Mouldboard ploughing has been associated with a loss in soil quality, while reduced tillage is often reported to result in crop yield declines. Occasional ploughing every few years could be an attractive compromise, but it remains unclear whether such a system results in a combined benefit of improved crop yield and soil quality. Here, we present data from a 43-year old field experiment on a clay soil in central Sweden. We analysed how three different tillage systems – annual mouldboard ploughing, continuous shallow tillage, and shallow tillage with occasional mouldboard ploughing – affect crop yields and soil properties with the objective of assessing joint response patterns between crop production and soil quality indicators reflecting soil structure, soil organic carbon storage, and habitat for soil biota. Crop yields were not affected by the tillage systems. Characteristics of the soil pore system and soil biota were similar in the occasional ploughing and annually mouldboard ploughed systems. Shallow tillage significantly altered microbial community composition relative to ploughed treatments, increasing bacterial and fungal abundances and reducing diversity in the upper topsoil layer, likely due to stratified soil carbon stocks. There was also a higher proportion of biopores in shallow tillage, which could be advantageous during dry spells that are expected to become more frequent and severe with climate change. Nevertheless, there were only small effects on water retention, biomass of nematodes and earthworms, and most of the abiotic soil properties. We conclude that occasional ploughing did not offer advantages at our site, and our results show that no system improved yield and all soil quality indicators simultaneously.
Biochar were synthesised from wood biomass via slow pyrolysis at temperatures of 400, 500, and 600°C, denoted B400, B500, and B600, and evaluated for their capacity to remove Pb, Cu, and Zn from aqueous solutions. The investigation assessed the influence of pyrolysis temperature on biochar yield, physicochemical and chemical properties, pore development, and adsorption performance for these metals. Analytical techniques included proximate and ultimate analyses, Brunauer–Emmett–Teller (BET) surface area measurements, scanning electron microscopy (SEM), and batch adsorption experiments. Increasing pyrolysis temperature enhanced pore development and adsorption capacity while reducing biochar yield. The BET surface area increased from 50.7 m2/g in the feedstock to 265.2 m2/g for B600, with a corresponding rise in micropore volume from 0.03 to 0.13 cm3/g. SEM analysis revealed that higher temperatures promoted greater pore volume and induced structural modifications in the biochar. Adsorption equilibrium was achieved within 180–240 min, with biochar produced at 600°C (B600) demonstrating the highest performance. At pH 8, maximum removal efficiencies were approximately 90–95% for Pb, 85–90% for Cu, and 90–95% for Zn, corresponding to adsorption capacities of 4–5 mg/g for Pb and 3–4 mg/g for Cu and Zn. The adsorption efficiency order was Pb > Cu > Zn. Adsorption data closely fit the Langmuir isotherm model (R2 ≈ 0.99), indicating monolayer adsorption on a uniform surface. Comparisons between pilot-scale Woodtek biochar (WTB) and laboratory-scale biochar (LSB) produced at 600°C showed comparable adsorption efficiencies and capacities. These findings suggest that scaling up biochar production does not compromise its effectiveness in removing heavy metals from water. Overall, the results highlight the potential of wood-derived biochar for large-scale remediation of heavy metals in contaminated water systems.
Iron (Fe)-based oxygen carriers (OCs) have been widely investigated for chemical looping gasification (CLG); however, most previous studies have focused on steam-assisted conversion of raw biomass in fluidised-bed systems, where devolatilisation, tar formation, char gasification, and OC redox cycling occur simultaneously, complicating interpretation of individual reaction steps. In particular, CO2 char gasification, a key rate-limiting reaction governing syngas composition and carbon conversion efficiency (CCE), remains insufficiently understood for Fe-based OC systems. In this study, biochar is deliberately employed as a model carbon feedstock to decouple char gasification from biomass pyrolysis and tar-related phenomena, enabling focused investigation of OC-carbon interactions under CO2-rich fixed-bed chemical looping conditions. The effects of operating temperature (700–900 °C), oxygen carrier-to-biochar (OC:BC) mass ratio (1:1–20:1), and metal doping of Fe-based OCs with cerium (Ce), cobalt (Co), nickel (Ni), lanthanum (La), and strontium (Sr) were evaluated under CO2 gasification conditions, using a fixed Fe-Al-Me (70:20:5) formulation to enable orderly comparison of dopant effects under reaction-limited conditions.The results demonstrate that temperature strongly influences gasification performance, with limited CCEs of approximately 10 wt% at 700 °C for both biochar (BC) and Fe2O3-biochar (Fe-BC) mixtures. Substantial improvements were observed at higher temperatures, with CCEs of 33.8 wt% and 50.4 wt% obtained for BC and Fe-BC at 800 °C, respectively, while further increases to 57.0 wt% and 94.0 wt% were achieved at 900 °C. Optimal gasification performance exceeding 90 wt% CCE was obtained at OC:BC of 5:1 and 10:1 at 900 °C over 120-minutes. At 800 °C, Al2O3-supported Fe2O3 exhibited lower gasification activity (46.4 wt% CCE) than unsupported Fe2O3 (54.7 wt% CCE), but showed enhanced structural stability as evidenced by post-reaction characterisation. La modification significantly enhanced Fe-Al OC performance, increasing CCE from 46.4 wt% to 62.8 wt%, whereas Ni doping produced no substantial improvement compared to undoped Fe-Al. XPS analysis indicated that dopant addition modified the surface oxygen environment without fundamentally altering the Fe2O3-based redox chemistry, suggesting that differences in gasification performance were associated with oxygen exchange behaviour rather than changes in the dominant Fe redox pathway. Short-term three-cycle testing of Fe-Al-La indicated retention of gasification activity following successive gasification-reoxidation treatments, demonstrating moderate stability under the conditions investigated.
Compact and efficient absorption refrigeration systems can effectively utilize industrial waste heat and renewable energy through microchannel membrane-based generator. Hydrophobic membrane plays a vital role within the generator. The effect of membrane hydrophobicity on the dynamic behavior of bubble was studied by numerical simulation. It was found that the bubble venting process can be divided into four stages: bubble growth, liquid film rupture and bubble deformation, alternating spreading and contracting movements, and stable bubble removal. In the second stage, after the bubble contacts the membrane, it primarily exhibits spreading behavior, with obvious venting behavior not occurring immediately. As membrane hydrophobicity increases, the fourth stage gradually disappears. During the venting process, an increase in bubble volume within the microchannel (such as due to higher wall superheat, increased wall hydrophobicity, or a greater number of bubbles) alters the frequency and amplitude of bubble movement within the above-mentioned stages. However, it does not significantly change the overall movement pattern. An increase in the inlet Reynolds number facilitates bubble removal but also reduces the bubble's residence time in the microchannel. Therefore, determining the optimal inlet Reynolds number is essential. Compared to hydrophobic membrane, superhydrophobic membrane exhibit higher exhaust efficiency.
