Implementation of anaerobic digestion for valorizing the organic fraction of municipal solid waste in developing countries: Technical insights from a systematic review

Insights into nutrients recovery from food waste liquid Digestate: A critical review and systematic analysis

This review paper presents a critical analysis of global research on the liquid fraction of food waste (FW) digestate. The study found that research on FW liquid fraction management accounted for 43% of the literature, followed by treatment methods (26%) and physical-chemical characterization (22%). By 2023, China led in scientific production on FW liquid fraction, contributing 46%, followed by Poland with 10% and the USA with 8%. The review emphasizes current technologies for nutrient recovery from the liquid fraction, as well as practical implications and limitations, identifying gaps in the literature. The most used methods for nutrient recovery were biofertilizer production from microalgae and membrane technologies. However, there is a need for further research on nutrient value, circular economy integration, the impact of food additives, ecological problems associated with FW decomposition, pathogen breeding, harmonized legislation to support recovered fertilizer commercialization and innovative nutrient recovery technologies. This approach provides valuable insights for stakeholders, enabling the creation of effective strategies that promote sustainable agricultural practices and circular economy initiatives through nutrient recovery from FW digestate.

Partitioning Ganoderma lucidum residue biochar differentially boosts anaerobic fermentation performance of cow manure via mediation of anaerobic microbiota assembly

Biochar is a promising strategy to solve the problem of low efficiency and ammonia inhibition during anaerobic digestion (AD). However, the correlation between biochar partitioning and its stimulatory effects on AD remains uncertain. Here, the effects of partitioned Ganoderma lucidum residue biochar (GLRB) on biogas and methane production were investigated. The GLRB produced at 450 °C, with richer functional groups on its surface, had the optimal enhancement effect on AD, resulting in a 20.59% increase in methane production compared with control. The doses of water-soluble GLRB (LZ450-W) and water-insoluble GLRB (LZ450-R) were not proportional to their enhancement effect on AD. However, the enhancement effect on AD by LZ450-R was better than that of LZ450-W. The optimal dosage of LZ450-W was 0.015 g, which increased methane production by 14.28%. Similarly, methane production increased by 26.91% with the addition of 0.603 g of LZ450-R. LZ450-R had more abundant functional groups on the surface and promoted the abundance of bacteria in the dominant phyla Bacteroidetes, Synergistetes, and Spirochaetes, increasing the rate of hydrolysis. Additionally, methanogens such as Methanobacterium and Methanospirillum were enriched, facilitating methane production by promoting the hydrogenotrophic pathway. Methanobacterium was also negatively correlated with most acid-producing bacteria, whereas Methanobrevibacter was positively correlated with Methanosphaera, Acetivibrio, and other acid-producing bacteria. These findings provide a basis for constructing synthetic microbial communities using biochar as a carrier of microbial inoculum.

From laboratory- to industrial-scale plants: Future of anaerobic digestion of olive mill solid wastes

In this review, the main properties of olive mill solid waste, the primary by-product of olive oil production, and its feasibility as a feedstock for anaerobic digesters operating at laboratory-, pilot- and industrial-scales are discussed in detail. Nutrient addition and thermal pretreatments were found to have the potential to address the challenges arising from the high carbon-to-nitrogen ratio, the low pH, and the high concentration of phenolic compounds. Furthermore, anaerobic co-digestion with different organic feedstocks has been identified as one of the most promising options to solve the aforementioned problems and the seasonality nature of olive waste, while improving the efficiency of anaerobic treatment plants that operate throughout the whole year. The insights generated from this study show co-digestion with wastes from animal farming to be the most environmentally and economically sustainable method for improving anaerobic digestion processes with olive mill solid waste.

Adding Granular Activated Carbon and Zerovalent Iron to the High-Solid Anaerobic Digestion System of the Organic Fraction of Municipal Solid Waste: Anaerobic Digestion Performance and Microbial Community Analysis

Anaerobic digestion (AD) performance and microbial dynamics were investigated in a high-solid anaerobic digestion (HSAD) system of the organic fraction of municipal solid waste (OFMSW). 1, 5, 10, and 15% (w/w, dry weight of the OFMSW) of granular activated carbon (GAC) and zerovalent iron (ZVI) were added to the HSAD system. The results showed that adding ZVI and GAC can improve the methane yield of the OFMSW. Notably, R-(GAC + ZVI) exhibited the highest cumulative methane yield of 343.0 mL/gVS, which was 57.1% higher than that of the R-control. At the genus level, the dominant bacteria included norank_f__norank_o__MBA03, norank_f__norank_o__norank_c__norank_p__Firmicutes, Fastidiosipila, norank_f__Rikenellaceae, and Sphaerochaeta, while Methanoculleus, Methanobacterium, and Methanosarcina were the dominant archaea. The highest relative abundance of norank_f__norank_o__norank_c__norank_p__Firmicutes was 30.8% for the R-(GAC + ZVI), which was 71.4% higher than that of the R-control. The relative abundance of Methanoculleus and Methanobacterium for the R-(GAC + ZVI) and the R-control group accounted for 79.0 and 90.8% of the total archaeal abundance, respectively. Additionally, the relative abundance of Methanosarcina was 10.6% for R-(GAC + ZVI), which was higher than that of the R-control (1.1%). After the addition of GAC and ZVI, the electron transfer capacity of the HSAD system was enhanced, resulting in promoted methane production. Thus, the simultaneous addition of GAC and ZVI to the HSAD system can be an effective strategy to promote the cumulative methane yield of the OFMSW.