matters. It provides insights into the DBP risk control in wastewater treatment, particularly during the COVID-19 pandemic.
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Affiliation(s)
- Liqi Peng
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Feifei Wang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China
| | - Di Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Chao Fang
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Jan Peter van der Hoek
- Department of Water Management, Delft University of Technology, P.O. Box 5048, 2600 GA Delft, the Netherlands; Research & Innovation, Waternet, Korte Ouderkerkerdijk 7, 1096 AC Amsterdam, the Netherlands
| | - Wenhai Chu
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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Xu Q, Wan Y, Wu Q, Xiao K, Yu W, Liang S, Zhu Y, Hou H, Liu B, Hu J, Yang Y, Yang J. An efficient hydrodynamic-biokinetic model for the optimization of operational strategy applied in a full-scale oxidation ditch by CFD integrated with ASM2. Water Res 2021; 193:116888. [PMID: 33581403 DOI: 10.1016/j.watres.2021.116888] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 12/20/2020] [Accepted: 02/01/2021] [Indexed: 06/12/2023]
Abstract
Oxidation ditches (ODs) are often used for wastewater treatment. However, limitations of ODs like high energy expenditure and increased sludge sedimentation hinder its wide application. In this study, the computational fluid dynamics (CFD) model integrated with Activated Sludge Model No. 2 (ASM2) was proposed and applied in a full-scale OD. The integrated model provided heterogeneous information on the characteristics of hydrodynamics and biokinetics of OD, especially with respect to the simulation of total phosphorus removal by CFD-ASM2 integration model for the first time. The simulated values of flow velocities, suspended solids (SS), dissolved oxygen, chemical oxygen demand, total nitrogen, ammonium nitrogen, and total phosphorus concentrations were well validated with the measured results, with the standard deviation errors of less than 5.56%, 0.28%, 0.74%, 7.39%, 3.17%, 5.27%, and 7.40%, respectively. Based on the integrated model, four different operational strategies were simulated. The proposed operational strategy of operating 7 surface aerators and 10 submerged impellers not only met the standard discharge requirements (GB 18918-2002) but also consumed less energy by 22.3%, compared with the original strategy of operating 9 surface aerators and 13 submerged impellers. Meanwhile, this proposed operational strategy also reduced the SS concentrations in the second and fourth channels, which was beneficial to elimination of sludge sedimentation. Moreover, the proposed operational strategy was successfully applied and validated in full-scale OD. The foregoing results collectively suggest that the CFD-AMS2 integration model is numerically capable to optimize the operational strategy of ODs.
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Affiliation(s)
- Qi Xu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China; Changjiang Institute of Survey, Planning, Design and Research, Jiefang Avenue 1863, Wuhan, Hubei, 430010, China
| | - Yanlei Wan
- Changjiang Institute of Survey, Planning, Design and Research, Jiefang Avenue 1863, Wuhan, Hubei, 430010, China
| | - Qiongxiang Wu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China
| | - Keke Xiao
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China.
| | - Wenbo Yu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China
| | - Sha Liang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China
| | - Yuwei Zhu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China
| | - Huijie Hou
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China
| | - Bingchuan Liu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China
| | - Jingping Hu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China
| | - Yin Yang
- Smith School of Enterprise and the Environment, University of Oxford, South Parks Road, Oxford OX1 3QY, United Kingdom
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Luoyu Road 1037, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China.
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6
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Zheng M, Zhou N, He S, Chang F, Zhong J, Xu S, Wang Z, Liu T. Nitrous oxide (N 2O) emissions from a pilot-scale oxidation ditch under different COD/N ratios, aeration rates and two shock-load conditions. J Environ Manage 2021; 280:111657. [PMID: 33229113 DOI: 10.1016/j.jenvman.2020.111657] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 09/23/2020] [Accepted: 11/06/2020] [Indexed: 06/11/2023]
Abstract
Nitrous oxide (N2O) generated from wastewater treatment plants (WWTPs) has drawn attention due to its high emission load and significant greenhouse effect. In the present study, N2O emissions from a pilot-scale Carrousel oxidation ditch under various chemical oxygen demand (COD) to nitrogen ratio (COD/N) and aeration rates were systematically investigated. The highest N2O emission factor was 0.142 ± 0.013%, at COD/N of 5 and aeration rate of 1.8 m3 h-1, which was much lower than the majority of previous studies. The results could be attributed to the high internal recycle ratio of the oxidation ditch process which lightened the burden of influent load to the system. The profiles of N2O emissions and dissolved N2O concentration along the channels showed a distinct spatial variation that N2O emissions primarily occurred in the aeration zones due to the air stripping effect. However, both the aeration and anoxic zones contributed to N2O generation due to autotrophic nitrification (AN), which was considered to be the main N2O generation process. In addition, two simulated shock-load conditions, ammonia overload shock and aeration failure shock, were carried out to explore the response of the biological nitrogen removal (BNR) system. The results indicated that both shock-loads lead to excessive N2O emissions, especially at higher aeration rates, which could be explained by the improved N2O generation by AN process during the shock-load period. This study offered new insights into the role of operational parameters to N2O emission and the alternative approach for N2O mitigation during both the steady-state operation and shock-load conditions in the oxidation ditch process.
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Affiliation(s)
- Maosheng Zheng
- Key Laboratory of Regional Energy Systems Optimization, Ministry of Education, College of Environmental Science and Technology, North China Electric Power University, Beijing, 102206, China
| | - Nan Zhou
- Key Laboratory of Regional Energy Systems Optimization, Ministry of Education, College of Environmental Science and Technology, North China Electric Power University, Beijing, 102206, China
| | - Shishi He
- Key Laboratory of Regional Energy Systems Optimization, Ministry of Education, College of Environmental Science and Technology, North China Electric Power University, Beijing, 102206, China
| | - Fang Chang
- Marine Resources Research Centre, Tianjin Research Institute for Water Transport Engineering, M.O.T., Tianjin, 300456, China
| | - Jie Zhong
- Key Laboratory of Regional Energy Systems Optimization, Ministry of Education, College of Environmental Science and Technology, North China Electric Power University, Beijing, 102206, China
| | - Shuo Xu
- Beijing Municipal Environmental Monitoring Center, Beijing, 100048, China
| | - Zhe Wang
- Key Laboratory of Regional Energy Systems Optimization, Ministry of Education, College of Environmental Science and Technology, North China Electric Power University, Beijing, 102206, China
| | - Tang Liu
- College of Environmental Sciences and Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, 100871, China.
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Zhou N, Dang C, Zhao Z, He S, Zheng M, Liu W, Wang X. Role of sludge retention time in mitigation of nitrous oxide emission from a pilot-scale oxidation ditch. Bioresour Technol 2019; 292:121961. [PMID: 31419708 DOI: 10.1016/j.biortech.2019.121961] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/01/2019] [Accepted: 08/04/2019] [Indexed: 06/10/2023]
Abstract
Nitrous oxide (N2O) emission from wastewater treatment plants (WWTPs) has become a focus of attention due to its significant greenhouse effect. In this study, the role of sludge retention time (SRT) in mitigation of N2O emission from a pilot-scale oxidation ditch was systematically investigated. The activated sludge system that operated at SRT of 25 days demonstrated significantly lower N2O emission factor, higher resistance to ammonia overload and aeration failure shock than those obtained at SRT of 15 days no matter which hydraulic retention time (HRT) was adopted. Batch experiments revealed that nitrifier denitrification (ND) was the primary mechanism of N2O generation. However, more microbes affiliated with Nitrospira genera were harbored in the system at SRT 25 d, which could effectively avoid nitrite accumulation, a key factor promoting N2O generation by ND. PICRUSt results further suggested the system at SRT 25 d possessed higher genetic potential for N2O reduction reflected by the more abundant nitrous-oxide reductase.
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Affiliation(s)
- Nan Zhou
- MOE Key Laboratory of Regional Energy Systems Optimization, Environmental Research Academy, North China Electric Power University, Beijing 102206, China
| | - Chenyuan Dang
- Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Zhirong Zhao
- MOE Key Laboratory of Regional Energy Systems Optimization, Environmental Research Academy, North China Electric Power University, Beijing 102206, China
| | - Shishi He
- MOE Key Laboratory of Regional Energy Systems Optimization, Environmental Research Academy, North China Electric Power University, Beijing 102206, China
| | - Maosheng Zheng
- MOE Key Laboratory of Regional Energy Systems Optimization, Environmental Research Academy, North China Electric Power University, Beijing 102206, China.
| | - Wen Liu
- Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Xiangke Wang
- MOE Key Laboratory of Regional Energy Systems Optimization, Environmental Research Academy, North China Electric Power University, Beijing 102206, China
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Yang T, Han Y, Liu J, Li L. Aerosols from a wastewater treatment plant using oxidation ditch process: Characteristics, source apportionment, and exposure risks. Environ Pollut 2019; 250:627-638. [PMID: 31035145 DOI: 10.1016/j.envpol.2019.04.071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 04/10/2019] [Accepted: 04/14/2019] [Indexed: 05/04/2023]
Abstract
The study of aerosol dispersion characteristics in wastewater treatment plants (WWTPs) has attracted extensive attention. Oxidation ditch (OD) is a commonly implemented process during biological wastewater treatment. This study assessed the component characteristics, source apportionment, and exposure risks of aerosols generated from a WWTP using the OD process (AWO). The results indicated that the aeration part of oxidation ditch (ODA) exhibited the highest concentrations and proportions of the respiratory fractions (RF) of bacteria, Enterobacteriaceae, Staphylococcus aureus, and Pseudomonas aeruginosa. Some pathogenic or opportunistic-pathogenic bacteria and carcinogenic metal(loid)s were detected in the AWO. The source apportionment results indicated that the outdoor wastewater treatment processes and ambient air contributed to the constitution of the AWO. The indoor aerosols were mainly constituted by composition of the wastewater treatment process such as the sludge dewatering room (SDR). The pathogenic or opportunistic-pathogenic bacteria with eight genera (Colinsella, Dermatophilus, Enterobactor, Erycherichia-Shigella, Ledionella, Selenomonas, Xanthobacter, and Veillonella) were largely attributed to wastewater or sludge. The risk assessment suggested that inhalation was the main exposure pathway for aerosols (including bacteria and metal(loid)s). Additionally, As indicated the highest non-carcinogenic risks. Furthermore, As, Cd, and Co were associated with high carcinogenic risks. The ODA and sludge dewatering room (SDR) indicated the highest carcinogenic and non-carcinogenic risks of metal(loid)s, respectively. Thus, the AWO should be sufficiently researched and monitored to mitigate their harmful effects on human health, particularly with regard to the health of the site workers.
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Affiliation(s)
- Tang Yang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing, 101408, PR China.
| | - Yunping Han
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing, 101408, PR China.
| | - Junxin Liu
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China.
| | - Lin Li
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing, 101408, PR China.
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9
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Abusam A, Mydlarczyk A. Assessment of the operational performances of two activated sludge systems in Kuwait. Environ Monit Assess 2018; 190:514. [PMID: 30105452 DOI: 10.1007/s10661-018-6879-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 07/25/2018] [Indexed: 06/08/2023]
Abstract
Activated sludge systems (ASSs) are the most globally used wastewater treatment systems. However, there is very little information about the operational practices of ASSs in developing countries. This paper presents how the Riqqa and Umm-Al-Haiman ASSs, in Kuwait, are operated and the methodology used to evaluate and compare their performances. Over a period of 9 months, weekly samples of the influents, aeration tank mixed liquors, and secondary effluents were collected and analyzed according to standard methods. Accordingly, the operational variables of the systems were estimated. The obtained results indicate that the plants were not operated within their recommended design values. The Riqqa ASS was inadequately aerated and hydraulically and organically overloaded, while the Umm-Al-Haiman ASS was operated at a very high mixed liquor suspended solids (MLSS) value. The method used by this study proved to be useful for identifying the operational problems of the studied ASSs, and it can be used to evaluating the performances of other ASSs.
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Affiliation(s)
- Adallah Abusam
- Wastewater Treatment and Reclamation Technology (WTRT) Program, Water Research Center, Kuwait Institute for Scientific Research, Kuwait, P.O. Box 24885, 13109, Safat, Kuwait.
| | - Andrzej Mydlarczyk
- Wastewater Treatment and Reclamation Technology (WTRT) Program, Water Research Center, Kuwait Institute for Scientific Research, Kuwait, P.O. Box 24885, 13109, Safat, Kuwait
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Zheng M, Tian Y, Liu T, Ma T, Li L, Li C, Ahmad M, Chen Q, Ni J. Minimization of nitrous oxide emission in a pilot-scale oxidation ditch: generation, spatial variation and microbial interpretation. Bioresour Technol 2015; 179:510-517. [PMID: 25575212 DOI: 10.1016/j.biortech.2014.12.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 06/04/2023]
Abstract
Nitrous oxide (N2O) emission from wastewater treatment plants (WWTPs) has received increasing attention. This paper presented how N2O emission was significantly reduced in a pilot-scale Carrousel oxidation ditch under reasonable nitrification and denitrification. N2O emission from the reactor was found as low as 0.027% of influent nitrogen, which was much less than that from other processes. Further measurements on spatial variation of N2O emission in the alternative aerobic/anoxic zones with help of a series of batch experiments demonstrated that about 90% of the emission was contributed by nitrifier denitrification (ND). Moreover, the taxonomic analysis based on high through-put 16S rRNA gene sequencing revealed that the high abundance of denitrifying bacteria and nitrite-oxidizing bacteria (NOB) was responsible for low nitrite accumulations and consequent low N2O emissions. However, N2O generation would be greatly increased upon the normal operation being shocked by either ammonia overload or aeration failure of the oxidation ditch system.
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Affiliation(s)
- Maosheng Zheng
- Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Yuhao Tian
- Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Tang Liu
- Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Tao Ma
- Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Li Li
- Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Can Li
- Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Muhammad Ahmad
- Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Qian Chen
- Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
| | - Jinren Ni
- Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China.
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Lei L, Ni J. Three-dimensional three-phase model for simulation of hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification in an oxidation ditch. Water Res 2014; 53:200-214. [PMID: 24525069 DOI: 10.1016/j.watres.2014.01.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 10/06/2013] [Accepted: 01/15/2014] [Indexed: 06/03/2023]
Abstract
A three-dimensional three-phase fluid model, supplemented by laboratory data, was developed to simulate the hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification processes in an oxidation ditch. The model provided detailed phase information on the liquid flow field, gas hold-up distribution and sludge sedimentation. The three-phase model described water-gas, water-sludge and gas-sludge interactions. Activated sludge was taken to be in a pseudo-solid phase, comprising an initially separated solid phase that was transported and later underwent biological reactions with the surrounding liquidmedia. Floc parameters were modified to improve the sludge viscosity, sludge density, oxygen mass transfer rate, and carbon substrate uptake due to adsorption onto the activated sludge. The validation test results were in very satisfactory agreement with laboratory data on the behavior of activated sludge in an oxidation ditch. By coupling species transport and biological process models, reasonable predictions are made of: (1) the biochemical kinetics of dissolved oxygen, chemical oxygen demand (COD) and nitrogen variation, and (2) the physical kinematics of sludge sedimentation.
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Affiliation(s)
- Li Lei
- Department of Environmental Engineering, Peking University, Beijing 100871, China; The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Peking University, Beijing 100871, China
| | - Jinren Ni
- Department of Environmental Engineering, Peking University, Beijing 100871, China; The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Peking University, Beijing 100871, China.
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