Feasibility of utilising porous aggregates for carbon sequestration in concrete.

Carbon sequestration in concrete has attracted increasing research attention. CO2 may be permanently stored in the cement paste of concrete by chemical reaction with the hydration products of cement, but this method leads to a significant reduction of the pH value of the concrete pore solution and may thus put the steel reinforcement at risk of corrosion. This paper proposes a new method for carbon sequestration in concrete using the space in porous coarse aggregates; the method involves presoaking the porous aggregates in an alkaline slurry and then using them for CO2 sequestration. The potential of utilising the space in the porous aggregates and the cations in the alkaline slurry is first discussed. An experimental study aiming to demonstrate the feasibility of the proposed method is then presented. The results show that CO2 can be successfully sequestrated and fixed as CaCO3 in the open pores of coarse coral aggregate presoaked in a Ca(OH)2 slurry. The amount of CO2 sequestration by concrete produced using the presoaked coral aggregate was around 20 kg/m3. Importantly, the proposed CO2 sequestration method did not affect the strength development of the concrete or the pH value of the concrete pore solution.

Effect of air pollution-controlled residue of a sewage sludge incinerator on the drying shrinkage and the pore structure of alkali-activated materials.

Recycling air pollution-controlled residues (APCR) generated from sewage sludge incinerators can be used for waste management, but the leaching of potentially toxic heavy metals from APCR poses environmental and human health issues. The present paper describes a procedure using APCR to produce alkali-activated materials and thereby realize their disposal. The effect of APCR on the compressive strength and drying shrinkage of the alkali-activated slag/glass powder was investigated. The pore structure characteristics were analyzed for clarifying its relationship with drying shrinkage. The results indicated that the drying shrinkage of the alkali-activated material was related to the mesopore volume. The drying shrinkage was slightly increased after the incorporation of the 10 % APCR, which was likely attributed to the high volume of mesopores compared to the 20 % APCR that lowered the drying shrinkage and compressive strength. This decrease in drying shrinkage was due to the recrystallization of sodium sulfate in the pore solution that can act as expansive agents and aggregates. The growth stress of the crystalline sodium sulfate within the matrix can offset the tension stress caused by the water loss. In addition, leaching studies using the SW-846 Method 1311 showed that recycling APCR into the alkali-activated system did not present a toxicity leaching risk or release unacceptable concentrations of heavy metals. The incorporation of waste APCR and waste glass can make AAMs a very promising and safe environmental technology.

Physicochemical and pozzolanic properties of municipal solid waste incineration fly ash with different pretreatments.

Swelling caused by gas generated from municipal solid waste incineration fly ash (MSWIFA) when it is mixed with alkali limits its uses. Besides, the leaching of anion salts and heavy metals contained in MSWIFA poses a high risk to environment. This study presents the feasibility of a one-step alkaline washing, one-step thermal quenching and two-step combination of alkaline washing and thermal quenching pretreatment methods in altering the key properties of MSWIFA for promoting its reusability. It was found that apart from H2(gas), NH3(gas) was also generated during the alkaline washing of the MSWIFA. Besides, pretreatments led to the reduction in particle size, the increase in pore volume and specific surface area of the MSWIFA, as well as the removal of chloride and sulfate anions. All the pretreatment methods were effective in reducing leaching of heavy metals to below levels of nonhazardous waste except Cd and Pb with alkaline washing. Furthermore, both the chemical Frattini test and the mechanical activity index test showed improvement in pozzolanic activities of the MSWIFA after the pretreatments. Overall, the combined pretreatment method was most effective in eliminating gas emission, and reducing leaching of metal ions and anions from the ash, while enhancing the pozzolanic activity of the ash.

Effect of alkaline washing treatment on leaching behavior of municipal solid waste incineration bottom ash.

This study aimed to find an effective, inexpensive, and safe washing treatment for municipal solid waste incineration bottom ash (MSWIBA) in order to reduce its potential harmful effects in disposal and recycling. The washing solutions, namely tap water (TW), saturated lime water (SLW), and wastewater from concrete batching plant (WW) were used to wash MSWIBA at different liquid-solid (L/S) ratios and for different durations. Leaching behavior of some heavy metals, chloride, and sulfate from MSWIBA was tested and evaluated. From the TCLP leaching test, when the L/S ratio was above 5, WW was the most effective solution in reducing As, Cd, Se, and Sb emissions from MSWIBA. The calcium and iron ions present in the WW were essential for controlling the leaching of As, Cd, and Sb from MSWIBA due to the formation of stable crystalline pharmacosiderite, cadmium hydroxide sulfate, and hydromeite during the washing process. Using WW showed the best effect in removing sulfate from MSWIBA. At a L/S ratio of 10, about 83% of the sulfate could be removed from MSWIBA after 20 min of washing. The L/S ratio was most influential in removing chloride from MSWIBA. The three washing treatments chosen were effective in reducing the chloride level in MSWIBA to below the level of hazardous waste. Nevertheless, there were still substantial amounts of chloride remaining in the treated MSWIBA. Under the Dutch Building Materials Decree, the treated MSWIBA may be used as a building material in parts which allow isolation, control, and monitoring (ICM).

An iron-biochar composite from co-pyrolysis of incinerated sewage sludge ash and peanut shell for arsenic removal: Role of silica.

Modification of biochar by low-cost iron sources has gained increasing attention to improve pollutants removal performance and reduce production costs compared to conventional chemical modifications. While such iron sources generally have complex compositions, their effects on properties of the iron-biochar composite are not well investigated. This study produced an iron-biochar (RBC) composite from co-pyrolysis of incinerated sewage sludge ash (ISSA) and peanut shell, and examined the role of silica with widespread existence in ISSA and other low-cost iron sources on properties of the iron-biochar composite relevant to As(III)/As(V) removal. Silica was found to react with iron during the pyrolysis process at 850 °C and formed iron silicon at the expense of producing zero valent iron and Fe3O4 which resulted in a poorer removal efficacy for As(III) and As(V) compared to the iron-biochar (FBC) made from pure Fe2O3 and peanut shell. Moreover, a high leaching of reactive silica from RBC was observed which affected the formation of corrosion products of ZVI and competed with arsenic for active adsorption sites. Despite this, RBC still exhibited a maximum adsorption capacity of 17.44 and 57.56 mg/g towards As(III) and As(V) respectively at pH 3.0. Overall, this study provides an interesting insight into upcycling ISSA into useful media for sorptive removal of arsenic from aqueous solutions.

Advances in the use of recycled non-ferrous slag as a resource for non-ferrous metal mine site remediation.

The growing global demand for non-ferrous metals has led to serious environmental issues involving uncovered mine site slag dumps that threaten the surrounding soils, surface waters, groundwater, and the atmosphere. Remediation of these slags using substitute cement materials for ordinary Portland cement (OPC) and precursors for alkali-activated materials (AAMs) can convert hazardous solid wastes into valuable construction materials, as well as to attain the desired solidification and stabilization (S/S) of heavy metal(loid)s (HM). This review discusses the current research on the effect of non-ferrous slags on the reaction mechanisms of the OPC and AAM. The S/S of HM from the non-ferrous slags in AAM and OPC is also reviewed. HM can be stabilized in these materials based on the complex salt effect and isomorphic effects. The major challenges faced in AAMs and OPC for HM stabilization include the long-term durability of the matrix (e.g., sulfate attack, stability of volume). The existing knowledge gaps and future trends for the sustainable application of non-ferrous slags are also discussed.

Recycling of phosphogypsum and red mud in low carbon and green cementitious materials for vertical barrier.

MgO activated slag and bentonite (MASB) slurry is a new and promising vertical barrier material along with excellent performances. Some solid wastes, such as phosphogypsum (PG), red mud (RM), fly ash and so on, show a positive effect on the performances of alkali activated slag. However, few studies focus on the recycling of these solid wastes in the system of MgO activated slag. The purpose of this paper is to study the incorporation of phosphogypsum and red mud on the mechanical property, permeability and hydration process of MASB slurry. The results showed that the addition of PG could significantly improve the mechanical strength and anti-permeability of the MASB slurry at early age (7 days), where the unconfined compressive strength (UCS) increased from 793.1 kPa to 1395.7 kPa and the permeability coefficient declined from 16.1 × 10-7 cm/s to 1.7 × 10-7 cm/s. In contrast, the introduction of RM had some negative effects on its macroscopic properties, resulting the UCS decreased to 580.4 kPa and the permeability coefficient rose to 25.9 × 10-7 cm/s at 7 days. The ettringite formed in the PG blended MASB slurry led to a notable increase in the absolute solid volume, which could satisfactorily fill the pores and block the pore channels. The combined addition of RM and PG had a synergistic effect on the promotion of hydration process and optimization of the pore structure, contributing to establish a low permeability and high mechanical strength matrix. The overall findings indicate that the use of solid wastes in the MASB slurry can not only improve its engineering properties, but also promotes its sustainability and economical efficiency, holding a great potential for popularization and application.

Immobilization and recycling of contaminated marine sediments in cement-based materials incorporating iron-biochar composites.

Sustainable stabilization/solidification (S/S) incorporating biochar for hazardous wastes has attracted increasing attention. In this study, contaminated marine sediments were remediated and recycled as useful materials via cement-based S/S process incorporating iron-biochar composites derived from incinerated sewage sludge ash (ISSA) and peanut shell. Results showed that incorporation of 20% iron-biochar composites notably increased the Cr immobilization (52.8% vs 92.1-99.7%), while attained similar As (70%) and Cu (95%) immobilization efficiencies compared to the control group (CK) prepared with plain cement as the binder based on the Toxicity Characteristic Leaching Procedure. S/S products with the addition of ISSA derived iron-biochar composite had a mechanical strength of 5.0 MPa, which was significantly higher than its counterparts derived from pure iron oxide or pristine biochar (< 4.5 MPa). Microstructural and spectroscopic characterizations and chemical leaching experiments demonstrated that reduction of Cr(VI) to Cr(III) followed by formation of Cr-Fe precipitates by zero valent iron in iron-biochar composites contributed to the enhanced immobilization efficacy of Cr(VI) compared to CK. Overall, these results demonstrated the potential of applying ISSA and peanut shell derived iron-biochar composites as additives in the cement-based S/S treatment for contaminated sediments.

Deep insight on mechanism and contribution of As(V) removal by thermal modification waste concrete powder.

Expanding the utilization strategy of waste concrete powder (WCP) is conducive to minimizing the environmental burden caused by construction & demolition wastes (C&DW). In this study, WCP prepared in the laboratory was thermally treated and used to remove As(V) from wastewater. Batch adsorption tests were implemented to explore the influence factors such as modification temperature (0-850 °C), pH (1.00-12.00), dosage (2-50 g/L), co-coexisting ions (SO42-, NO3-, Cl- and PO43-) and temperature (25-45 °C). Various methods including spectroscopic tests, Rietveld refinement and sequential extraction process were employed to examine the mechanisms and their contribution to As(V) removal. Results show that the As(V) removal capacity of WCP was slightly enhanced after treatment at 200 °C, the pseudo-second-order kinetics model and Langmuir model could describe the adsorption process well. The maximum uptake capacity for As(V) calculated by Langmuir model at 25, 35 and 45 °C were 31.89, 25.56 and 17.42 mg/g respectively, and the removal rate reached a maximum of 95.37% (C0 = 100 mg/L). Thermodynamically, the As(V) elimination was exothermic and spontaneous. The ettringite produced by rehydration of WCP proved to be essential for As(V) removal. Electrostatic attraction, precipitation, complexation and ion exchange were identified to be the main mechanisms of As(V) adsorption. This study confirmed the potential of WCP in removing As(V) from wastewater and provided a new insight into the removal mechanisms.

Sewage sludge ash-incorporated stabilisation/solidification for recycling and remediation of marine sediments.

Finding suitable disposal sites for dredged marine sediments and incinerated sewage sludge ash (ISSA) is a challenge. Stabilisation/solidification (S/S) has become an increasingly popular remediation technology. This study sheds light on the possible beneficial use of ISSA together with traditional binders to stabilise/solidify marine sediments. The performance of the binders on S/S of sediment 1 (clean) and sediment 2 (contaminated) was also compared. The results showed that the use of ISSA as part of the binder was effective in promoting the strength of the sediment with a high initial moisture content due to ISSA porous and high water absorption characteristics. The sediments treated with 10% cement and 20% ISSA attained the highest strength. Also, cement hydration as well as pozzolanic reactions between ISSA and Ca(OH)2 made contributions to the strength development. This was supported by the microstructural analysis, in particular the porosity results. In terms of environmental impacts, two leaching tests (toxicity characteristic leaching procedure and synthetic precipitation leaching procedure) found that all the S/S treated sediment by 10% lime and 20% ISSA resulted in the lowest leachate concentrations under the on-site reuse scenario or under simulative acidic rainfall conditions. Therefore, recycling waste ISSA with lime can be used as an appealing binder to replace cement to stabilise/solidify dredged marine sediments for producing fill materials.

Novel recycling of phosphorus-recovered incinerated sewage sludge ash residues by co-pyrolysis with lignin for reductive/sorptive removal of hexavalent chromium from aqueous solutions.

Incinerated sewage sludge ash (ISSA), a by-product generated from the combustion of dewatered sewage sludge, has been extensively studied as a secondary resource for phosphorus recovery by acid extraction methods. Recycling of the P-recovered ISSA residues is crucial to complete and sustain the whole process. In this study, the ISSA residue rich in iron was reused and co-pyrolyzed with lignin at 650, 850 and 1050 °C under N2 atmosphere for the synthesis of a composite material to remove hexavalent chromium (Cr(VI)) from aqueous solutions. Characterization analysis including XRD, XPS, and FTIR showed that iron oxides in the residue were reduced to zero valent iron at 1050 °C that exhibits the optimal Cr(VI) removal performance. The Cr(VI) removal process was rapid and reached a plateau at around 30 min. The maximum removal rate was obtained at pH 2.0, which was conducive for the treatment of a synthetic Cr(VI)-containing wastewater in fix-bed column experiments, whereby Cr(VI) as well as total Cr were continuously removed. Overall, this study proposed a new routine for the recycling of ISSA residue after phosphorus recovery by the acid extraction method and provided a value-added product for Cr(VI) removal from wastewaters.

Immobilization of high-Pb contaminated soil by oxalic acid activated incinerated sewage sludge ash.

Identifying effective and low-cost agents for the remediation of Pb-contaminated soil is of great importance for field-scale applications. In this study, the feasibility of reusing incinerated sewage sludge ash (ISSA), a waste rich in phosphorus, under activation by oxalic acid (OA) for the remediation of high-Pb contaminated soil was investigated. ISSA and OA were mixed at different proportions for the treatment of the high-Pb contaminated soil (5000 mg/kg). The Pb immobilization efficacy was further examined by both the standard deionized water leaching test and the toxicity characteristic leaching procedure (TCLP). The overall results showed that the use of the ISSA alone and an appropriate mixture of the ISSA and OA could effectively reduce the leachability of Pb from soil. 20% ISSA together with 30% OA (0.2 mol/L) reduced leached Pb concentration by 99%. The main stabilization mechanisms were then explored by different microstructural and spectroscopic analytical techniques including SEM, XRD and FTIR. Apparently, OA released phosphate from the ISSA and Pb from soil via acid attack, which combined and precipitated as stable lead phosphate minerals. However, excessive OA could cause high leaching of phosphate and zinc from the ISSA. Overall, this study indicates that ISSA could be used together with OA to remediate high-Pb contaminated soil, but careful design of mix proportions is necessary before practical application to avoid excessive leaching of phosphate and zinc from the ISSA.

Novel recycling of incinerated sewage sludge ash (ISSA) and waste bentonite as ceramsite for Pb-containing wastewater treatment: Performance and mechanism.

With rapid economic growth and urbanisation, the reuse and recycling of solid wastes has become a high priority for the sustainable development of modern cities. In this study, two typical solid wastes, incinerated sewage sludge ash (ISSA) and waste bentonite, were co-valorised to produce granular adsorbents through a simple and energy-saving pelletisation/sintering process. A mixture of ISSA and bentonite at a weight ratio of 3:1 was pelletised and sintered at 700 °C. The resultant ceramsite, with good mechanical strength, could effectively remove Pb(Ⅱ) from aqueous solutions. The adsorption kinetics can be described by the pseudo-first-order (PFO) model. The results indicated that the Pb(Ⅱ) adsorption process was dominated by electrostatic attraction, precipitation, and complexation. The isothermal data exhibited a good correlation with the Freundlich model, indicating that the adsorption process was non-ideal and spontaneous. The maximum adsorption capacity was approximately 21.6 ± 0.35 mg/g at 318 K. After 5 cycles of regeneration, the adsorbent maintained good adsorption performance. Moreover, the removal rate was not greatly affected by ionic strength. These findings demonstrate that the granular adsorbent prepared with ISSA and waste bentonite can be recognised as a promising adsorbent for Pb-containing wastewater treatment.

Sustainable stabilization/solidification of arsenic-containing soil by blast slag and cement blends.

Arsenic (As) is a naturally occurring trace element that may pose a threat to human health and the ecosystem, while effective remediation and sustainable reuse of As-containing soil is a challenge. This study investigated the geoenvironmental characteristics of a geogenic As-rich soil, and green binders (ground granulated blast slag (GGBS) and cement blends) were employed for the stabilization/solidification (S/S) of the soil under field-relevant conditions. Results indicate that the use of 10% binder could effectively immobilize As and chemical stabilization/physical encapsulation jointly determined the leaching characteristics of the S/S soils. The geogenic As could be effectively immobilized at the pH range of 5.5-6.5. The increasing use of GGBS enhanced the strength of the 28-d cured S/S soils because of long-term pozzolanic reaction, but also slightly improved the As leachability. Besides, the moisture content of the contaminated soils should be suitably adjusted to allow for desirable compaction of S/S soils, which resulted in high compressive strength and low of As leachability. Results show that soil moisture content of 20% was the most appropriate, which resulted in the highest strength and relatively lower As leaching. In summary, this study presents a sustainable S/S binder for recycling As-contaminated soil by using a combination of cement and GGBS.

Use of thermally modified waste concrete powder for removal of Pb (II) from wastewater: Effects and mechanism.

Exploring effective uses of waste concrete powder (WCP), produced from recycling of construction & demolition waste is beneficial to the environment and sustainable development. In this study, WCP was first treated thermally to enhance the ability to remove Pb (II) from aqueous solutions. The experimental results revealed that the thermal treatment could enhance adsorption capacity due to modification of calcium bonding and pore structure of WCP. Preparation parameters such as temperature, particle size, and water-cement ratio were investigated to obtain the optimal operational conditions. Batch adsorption experiments were performed to explore influence factors of pH (1.00-6.00), ionic strength (0.05-2 mol/L), dosage (2-50 g/L), and temperature (25-45 °C). The pseudo-second-order kinetics model could adequately describe the adsorption process, and the Langmuir model was capable to predict the isotherm data well in the low concentration region (C0 < 500 mg/L). The maximum uptake capacity for Pb (II) calculated by Langmuir model at 25, 35 and 45 °C were 46.02, 38.58 and 30.01 mg/g respectively, and the removal rate of Pb (II) was 92.96% at a dosage of 50 g/L (C0 = 1000 mg/L). Precipitation, ion exchange, and surface complexation were identified to be the main mechanisms of Pb (II) adsorption through microscopic investigation by SEM-EDX, XRD, FTIR, XPS, and BET inspections. The study confirms that the WCP after thermal modification, can be selected as a promising adsorbent for the high performance and eco-friendliness.

Alkaline modification of the acid residue of incinerated sewage sludge ash after phosphorus recovery for heavy metal removal from aqueous solutions.

Enriched in phosphorus, sewage sludge ash has been extensively studied and applied as a secondary source for phosphorus recovery. Wet extraction, especially acid washing, is one of the most feasible methods to recover phosphorus from the ash due to its ease of operation, high efficiency and low cost. However, the management of the resultant acid residue was seldom addressed. In this study, special focus was paid to the reuse and recycling of the acid residue by an alkaline activation method. Its adsorption performance towards four different heavy metals in aqueous solutions was evaluated by batch and fixed-bed column adsorption experiments. The obtained material showed a high BET specific area (98.29 m2/g) and a total pore volume (0.114 cm3/g), and effectively removed Cd(II), Cu(II), Pb(II) and Zn(II) from aqueous solutions with the maximum adsorption capacity of around 26.8, 22.2, 53.3 and 13.5 mg/g respectively. It could be loaded in a fixed-bed column to continuously remove heavy metals especially for Pb(II). The proposed method to recycle the acid residue makes the wet extraction methods designing to recover phosphorus from incinerated sewage sludge complete without the generation of waste, which contributes to circular economy and a sustainable future.

A cross-region analysis of commercial food waste recycling behaviour.

To tackle the crisis associated with the rising commercial food waste generation, it is imperative to comprehend how corporates' recycling behaviour is influenced by different industry structures and economies. This study aims to fill in the information gap that various factors might be affecting corporates' recycling behaviour in two different economies due to environmental inequality by comparing upper-middle-income region (Malaysia) and high-income region (Hong Kong), respectively. A questionnaire survey regarding food waste management according to the Theory of Planned Behaviour was conducted with representatives coming from diverse industries of the hotel, food and beverage, and property management. The questionnaire responses were evaluated based on quantitative structural equation modelling and correlation analysis. The analysis results showed that the model fit the data well, explaining 78% of the variance in recycling behaviour. The findings demonstrated that the most substantial factor on individual's recycling intention by Malaysian commercial food waste generators was perceived behavioural control, and logistics and management incentives. Subjective norms demonstrated significant and adverse effects on the behaviour of food waste recycling. The variable of administrative incentives and corporate support presented strong positive correlations with moral attitudes as well as logistics and management incentives. Hotel industries from both Hong Kong and Malaysia have a higher acceptance level on human resources regarding food waste recycling. In comparison, food and beverage industries from both regions have a lower acceptance level. These findings could enrich our knowledge of the concerns in establishing regional policy strategies to encourage economic behavioural changes for sustainable development.

Highly-efficient green photocatalytic cementitious materials with robust weathering resistance: From laboratory to application.

The combined use of nano-TiO2 with cementitious materials offers an environmentally-friendly way to combat the air pollution problem. However, a trade-off between a high efficiency and a robust weathering resistance has often to be made for most of the attempted nano-TiO2 incorporation methods. This paper developed a simple and effective "spraying" method to coat nano-TiO2 particles on the surface of concrete surface layers (CSL). The results showed that the NOx removal rate of the samples increased with an increase in both the concentrations of nano-TiO2 solutions and the number of times of the spraying action. And the conditions for preparation of the Spray AB (the CSL were first sprayed with the 30 g L-1 TiO2-solution 20 times, followed by mechanical compaction, and for another 20 times after the compaction) were found to be optimal in terms of NOx removal performance and weathering resistance. The Spray AB was superior to the 5% TiO2-intermixed samples with respect to photocatalytic NOx removal ability. Compared with TiO2-dip-coated samples, the Spray AB samples had better and robust weathering resistance. A case study on the factory-fabricated green Eco-blocks (produced by the laboratory-developed spray method and the conventional intermix method) was performed. Examination and comparison on their respective photocatalytic NOx removal further verified the advantages of the spray method over the intermix method.

Arsenate(V) removal from aqueous system by using modified incinerated sewage sludge ash (ISSA) as a novel adsorbent.

Adsorption methods have been widely used in wastewater treatment due to its high removal efficiency, easy operation and handling, economic efficiency and little secondary pollution to the environment. In this paper, a high-iron containing incineration sewage sludge ash (ISSA) was modified by combined acid leaching and precipitation processes to improve its adsorption capacity of As(V). The effects of pH, time, temperature and ionic strength on the adsorption of As(V) were investigated by batch adsorption experiments. The results indicated that iron (mainly present as hematite) in the ISSA was rearranged to Fe(SO4)OH. The modified ISSA showed an excellent adsorption potential for As(V) under acidic conditions and the adsorption capacity was around 9 times of the unmodified ISSA at pH 2-3. The adsorption process was fast during the first 2 h and reached an equilibrium at around 6 h. The Freundlich model could well fit the adsorption isotherm data, the presence of NO3- and Cl- had a negligible influence on the As(V) removal by the modified ISSA, while PO43- and SO42- could significantly suppress As(V) removal via competitive adsorption. After 3 cycles of regeneration, the modified ISSA still showed a satisfying adsorption capacity. As(V) was removed by the modified ISSA mainly through ligand exchange reaction with hydroxyl oxygen (OH-) to form inner-sphere complexes. Therefore, the modified ISSA can be a promising material for As(V) removal from wastewater in particular due to the waste recycling potential.

Evaluating the environmental impacts of stabilization and solidification technologies for managing hazardous wastes through life cycle assessment: A case study of Hong Kong.

Proper management of hazardous materials arouses widespread environmental concerns due to its enormous ecological and health impacts. The development of green stabilization/solidification (S/S) technology for resourceful utilization of hazardous materials, as well as the immobilization of potentially toxic elements is of great scientific interests. Cement-based S/S is often considered a low-cost and highly efficient technology, but the environmental sustainability of a broad spectrum of S/S technologies has yet to be evaluated. Therefore, this study assessed the environmental sustainability of S/S technologies for managing two common types of hazardous wastes, i.e., contaminated marine sediment and municipal solid waste incineration fly ash (MIFA) by using life cycle assessment (LCA). A total of 17 scenarios under three strategies for sediment and two strategies for MIFA S/S technologies were comprehensively evaluated. The LCA results identified the most preferable S/S technology in each strategy. In particular, Scenario 1 (mixture of sediment with a small percentage of ordinary Portland cement and incinerated sewage sludge ash) of Strategy 1 (use as fill materials) would be the preferred option, as it reduces about 54% and 70% global warming potential compared to those of Scenarios 2 and 3, respectively. This is the first initiative for evaluating the environmental impacts of a wide range of recently developed S/S technologies using green/alternative binders for diverting hazardous wastes from disposal. The results can serve as a decision support for the practical application of the environmentally friendly S/S technology for sustainable remediation.