Waste Valorization Research Articles

Biochar for wastewater treatment: Addressing contaminants and enhancing sustainability: Challenges and solutions

In recent years, biochar has gained interest for its potential use in treating and removing contaminants from domestic, municipal, and industrial wastewater. When applied in fixed filter columns (BFCs), biochar can effectively immobilize, filter, and recover contaminants with high treatment efficiency. On average, COD removal is 80 %, nutrient removal is 71 % for nitrogen-ammonium and 57 % for phosphorus-phosphate, and pathogen reduction averages 2.4 log10 units. These results vary depending on factors such as the biochar's surface area, the conditions under which it was pyrolyzed, and operational parameters like hydraulic loading and retention time. Biochar addresses limitations in traditional wastewater treatment by leveraging adsorption, ion exchange, and biological degradation mechanisms. The larger surface area and functionalized surface of engineered biochar make it particularly effective in treating diverse pollutants, including heavy metals, nutrients, and emerging contaminants, such as antibiotic-resistant bacteria. As the global population and industrial activities increase, there is a pressing need for sustainable wastewater treatment technologies. Biochar addresses this need and serves as a waste valorization tool, contributing to bioenergy production, soil improvement, and other applications. The present review focuses on improving biochar's performance and durability in real-world applications by addressing challenges like physical degradation. It also proposes strategies to enhance biochar's properties and reuse potential.

Alkali activated binders based on rock sawing sludges: Synthesis, characterization and future perspectives

In this work, the finest waste resulting from rock cutting and polishing processes, i.e., sawing sludges, is used as precursor to produce inorganic polymeric binders known as alkaline activated materials. The selected mix designs were characterized from a mineralogical, microstructural, chemical, physical (pH and electrical conductivity) and mechanical (compressive and flexural strength) point of view with satisfying results. The obtained outcomes give a complete overview of their potential application in the construction and conservation/restoration fields, promoting the valorisation of industrial wastes in the optic of circular economy and sustainability.

Advancing Circular Economy through Knowledge Transfer: A Decade of Research Insights

Economic growth and sustainable development are central themes of the Sustainable Development Goals (SDGs) set by the United Nations and adopted by the European Commission for EU member countries. Transitioning to a circular economy (CE) aligns with the SDGs, particularly through the principles of reduce, reuse, and recycle (3Rs). This comparative analysis synthesises the contributions of multiple scholars, providing a cohesive understanding of current advancements and challenges in CE and sustainable resource management. Key themes include stakeholder collaboration, technological innovations, waste management, and policy frameworks. Effective waste management and valorisation of materials are highlighted, with significant advancements in electronic waste treatment, automotive shredder residue processing, and construction waste recycling. Moreover, the study emphasises the importance of cooperation through partnerships, as outlined in SDG17, and knowledge transfer in building trust within developed countries. The literature review reveals interactions between knowledge transfer components, such as research and development, foreign direct investment, and CE indicators, including circular material use rate and recycling rate. A bibliometric technique and VOSviewer were employed for visually representative and comprehensible literature analysis. The findings suggest that the integrated efforts of various stakeholders, technological advancements, and robust policy frameworks are essential for achieving a sustainable and circular future. By analysing these components, the research aims to evaluate the potential of EU member states to achieve sustainable development, providing valuable insights into the theoretical approaches and indicators used in CE and knowledge transfer studies.

Catalytic Hydrodeoxygenation of Mixed Plastic Wastes into Sustainable Naphthenes.

The chemical upcycling of plastic wastes by converting them into valuable fuels and chemicals represents a sustainable approach as opposed to landfilling and incineration. However, it encounters challenges in dealing with mixed plastic wastes due to their complex composition and sorting/cleaning costs. Here, we present a one-pot hydrodeoxygenation (HDO) method for converting mixed plastic wastes containing poly(ethylene terephthalate) (PET), polycarbonate (PC), and poly(phenylene oxide) (PPO) into sustainable naphthenes under mild reaction conditions. To facilitate this process, we developed a cost-effective, contaminant-tolerant, and reusable Ni/HZSM-5 bifunctional catalyst through an ethylene glycol-assisted impregnation method. The metallic Ni site plays a pivotal role in catalyzing C-O and C-C cleavages as well as hydrogenation reactions, while the acidic site of HZSM-5 facilitates dehydration and isomerization reactions. The collaboration between metal and acid dual sites on Ni/HZSM-5 enabled efficient HDO of a wide range of substrates, including bottles, textile fibers, pellets, sheets, CDs/DVDs, and plastics without cleaning or pigments removal and even their various mixtures, into naphthenes with a high yield up to 99% at 250 °C and 4 MPa H2 within 4-6 h. Furthermore, the metal-acid balance of the Ni/HZSM-5 catalyst is crucial for determining both HDO activity and product distribution. This proposed one-pot HDO process utilizing earth-abundant metal catalysts provides a promising avenue toward practical valorization of mixed plastic wastes.

Challenges in the Valorization of Green Waste in the Central European Region: Case Study of Warsaw

Expanding green areas in cities results in growth in green waste generation. This study presents the findings of an investigation into green waste from selective collection in a large Central European city (Warsaw, Poland), which can be identified as a valuable biomass resource. The research objective was to identify the properties of garden waste from single-family housing to determine valorization opportunities, emphasizing the utilization of GW as a source of energy. The research yielded several findings, including a notable degree of variability in fuel properties, including moisture content (CV = 30%), lower heating value (CV = 14.3%), and ash content (CV = 62.7/56.2%). The moisture content suggests composting, while the fertilizing properties indicate suitability for anaerobic digestion. The instability of the fuel properties, coupled with the elevated levels of chlorine, sulfur, and moisture, constrains the use of garden waste in thermal processes and alternative fuel production. Pyrolysis could be a viable approach for green waste feedstock, offering value-added products depending on the processing conditions and pre-treatment. Nevertheless, implementing a selective collection system is a critical condition for the optimal utilization of bio-waste, facilitating the quality and property control of green and food waste. This is essential for their effective processing, including energy recovery, thereby contributing to the efficient valorization of biomass.

Revolutionizing waste: Harnessing agro-food hydrochar for potent adsorption of organic and inorganic contaminants in water.

Constant pollution from a wide range of human activities has a negative impact on the quantity and quality of the planet's water resources. On the other hand, agro-food waste can impact climate change and other forms of life, in addition to having social, economic, and environmental consequences. However, as a result of their inherent physicochemical properties and lignocellulosic composition, these residues are becoming increasingly recognized as valuable products in line with government policies advocating zero waste and circular economies. An advantageous way to convert these wastes into energy and chemicals is hydrothermal carbonization (HTC). This review highlights the valorization of agro-food waste into hydrochar-based adsorbents for the elimination of organic and inorganic contaminants from aqueous environments. An overview of the toxicity of pollutants in aqueous environments, food waste management, as well as HTC technology was initially proposed. Then, a discussion on the conversion of major agro-food wastes into contaminant adsorbents was given in detail. Adsorption mechanisms as well as the possibility of reuse of adsorbents were also discussed. Enhanced properties of the produced materials enable them to provide competent solutions to various ecological contexts, including removing pollutants from wastewater with cost-effectiveness and satisfactory results. Besides addressing environmental concerns, this sustainable approach opens the door for more environmentally-friendly and resource-efficient applications in the future, making it an exciting prospect.

Legal Barriers in Sustainable Agriculture: Valorization of Agri-Food Waste and Pesticide Use Reduction

The transition to sustainability in agriculture faces significant challenges, especially to balance environmental goals with the practical demands of food production. This paper examines two different case studies that reveal the complexities of agricultural regulation. The first case focuses on the valorization of agri-food residual biomasses, highlighting the potential to transform food waste into valuable bioproducts such as bioenergy and biofertilizers. Despite the clear environmental and economic benefits, the absence of specific European regulations hinders the widespread adoption of these practices. Without clear rules for achieving “end-of-waste” status, the development and marketing of bio-based products remain restricted. The second case study examines the European Union’s unsuccessful effort to implement the Sustainable Use of Pesticides Regulation (SUR), which aimed to reduce pesticide use by 50% by 2030. Although the regulation sought to align agricultural practices with the EU’s Green Deal, it triggered widespread protests from farmers concerned about the potential economic losses and decreased productivity. These two cases, one showing under-regulation and the other over-regulation, highlight the need for balanced and practical regulatory frameworks that promote sustainability without imposing unrealistic demands on stakeholders. This paper ends with recommendations to harmonize regulations across Europe, ensuring that both innovation in agricultural waste management and practical pesticide reduction strategies are implemented in a way that supports farmers and producers, minimizing economic disruptions and encouraging sustainable agricultural practices.

Valorization of Eggshell as Renewable Materials for Sustainable Biocomposite Adsorbents—An Overview

The production and buildup of eggshell waste represents a challenge and an opportunity. The challenge is that uncontrolled disposal of generated eggshell waste relates to a sustainability concern for the environment. The opportunity relates to utilization of this biomass resource via recycling for waste valorization, cleaner production, and development of a circular economy. This review explores the development of eggshell powder (ESP) from eggshell waste and a coverage of various ESP composite sorbents with an emphasis on their potential utility as adsorbent materials for model pollutants in solid–liquid systems. An overview of literature since 2014 outlines the development of eggshell powder (ESP) and ESP composite adsorbents for solid–liquid adsorption processes. The isolation and treatment of ESP in its pristine or modified forms by various thermal or chemical treatments, along with the preparation of ESP biocomposites is described. An overview of the physico-chemical characterization of ESP and its biocomposites include an assessment of the adsorption properties with various model pollutants (cations, anions, and organic dyes). A coverage of equilibrium and kinetic adsorption isotherm models is provided, along with relevant thermodynamic parameters that govern the adsorption process for ESP-based adsorbents. This review reveals that ESP biocomposite adsorbents represent an emerging class of sustainable materials with tailored properties via modular synthetic strategies. This review will serve to encourage the recycling and utilization of eggshell biomass waste and its valorization as potential adsorbent systems. The impact of such ESP biosorbents cover a diverse range of adsorption-based applications from environmental remediation to slow-release fertilizer carrier systems in agricultural production.

Hydrochar from sawdust and sewage sludge – a potential media for retaining heavy metals in sustainable drainage systems (SuDS)

ABSTRACT Waste valorization is an essential aspect of sustainable development. From this perspective, co-hydrothermal carbonization (Co-HTC) is a promising thermochemical process for converting organic waste into hydrochar. Hydrochar is a solid material whose physicochemical properties could make it suitable for adsorbing pollutants such as heavy metals. Accordingly, this work evaluated the hydrochar from Co-HTC of sawdust and non-dewatered sewage sludge as a potential adsorbent of heavy metals at low concentrations. In the context of sustainable drainage systems (SuDS), it is notable that heavy metals are present at very low but still potentially harmful concentrations, which presents a potential opportunity for the application of hydrochar. Thus, three hydrochars (H-180, H-215, and H-250), produced by Co-HTC at 180, 215, and 250 °C, were tested herein for their ability to retain lead (Pb2+). The H-180 presented better performance than other hydrochars (H-215 and H-250), suggesting that chemisorption could be the main adsorption mechanism. Interestingly, the presence of other cationic heavy metals (Cu2+, Zn2+, Cd2+, Cr6+, and Ni2+) did not hinder the Pb2+ adsorption, for which the removal efficiency remained close to 100%. In fact, in such a multi-metal system, hydrochar can be suitable for capturing both lead and cadmium. Therefore, the hydrochar from Co-HTC of sawdust and non-dewatered sewage sludge can be useful for removing heavy metals at low concentrations, such as those found in urban runoff waters. Although further studies are required, these findings suggest hydrochar as a potential material for application in SuDS.

Biocatalytic Production of Solketal Esters from Used Oil Utilizing Treated Macauba Epicarp Particles as Lipase Immobilization Support: A Dual Valorization of Wastes for Sustainable Chemistry

This study describes the production of solketal esters from used soybean cooking oil (USCO) via enzymatic hydroesterification. This process consists of the complete hydrolysis of USCO into free fatty acids (FFAs) catalyzed by crude lipase extract from Candida rugosa (CRL). The resulting FFAs were recovered and utilized as the raw material for an esterification reaction with solketal, which was achieved via an open reaction. For this purpose, lipase Eversa® Transform 2.0 (ET2.0) was immobilized via physical adsorption on treated epicarp particles from Acrocomia aculeata (macauba), a lignocellulosic residue. A protein loading of 25.2 ± 1.3 mg g−1 with a support and immobilization yield of 64.8 ± 2.5% was achieved using an initial protein loading of 40 mg g−1 of support. The influence of certain parameters on the esterification reaction was evaluated using a central composite rotatable design (CCRD). Under optimal conditions, a FFAs conversion of 72.5 ± 0.8% was obtained after 150 min of reaction at 46 °C using a biocatalyst concentration of 20% wt. and a FFAs–solketal molar ratio of 1:1.6. The biocatalyst retained 70% of its original activity after ten esterification batches. This paper shows the conversion of two agro-industrial waste into valuable materials (enzyme immobilization support and solketal esters).

Exploring the integrated potential of pyrolysis and low-temperature wet torrefaction for typical medical waste valorization: A multifaceted approach leveraging online TG-FTIR-MS, 2D-COS, iso-conversional kinetics, and reaction mechanisms

The rapid growth of medical waste, exacerbated by the COVID-19 pandemic and advancements in healthcare, has drawn increased public scrutiny regarding its proper disposal and treatment. This research aimed to characterize the wet torrefaction of a typical medical waste biomass (MWB) composition, comprising bamboo swabs, skewers, splints, cotton balls, tongue depressors, toothpicks, and chopsticks, followed by its co-pyrolysis with medical waste plastic (MWP) including catheter bags, drapes, IV tubing, IV bags, oxygen masks, syringes, and test tubes. The study employed thermogravimetric analysis, TG-FTIR, 2D correlation spectroscopy, iso-conversional kinetics, and mass spectrometry techniques elucidated the driving factors, behaviors, products, mechanisms, and pathways involved. The pyrolysis temperature ranges were 180.15 to 400 °C for TMWB and 380.04 to 550 °C for MWP, with average activation energies of 150.22 and 221.59 kJ/mol for their respective devolatilization processes. Incorporating 20 % and 40 % MWP into the co-pyrolysis process yielded the best performance, characterized by the lowest activation energy. The co-pyrolysis process promoted the release of cyclic hydrocarbons and chain hydrocarbons, but decreased the yields of alcohols, esters, ethers, phenols, and acids, through synergistic mechanisms. Unraveling the pyrolysis pathways and dynamics of these representative medical waste streams offers valuable insights into improving energy recovery, mitigating pollution, diminishing waste volumes, and optimizing industrial thermochemical conversion processes for safely treating these hazardous materials.

Synthesis of nanoporous carbon from Ulva lactuca activated by eggshell for CO2 capture: a novel approach to waste valorization.

Facing the daunting challenge of climate change, driven by escalating greenhouse gas concentrations, our research introduces an innovative solution for CO2 capture. We explore a novel nanoporous carbon derived from Ulva lactuca, activated with eggshell waste, spotlighting waste valorization in mitigating atmospheric CO2. Through a systematic methodology encompassing variable carbonization temperatures (700-900°C) and nitrogen flow rates (2-4ml/min), complemented by a suite of characterization techniques, we unveil the synthesis of this pioneering adsorbent. Our study not only presents a novel, sustainable pathway for CO2 capture but also demonstrates superior performance, particularly with the NC800-4 sample, achieving a CO2 capture capacity of 1.40mmol/g at 30°C, alongside demonstrating consistent adsorption efficiency over four successive adsorption/desorption cycles. This breakthrough underscores the potential of leveraging waste for environmental remediation, offering a dual solution to waste management and carbon capture, utilization, and storage (CCUS) applications.

Kinetics Analysis of Crystal Violet Adsorption from Aqueous Solution onto Flamboyant Pod Biochar

The increasing presence of presistent synthetic dyes, like crystal violet (CV), in wastewater poses a significant threat to aquatic ecosystems and human health due to its genotoxicity and carcinogenicity. Biochar derived from agricultural waste offers a promising, cost-effective, and eco-friendly approach for dye removal. This study explores the potential of flamboyant pod biochar (FPB) as a novel and sustainable adsorbent for CV removal. FPB offers a unique advantage as it utilizes readily available flamboyant pod waste, promoting waste valorization and a cost-effective approach. FPB was synthesized through a simple process involving milling, sun-drying, and pyrolyzing flamboyant pod waste at 300 °C. Batch adsorption experiments were conducted to evaluate the influence of contact time and initial dye concentration on removal efficiency. Kinetic modeling using pseudo-first-order and pseudo-second-order models explored the underlying mechanisms governing the adsorption process. The pseudo-second-order kinetic model exhibited a superior fit (R² > 0.87) compared to the pseudo-first-order model, suggesting a chemisorption mechanism governing the adsorption process. These findings demonstrate the potential of FPB as a low-cost, sustainable adsorbent for CV removal from wastewater.

A simulation-based techno-economic-safety-social-environmental decision-making framework for prioritizing plastic waste treatment processes

Chemical recycling technologies hold promising potential in converting mixed plastic waste into energy and chemicals. This study proposed a simulation-based quantitative life cycle sustainability assessment framework for the potential plastic waste valorization processes. Sustainability metrics including environment, economy, safety, society, and energy were quantified and comprehensively investigated. Based on the Bayesian best-worst weighting and vector-based ranking methods, the normalized and weighted life cycle sustainability scores were used to prioritize the best process. Gasification-based technology was found superior than incineration-based technology, especially in the economic, techno-energetic, and social aspects. However, incinerated-based process with direct CO2 emissions performed better in the environmental aspects compared with the process integrating with carbon capture and utilization unit. Additional environmental burdens were brought to the system when incorporating the carbon capture and methanol synthesis process. Increased system complexity might bring unexpected environmental burdens, and sometimes even outweighed the benefits. Various weights were assigned to the multi-criteria decision-making model, and the gasification-based process consistently ranked first across all scenarios.

Sardine Processing Waste: Biological Treatment Strategies and Their Implications

This study explores sustainable methods for Sardine Processing Waste (SPW) valorization. Two approaches were investigated: (a) SPW microbial pretreatment adding Saccharomyces cerevisiae or Bacillus sp. in a two-stage anaerobic digestion (AD) for enzyme and biomethane production and (b) a single-stage AD without SPW pretreatment. Both S. cerevisiae and Bacillus sp. secreted proteases (0.66 and 0.58 U mL−1, respectively) and lipases (3.8 and 4.3 U mL−1, respectively) during hydrolysis, thus reducing viscosity (2.8 and 2.9 cP, respectively) compared with the untreated SPW (4.1 cP). Biomethane production was higher in the single-stage AD (1174 mL CH4 g−1 VS−1) when compared with the two-stage AD (821.5 and 260 mL CH4 g−1 VS−1 with S. cerevisiae and Bacillus sp., respectively). S. cerevisiae addition enhanced SPW degradation as implied by VS and sCOD values (70 and 84%, respectively), but this also resulted in a higher toxicity due to a three-fold increment in NH4-N content, reducing methanogen activity. This research demonstrates the innovative application of S. cerevisiae, a common bread-making yeast, in the biotechnological enhancement of SPW hydrolysis. Non-genetically engineered S. cerevisiae not only co-produced proteases and lipases but also significantly improved solubilization, degradation, and viscosity reduction, thereby rendering the yeast a key player in solid fish waste valorization, beyond its traditional applications.

Fast, sensitive, and sustainable colorimetric detection of chlorogenic acid in artichoke waste material

Caffeoylquinic acids (CQAs) are nutraceutical polyphenols highly represented in natural sources, including artichoke waste (AW). In this study a colorimetric method for rapid and sustainable detection of a 5-CQA isomer (Chlorogenic acid) in AW extract was developed by using alkaline Tris buffer (10 mmol L−1, pH 9) to generate a yellow color associated with 5- to 3-CQA isomerization reaction, as suggested by NMR and MS analyses. The strong absorbance at 360 nm was followed by standard UV–Vis methodology. The colorimetric assay was exploited for detection of 5-CQA into leaf extract from artichoke, obtaining a value of 15.2 ± 0.3 μg/mg of dry extract, in agreement with HPLC analysis (14.3 ± 0.7 μg/mg, 106 ± 2 % recovery) used as validation technique, with excellent linear correlation and precision (R2 = 0.9996, avRSD% = 3.2 %). The method is fast and selective, offering a valuable tool for nutraceuticals identification and food waste valorization.

Convert food waste into easily biodegradable liquid substrate: New insights into wet oxidation as a pretreatment for anaerobic digestion

This study is the first comprehensive investigation into the industrial application of wet oxidation (WO) for food waste (FW) valorization. We analyzed the physicochemical properties of WO products and performed a material flow analysis. WO achieved a 25.7 % reduction in chemical oxygen demand and produced liquid and solid products suitable for high-value applications. The liquid product featured high biodegradability (B/C ratio of 0.65), significant BOD5 (33 ± 9 g/L), low total solids (3.5 % ± 0.4 %), and low metal concentrations, making it ideal for high-efficiency anaerobic digestion or as a carbon source in wastewater treatment. The solid product, with a total solids content of 63.9 % ± 1.4 %, is a potential organic fertilizer alternative. Life cycle assessment showed that WO-related scenarios offered superior greenhouse gas (GHG) reduction compared to conventional anaerobic digestion (11.30 kg CO2-eq/t FW slurry). The most effective scenario, combining WO with a carbon source and organic fertilizer alternative, achieved a GHG reduction of −21.80 kg CO2-eq/t FW slurry. Consequently, this study demonstrates that WO, as a pretreatment for food waste valorization, is both technically feasible and environmentally sound, offering valuable engineering references for the implementation of high-efficiency anaerobic digestion processes for food waste.

Impact of CO2 on the pyrolysis of mixed polymer wastes into combustible fuel: A case study for footwear waste

Plastic waste is a promising resource for producing liquid fuels that can be integrated into existing hydrocarbon infrastructures. However, the heterogeneous nature of plastic-derived liquid fuels limits direct application in internal combustion engines, necessitating their refinement into a usable form. To address these issues, this study explored the enhancement of combustible gaseous fuels derived from plastic waste, footwear waste, as a viable alternative. This approach involves the introduction of carbon dioxide as a reactive feedstock during the pyrolysis process. Analytical techniques were employed to precisely determine the types and compositions of four polymers present in footwear waste. The compositional matrices of the primary pyrogenic products were also identified. However, incorporating carbon dioxide into pyrolysis leads to its interaction with volatile compounds, converting them into lighter gaseous products, particularly carbon monoxide. The homogeneous reactivity of carbon dioxide was further enhanced by the application of heat and a nickel-based catalyst. The gaseous product yield from catalytic pyrolysis in the presence of carbon dioxide increased proportionally with the test temperature. Specifically, the use of carbon dioxide led to a 1.92-fold increase in gaseous product yield at 700 ˚C, in reference to the results from nitrogen. This study demonstrates a technical advancement in pyrolytic valorisation of footwear waste by incorporating carbon dioxide and provides a detailed investigation into its mechanical role in maximising the production of combustible gaseous fuels.

Novel synthesis and application of zeolite-Y from waste clay for efficient CO2 capture and water purification

In the present study, the microwave-assisted hydrothermal method using sodium hydroxide (NaOH) has been used to synthesise zeolite-Y from three different waste clays (WC) from Teesside, Northeast of England, UK. The effects of microwave time intervals and WC type were investigated to produce crystalline zeolite-Y. All WCs and synthesised zeolites were characterised by scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller surface area measurement (BET). The characterisation results showed that the zeolite-Y samples synthesised at 6 min intervals exhibited larger total pore volumes, higher surface areas, and higher crystallinity compared to the samples synthesised at 4 min intervals. Especially, the synthesised zeolite-Y from Clay 1 displayed high CO2 adsorption capacity, achieving 5.23 mmol/g at 298 K and 1 bar, with a maximum methylene blue removal of 94.3 %. This sample showed a surface area of 485 m²/g and a pore volume of 0.24 cm³/g, alongside an Si/Al ratio of 3.7, highlighting its excellent thermal stability at elevated temperatures. The high CO2 adsorption capacity combined with the high methylene blue removal efficacy makes the synthesised zeolite-Y from WC an excellent candidate for efficient CO2 capture and removal of methylene blue from contaminated water. Additionally, this study illustrates the potential for waste valorisation through the conversion of low-value WC into high-performance, value-added materials. This transformation not only mitigates waste disposal issues but also contributes to sustainable resource management and environmental protection by offering a practical solution for treating industrial effluents and gas emissions.

A novel synthesis of solid Na-silicate based on Si-rich diatomite waste

Sodium silicate is widely used in industry, and its production typically depends on traditional raw materials and high energy consumption. The present study investigated the synthesis of an alternative Na-silicate based on diatomaceous earth waste. The Si-rich waste exhibited a high surface area and porosity. Diatomite waste and NaOH were used as reagents, and the synthesis route was carried out by wet method and thermal treatment at 400 °C. The synthesis product presented more than 90 % Na2SiO3, and Si-O-(Na) type bonds were observed. These findings may be useful in the development of sustainable and high-value-added materials obtained by the waste valorization.