Enhance Resource Recovery Research Articles

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The cover illustrates electrochemical recycling advancements for lithium‐ion batteries, showcasing a selective recovery process for valuable metals such as lithium, cobalt, and nickel. This approach focuses on reducing environmental impact by minimizing chemical usage and energy consumption. We emphasize the importance of sustainable technologies to enhance resource recovery, critical for supporting the energy transition and addressing resource scarcity. image

Low Temperature Pyrolysis and Exfoliation of Waste Printed Circuit Boards: Recovery of High Purity Copper Foils

Although several techniques have been developed to extract copper from waste printed circuit boards (PCBs), there remain several challenges regarding energy consumption, local area contamination and environmental damage. A novel technique has been developed for extracting copper foils from waste PCBs based on low temperature pyrolysis followed by exfoliation to overcome these issues. The standard pretreatment steps of removing electronic components from PCBs and mechanical processing/size-reduction/powdering, etc., were minimized in this study. Several unsorted ‘as received’ PCBs were heat treated in the temperature range 750–850 °C for 5–20 min. in an argon atmosphere. Brittle dark chars and other residues on the heat-treated specimens were scrapped off to separate copper foils and other residuals. Most of the electronic components mounted on PCBs had dropped off during the heat treatment. Good-quality copper foils were recovered in all cases; the purity of copper was in excess of 85 wt.%. Key impurities present were Pb, Sn and Zn with typical concentrations less than 4 wt.%. Key features of the technique include minimizing energy intensive pre-treatment processes and waste handling, low pyrolysis temperatures and short heating times. This energy-efficient approach has the potential to enhance resource recovery while reducing the loss of materials, local area contamination and pollution near e-waste processing facilities.

Smart bins for enhanced resource recovery and sustainable urban waste practices in smart cities: A systematic literature review

Waste collection bins with smart capabilities play a crucial role in contemporary urban landscapes, forming integral components of efficient and sustainable waste management practices worldwide. This paper conducts a thorough review of state-of-the-art smart bins, emphasizing advanced features such as material separation and integrated automation. The analysis, based on 79 selected articles from a pool of over 1400 publications, underscores critical gaps in the existing literature. While a widely accepted common ground that outlines the definition for smart bins exists, in the form of waste disposal containers incorporating functionalities such as fill-level monitoring and IoT connectivity, this research identifies substantial areas for improvement. Specifically, material separation practices, including automated waste segregation, and the overall maturity of conceptual frameworks present significant challenges, hindering the optimization of resource recovery essential for pioneering circular economy models. Moreover, a lack of uniformity and standardization in automation techniques is apparent across studies. Various articles propose divergent approaches, each with distinct advantages and drawbacks. Notably, no unified solution emerges that could harness collective strengths and mitigate shortcomings. Identifying these issues is paramount for advancing the field and tackle sustainability-related challenges within modern smart cities.

Enhancing Deposit Exploitation Efficiency Utilizing Small-Diameter Radial Boreholes via Hydraulic Drilling Nozzles for Optimal Resource Recovery

The exploration and development of new hydrocarbon deposits is facing increasing challenges as the global shift to renewable energy sources, such as shallow geothermal deposits, wind farms, and photovoltaics, reduces the dependence on hydrocarbons. To navigate this evolving landscape, it becomes crucial to find solutions that optimize the energy extraction efficiency while maximizing the use of hydrocarbon deposits. This requires exploring opportunities in existing fields and wells, including those slated for decommissioning. This article discusses the potential for extracting resources from seemingly depleted fields, where some 60–70% of the resources remain unrecoverable due to low reservoir energy. Meeting this challenge requires the implementation of secondary and tertiary EOR methods that involve the introduction of external energy to increase reservoir pressure and enhance resource recovery. One of the proposed innovative tertiary methods involves reaming the reservoir using multiple small-diameter radial boreholes generated by a hydraulic drilling nozzle. This strategy is designed to intensify the contact between the production hole and the reservoir layer, resulting in increased or commenced production in certain cases. The described method proves to be a practical application in hydrocarbon deposits, offering the dual benefits of mitigating environmental pollution by eliminating the need for drilling new boreholes and providing a cost-effective means of accessing resources in decommissioned deposits with insufficient reservoir energy for self-exploitation. Another article points out the design variation of a hydraulic drilling nozzle tailored specifically for reaming a reservoir layer. Taking the above into account, this article provides very practical information for future projects in which paths should be sought for the design and development of hydraulic wellheads, among other things, in order to intensify the production from hydrocarbon deposits.

Effect of iron sources on methane production and phosphorous transformation in an anaerobic digestion system of waste activated sludge

The iron materials are commonly employed to enhance resource recovery from waste activated sludge through anaerobic digestion (AD). The influence of different iron sources, such as Fe2O3, Fe3O4, and FeCl3 on methane production and phosphorus transformation in AD systems with thermal hydrolyzed sludge as the substrate was assessed in this study. The results indicated that iron oxides effectively promote methane yield and methane production rate in AD systems, resulting in a maximum increase in methane production by 1.6 times. Soluble FeCl3 facilitated the removal of 92.3% of phosphorus from the supernatant through the formation of recoverable precipitates in the sludge. The introduction of iron led to an increase in the abundance of bacteria responsible for hydrolysis and hydrogenotrophic methanogenesis. However, the enrichment of microbial communities varied depending on the specific irons used. This study provides support for AD systems that recover phosphorus and produce methane efficiently from waste sludge.

Utilizing scrap metals in electrocoagulation: Revolutionizing water treatment with AI applications for enhanced resource recovery

Utilizing scrap metals in electrocoagulation: Revolutionizing water treatment with AI applications for enhanced resource recovery

Ultrasound-enhanced peracetic acid oxidation improves short-chain fatty acids production from waste activated sludge

This study proposed a new technology, i.e., ultrasound (US)-enhanced peracetic acid (PAA) pretreatment, to enhance resource recovery from anaerobic sludge fermentation. Results show that the optimum operation condition was achieved with US-enhanced 10 mg PAA/g TSS (total suspended solids), leading to a remarkable 31.72-fold increase in short-chain fatty acids (SCFAs) production compared to the control group (with PAA contribution in SCFAs deducted). Mechanism explorations prove that US-enhanced PAA pretreatment significantly promoted sludge disruption and organic matter release, creating a substantial amount of soluble substances (i.e., tyrosine-like and tryptophan-like substances) for subsequent fermentation. Fourier transform infrared (FTIR) analysis indicates that US-enhanced PAA pretreatment induced alterations in the protein secondary structure and facilitated its transformation. Quenching experiments imply that the contribution of reactive species during sludge oxidation followed the order: 1O2 >OH > CH3C(O)O/CH3C(O)OO. These reactive species played essential roles in the inherent mechanisms responsible for sludge disintegration and organic conversion. On the other hand, the analysis of key enzyme activities reveals a severe inhibition of the enzymes associated with SCFAs consumption. Further microbial community investigation confirms the enrichment of acidogenic microorganisms, such as Clostridium_sensu_stricto_10 sp., norank_f__norank_o__Bacteroidales sp., etc. Overall, US-enhanced PAA pretreatment can facilitate energy recovery and enhance the efficiency of anaerobic fermentation, offering significant benefits in sustainable sludge management.

Simultaneous biohythane and volatile fatty acids production from food waste in microbial electrolysis cell-assisted acidogenic reactor

To enhance resource recovery from food waste (FW), a semi-continuous experiment was conducted to study simultaneous biohythane and volatile fatty acids (VFAs) production from it in a microbial electrolysis cell-assisted acidogenic reactor (MEC-AR). Anaerobic fermentation of FW at acid pH (3.71–5.19) produced CH4 through acclimating acid-tolerant methanogens. The MEC-AR with 1.2 V and pH 5.04 ± 0.10 simultaneously produced 2.73 ± 0.05 L/L/d biohythane (with 34.80 ± 1.09% CH4, 14.95 ± 0.86% H2, and 28.74 ± 1.11% H2/(H2+CH4)) and 19.39 ± 0.44 g chemical oxygen demand/L VFAs during steady period. The pH of the fermentation liquid and MEC were the primary factors that influenced the production of biohythane and VFAs. No hydrogen was produced in the reactor at low pH (3.50–4.00) or no applied voltage. The MEC also affected the composition of VFAs with high acetic acid (65.43 ± 2.42%) and low propionic acid (3.71 ± 0.76%) contents and increased the relative abundances of Olsenella and Methanobacterium. Energy analysis showed that the MEC improved the energy efficiency of anaerobic fermentation of FW. This study thus provided a novel, efficient, and applicable strategy for resource recovery and valorization of FW.

Performance and mechanism of calcium peroxide reducing H2S production from sludge anaerobic fermentation

Calcium peroxide (CaO2) addition is widely regarded as a high-efficient sludge treatment method to degrade pollutants and enhance resource recovery. In this study, it was further found that CaO2 addition changed sulfur distribution during sludge anaerobic treatment, which promoted sulfur flow from sludge solid to liquid phase but significantly inhibited toxic hydrogen sulfide (H2S) gas production. With CaO2 addition increased from 0 to 0.25 g/g VSS, the accumulated H2S yield decreased from 314.6 × 10−4 to 61.3 × 10−4 mg/g VSS while the accumulated SCFAs and hydrogen yields increased from 46.2 to 266.5 mg COD/g VSS, and 0.9 to 10.2 mL/g VSS. Mechanism analysis showed that the released OH– and oxidizing substances (e.g., ·OH and ·O2–) firstly destroyed functional groups and hydrogen bonding networks contained in sludge EPS, with the contents of C=O group, β-sheet and α-Helix being reduced by 24%, 19.7%, and 23.2%, respectively. This caused the cracking of sludge EPS and releases of soluble metal ions (e.g., Al, Mg, and Fe). The released metal ions in alkaline environment promoted the transformation of H2S gas and dissolved sulfide to metal sulfide, which was one important reason to reduce H2S gas release. Then, the free radicals further attacked sludge cells without EPS protection and caused cell lysis. Flow cytometry analysis showed that 0.25 g/g VSS CaO2 reduced the rate of living cells from 90.7% to 81.4%. Microbial analysis unveiled that CaO2 reduced the content of S2− producers (e.g., Desulfobulbus and Desulfovibrio) and the expression of related genes (e.g., PepD and Sat). Moreover, the activities of S2− producers, e.g., methionine lyase and adenosine-5′-phosphosulfate reductase also reduced by 41.3% and 64.8% with 0.25 g/g VSS CaO2 addition. These findings provide new insights into CaO2-based sludge treatment and might have significant implications for sludge treatment.

Environmental impacts and optimization simulation of aerobic anaerobic combination treatment technology for food waste with life cycle assessment

After the implementation of waste sorting policy in Shanghai, the amount of food waste (FW) separation and treatment demand has increased significantly. It is necessary to establish the life cycle assessment (LCA) to assess the environmental impacts of various treatment technologies comprehensively, thus provide support for sorting, recycling, treatment and disposal strategies of FW. In this study, a local FW treatment plant in Shanghai, using typically aerobic anaerobic combination treatment technology was selected to analyze the environmental impacts with LCA. The process mainly included pretreatment, power, aerobic composting, anaerobic digestion, and further process systems. LCA results showed that the environmental impacts mainly came from the power and aerobic composting systems on the fine particulate matter formation and eutrophication, and freshwater ecotoxicity and terrestrial acidification, respectively. Considering the carbon footprint, the aerobic composting system contributed 3.61E + 02 kg CO2 eq and represented the largest source of carbon emission. The soil conditioner yielded both environmental benefits on eutrophication and terrestrial ecotoxicity, and ecological benefits of 75.33 million CNY per year being the major revenue for the treatment plant. It also suggested that the biogas generation capacity of anaerobic digestion could be increased to achieve electricity self-sufficiency, thus save about 7.12 million CNY per year in electricity costs, and avoid corresponding environmental impacts caused by coal-fired. In summary, the aerobic anaerobic combination treatment could be further optimized and applied in FW treatment to reduce the environmental impacts, and enhance resource recovery and secondary pollution control.

Species traits determined different responses to “zero-growth” policy in China’s marine fisheries

China remains the largest nation of marine capture fisheries in the world in the last few decades, at the cost of offshore fisheries degradation by overfishing. Although fisheries regulations have become gradually tightened, the recovering evidences are weak and the catch species compositions are far from satisfactory. To explore better and reasonable countermeasures, besides the “zero growth” policy (i.e. the national total fisheries production limitation), five targets with different ecological traits were selected for stock assessment and rebuilding by Monte Carlo Catch-Maximum Sustainable Yield method. The results showed the control of total rather than species catch could not lead to the recovery of fisheries and maintain community function. Individual species showed different responses to overfishing according to their biological characteristics. High trophic level species can be sensitive to overfishing, and difficult to rebuild stocks after collapse. Pelagic small fish resources increased first but eventually decreased under high fishing pressure. Scientific-based restocking can enhance resource recovery. Besides “zero growth” policy, fisheries management should be further refined, in particular for main economic species based on their biological traits, as well as the support of reliable fisheries statistics and regulation implementation in place. To relieve the conflict between rising fishery products demand and falling catches, aquaculture and seeking resources from the high seas and EEZs are supposed to be successful ways, on the premise of taking full account of ecological health, maritime safety, and food security.

Review on research achievements of blackwater anaerobic digestion for enhanced resource recovery

Review on research achievements of blackwater anaerobic digestion for enhanced resource recovery

Cleaner production through enhanced resource recovery and reuse in dye intermediates industry: Integration of Vinyl Sulphone with H-acid production

H-Acid (HA) and para-base ester Vinyl Sulphone (VS) are the significant raw materials for several industrially important dyes consumed worldwide. Owing to the toxicity and non-biodegradability of HA and VS as well as the associated by-products and hazardous wastes, most developed countries in the world have banned their production. Many states in the Union of India, too, have banned the production of HA. Due to the economic significance of the dye intermediates sector, especially in international trade, the regulatory agencies in India as well as the international importers of dye intermediates are demanding a transition to cleaner production through enhanced recycle and reuse of wastes and minimization of resource consumption. In this context, this study focuses on the ways for enhancing cleaner production as well as maximizing reuse and recycle in HA and VS production through: (i) enhancing resource recovery and internal reuse of recovered water, (ii) exploring possibilities of co-processing of wastes by linking unit operations and unit processes in HA and VS production, and (iii) balancing the scales of production of HA and VS to enhance the benefits of the so-called ‘Zero Liquid Discharge’ to potentially minimize operating costs, increase resource efficiency, and lower environmental footprint. In addition, this is the first study to address the resource intensity and pollution intensity in the production of VS. The two cleaner production opportunities identified and evaluated in this study are (1) Reuse of Spent Mixed Acid and (2) Recovery and reuse of Glauber's Salt. The optimum production quantities of HA and VS were determined to be 2256 MT HA and 5000 MT VS so that the complete reuse of Spent Mixed Acid (i.e. 0% emission) can be achieved. This balanced production of HA and VS will be able to achieve several production benefits such as: 37% reuse of Glauber's Salt (67% sold to other industries), reduced freshwater consumption (55% reduction in HA and 7.2% reduction in VS), and reduced acid consumption (45% reduction in HA and 26% reduction in VS). Further, the balanced production of HA and VS will be able to achieve environmental benefits such as a 26% reduction in wastewater generation and a 74% reduction in waste salt sent to engineered hazardous waste management facilities.

Fabrication of a magnetic hydrochar composite via an in situ one-pot hydrocarbonization strategy for efficient herbicide removal

This study explores the feasibility of the production of a new bioproduct from an abundantly available waste material to enhance resource recovery opportunities. A novel magnetic hydrochar was produced via hydrothermal carbonization of pomegranate waste (PW). The hydrothermal carbonization process needs to be optimized, hence we have investigated the effects of residence temperature (RT; 180–220 °C) and residence time (Rt; 6–24 h) on the hydrochar characteristics such as atomic carbon content, energy density and higher heating values. The optimum conditions were determined as 220 °C and 12 h and the synchronous carbonization and magnetization of PW were fulfilled under the aforementioned conditions by a one-step hydrothermal process. This new magnetic material (Fe@PWHC) was featured by exhaustive spectral analyses including XRF, XPS, XRD, SEM/EDX, FTIR, Raman and VSM measurements and then tested for its adsorption ability towards 2,4 dichlorophenoxyacetic acid (2,4-D). The formation mechanism of magnetic hydrochar was elucidated and the plausible uptake mechanism of 2,4-D by Fe@PWHC was also discussed. Freundlich model satisfactorily explains the adsorption process when compared to the Langmuir model. Thermodynamic studies revealed the endothermic spontaneous adsorption of 2,4-D. Good adsorption potential for 2,4-D (qmax: 101.10 mg/g) and easy separable feature of Fe@PWHC reveals that it could be a cost-effective, effectual and green adsorbent for decontamination of 2,4-D bearing water.

Enhanced resource recovery from wastewater using electrochemical-osmotic system with nanofiltration membranes

Mining diverse resources from electroplating wastewater are critical for maximizing wastewater economic value and minimizing adverse environmental impacts. We have demonstrated an autonomous electrochemical-osmotic system (EOS), which can simultaneously recover copper metals, water, and electric energy from electroplating wastewater. In this study, we enhanced water production, electricity generation, and metal recovery of the EOS using polyelectrolyte multilayer nanofiltration (PMNF) membranes instead of the forward osmosis membranes. The PMNF membrane is fabricated by alternately depositing two oppositely charged polymers, poly(diallyldimethylammonium chloride) (PDADMAC, (+)) and poly(sodium 4-styrenesulfonate) (PSS, (−)), on the nanofiltration (NF) membrane substrate. Results suggested that the water/salt selectivity of the PMNF membrane increase to 25.1 L mol−1 with the increase of the number of the polyelectrolyte deposited layers to 6.0. The EOS assembled with a 1.5-layer PMNF membrane achieved a water production rate of 6.06 L m−2h−1 and a maximum power density of 1.18 mW cm−2 by treating synthetic electroplating wastewater, 2.63 and 1.21 times higher than conventional EOS (i.e., FO membrane), respectively. Further, we clarified that the PMNF-EOS effectively inhibited the forward transport of various metal cations (e.g., Cu2+, Cr6+, Zn2+, and Ni2+) while also extracting freshwater, generating power, and recovering copper from electroplating wastewater. Our study provided a new avenue for developing a high-performance EOS to reclaim multiple resources from electroplating wastewater.

Where is the greatest potential for resource recovery in wastewater treatment plants?

The restorative and regenerative ability of the circular economy has led to the rapid growth of this concept over the past decade, as it facilitates the broadly adopted principles of sustainable development and beyond, through restorative and regenerative actions. The water sector is poised to benefit from this transition, due to its intrinsic circularity and the resources it handles, predominantly found in wastewater, that are valuable and critical. Currently, the vast range of resource recovery technologies coupled with few industrial examples hinder strategic decision making. Resource recovery on a regional scale improves market share and mitigates investment risk, therefore, a structured approach has been developed for the selection of priority technologies to act as a guide for strategic planning. A representative UK wastewater model acts as the baseline, with multi-criteria analysis used to select resources and create an enhanced resource recovery scenario. It was found that implementing the recovery of 5 ‘priority resources’ (and technology pathways) increased nitrogen and phosphorus recovery by 68% and 71%, respectively. Lastly, the need for a cross-cutting approach for the holistic assessment of circular solutions is discussed.

Ferric chloride aiding nitrite pretreatment for the enhancement of the quantity and quality of short-chain fatty acids production in waste activated sludge

The production of short-chain fatty acids (SCFAs) via anaerobic fermentation of waste activated sludge (WAS) is often limited with poor quality of SCFAs and long fermentation time. To overcome these issues, we provided an efficient strategy by using ferric chloride (FC) to aid nitrite pretreatment. Experimental results showed that the maximal SCFAs production of 211.3 ± 3.1 mg COD/g VS was achieved with 4 mmol/L of FC integrated with 250 mg/L of nitrite pretreatment on day 5, which was 4.1-fold higher than that of the blank control (52 ± 5 mg COD/g VS, day 7). Besides, the enrichment of acetic acid was observed in the combined system, which accounted for 54.6 ± 3.5% of total SCFAs, while the proportion was only 31.5 ± 4.9% in the blank control. Propionic acid, isobutyric acid, n-butyric acid, n-valeric acid and isovaleric acid accounted for 14.7 ± 1.5%, 6.9 ± 1.4%, 7.4 ± 1.5%, 13.1 ± 1.0%, and 3.3 ± 1.5% of total SCFAs in the combined system and 22.8 ± 4.0%, 11.9 ± 3.0%, 6.7 ± 3.1%, 17.6 ± 2.0%, and 9.5 ± 3.9% of total SCFAs in the blank control, respectively. It was found that soluble proteins and carbohydrates in the combined system were higher than those in the blank control, suggesting that FC and nitrite pretreatment was beneficial for WAS disintegration. The fluorescence spectrum results suggested that FC and nitrite pretreatment improved the biodegradability of released organics, which provided more biodegradable substances for the subsequent SCFAs production. This was because the addition of FC induced the formation of free nitrous acid from nitrite. Besides, FC-induced iron reduction also promoted the conversion of recalcitrant organics to biodegradable organic matter. Microbial community structure analysis demonstrated that the functional bacteria involved in acetogenesis process such as Enterococcus, Proteiniclasticum, and Petrimonas were highly enriched due to the pretreatment of FC and nitrite, indicating this method could improve the relative abundance of SCFAs producers. Overall, this study revealed that the pretreatment of FC and nitrite promoted the formation of free nitrous acid and increased the yield of SCFAs, which provided a novel method for wastewater treatment plants to ameliorate the sewage treatment craft and rationally use the existing substances in WAS to enhance resource recovery.

Enhanced Resource Recovery from Wastewater Using Electrochemical-Osmotic System with Nanofiltration Membranes

Enhanced Resource Recovery from Wastewater Using Electrochemical-Osmotic System with Nanofiltration Membranes

Stepwise freezing-thawing treatment promotes short-chain fatty acids production from waste activated sludge

Waste activated sludge (WAS), as the byproducts of wastewater treatment plants, has been greatly produced. With high cost and environmental risk of WAS disposal, to explore a low-cost and environment-friendly technology has been a great challenge. Considering that WAS is a collection of organic matters, anaerobic fermentation has been selected as a sustainable way to simultaneously recover resources and reduce environmental pollution. To recover short-chain fatty acids (SCFAs) has gained great concern because of the high value-added application and high-efficiency production process. Considering the temperature in some areas of the world can reach to below 0 °C, this study proposed an efficient strategy, i.e., stepwise freezing and thawing treatment, to promote SCFAs production. The maximal production of SCFAs, i.e., 246 mg COD/g volatile suspended solid, was obtained with the shortened retention time of five days. Mechanistic studies showed that the solubilization of both extracellular polymeric substances (EPSs) and microbial cells could be accelerated, with the EPSs removal of 58.3% for proteins and 59.0% for polysaccharides. Also, the hydrolysis process was promoted to provide more substrates for subsequent acidogenisis, and the functional microorganisms, such as Romboutsia, Paraclostridium, Macellibacteroides and Conexibacter, were greatly enriched, with a total abundance of 26.2%. Moreover, compared to control, methanogenesis was inhibited at a shortened sludge retention time (e.g., five days), which benefited to the accumulation of SCFAs, but the methane production was increased by 25.2% at a longer sludge retention time (e.g., ten days). Thus, these findings of this work may provide some new solutions for the enhanced resource recovery from WAS, and further for carbon-neutral operation of wastewater treatment plants.

Hydrothermal carbonization of household wet waste – characterization of hydrochar and process wastewater stream

In the present study, household wet waste (HWW) pretreatment was explored using hydrothermal carbonization (HTC) to enhance resource recovery opportunities. The pretreatment was performed at 200 °C for 1–8 h duration in a 2 L high pressure reactor. After HTC, the recovered solid hydrochar (HC) showed high calorific value of ∼ 27 MJ/kg compared to 18 MJ/kg of HWW. Moreover, it contained significant amount of oxygen containing acidic functional groups, hence the waste derived HC may also be utilized as adsorbent in wastewater treatment and soil conditioner. The process wastewater (PW) contained several value-added organics including proteins and furfurals. The HTC reaction kinetics showed the conversion of HWW to primary HC as the fastest step (rate constant = 0.0126 min−1). Moreover, the biochemical methane potential test on PW revealed generation of significant amounts of biogas with 55–75% methane. The total energy production from HC and PW was estimated as ∼ 3.3 MJ/kg of HWW.