Wastewater recovery for sustainable agricultural systems in the circular economy - A systematic literature review of Life Cycle Assessments.

Water availability and quality are known to affect agricultural production and nutrition. The aim of this study was to elaborate a systematic literature review of the most sustainable ways of wastewater treatment towards achieving circular economy (CE) in agro-industry activities. From the SLR, the authors selected twenty-seven papers that they classified into the three research themes of recovery of wastewater into irrigation water, extraction of sludge for production of bio-based compounds, and recovery of nutrients for soil amendment, including recovering of feeds for aquaculture, and recovery of nutrient biosolids for soil amendment.

Microwave regeneration of granular activated carbon saturated with PFAS.

This study investigated the regeneration of PFAS-saturated granular activated carbons (GACs) by microwave (MW) irradiation. Two commercially available GACs (bituminous coal based GAC [BCGAC] and lignite coal based GAC [LCGAC]) were saturated with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) and then irradiated at different MW conditions (applied power = 125 - 500 W, irradiation time = 3 - 12 min). The performance of MW regeneration for PFOS- or PFOA-saturated GACs was assessed by evaluating the variation of GAC adsorption capacity (regeneration efficiency, RE) and weight loss percentage (WL).

Remediation of petrol hydrocarbon-contaminated marine sediments by thermal desorption.

In this study, a hydrocarbon-contaminated marine sediment was treated applying ex-situ thermal desorption (ESTD) at bench-scale. Temperatures up to 280 °C and heating times (t) in the 5-30 min range were investigated. Results revealed that temperatures in the range 200-280 °C led to Total Petrol Hydrocarbon (TPH)-removal efficiency (RE) from 75 to 85% (t = 10 min).

Microwave based regenerating permeable reactive barriers (MW-PRBs): Proof of concept and application for Cs removal.

The present study evaluates the concept of permeable reactive barrier (PRB) coupled with microwaves (MWs) as in situ-regenerating technology with focus on Cs-contaminated water. Experimental and modelling results data from batch and column tests were carried out, evaluating several chemical-physical and environmental parameters. Main results showed a very rapid increase in GAC temperature during MW irradiation up to ∼680 °C.

Field technical applicability and cost analysis for microwave based regenerating permeable reactive barriers (MW-PRBs) operating in Cs-contaminated groundwater treatment.

The present study tests the potentiality of a novel microwave based regenerating permeable reactive barrier (MW-PRB) system as combined treatment for Cs-contaminated groundwater. Granular activated carbon (GAC) was selected as adsorptive materials in batch and column MW-regeneration experiments. Experimental and modeling data were elaborated for technical and economic considerations in order to assess the MW-PRB feasibility jointly with essential information regarding its real field applicability.

Removal of poly- and perfluoroalkyl substances (PFAS) from water by adsorption: Role of PFAS chain length, effect of organic matter and challenges in adsorbent regeneration.

Poly- and perfluoroalkyl substances (PFAS) are a wide group of environmentally persistent organic compounds of industrial origin, which are of great concern due to their harmful impact on human health and ecosystems. Amongst long-chain PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are the most detected in the aquatic environment, even though their use has been limited by recent regulations. Recently, more attention has been posed on the short-chain compounds, due to their use as an alternative to long-chain ones, and to their high mobility in the water bodies.

Environmental Life Cycle Assessment of marine sediment decontamination by citric acid enhanced-microwave heating.

The potential ability of microwave heating (MWH) for the remediation of marine sediments affected by severe hydrocarbon (HC) contamination was investigated. Decontamination effectiveness and environmental sustainability through a comparative Life Cycle Assessment (LCA) were addressed. Main results revealed that the application of a 650-W MWH treatment resulted in a rapid (15min) HC removal.

Application of a γRS index-based method and techno-economic analysis for in situ treatment of Cs-contaminated soils by cement-barite based stabilisation/solidification.

This paper examines the application of cement (C)-barite (Ba) based-Stabilisation/Solidification (S/S) for the remediation of Cs-contaminated soils, investigating the influence of soil: grout and C: Ba ratios on the shielding performance of the S/S mix assessed as gamma radiation shielding (γRS) index variation. Results from experiments were used to perform a novel approach and an economic analysis in order to calculate the effective dose reduction achievable by S/S and to assess the optimum quantities and costs of selected mixes, respectively. Gamma ray spectrometer measurements indicate that γRS index increases with increasing barite percentage up to a maximum level of 50%; however a further increase results in a worsening of the shielding performances.

Stabilisation/solidification of Cs-contaminated soils using novel high-density grouts: γ-ray shielding properties, contaminant immobilisation and a γRS index-based approach for in situ applicability.

In this work, γ-ray shielding and Cs immobilisation performances of high-density magnetite (MG) and iron powder (IP) in Portland cement (PC) based-S/S treatment were investigated. Experimental results were elaborated using a γ-radiation shielding (γRS) index-based approach for assessing the effectiveness of in situ S/S of Cs-contaminated soils. Main results reveal that the replacement of PC by MG or IP (up to 50%) leads to a marked increase (up to about 4-fold) in the γ-ray shielding performance, whereas a further material addition decreases the S/S shielding performance.

Lab-scale investigation on remediation of diesel-contaminated aquifer using microwave energy.

Aquifer contamination with diesel fuel is a worldwide environmental problem, and related available remediation technologies may not be adequately efficient, especially for the simultaneous treatment of both solid and water phases. In this paper, a lab-scale 2.45 GHz microwave (MW) treatment of an artificially diesel-contaminated aquifer was applied to investigate the effects of operating power (160, 350 and 500 W) and time on temperature profiles and contaminant removal from both solid and water phases.

Performance study and influence of radiation emission energy and soil contamination level on γ-radiation shielding of stabilised/solidified radionuclide-polluted soils.

This work focuses on the stabilisation/solidification (S/S) of radionuclide-polluted soils at different (232)Th levels using Portland cement alone and with barite aggregates. The potential of S/S was assessed applying a full testing protocol and calculating γ-radiation shielding (γRS) index, that included the measurement of soil radioactivity before and after the S/S as a function of the emission energy and soil contamination level. The results indicate that setting processes are strongly dependent on the contaminant concentration, and for contamination level higher than 5%, setting time values longer than 72 h.