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Effects of calcined aluminum salts on the advanced dewatering and solidification/stabilization of sewage sludge

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Journal of Environmental Sciences 2011年第7期23卷 1225-1232页

作者： Guangyin Zhen Xiaofei Yan Haiyan Zhou Hua Chen Tiantao Zhao Youcai Zhao The State Key Laboratory of Pollution Control and Resource Reuse School of Environmental Science and Engineering Tongji University Shanghai 200092 China Shanghai Sewage Company Shanghai 200233 China Shanghai Laogang Waste Treatment Company Shanghai 201302 China

The high moisture content （80%） in the sewage dewatered sludge is the main obstacle to disposal and recycling. A chemical dewatering and stabilization/solidification （S/S） alternative for the sludge was developed, using calcined aluminum salts （AS） as solidifier, and CaCl 2 , Na 2 SO 4 and CaSO 4 as accelerators, to enhance the mechanical compressibility making the landfill operation possible. The properties of the resultant matrixes were determined in terms of moisture contents, unconfined compressive strength, products of hydration, and toxicity characteristics. The results showed that AS exhibited a moderate pozzolanic activity, and the mortar AS 0 obtained with 5% AS and 10% CaSO 4 of AS by weight presented a moisture contents below 50%–60% and a compressive strength of （51.32 ± 2.9） kPa after 5–7 days of curing time, meeting the minimum requirement for sanitary landfill. The use of CaSO 4 obviously improved the S/S performance, causing higher strength level. X-ray diffraction, scanning electron microscopy and thermogravimetry- differential scanning calorimetry investigations revealed that a large amount of hydrates （viz., gismondine and CaCO 3 ） were present in solidified sludge, leading to the depletion of evaporable water and the enhancement of the strength. In addition, the toxicity characteristic leaching procedure （TCLP） and horizontal vibration （HJ 557-2009） leaching test were conducted to evaluate their environmental compatibility. It was found that the solidified products conformed to the toxicity characteristic criteria in China and could be safely disposed of in a sanitary landfill.

关键词： solidification/stabilization solidifier pozzolanic activity leaching test sanitary landfill

Cement-based solidification/stabilization of contaminated soils by nitrobenzene

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Frontiers of Environmental Science & Engineering 2012年第3期6卷 437-443页

作者： Jianguo LIU Xiaoqin NIE Xianwei ZENG Zhaoji SU School of Environment Tsinghua UniversityBeijing 100084China

The cement-based solidification/stabilization （S/S） of nitrobenzene （NB） contaminated soils, with cement and lime as binders, sodium silicate solution and powder activated carbon （PAC） as additives, was optimized through an orthogonal experiment, and S/S efficiency was estimated by both leaching test and volatilization measurement. The leaching test results showed that the factors affecting S/S efficiency were NB concentration, cement-to-lime ratio and binder-to-soils ratio, in sequence. With increasing curing time, the leaching concentration of NB between different levels of the same factor in the orthogonal experiment decreased, and less than 9% NB leached out from the 28 d cured samples. The volatilization measurement results indicated that 0.5 %0 of NB was volatilized during the mixing and curing processes for the samples without PAC in the 28 d cycle, whereas adding 2 wt% and 5 wt% PAC, with respect to the weight of contaminated soils, could reduce NB volatilization to half of its original values either during the mixing or curing process. The optimizing formula, that is, contaminated soils （dry weight）：cement：lime = 100：25：25, with 5 wt% additional sodium silicate and 2 wt% additional PAC, was applied to the engineering application of NB contaminated soils. Both the leaching test results of the product and the ambient air quality monitoring results met related regulations during the treating process.

关键词： solidification/stabilization nitrobenzene contaminated soils powder activated carbon

An integrated method for the rapid dewatering and solidification/stabilization of dredged contaminated sediment with a high water content

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Frontiers of Environmental Science & Engineering 2021年第4期15卷 229-240页

作者： Hefu Pu Aamir Khan Mastoi Xunlong Chen Dingbao Song Jinwei Qiu Peng Yang Institute of Geotechnical and Underground Engineering Huazhong University of Science and TechnologyWuhan430074China Department of Civil Engineering Quaid-e-Awam University of EngineeringSciences and TechnologySindh67450Pakistan

To more efficiently treat the dredged contaminated sediment(DCS)with a high water content,this study proposes an integrated method(called PHDVPSS)that uses the solidifying/stabilizing(S/S)agents and prefabricated horizontal drain(PHD)assisted by vacuum pressure(VP).Using this method,dewatering and solidification/stabilization can be carried out simultaneously such that the treatment time can be significantly shortened and the treatment efficacy can be significantly improved.A series of model tests was conducted to investigate the effectiveness of the proposed method.Experimental results indicated that the proposed PHDVPSS method showed superior performance compared to the conventional S/S method that uses Portland cement(PC)directly without prior dewatering.The 56-day unconfined compressive strength of DCS treated by the proposed method with GGBS-MgO as the binder is 12–17 times higher than that by the conventional S/S method.DCS treated by the PHDVPSS method exhibited continuous decrease in leaching concentration of Zn with increasing curing age.The reduction of Zn leachability is more obvious when using GGBS-MgO as the binder than when using PC,because GGBS-MgO increased the residual fraction and decreased the acid soluble fraction of Zn.The microstructure analysis reveals the formation of hydrotalcite in GGBS-MgO binder,which resulted in higher mechanical strength and higher Zn stabilization efficiency.

关键词： Dredged contaminated sediment Dewatering solidification/stabilization Vacuum preloading Prefabricated horizontal drain Heavy metal

MSWI Fly Ash Based Novel solidification/stabilization Matrices for Heavy Metals

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Journal of Wuhan University of Technology(Materials Science) 2008年第6期23卷 955-960页

作者：邓发庆钱光人 Institute of Environment and Chemical Engineering Shanghai University

The possibilities of MSWI fly ash as a major constituent of novel solidification/stabilization matrices for secure landfill were investigated by mixing MSWI fly ash with rich aluminum components, which was added as bauxite cement or metakaolinite instead, to form Friedel and Ettringite phases with high fixing capacities for heavy metals. The physical properties, heavy metals-fixing capacity, mineral phases and its vibration bands in the novel matrices were characterized by compressive strength, TCLP（toxic characteristic leaching procedure）, XRD （x-ray diffraction） , DTG （derivative thermogravimetry）, and FTIR （fourier transform infrared spectroscopy）, respectively. The Tessier＇s five-step sequential extraction procedure was used to analyze the fractions of chemical speciation for Pb, Cd and Zn ions. The experimental results indicate that Friedel-Ettringite based novel solidification/stabilization matrices can incorporate Pb, Cd and Zn ions effectively by physical encapsulation and chemical fixation, and it exhibits a great potential in co-landfill treatment of MSWI fly ash with some heavy metals-bearing hazardous wastes.

关键词： MSWI fly ash heavy metals chemical speciation fraction secure landfill solidification/stabilization

solidification Efficiency and Mechanism of Conventional Curing Agents for Sewage Sludge stabilization and Dewatering

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Journal of Harbin Institute of Technology(New Series) 2015年第6期22卷 1-10页

作者： Siliang Li Liangliang Wei Qingliang Zhao Lu Li School of Municipal and Environmental Engineering Harbin Institute of Technology Harbin 150090 China Longjiang Environmental Protection Group Co. LTD Harbin 150056 China

One of the challenges faced by sewage sludge treatment and disposal is its higher water content,and how to efficient dewater those hazardous materials properly is welcome in practice. This study stabilized the sewage sludge via the using of conventional curing agents and calcined aluminum salts,and the corresponding dewatering mechanisms and structural changes of the stabilized sludge were further comparable analyzed.Experimental results showed that wollastonite and kaolin exhibit a relative higher dewatering efficiency as compared to other conventional curing agents; however the releasing rate of heavy metals of Cu,Cr,Ni for kaolin solidification and Zn,Pb for wollastonite solidification is higher than the sludge samples solidified by other curing agents. For comparison,the sludge samples solidified by calcined aluminum salts (AS),calcium ash,Mg-based curing agent,tricalcium aluminate( C_3A) show a lower heavy metals leaching potential and unconfined compressive strength. In addition,the economic characteristics and local availability of AS,calcium ash,C_3A and CaO makes it have a broad prospect in extension and application. These findings are of great significance for stabilization and dewatering of sewage sludge.

关键词： sludge dewatering curing agents solidification/stabilization heavy metal leaching

Geotechnical and mechanical properties of solidification/ stabilization treatment technology for dredged sludge

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Geotechnical and mechanical properties of solidification/ st...

Cleaner geopolymer prepared by co-activation of gasification coal fly ash and steel slag:durability properties and economic assessment

The 2nd International Conference on Environmental and Engineering Geophysics

作者： Min Zhou Haobo Hou Zhiwei Li Guojin Cao School of Resource and Environmental Science Wuhan University Wuhan China Guangzhou Department of Water Conservancy Pearl River Construction Office Guangzhou China

＜正＞solidification/stabilization （S/S） treatment is used to treat hazardous wastes for disposal, and in the remediation of contaminated land. S/S is also an increasingly popular technology for Brownfields redevelopment since treated wastes can often be left on-site and to actually improve the site’s soil for subsequent construction. In order to meet to the requirements of the dredged sludge and soils treatment of the Pearl River Estuary Channel, the potential uses of treated dredged sludge by S/S as valuable structural fill was investigate. A comprehensive series of laboratory tests was conducted. The relationship between the microstructure and engineering properties of treated sludge are examined. The geotechnical and engineering properties that were measured include the water content, Atterberg limit, compactibility and unconfined compressive strength. The microstructure was investigated using x-ray diffraction. Following S/S treatment, tests have indicated that the material becomes inorganic low plasticity silt （ML） whereas the untreated sludge is classified as organic clay of high plasticity （OH）. The strength will develop significantly accompanied with the increasing of HAS content. It is proved that HAS treated sludge has a strong ability of anti-soften in wetting conditions. Our result indicate that the multitude of changes in the properties and behavior of HAS treated dredged sludge can be used in a cost-effective way as non-structural or embankment fill.

关键词： dredged sludge solidification/stabilization compactibility unconfined compressive strength

来源： cnki会议评论

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Frontiers of Environmental Science & Engineering 2023年第12期17卷 109-121页

作者： Xian Zhou Xia Chen Ziling Peng Yongmen Zhou Yan Li Wang Jian Zeyu Fan Yuchi Chen Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources Changjiang River Scientific Research InstituteWuhan 430010China Jiangxi Research Center on Hydraulic Structures Jiangxi Provincial Institute of Water SciencesNanchang 330029China Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China

Geopolymer is a material with high early strength.However,the insufficient durability properties,such as long-term strength,acid-base resistance,freeze-thaw resistance,leaching toxicity,thermal stability,sulfate resistance and carbonation resistance,restrain its practical application.Herein,a longterm stable geopolymer composite with high final strength(ASK1)was synthesized from shell coal gasification fly ash(SFA)and steel slag(SS).Additionally,a geopolymer composite with high early strength(ASK2)was also synthesized for comparison.The results showed that ASK1 exhibited better performance on freezing-thawing resistance,carbonization resistance and heavy metals stabilization compared to the ASK2 at long-term curing.Raising the curing temperature could accelerate the unconfined compressive strength(UCS)development at initial curing ages of 3 to 7 d.Both ASK1 and ASK2 exhibited excellent acid-base and sulfate corrosion resistance.An increase for UCS was seen under KOH solution and MgSO_(4)solution corrosion for ASK1.All leaching concentrations of heavy metals out of the two geopolymers were below the standard threshold,even after 50 freezingthawing cycles.Both ASK1 and ASK2 geopolymer concrete exhibited higher sustainability and economic efficiency than Portland cement concrete.The result of this study not only provides a suitable way for the utilization of industrial solid waste in civil and environmental engineering,but also opens a new approach to improve the long-term stabilities of the geopolymers.

关键词： Geopolymer Shell coal gasification fly ash Steel slag Heavy metal solidification/stabilization Durability

Review of harmless treatment of municipal solid waste incineration fly ash

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Waste Disposal and Sustainable Energy 2020年第1期2卷 1-25页

作者： Yike Zhang Zengyi Ma Zhuoting Fang Yuandong Qian Pucheng Zhong Jianhua Yan State Key Laboratory of Energy Clean Utilization Zhejiang UniversityHangzhou 310027China Ningbo Research Institute Zhejiang UniversityNingbo 315100China

Incineration is widely adopted in municipal solid waste management,which produces large amounts of municipal solid waste incineration(MSWI)fly ash.The harmless treatment of MSWI fly ash requires the appropriate disposal of heavy metals and dioxins that are enriched in fly ash.This review summarizes recently developed harmless disposal methods for MSWI fly ash including solidification/stabilization,thermal treatment,and separation/extraction.In addition,we discuss heavy metal and dioxin fixation,and the removal capacity of fly ash via solidification/stabilization(including cement solidification,chemical stabilization,hydrothermal processes,and mechano-chemical methods),thermal treatment(including sintering,fuel-burning,or electric melting/vitrification),and separation/extraction(including water-washing,chemical reagent leaching,biological leaching,electrodialysis separation,chemical reagent extraction,and nanomaterials extraction).The advantages and disadvantages of different harmless treatment methods are compared and future research prospects and suggestions are summarized.This review provides general guidelines for the harmless treatment of MSWI fly ash in the future.

关键词： Fly ash Municipal solid waste incineration solidification/stabilization Thermal treatment Separation/extraction

Research on Acidic Stability of Immobilized Heavy Metals in Sediment from Polluted River

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Meteorological and Environmental Research 2020年第2期11卷 76-81页

作者： Deqin ZHAI Dingpeng XIONG Yuxi YANG Shuo TAN PowerChina Eco-Environmental Group Co. Ltd.Shenzhen 518102China Shenzhen Guoshui Testing Technology Co. Ltd.Shenzhen 518126China

The heavy metals can accumulate in sediment after discharged into surface water bodies. Before the sediment can be further landfilled or recycled,a large amount of heavy metal in it needs to be treated,known as solidification/stabilization. The properties of treated sediment may change with environment such as acid rain and landfill time,which may lead to the release of heavy metals from treated sediment into environment,posing great risks to environment and human health. In this study,the quantitative relationship has been tested between the dissolution of heavy metals from treated sediment and the p H of the leaching solution,by changing the p H of the treated sediment-leaching solution continuously. The results showed that when the p H of the treated sediment-leaching solution was higher than 5. 5,the heavy metals released from the treated sediment into solution were relatively low;when the p H of the treated sediment-leaching solution dropped to about 5. 5,a large amount of Cu,Zn,Ni and other heavy metals were released. The solidification of Cu,Zn,Cr and Cd in the treated sediment is relatively stable,while that of Ni and Pb still need to be improved. The buffer capacity of the treated sediment to acid is 0. 999 meq/g,which means it has relatively high capacity to buffer the pH change caused by external acid.

关键词： Treated sediment Heavy metals solidification/stabilization Buffer capacity solidification stability