Waste Volume Reduction Research Articles

SCADA for waste sorting system as an environmental conservation effort

Improperly managed household waste has led to environmental pollution. The methods of reducing, reusing, and recycling are effective in reducing waste volume. Therefore, waste needs to be sorted by type. Automated waste sorting using the SCADA (Supervisory Control and Data Acquisition) system consists of Capacitive Proximity Sensors, Inductive Proximity Sensors, and Infrared Proximity Sensors to detect the types of waste, a PLC TM221CE40R as the controller, and an Android-based HMI (Human Machine Interface) to monitor real-time waste bin fill levels. The types of waste to be sorted are organic, inorganic, and metal. The system comprises 1 main bin for users to deposit waste and 3 waste bins for the sorted materials. When users deposit a certain type of waste, the sensors detect the type of waste. This information triggers the motors of the 3 waste bins to rotate and stop right beneath the main bin, matching the waste type. The bottom of the main bin opens, allowing the waste to enter the appropriate container. Test results have shown that the system is capable of correctly sorting all types of organic and metal waste. However, for inorganic waste, the system correctly sorts only when the waste is clear in color.

PROSPECTS FOR THE INTEGRATION OF QUARTZ-FELDSPAR CONCENTRATE OBTAINED FROM KAOLIN ENRICHMENT INTO CERAMIC PRODUCTION PROCESSES

ABSTRACT. The paper examin es the potential use of quartz feldspar concentrate obtained as a result of kaolin enrichment to meet the growing demand for quartz feldspar materials, which are essential components in the production of ceramic tiles, sanitary ceramics and other products. The research methodology includes laboratory tests of the chemical composition of kaolin enrichment waste and analysis of the possibility for obtaining marketa ble quartz feldspar concentrates using flotation and electrostatic separation methods. The result s showed that high quality concentrates (possessing the necessary physical and chemical properties) that are suitable for ceramic production can be obtained by flotation of such waste. The use of such waste contributes to reducing waste volumes and ensuring a stable supply of raw materials for the ceramics industry.

THE IMPLEMENTATION OF THE OJIR APPLICATION AT CENTRAL WASTE BANK IN MALANG DISTRICT FOR THE MANAGEMENT OF HOUSEHOLD-SCALE ORGANIC WASTE DIVERSIFICATION PROCESSES

The Ojir application, a mobile-based innovation for organic waste management at Central Malang Waste Bank (BCM), provides an effective solution to streamline the collection and management of organic waste. Addressing environmental concerns such as food scraps, dry leaves, and fruits, the application responds to Ministry of Environment and Forestry (KLHK) data indicating that approximately 61.50% of total waste is organic, necessitating efficient management to reduce waste volume. Established in 2016, BCM faced challenges in manual data management and limited organic waste search capabilities. To address these issues, Ojir was introduced to modernize the organic waste management system. This innovation surpasses traditional waste management by incorporating a process of diversifying organic waste into maggot raw material. Beyond resolving existing waste bank issues, Ojir enhances management efficiency, allowing users to easily track and manage organic waste with increased accuracy. Consequently, the paradigm of organic waste management shifts towards modernity, effectiveness, and efficiency. Aligned with efforts to create a clean and sustainable environment, Ojir represents an innovative step in reinforcing the role of waste banks in handling organic waste in the technological era. The incorporation of the maggot raw material process further exemplifies the forward-thinking approach in sustainable waste management

Hydrothermal Liquefaction: How the Holistic Approach by Nature Will Help Solve the Environmental Conundrum.

Hydrothermal liquefaction (HTL) represents a beacon of scientific innovation, which unlocks nature's alchemical wonders while reshaping the waste-to-energy platform. This transformative technology offers sustainable solutions for converting a variety of waste materials to valuable energy products and chemicals-thus addressing environmental concerns, inefficiencies, and high costs associated with conventional waste-management practices. By operating under high temperature and pressure conditions, HTL efficiently reduces waste volume, mitigates harmful pollutant release, and extracts valuable energy from organic waste materials. This comprehensive review delves into the intricacies of the HTL process and explores its applications. Key process parameters, diverse feedstocks, various reactor designs, and recent advancements in HTL technology are thoroughly discussed. Diverse applications of HTL products are examined, and their economic viability toward integration in the market is assessed. Knowledge gaps and opportunities for further exploration are accordingly identified, with a focus on optimizing and scaling up the HTL process for commercial applications. In conclusion, HTL holds great promise as a sustainable technology for waste management, chemical synthesis, and energy production, thus making a significant contribution to a more sustainable future. Its potential to foster a circular economy and its versatility in producing valuable products underscore its transformative role in shaping a more sustainable world.

Prospects for melt refining of radioactive waste from fusion reactors

Fusion has the prospect of producing only low-level radioactive waste, but the volume of this waste is potentially very large. A possible means of reducing the volume of this waste is to recycle the activated materials, e.g. within the fusion industry. In the process of steelmaking, certain impurities are removed via accumulation in slag or fumes produced during the process, and this has been successfully employed as a means of clearing surface-contaminated LWR steels (e.g. steam generators). In this work, we simulate the process applied to neutron-activated fusion reactor components including the blanket, divertors, and shielding.The process is based on a well known partitioning between melt, slag, dust, and gas that is based on the oxidation potential of the elements and their volatility. We model this partitioning of activated materials and use FISPACT-II to simulate their activation during operation; the processes are repeated cyclically to simulate the long-term accumulation of activation products in the steel and waste products. The principal findings are that most of the induced activity remains in the metal rather than accumulating in the slag, and that while the slag remains a low-level waste under the assumptions employed, its volume actually exceeds that of the recycled material, and it therefore did not constitute a successful waste volume reduction technique.

Rare Earth Elements Recovery and Waste Management of Municipal Solid Waste Incineration Ash.

The advancements in high-tech products and pursuit of renewable energy demand a massive and continuously growing supply of rare earth elements (REE). However, REE production from mining is heavily restricted by technoeconomic limitations and global geopolitical tensions. Municipal solid waste incineration ash (MSWIA) has been recently recognized as a potential alternative for REE recovery. This study applies and optimizes a green modular treatment system using organic ligands for effective REE recovery and concentration from MSWIA with minimal generation of secondary wastes. Citrate extracted >80% of total REE at pH 2.0 and ∼60% at pH 4.0. A subsequent oxalate precipitation step selectively concentrated >98% of extracted REE by ∼7-12 times compared to raw MSWIA. Waste byproducts were upcycled to synthesize zeolites, resulting in an overall solid waste volume reduction of ∼80% and heavy metal immobilization efficiency of ∼75% with negligible leaching, bringing the dual benefits of REE recovery and waste management. This work serves as a pioneer study in REE recovery from an emerging source and provides system level insights on the practicality of a simple three-step treatment system. Compared to existing literature, this system features a low chemical/energy input and a light environmental footprint.

The development of an integrated GIS-based optimization framework for power generation from municipal solid waste-to-energy facilities

Waste-to-energy (WtE) is one of the municipal solid waste (MSW) management pathways that can reduce waste volumes while recovering energy. There has been considerable focus on using MSW for energy production; however, there are few integrated assessments of the optimal location and scale of the conversion of MSW to energy. This research develops a novel framework that integrates the analysis of candidate sites for MSW gasification facilities using a geographical information system (GIS) through a multi-criterion decision-making (MCDM) model with a mixed-integer linear programming (MILP) model to determine optimal scale and location. The most suitable candidate locations were identified through a GIS-based location-allocation analysis. A MILP model integrated with GIS was then used to determine the minimum per-unit electricity production costs by optimizing the numbers, locations, and sizes of the proposed WtE and preprocessing facilities. The key inputs to the optimization model are actual road and railway transportation distances, WtE gasification and preprocessing facility capital and installation costs, operation and maintenance costs, gate fee and tipping fees (the fee for disposal of ash at the landfill), and the municipal guidelines. The proposed integrated framework was applied in a case study for Alberta, a western province in Canada. The results indicate that at a 10% rate of return, electricity production is cost-competitive with current electricity prices. The per-unit cost of electricity production (COEP) was found to be only 16.14 $/MWh when the gate fee was treated as a revenue component. The optimal plant location was in Edmonton and the optimum plant size was 175 MW. Sensitivity and uncertainty analysis was conducted to understand the critical input parameters that impact the COEP. The results indicate that the COEP is most sensitive to changes in tipping fees, plant efficiency, capital cost, discount rate, and transportation cost. The developed framework is critical for investment decisions and policy development, and it can be applied globally with adjustments to data and assumptions.

The potential of using sweet corn (Zea mays Saccharata) husk waste as a source for biodegradable plastics

Synthetic plastics are generally challenging to degrade in the environment and capable of releasing harmful chemicals upon improper disposal, endangering both wildlife and humans. Therefore, this study aimed to develop cellulose-based bioplastics from corn husk waste and carboxymethyl cellulose (CMC) using sorbitol as a plasticizer. The effect of corn husk delignification, CMC addition, and variations in sorbitol concentration were investigated. The results of Chesson's test showed that the delignification process increased cellulose content to 77.30% and decreased lignin content to 3.6%. Additionally, Fourier-transform infrared (FTIR) demonstrated the effective removal of lignin and hemicellulose components from corn husk fibers. X-ray diffraction (XRD) analysis indicated the elevation of corn husk crystallinity from 63.97% to 80.83% after the treatment. Scanning electron microscopy (SEM) revealed bioplastic morphologies featuring porous and smooth surfaces juxtaposed with uneven and lumpy characteristics. Biodegradation assessment yielded a peak value of 33.4% under a composition comprising 3% CMC and 1.5% sorbitol. The swelling test performed on corn husk bioplastic samples produced values ranging from 52.89 to 66%, with the highest value recorded at 66% for the bioplastic formulation consisting of 3% CMC and 1.5% sorbitol. Resistance testing on samples containing 3% CMC, with a soaking time of four days in acidic environments, indicated a maximum weight loss of 61.3% (10% H2SO4) and 62.5% (20% H2SO4). Alkaline resistance tests displayed a 95.6% (10% NaOH) and 94.6% (20% NaOH) weight loss under similar conditions. These results suggested the potential utility of corn husk waste as a viable bioplastic source, promoting the circular economy concept in Indonesia while mitigating greenhouse gas emissions, reducing waste volume, and increasing rural economic growth.

Toward sustainable waste management in small islands developing states: integrated waste-to-energy solutions in Maldives context

Effective waste management is a major challenge for Small Island Developing States (SIDS) like Maldives due to limited land availability. Maldives exemplifies these issues as one of the most geographically dispersed countries, with a population unevenly distributed across numerous islands varying greatly in size and population density. This study provides an in-depth analysis of the unique waste management practices across different regions of Maldives in relation to its natural and socioeconomic context. Data shows Maldives has one of the highest population density and per capita waste generation among SIDS, despite its small land area and medium GDP per capita. Large disparities exist between the densely populated capital Male’ with only 5.8 km2 area generating 63% of waste and the ∼194 scattered outer islands with ad hoc waste management practices. Given Male’s dense population and high calorific waste, incineration could generate up to ∼30 GW/a energy and even increase Maldives’ renewable energy supply by 200%. In contrast, decentralized anaerobic digestion presents an optimal solution for outer islands to reduce waste volume while providing over 40%–100% energy supply for daily cooking in local families. This timely study delivers valuable insights into designing context-specific waste-to-energy systems and integrated waste policies tailored to Maldives’ distinct regions. The framework presented can also guide other SIDS facing similar challenges as Maldives in establishing sustainable, ecologically sound waste management strategies.

Assessment of Effluent Recycling Process and Drilling Waste Management Procedure in Some Niger Delta States

The assessment of effluent recycling process and drilling waste management procedure in some Niger Delta States in Nigeria to identify ways to minimize cost in oil production, have been investigated. Niger Delta States are located in southern part of Nigeria, which are known to be the highest in crude oil production in Nigeria, however, the process of exploration and extracting of the oil also affects the ecosystem of that particular area. A comparative design was taken, which analysed various indices in the conventional methods of drilling waste management applied in a site in Edo State northern part of Nigeria, and comparing it to some modified methods employed in the wellhole locations in Imo State. The research was conducted in a wellhole site located in Ohaji Imo state, southern part of Nigeria, afterward, a correlation was drawn between the volume of generated waste and the drilling waste management, in order to develop a cost-effective model of waste management in the region. From the result obtained from the quantitative measures taken at the four drilling sites in Edo and Imo States, a significant reduction in waste volume of about 50% was observed, which therefore minimized the cost of drilling observed in Ohaji site, maybe as a result of the enhanced drilling design layouts using the effluent recycling method adopted in that location. The study therefore recommends the adoption of effluent recycling as a technique to be incorporated in the management of drilling waste during onshore petroleum development in the Niger Delta, among others, which would improve productivity.

Sustainable Management of Bio Medical Waste in Chennai: A case study

The aim of the current research article is to study various treatment techniques involved in the management of bio medical waste and select the most appropriate treatment method in terms of cost savings, energy recovery and waste volume reduction in a sustainable manner. Most of the HCF (Health Care Facilities) lacks the provision for on-site waste treatment facility. One of the major reasons might be the fear of high pollutant emission levels from multiple machines or equipment used in the treatment process. At times, it could be due to lack of sufficient space within the clinical premises. To overcome this situation, a minor amendment has to be introduced in the bio medical waste management rules 2016, which includes providing a suitable area necessary for medical waste treatment within the premises, during the construction stage itself. Further, the identification of appropriate treatment techniques based on the type of waste generated is also important. Even a primary HCF too should be equipped with the requisite treatment facilities, considering the emission levels to be within the standards. This sort of installing an on-site waste treatment facility will reduce the amount spent upon external agencies for disposal and treatment of the medical waste. Then, the leftover residue is securely landfilled in the dedicated site or even be liable to mix with the municipal solid garbage. The current study concludes that the implementation of one of the treatment techniques in a specific hospital helps in energy recovery, huge reduction in the volume of waste generation and avoids illegal dumping of the waste, thereby creating less impact on the surrounding environment.

Ultra-effective modified clinoptilolite adsorbent for selective thorium removal from radioactive residue

This study investigated the efficacy of using phosphate-modified zeolite (PZ) as an adsorbent for removing thorium from aqueous solutions. The effects of various factors such as contact time, adsorbent mass, initial thorium concentration, and pH value of the solution on the removal efficiency were analyzed using the batch technique to obtain optimum adsorption condition. The results revealed that the optimal conditions for thorium adsorption were a contact time of 24 h, 0.03 g of PZ adsorbent, pH 3, and a temperature of 25 °C. Isotherm and kinetics parameters of the thorium adsorption on PZ were also determined, with equilibrium studies showing that the experimental data followed the Langmuir isotherm model. The maximum adsorption capacity (Qo) for thorium was found to be 17.3 mg/g with the Langmuir isotherm coefficient of 0.09 L/mg. Using phosphate anions to modify natural zeolite increased its adsorption capacity. Furthermore, adsorption kinetics studies demonstrated that the adsorption of thorium onto PZ adsorbent fitted well with the pseudo-second-order model. The applicability of the PZ adsorbent in removing thorium from real radioactive waste was also investigated, and nearly complete thorium removal was achieved (> 99%) from the leached solution obtained from cracking and leaching processes of rare earth industrial residue under optimized conditions. This study elucidates the potential of PZ adsorbent for efficient removal of thorium from rare earth residue via adsorption, leading to a reduction in waste volume for ultimate disposition.

Design and analysis of heat melt refuse compactor for solid waste with E-control mechanism

As a technology, a Heat Melt Refuse Compactor (HMRC) has been developed to process municipal solid waste by converting into tiles and on-site valuable products. The HMRC compacts, heats the solid waste to 200°C and recovers the water from the MSW. The heating causes volatile contaminants to be released into the air. The model has evaluated the design and testing parametrs for MSW processing and analysis. HMRC testing has demonstrated water recovery upto 99%, waste volume reduction upto 80%, tile stabilization for long-term, passive separation of liquid/gas phase, and operations with low maintenance cost.Heat melt refuse compactor has designed to compress by compaction process, encapsulate the waste bi-product, residual gas/water at atmoshpheric pressure, waste volume reduction and microbial stabilization. The model design shows the benefit of a heat melt refuse compactor on-site use by converting the solid waste into valuable products with thermal and compression technique. HMRC model has processed ∼1300 kg of solid waste; which produced ∼700 kg of tile, recovered ∼400 kg of water, and ∼200 kg of gaseous and residual waste. The compression ratio (Cc) of solid waste has been estimated with a compression cell with a diameter between 65 to 100 mm, mesoscale data for a diameter of 195 mm to 265 mm and high-scale data for a diameter of 300 to 400 mm. Cc is a more sensitive variable in formation of bi-products from MSW. Ground base HMRC has designed for Cc stress ranges from 20 to 300 kPa to function within the physical and environmental constraints.E-control contaminant removal mechanism keeps the environment clean and safe.

Use of Agroindustrial Materials as Activated Carbon Precursors for Caffeine Removal: Global Overview

Objective: Prepare a global overview of agro-industrial residues used for activated carbon (CA) production, seeking caffeine removal of water bodies. Theoretical reference: Aiming the adequate understand of involved processes, as well as each stage when adsorption occurred. The theoretical concepts might help to analyse how important is pollution of emerging contaminants in water bodies, as a current environmental problem. Method: A data survey was developed in general perspective, using information from literature published in online repositories, such as Scopus and Science Direct, trough investigations that seek the use of agro-industrial residues for production of activated carbons and, also, their caffeine removal parameters analysis. Results and conclusion: The analysis results of the different methodologies applied in studies for activated carbon production from agro-industrial residues, showed that good caffeine adsorption process and the adequate characteristics of each adsorbent material, depend on processes and conditions adopted by each researcher. In this way, the different studies here analysed showed the importance of using industry waste, helping to reduce waste volumes in landfills and, at the same time, the search for new technologies that could help to remove emerging contaminants, such as caffeine. Originality/value: This study provides different basic and methodological concepts related to carbonization processes from agro-industrial waste, verified and studied by different authors for caffeine elimination; and also the importance of tracking new economical and environmentally friendly precursor materials.

Experimental analysis for thermodynamic characteristics of municipal solid waste for energy generation with environmental and economic assessment in Indian scenario

Excessive energy use has caused a disturbance in the planet’s life support system. It has created an adverse impact on water and natural resources. Power generation from solid waste can be an alternative to reduce waste volume and has an extra advantage in cleaning the surround-ing with the gain of electric power supply. Innovative technologies and future perspectives of MSWI were highlighted. Moreover, the latest understanding of immobilization mecha-nisms and advanced characterization technologies were elaborated to foster the future design of treatment technologies and the actualization of sustainable management for MSWI. Solid waste to energy conversion provides economic and atmospheric benefits by introducing re-newableenergy sources at minimum environmental influences.This analysis has focused on MSW to energy conversion system by incineration technique to generate electricity along with other bi-product and determines the system’s financial feasibility. The experiment has been conducted to calculate the physio-chemical characteristics of municipal waste with a bomb calorimeter and incinerator for electricity generation. Solid waste characteristics like chemical exergy, entropy, higher heating point, energy flux, and potential have been analyzed for the in-cineration technique’s viability.The thermal properties have been analytically described in the experiment. The result shows that MSW has a higher calorific value of 8.5-12.5 Mega Joule/kg, and charcoal has a higher calorific value of 27-32 Megajoule/kg.It also analyses that one-ton MSW can produce 600 kWh electricity with 360 gm CO2-eq/kWh generation.

Selective recovery of caprolactam from the thermo-catalytic conversion of textile waste over γ-Al2O3 supported metal catalysts

The massive generation of synthetic textile waste has drawn considerable attention. Landfilling/incineration of textile waste has been widely made. To abate the environmental burdensome from the conventional management processes, a thermo-catalytic conversion was used for rapid volume reduction of textile waste and simultaneous valorization by recovering textile monomer in this study. Stockings were chosen as a model feedstock. Because stockings consisted of nylon with other contents, different products (caprolactam (nylon monomer), imines, cyclic dimers, and azepines) were recovered. The yield of caprolactam from the thermal conversion at 500 °C was 53.6 wt%. To selectively enhance the caprolactam yield, catalytic pyrolysis was done using γ-Al2O3 supported metal catalysts (Ni, Cu, Fe, or Co). γ-Al2O3 itself increased the caprolactam yield up to 69.0 wt% via a based-catalyzed reaction of nylon depolymerization and intramolecular cyclization. Under the presence of metal catalysts, the caprolactam yield increased up to 73.3 wt%. To offer desired feature of green chemistry, CO2 was adopted as reactive gas. Under the CO2-mediated catalytic pyrolysis, caprolactam yield was enhanced up to 77.1 wt% over Cu/Al2O3 (basis: stocking mass). Based on the net content of nylon in the stockings, the yield of caprolactam was deemed 95.3 wt%. This study proves that textile waste (stocking) and CO2 are useful resources for recovery of nylon monomer, which can reduce the waste generation with simultaneous recovery of value-added product.

Synergity and Community Empowerment in Organic Waste Management in Wringinanom, Gresik

This research aims to examine the processing of organic waste into useful products for the community. Departing from the high volume of organic waste produced (61.97 kg per RT per day) along with bad impacts, the strategy used is the processing of waste followed by the dissemination of processing results by the composter method. This research used is descriptive analytic and participatory rural appraisal (PRA) approach which aims to encourage community participation in program implementation. This research was carried out in Pasinan Lemah Putih Village, Wringinom Subdistrict, Gresik Regency by collaborating with several stakeholders, namely the local village government, community, and implementor/expert/academic team. Data source in the form of narratives resulting from discussions and observations, secondary data, and documentation. The results show that the processing of organic waste can reducing waste volume per day and adverse effects. From an economic perspective (livelihood), processed organic waste is capable of producing 15-20 liters of liquid organic fertilizer (POC) valued at IDR 975,000 to IDR 6,000,000 in one RT per day. From a social and environmental perspective, organic waste processing, which is continued with dissemination, has provided environmental insights and new experiences for all levels of society in Pasinan Lemah Putih Village in the form of improving the quality of life of the community, the spirit of preserving environmental beauty, the spirit of preventing littering, and reducing the adverse effects of waste such as bad smell and disease.

Two-step synthesis of a macroporous LTA zeolite sorbent by supercritical CO2 coating and hydrothermal conversion: Implementation in fixed-bed nuclear wastewater treatment

Fixed-bed sorption on solid substrate is a common approach to safely extract cationic radionuclides (such as 90Sr2+) from nuclear wastewater and minimize final waste volumes. This article describes the preparation and characterization of a new hierarchical zeolite–glass bead composite for this application. A homogeneous layer of microporous amorphous silica is deposited on the beads in supercritical CO2 and then transformed into a 1 µm-thick LTA (Linde Type A) zeolite film (40 wt% of the composite) by hydrothermal treatment. Microstructural data show that this design improves the accessibility of the sorbent sites for Sr2+ cations. Batch sorption data in different types of simulated wastewater quantify the effects of competing cations and high salinity. Dynamic breakthrough experiments with simulated saline wastewater show that the proposed composite has delayed leakage and faster exchange kinetics than an existing commercial LTA-zeolite sorbent, which should translate into greater waste volume reduction in industrial fixed-bed extraction systems.

Optimizing mixotrophic cultivation of oil-rich Tribonema minus using volatile fatty acids and glycerin: A promising approach for pH-controlling and enhancing lipid productivity

Volatile Fatty Acids (VFAs) have become a subject of significant interest recently, primarily because they can serve as a carbon source for microorganisms that produce bioactive compounds, biodegradable materials, and energy. VFAs can be produced from various waste streams via anaerobic fermentation (AF) in a cost-effective manner, providing a potential avenue for producing biofuels and biochemicals while reducing waste volume. In this study, different VFAs and glycerin individually or in combination were used as the sole carbon source in the mixotrophic cultivation of oil-rich filamentous Tribonema minus. Using different VFAs or glycerin individually caused pH fluctuation in the culture, which led to the accumulation of free ammonia, which produced protons, acidifying the environment and inhibiting microalgae growth. To minimize pH fluctuation, different proportions of organic carbon sources were combined. Under combined organic carbon sources, the growth and photosynthetic performance of T. minus were all higher than those of the single carbon source groups. When Cacetic acid:Cbutyric acid:Cglycerin was set to 0.5:0.5:1, pH in the culture remained close to neutrality, and the removal of NH4+-N and carbon reached the maximum of 81.17 and 97.79%, respectively. The microalgal biomass and lipid productivity reached the highest of 223.80 and 108.16 mg L−1 d−1, respectively. Under the optimized carbon source condition, the fatty acids and biodiesel-related qualities of T. minus were improved. This study provided a reference for the precise design of carbon sources to maximize the resource utilization of butyric acid-type AF effluent by oil-rich T. minus. These conditions also can be achieved on a large scale by adding glycerin wastes to butyric acid-type AF effluent, mainly composed of acetic and butyric acids to get the recommended ratio for microalgae cultivation.

Toward Deep Decontamination of Intermediate-Level-Activity Spent Ion-Exchange Resins Containing Poorly Soluble Inorganic Deposits

Spent ion-exchange resins (SIERs) generated yearly in large volumes in nuclear power plants (NPPs) require particular predisposal handling and treatment with the primary objectives of waste volume reduction and lowering the disposal class. Deep decontamination of the SIERs using solution chemistry is a promising approach to reduce the amount of intermediate-level radioactive waste (ILW) and, thus, SIER disposal costs. However, the entrapment of nonexchangeable radionuclides in poorly soluble inorganic deposits on SIERs significantly complicates the implementation of this approach. In this work, the elemental and radiochemical compositions of inorganic deposits in an intermediate-level-activity SIER sample with an activity of 310 kBq/g have been analyzed, and a feasibility study of SIER decontamination using solution chemistry has been conducted. The suggested approach included the magnetic separation of crud, removal of cesium radionuclides using alkaline solutions in the presence of magnetic resorcinol-formaldehyde resin, removal of cobalt radionuclides using acidic EDTA-containing solutions, and hydrothermal oxidation of EDTA-containing liquid wastes with immobilization of radionuclides in poorly soluble oxides. The decontamination factors for 137Cs, 60Co, and 94Nb radionuclides were 3.9 × 103, 7.6 × 102, and 1.3 × 102, respectively, whereas the activity of the decontaminated SIER was 17 Bq/g, which allows us to classify it as very low-level waste.