Waste

The juice industry generates substantial quantities of solid waste and wastewater. Consequently, efforts have focused on their treatment and valorization to obtain high-value-added products. Traditionally, these wastes are managed through landfill disposal and treatment in municipal wastewater facilities, respectively. In the present work, two alternative scenarios for the valorization of orange juice waste were developed and assessed in comparison to the conventional approach by performing a Life Cycle Assessment (LCA). Scenario 1 involved hydro-distillation of solid waste for essential oil recovery, followed by anaerobic digestion for biogas and fertilizer production, with wastewater treated via membrane filtration and chlorination. In Scenario 2, solvent-free microwave extraction (SFME) was employed for essential oil recovery, followed by anaerobic digestion. Wastewater was treated in a membrane bioreactor followed by ultraviolet treatment. According to the results, Scenario 1 achieved a 36% reduction in greenhouse gas emissions due to the beneficial effects of biogas and fertilizer production, despite its high energy demands. Scenario 2 exhibited the best environmental performance due to lower energy demands and higher extraction efficiency compared to Scenario 1, with reductions of 46% in greenhouse gas emissions and 48% in resource depletion. Overall, the findings highlight the potential of integrating innovative, energy-efficient technologies for the sustainable valorization of juice industry waste, offering measurable environmental advantages for industrial-scale implementation.

Advanced phosphorus (P) recycling from wastewater is critical for improving nutrient circularity and reducing soil pollution associated with the direct application of sewage sludge in agriculture. However, few studies evaluate the long-term environmental and economic trade-offs between recycled P products and raw sewage sludge application. This study compares struvite, vivianite, and dicalcium phosphate (CaP) as P alternatives to sludge to mitigate heavy metal accumulation in Spanish agricultural soils. Using data from 27,835 plots, heavy metal accumulation was simulated over 50- and 100-year fertilisation scenarios. The results indicate that continuous sludge application leads to widespread exceedances of zinc, copper, and cadmium, especially in alkaline soils, whereas substitution with recycled products can substantially reduce these risks. Vivianite balances P recycling and costs, CaP offers the best environmental performance but with higher investment, and struvite suits smaller regions prioritising environmental safety. Economic analysis favours advanced recycling over sludge, especially considering externalities such as soil remediation costs. Despite limitations, our findings emphasise the importance of integrating environmental externalities into economic assessments and the value of advanced P recycling for sustainable soil management.

The utilization of Solid Waste Compost (SWC) as an organic fertilizer (OF) in agriculture has garnered significant attention in recent years due to growing concerns about worsening waste management issues. This empirical study investigates paddy farmers’ perceptions of SWC under Sri Lanka’s organic farming policy and uniquely addresses its underexploited potential as an organic fertilizer. Data were collected from 254 respondents in the Attanagalla Divisional Secretariat Division via a structured questionnaire. Nine key performance indicators were established to evaluate SWC against other organic fertilizers considered for the study. Findings revealed that meeting the ‘required quantity’ OF was the most challenging aspect (91%) for organic paddy cultivation, while only 14.2% of paddy farmers were able to utilize SWC for paddy fields due to limited availability. Farmers appreciated SWC as the most effective in balancing pest–predator interactions, even surpassing straw; however, its availability lagged compared to alternatives such as straw. Farmers expressed a higher likelihood of adopting SWC if it met government certification standards. The findings conclude that, while increasing production of SWC could enhance its role as an organic fertilizer in paddy farming, achieving its quality standards for paddy farming through government standard certification is crucial for successful implementation.