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Plastic pollution caused by mulching film residues (MFRs) is escalating in arable lands, which affects the function of agricultural ecosystems, and poses a serious obstacle to agricultural sustainable development in arid regions. Internationally, increasing recycling rate of polyethylene (PE) film and adopting biodegradable films are recommended strategies to mitigate plastic pollution in farmland, aiming to increase agricultural sustainability and food security. However, impacts of the future of these strategies remain underexplored. This study estimated MFRs accumulation over the next 50 years under varying PE and polybutylene adipate terephthalate (PBAT) film recovery scenarios: no recovery, and recovery rates increased to 80%, 85%, 90%, and 95%. Additionally, cumulative ecological effects (CEEs) of MFR pollution were assessed based on historical MFRs accumulations of 75 kg hm−2, 160 kg hm−2, 220 kg hm−2, 300 kg hm−2, and 400 kg hm−2, by evaluating direct and indirect ecological effects. The findings revealed that (1) with no recovery, PE film residues could increase by 480 kg hm−2, whereas achieving a 95% recovery rate could limit residues increasing to below the national threshold of 75 kg hm−2, outperforming the 80%, 85%, and 90% recovery rates. On the other hand, using PBAT film would maintain the increasing MFRs below 75 kg hm−2 regardless of recovery rate. (2) Without PE film recovery, CEEs would intensify significantly, as both the direct and indirect effects increase notably, while the CEEs of MFRs could maintain the current status or decrease under the strategy of 95% recovery rate of PE film and using PBAT film, similar to the variation of direct effects. However, indirect effects would persist due to ongoing microplastics (MPs) and phthalate esters (PAEs) released from residual films. Overall, a 95% PE film recycling rate and PBAT film usage emerged as particularly effective strategies for minimizing MFRs accumulation and mitigating ecological impacts over the next 50 years. Further research should prioritize the indirect ecological effects of MFRs, given their persistence despite reduction efforts. The results could provide a theoretical support for agricultural sustainable development in arid regions. [ABSTRACT FROM AUTHOR]

The use of natural agro-industrial materials as suspended fillers (SFs) in floating treatment wetlands (FTWs) to enhance nutrient removal performance has recently been gaining significant attention. However, the knowledge concerning the nutrient removal performance enhancement by different SFs (alone and in mixtures) and the major removal pathways is so far inadequate. The current research, for the first time, carried out a critical analysis using five different natural agro-industrial materials (biochar, zeolite, alum sludge, woodchip, flexible solid packing) as SFs in various FTWs of 20 L microcosm tanks, 450 L outdoor mesocosms, and a field-scale urban pond treating real wastewater over 180 d. The findings demonstrated that the incorporation of SFs in FTWs enhanced the removal performance of total nitrogen (TN) by 20–57% and total phosphorus (TP) by 23–63%. SFs further enhanced macrophyte growth and biomass production, leading to considerable increases in nutrient standing stocks. Although all the hybrid FTWs showed acceptable treatment performances, FTWs set up with mixtures of all five SFs significantly enhanced biofilm formation and enriched the abundances of the microbial community related to nitrification and denitrification processes, supporting the detected excellent N retention. N mass balance assessment demonstrated that nitrification-denitrification was the major N removal pathway in reinforced FTWs, and the high removal efficiency of TP was attributable to the incorporation of SFs into the FTWs. Nutrient removal efficiencies ranked in the following order among the various trials: microcosm scale (TN: 99.3% and TP: 98.4%) > mesocosm scale (TN: 84.0% and TP: 95.0%) > field scale (TN: −15.0–73.7% and TP: −31.5–77.1%). These findings demonstrate that hybrid FTWs could be easily scaled up for the removal of pollutants from eutrophic freshwater systems over the medium term in an environmentally-friendly way in regions with similar environmental conditions. Moreover, it demonstrates hybrid FTW as a novel way of disposing of significant quantities of wastes, showing a win-win means with a huge potential for large-scale application. [Display omitted] • Natural agro-industrial materials facilely incorporated into floating wetlands for enahanced nutrient removal. • A combined natural agro-industrial materials system improved N and P removal to an acceptable level. • Combination of various substrates enriched nutrient-related genera and improved micribial diversity. • Microbial action was the major mechanism for N removal from wastewater. • Hybrid FTW facilely up-scaled to eliminate N and P from eutrophic pond water. [ABSTRACT FROM AUTHOR]