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He W, Luo J, Huang J, Tang C, Yang Z. Two-stage injection of polymer and microsand during ballasted flocculation for treating kaolin waters with or without humic acid: Floc evolutional characteristics, performance and mechanisms. WATER RESEARCH 2024; 259:121846. [PMID: 38820733 DOI: 10.1016/j.watres.2024.121846] [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: 02/24/2024] [Revised: 05/26/2024] [Accepted: 05/27/2024] [Indexed: 06/02/2024]
Abstract
Ballasted flocculation is regarded as a most promising water treatment technology in aspects of retrofit and high-rate applications. To deep understand the incorporation behaviors of ballasting agent into ballasted floc growth, two distinct injection modes (namely a two-stage injection of polyacrylamide (PAM) alone, and a two-stage injection of both PAM and microsand) were developed in this study. Then, ballasted flocculation tests of kaolin and kaolin-HA (humic acid) waters were conducted at varying split ratios for fixed total dosages of both PAM and microsand. The experimental results showed that for either two-stage injection mode, the higher the second percentage of each split ratio, the greater the average size of maturated flocs at the second sub-stage of maturation. Meanwhile, the turbidity and UV254 values of settled water became lower at 30 and 180 s of sedimentation, suggesting that varying split ratios significantly affected the kinetics of ballasted floc growth. Moreover, it was suggested that the selection of either two-stage injection mode or corresponding split ratios played a more pronounced role in the HA removal than the total dosage of PAM. This suggestion was supported by SEM, FTIR and XPS analyses for surface morphological details, functional groups and chemical states of maturated flocs eventually formed in the kaolin-HA water through both two-stage injection modes. Accordingly, newly-established conceptual models of ballasted floc growth were proposed to explore the potential influencing mechanisms of varying split ratios on the ballasted flocculation performance. At each sub-stage of maturation, an appropriate dosage ratio between PAM and microsand was of great importance to effectively incorporate microsand particles into ballasted floc formation, besides the hydrolyzed produces of AS coagulant formed at the coagulation stage of ballasted flocculation. This study is expected to provide valuable insights for making ballasted flocculation more effective, economical and sustainable in water treatment engineering.
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Affiliation(s)
- Weipeng He
- Hunan Engineering Research Center of Water Security Technology and Application, College of Civil Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Building Safety and Energy Efficiency (Ministry of Education), College of Civil Engineering, Hunan University, Changsha 410082, PR China.
| | - Jiacheng Luo
- Hunan Engineering Research Center of Water Security Technology and Application, College of Civil Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Building Safety and Energy Efficiency (Ministry of Education), College of Civil Engineering, Hunan University, Changsha 410082, PR China
| | - Jinguo Huang
- Changsha Public Engineering Construction Center, Changsha 410023, PR China
| | - Chen Tang
- Hunan Engineering Research Center of Water Security Technology and Application, College of Civil Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Building Safety and Energy Efficiency (Ministry of Education), College of Civil Engineering, Hunan University, Changsha 410082, PR China
| | - Zhen Yang
- Hunan Engineering Research Center of Water Security Technology and Application, College of Civil Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Building Safety and Energy Efficiency (Ministry of Education), College of Civil Engineering, Hunan University, Changsha 410082, PR China
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Sang Y, Lu T, Lu X, Wang S, Shao X, Han Y, Li L. Pilot-scale microsand-ballasted flocculation of wastewater: turbidity removal, parameters optimization, and mechanism analysis. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:32161-32170. [PMID: 35015230 DOI: 10.1007/s11356-021-18453-8] [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: 11/15/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
The flocs formed during microsand-ballasted flocculation (MBF) have attracted much attention. However, few studies have reported on comprehensive process parameters of MBF and its mechanism is still not well understood. Jar test and pilot-scale continuous experiments were here conducted on two kinds of simulated wastewater, labeled S1 (21.6-25.9 NTU) and S2 (96-105 NTU). Results revealed the hydraulic retention time ratio in the coagulation cell, injection and maturation cell, lamella settler of pilot-scale MBF equipment was 1:3:7.3. The optimum poly aluminum chloride doses for samples S1 and S2 were 0.875 g/L and 1.0 g/L. Besides, the optimum size of microsand was 49-106 μm and the optimum dose was 1.0 g/L. Under aforementioned conditions, the effluent turbidity of S1 was below 0.47 NTU, even lower than the Chinese drinking water standard; that of S2 was below 1.7 NTU, meeting the Chinese recycled water standard. Turbidity removal ranged from 98.0 to 98.8% for S1 and 98.5 to 99.5% for S2 when microsand was added. Therefore, microsand addition enhances MBF performance, where microsand serves as an initial core particle. Some microsand core particles bond together to form a dense core structure of micro-flocs by the adsorption bridging of inorganic polymeric flocculant. Moreover, the size of the largest micro-flocs may be controllable as long as the effective energy dissipation coefficient is adjusted appropriately through specific stirring speeds. This work provides comprehensive pilot-scale process parameters for using MBF to effectively treat wastewater and offers a clearer explanation of the formation mechanism of microsand-ballasted flocs.
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Affiliation(s)
- Yimin Sang
- Department of Environmental Engineering, Beijing Institute of Petrochemical Technology, Beijing, 102617, China.
| | - Taotao Lu
- Department of Environmental Engineering, Beijing Institute of Petrochemical Technology, Beijing, 102617, China
| | - Xianchun Lu
- SDIC Xinkai Water Environment Investment Co. Ltd, Beijing, 101101, China
| | - Shuguang Wang
- Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Xueting Shao
- Technical Centre for Soil, Agricultural and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing, 100012, China.
| | - Yanhe Han
- Department of Environmental Engineering, Beijing Institute of Petrochemical Technology, Beijing, 102617, China
| | - Lili Li
- Department of Environmental Engineering, Beijing Institute of Petrochemical Technology, Beijing, 102617, China
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Lee KH, Qasim M, Lee KG, Inam MA, Khan IA, Khan R, Wie YM. Use of ballasted flocculation (BF) sludge for the manufacturing of lightweight aggregates. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 305:114379. [PMID: 34959062 DOI: 10.1016/j.jenvman.2021.114379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/19/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
Ballasted flocculation (BF) is an efficient way to remove the turbidity from surface water. The objective of the present study is to optimize the ballast (magnetite), coagulant (poly aluminum chloride) concentration and pH for efficient turbidity removal from surface water. To do this, the sludge produced from an optimized dose of a BF treatment was utilized for the production of lightweight (LW) aggregates by combining it with hard clay and sewage sludge. The LW aggregates were formed by means of rapid sintering in the temperature range of 1000-1200 °C with an exposure time of 10 min. The physical properties of the LW aggregates, in this case the leaching of heavy metals, the bulk density and the microstructure, were investigated. The results indicated that corresponding ballast and coagulant concentrations of 0.75 g/L and 30 mg/L (poly aluminum chloride (PAC)) resulted in the maximum removal efficiency of ≈95%. Using a mixture of BF sludge (30 wt%), dry sewage sludge (20 wt%), and hard clay (50 wt%), aggregates with a density of around 1.0 g/cm3 could be produced. In addition, it was confirmed that the manufactured aggregate was environmentally stable as the elution of heavy metals was suppressed.
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Affiliation(s)
- Kang Hoon Lee
- Department of Civil &Environmental Engineering, Hanyang University, 222 Seongdong-gu, Seoul, 04763, South Korea.
| | - Muhammad Qasim
- Department of Civil &Environmental Engineering, Hanyang University, 222 Seongdong-gu, Seoul, 04763, South Korea.
| | - Ki Gang Lee
- Department of Materials Engineering, Kyonggi University, Suwon, Gyeonggi-do, 16227, South Korea.
| | - Muhammad Ali Inam
- Institute of Environmental Sciences and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), H-12 Campus, National University of Sciences and Technology (NUST), Islamabad, 44000, Pakistan.
| | - Imtiaz Afzal Khan
- Department of Civil &Environmental Engineering, Hanyang University, 222 Seongdong-gu, Seoul, 04763, South Korea.
| | - Rizwan Khan
- Department of Chemical Engineering, Quaid-e-Awam University of Engineering, Science and Technology (QUEST), Nawabshah, 67480, Pakistan.
| | - Young Min Wie
- Department of Materials Engineering, Kyonggi University, Suwon, Gyeonggi-do, 16227, South Korea.
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Unraveling the role of ballast surface charge at floc growth behavior in ballasted flocculation. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2021.119507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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He C, Wang K, Fang K, Gong H, Jin Z, He Q, Wang Q. Up-concentration processes of organics for municipal wastewater treatment: New trends in separation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 787:147690. [PMID: 34004540 DOI: 10.1016/j.scitotenv.2021.147690] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 06/12/2023]
Abstract
Carbon neutrality is a pressing goal for the whole society. Over 20% of municipality electrical energy on public utilities was consumed by the operation of wastewater treatment plants (WWTPs). Up-concentration of organic matters and maximum energy recovery is essential for a more sophisticated municipal wastewater management. Chemical coagulation and biological adsorption have been used to achieve efficient carbon capture, while separation is an overlooked step. It may lead to poor effluent quality, as well as consume most of the time and volume. The introduction of new driving forces, such as pressure and magnetism, significantly improved the retention rate and speed, respectively. In this paper, recent works were comprehensively reviewed and a horizontal comparison was conducted from aspects of separation speed, retention rate, concentrate characteristics and economic costs. This review also discussed the selection of technologies under different conditions. Finally, the practical application, fouling mitigation with considering the value of the concentrate, identification of unique concentrate characteristics, and the establishment of an evaluation system was suggested as core issues for future researches. This review will promote the development of an energy-efficient wastewater treatment system with up-concentration processes.
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Affiliation(s)
- Conghui He
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Kaijun Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Kuo Fang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China.
| | - Hui Gong
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Zhengyu Jin
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Qiuhang He
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Qi Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
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