Search Results (41)

In the last 32 years (1993–2024), the application of electric fields in soil management (soil electrokinetic, SEK) has undergone several stages of optimization and intensification. SEK has used both alternating current (AC) and direct current (DC). Numerous fields, including agriculture, sedimentation, phosphorus management in soil and sludge, fertilizer production, consolidation, reclaiming salt-affected soils, metal extraction, dewatering, remediation of contaminated soil (both organic, such as PFAS, and inorganic, such as heavy metals), and soil nutrient availability, have utilized the SEK concept. Numerous innovations were included in the SEK equipment’s design or combined with other biological, chemical, and physical processes. While we recently published a review article on soil electrokinetic/electroosmosis–vacuum systems for sustainable soil improvement and contaminant separation, the current study illustrates the role of applying the pressure-assisted soil electrokinetics technique and shows the effect of the opposite technique. Four points were used to show the function of pressure-assisted soil electrokinetics based on our analysis of six search engines from 1993 to 2024 (the previous 32 years), including (1) polluted soil remediation, (2) dewatering, (3) soil improvement, and (4) making soil ready for electrokinetic action by applying pressure. In contrast to other intensification methods (such as reverse polarity, pulsed electric field, and design change), we found very few publications addressing pressure-assisted soil electrokinetics throughout the literature search. Most investigations focused on the dewatering mechanism, despite the paucity of relevant papers. In contrast to conventional electrokinetic remediation, pump-assisted electrokinetic-flushing remediation increased the removal efficiencies of Cs⁺ and Co²⁺ from contaminated soil by 2% and 6%, respectively. Additionally, the results demonstrated that the pressured electro-osmotic dewatering approach outperformed the conventional electrokinetic techniques. At 40 kPa, hydraulic conductivity was reduced four-fold by electro-rehabilitation for alternative fuels, while at 100 kPa, it was reduced three-fold. It was also observed that pressure may be used to achieve the soil ready for electrokinetic action in order to guarantee proper operation. Since there are not many articles on the subject, future research may examine how pressure-assisted soil electrokinetics can be integrated with vacuum systems, reverse polarity mode, pulsed electric field mode, modifying the SEK design, overcoming the formation of cracks, etc. Full article

Mining activities often result in ecosystem degradation and landscape destruction. The restoration of abandoned mine lands is particularly challenging due to the poor physicochemical properties and low fertility of the soil, which necessitate the use of soil amendments. Sewage sludge, which contains abundant nutrients, has potential for use in mine soil restoration. Four separate piles of sewage sludge, each weighing 5 tons, were subjected to aerobic composting and then applied at different rates (0%, 2%, 5%, 10%, and 20%) to reclaim an abandoned mine land site (500 m²). During the composting process, the pH, moisture content, organic matter (OM), and dissolved organic matter (DOM) of the sewage sludge all decreased, while electrical conductivity (EC) and germination index (GI) increased. The sewage sludge compost reached maturity after 83 days. Soil pH and bulk density decreased with increasing application levels, whereas soil fertility, such as OM, alkali-hydrolyzable nitrogen, available phosphorus (AP), and available potassium (AK), significantly improved after application of sewage sludge compost. Vegetation coverage (ryegrass and alfalfa) reached 100% after 2 months at the 20% application level. Fresh biomass and plant height were significantly higher at all application levels compared to the control (p < 0.05). Results from Pearson’s correlation, redundancy analysis (RDA), and the random forest model indicated that soil fertility, particularly AP, OM, and alkali-hydrolyzable nitrogen, rather than soil physicochemical properties, was the key factor influencing the restoration success of the mine site. The use of sewage sludge compost as a soil amendment for reclaiming abandoned mine lands is feasible and can help reduce the ecological restoration costs of mining. Full article

This study aimed to conduct an ecotoxicological assessment of soils reclaimed with waste, assessing the treatments’ impacts on both plants and the soils themselves. The reclamation experiment was conducted on the former sulfur mine “Jeziórko”. A microplot experiment was established on a slightly clayey sand to assess the possibilities of different technologies for applying mineral wool to degraded soil. The highest toxicity level was observed in the unreclaimed degraded soil. The M index value was 200%, indicating the death of half of the test organisms. At the same time, root growth inhibition reached 75%, indicating significantly limited root system development. The addition of lime and mineral fertilizers contributed to a slight reduction in toxicity—M = 250%, GI = 50%. Application of sewage sludge at a dose of 100 Mg·ha⁻¹ significantly reduced environmental toxicity—M decreased to 333.3% and 500%, and GI to 35% and 10%, respectively. The addition of mineral wool resulted in further improvement. The best results were achieved in the variant where the soil was enriched with lime, sewage sludge and a large volume of mineral wool (400 m³·ha⁻¹). The GI and M levels indicate that, in this variant, soil toxicity was practically eliminated. Full article

Wastewater is a sustainable water supply which uses reclamation and reuse processes to protect freshwater resources. Biochar application is considered an efficient and low-cost wastewater reclamation and reuse technique in recent years. From this perspective, this paper mainly aimed to obtain reclaimed water using biochar application, with an aim of contributing to a circular economy. The major aim of this study was to assess the quality and reuse potential of treated water through the biochar adsorption process. The assessment was based on the EU (741/2020) wastewater reuse legislation. Turbidity, Biological Oxygen Demand (BOD₅), Total Suspended Solid (TSS), and E. coli analyses were performed to determine the effluent quality. In the end of the biochar adsorption process, a Class B reclaimed water quality according to EU legislation was obtained. This study validated that malt-dust-derived biochar is an efficient and low-cost adsorbent and can achieve a high quality of reclaimed water. An average reduction of 31.3% in operational costs was reported compared to an activated sludge system. Full article

Fly ash does not contain organic matter to initiate soil-forming processes and the proper development of plant cover. Therefore, in the reclamation of fly ash landfills, an integrated approach is required, including the introduction of exogenous organic matter into the top layer of ash. This study assessed changes in the content and quality of organic matter in soils developing on a reclaimed fly ash landfill. This study included reclaimed areas without the introduction of EOM (RV_1—the direct introduction of plants) and with the introduction of EOM (RV_2—surface humus and RV_3—sewage sludge). In samples taken 15 years after reclamation, the contents of total organic carbon (TOC) and total nitrogen (TN), the fractional composition of organic matter, the susceptibility of organic matter to oxidation, and soil carbon management indices (carbon pool index (CPI), C lability (L), lability index (LI), and carbon management index (CMI)) were determined. The study results showed that the use of EOM in the reclamation of the ash dump significantly increased the content and improved the quality parameters of organic matter and thus influenced the initiation of the process of organic matter accumulation. In RV_1 soil, the accumulation of carbon resources was only found in the topsoil. An increase in carbon resources in the 15–40 cm layer was only noted in the variants in which EOM was introduced (RV_2 and RV_3). Carbon management indices showed that organic matter transformations covered only the top layers of these soils and were closely related to the EOM inflow. The interdependence of the CPI and L was most beneficial in the soil reclaimed with sewage sludge. In the soil of this reclaiming variant, the CMI had a value above 100, which indicates the initiation of the soil-forming process. Significant differences between the assessed reclamation variants were confirmed by means of PCA based on organic matter quality indicators. The organic matter content and quality indicators were the most favorable in the soil of variant RV_3. The obtained results confirmed that the introduction of EOM into the top layer of fly ash has a beneficial effect on the accumulation and quality indicators of organic matter and thus on the development of the soil-forming process in Technosols developing on a reclaimed fly ash landfill. Full article

Synchronously recovering phosphorus as vivianite and humic acids (HAs) from waste activated sludge (WAS) is of great significance for the carbon neutralization of wastewater. In this study, flocculation, enzyme degradation (lysozyme/protease/amylase/cellulase in a 1:1:1:1 ratio), and pH adjustment were used to reclaim vivianite and HAs. After FeCl₃ coagulation–precipitation and enzymatic hydrolysis of the sludge for 11 h, the supernatant was enriched with Fe²⁺ and PO₄³⁻, with the molar ratio of Fe²⁺:PO₄³⁻ of 2.21. To improve the purity of the vivianite, the crude protein was separated at pI 6.0. The purity of the crystals reached a peak of 97.44 ± 0.04% at pH 7.5. HAs extracted from the residuals had a high affinity for metal adsorption, and the adsorption process was both endothermic and efficient. Overall, this study demonstrates the feasibility and effectiveness of the joint reclaiming of vivianite and HAs, providing new insights into multiple resource recovery from WAS. Full article

Many pharmaceuticals (PhMs), compounds for the treatment or prevention of diseases in humans and animals, have been identified as pollutants of emerging concern (PECs) due to their wide environmental distribution and potential adverse impact on nontarget organisms and populations. They are often found at significant levels in soils due to the continuous release of effluent and sludge from wastewater treatment plants (WWTPs), the release of which occurs much faster than the removal of PhMs. Although they are generally present at low environmental concentrations, conventional wastewater treatment cannot successfully remove PhMs from influent streams or biosolids. In addition, the soil application of animal manure can result in the pollution of soil, surface water, and groundwater with PhMs through surface runoff and leaching. In arid and semiarid regions, irrigation with reclaimed wastewater and the soil application of biosolids are usual agricultural practices, resulting in the distribution of a wide number of PhMs in agricultural soils. The ability to accurately study the fate of PhMs in soils is critical for careful risk evaluation associated with wastewater reuse or biosolid return to the environment. The behavior and fate of PhMs in soils are determined by a number of processes, including adsorption/desorption (accumulation) to soil colloids, biotic (biodegradation) and abiotic (chemical and photochemical degradation) degradation, and transfer (movement) through the soil profile. The sorption/desorption of PhMs in soils is the main determinant of the amount of organic chemicals taken up by plant roots. The magnitude of this process depends on several factors, such as crop type, the physicochemical properties of the compound, environmental properties, and soil–plant characteristics. PhMs are assumed to be readily bioavailable in soil solutions for uptake by plants, and such solutions act as carriers to transport PhMs into plants. Determining microbial responses under exposure conditions can assist in elucidating the impact of PhMs on soil microbial activity and community size. For all of the above reasons, soil remediation is critical when soil pollutants threaten the environment. Full article

This work concerns the assessment of soil reclamation and its impact on biological life in areas destroyed by the sulfur industry in Jeziórko. Sulfur extraction using the borehole method causes enormous destruction to the soil environment. Among the many forms of degradation, the most pronounced are the chemical transformations of the environment and the disturbances in water relations in large areas, which could theoretically impact areas not within the direct range of the mining plant. This work aimed to assess the condition of biological life in soil reclaimed with waste in areas devastated by the sulfur industry in Jeziórko. The reclamation of these soils was difficult but necessary due to the complete disappearance of biological life. Appropriate actions were taken to restore and improve the properties of the soil, which resulted in an improvement in their production capacity. Reclamation was carried out, among other techniques, by deacidifying the soil using post-flotation lime and fertilizing the soil with municipal sewage sludge and post-use mineral wool. Studies have shown an improvement in many soil properties, such as its physical, water, chemical, and biological properties. The implemented reclamation methods significantly influenced, among other things, the density and water properties of the degraded soil. The soil reclaimed with mineral wool and sewage sludge recorded the highest density and water capacity. Applying mineral wool to the degraded soil influenced the changes in the analyzed physical and water properties. The obtained research results also show the beneficial effect of mineral wool and sewage sludge on the increase in organic carbon content. In the soil treated with these substances, the organic carbon content ranged from 13.60 g·kg⁻¹ to 14.30 g·kg⁻¹. It is shown that reclamation has had a considerable impact on and is essential for biological life in Jeziórko. Full article

Waste Cooking Oil (WCO), Soy Oil (SO), and Wastewater Sludge (WWS) have great potential to increase reclaimed asphalt pavement (RAP) content for economic and environmental benefits. This study explored the effects of SO and WCO on rutting, fatigue cracking, and low-temperature cracking performance of binders and Hot Mix Asphalt (HMA) with high RAP content. The potential effect of WWS on the performance and compaction efforts of high RAP content mixes at a 10 °C (50 °F) lower compaction temperature than the control compaction temperature was also investigated. The results indicated that 85% of the RAP binders can be incorporated while maintaining similar performance compared to the control by using 15% SO or 12.5% WCO as a rejuvenator with 2.5% virgin binder. Adding 1% WWS by weight of the total binder improved the binder’s rheological properties, the mix’s cracking performance, and the mix’s density at lower compaction temperatures. Full article

The irrigation of soils with reclaimed contaminated wastewater or its amendment with sewage sludge contributes to the uptake of pharmaceuticals by vegetables growing in the soil. A multiresidue method has been devised to determine five pharmaceuticals and nine of their main metabolites in leafy and root vegetables. The method employs ultrasound-assisted extraction, clean-up via dispersive solid-phase extraction, and analysis through liquid chromatography–tandem mass spectrometry. Box–Behnken design was used to refine variables such as extraction solvent volume, time of extraction, number of extraction cycles, and the type and amount of d-SPE sorbent. The method achieved linearity (R²) greater than 0.994, precision (relative standard deviation) under 16% for most compounds, and detection limits ranging from 0.007 to 2.25 ng g⁻¹ dry weight. This method was applied to a leafy vegetable (lettuce) and to a root vegetable (carrot) sourced from a local market. Parent compounds were detected at higher concentrations than their metabolites, with the exception of carbamazepine-10,11-epoxide. Full article

Phosphorus (P) recovery from wastewater is considered to be a positive human intervention towards sustainable P use in the global P cycle. This study investigated the feasibility of synthesizing a superparamagnetic nano-sorbent that was functionalized by lanthanum silicate nanorods (NR_La-Si) using drinking water treatment sludge (DWTS), evaluating both its P adsorption capacity and fertilization effect. The DWTS-based La-modified P nano-sorbent (P-sorbent _D) exhibited complicated but single-layer-dominant adsorption for phosphate, with a maximum adsorption capacity up to 26.8 mg/g, which was superior to that of most of the similar sludge-based P-sorbent. The NR_La-Si-modified P-sorbent _D was identified with several characterization techniques and the leaching metal elements from the nano-sorbent were tested, which were below the limits proposed by the Food and Agriculture Organization of the United Nations. In addition, the growth and vigorousness of Arabidopsis thaliana indicated that the exhausted P-sorbent _D could be used as a potential water-soluble moderate-release P fertilizer, which was also confirmed by the well-fitted P uptake model and the P desorption pattern from the sorbent–fertilizer. The doped lanthanum silicate nanorods could play the dual role of P complexation enhancement and health/growth promotion. In light of this, this study proposed a new way of reclaiming DWTS as a P-sorbent for fertilization, offering new insights into the path toward “closing the P loop”. Full article

Rivers in Africa have experienced dire pollution as a result of the poor management of wastewater effluent emanating from water resource recovery facilities (WRRFs). An integrated wastewater resource recovery model was developed and applied to identify ideal wastewater resource recovery technologies that can be used to recover valuable resources from a mixture of wastewater effluents in a case study in the Burgersfort WRRF in the Limpopo province, South Africa. This novel model incorporates the process of biological nutrient removal (BNR) with an extension of conventional methods of resource recovery applicable to wastewater. The assessment of results of effluent quality from 2016 to 2022 revealed that ammonia, chemical oxygen demand, total coliform, fecal coliform, and Escherichia coli levels were critically non-compliant with the permissible effluent guidelines, indicating a stable upward trend in terms of concentrations, and scored a very bad wastewater quality index rating. All variables assessed showed a significant loading, except for orthophosphates, and significant correlations were observed among the variables. The results of the integrated wastewater resource recovery model revealed a high probability of reclaiming recoverable resources such as nutrients, sludge, bioplastics, biofuel, metals, and water from wastewater, which have economic, environmental, and social benefits, thereby improving the effluent quality of a WRRF. Full article

Knowledge regarding how abiotic and biotic environmental factors operate in soil microbiome reassembly remains rudimentary in coastal saline–alkaline soils amended by different organic ameliorants. In this study, field trials were conducted to investigate the impacts and underlying mechanisms of sewage sludge (S) and sludge-based vermicompost (V) at the application amounts of 0, 50, and 100 t ha⁻¹ on soil physicochemical characteristics, carbon source utilization pattern, and bacteriome in coastal saline–alkaline soils. Results revealed that impacts of the organic ameliorants on soil’s physicochemical and microbial attributes were highly dependent upon the carbon types and amounts applied. Unsurprisingly, applying sewage sludge and vermicompost significantly alleviated environmental constraints, such as saline–alkaline stress and nutrient deficiency, with lower pH, salinity, and higher soil organic carbon content observed in organics-amended soils. Specifically, higher microbial substrate metabolic activity, but lower diversity was observed in saline–alkaline soils amended by organic ameliorants. In addition, reassembled bacteriomes harboring distinguishable core and unique community profiles were observed in reclaimed soils as compared to unamended saline–alkaline soil. Procrustes analysis showed that the soil microbial utilization pattern of carbon sources was significantly related to the alterations in their physicochemical property and bacterial core microbiome. Additionally, Redundancy Analysis (RDA) revealed that soil core bacteriome reassembly was dominated by the integrated impacts of soil salinity, successively followed by carbohydrates, amino acids, polymers, pH, soil organic carbon (SOC), and available nitrogen (AN). Overall, this study provides a comprehensive understanding of soil abiotic and biotic determinants in bacteriome assembly in coastal saline–alkaline soil remediation mediated by organic ameliorants. Full article

In recent decades, the international community has recognized the detrimental impact of the construction industry on the environment. In recent years, the use of recycled aggregates has attracted increasing interest as a sustainable and cost-effective solution for the construction and maintenance of road pavements. The life cycle assessment (LCA) represents a valuable methodology for evaluating the environmental sustainability of technologies involving the use of such materials. This study deals with the LCA of alternative solutions for the construction and maintenance of unpaved rural roads. Different scenarios using recycled materials, such as reclaimed asphalt and mineral sludge, are analyzed and compared to a reference solution that employs only virgin aggregates. The environmental sustainability of the proposed alternatives is assessed by considering the global warming potential (GWP), energy requirements, and water consumption. The LCA analysis is performed using SimaPro software (version 9.1.1.7). The obtained results demonstrate that solutions involving the use of recycled materials represent a more sustainable and environmentally friendly option. In particular, a significant reduction in water depletion was found for the alternative scenarios, with savings between 56% and 99%. For GWP and energy, the total savings ranged from approximately 20% to 40%. Full article

In recent years, promising developments in the hydrothermal carbonization (HTC) of sewage sludge, as well as the potential to reclaim phosphorus and nitrogen, have emerged. In this study, the HTC of digested sewage sludge (DSS) was investigated for the downstream production of heavy metal (HM)-free fertilizer and the use of freeze concentration (FC) as a novel technology for process water treatment. To obtain clean fertilizer, phosphatic acid extracts were first treated with ion-exchange resins to remove dissolved HM, as well as phosphorus precipitating agents (i.e., aluminum and iron). Over 98% of the aluminum (Al) and 97% of the iron (Fe) could be removed in a single treatment step. The purified extract was then used for the precipitation of HM-free struvite crystals, with P-recovery rates exceeding 89%. Process water (PW) makes up the largest share of the two main HTC-products (i.e., hydrochar and PW) and is very rich in organic compounds. Compared to evaporation or membrane separation, FC is a promising technology for concentrating solutes from PW. Separation experiments resulted in the recovery of over 90% of the dissolved compounds in the concentrate. In our study, the concentrate was later utilized as an ammonium source for struvite precipitation, and the subsequent aerobic digestion of the remaining ice water resulted in an 85% reduction in chemical oxygen demand (COD) in 15 days. Full article