Nutrient Recovery Via Anaerobic Digestion Of Supermarket Food Waste And Re-Use As Fertiliser In Potting Media For The Urban Retail Market; A Proof Of Concept Using Digestate And Biochar

Food waste can be diverted from landfill and utilised via anaerobic digestion (AD) to produce biogas. The liquid by-product of AD is commonly referred to as digestate, and this can be an organic certifiable biofertilizer. Digestate in Europe is frequently used in agriculture, though is not commonly used in the urban retail market. Biochar is another organic matter which can adsorb and retain the nutrients, and also could decrease the adverse effects of high nitrogen content of soil

Microalgae and Phototrophic Purple Bacteria for Nutrient Recovery from Agri-Industrial Effluents; Influences on Plant Growth, Rhizosphere Bacteria, and Putative C & N Cycling Genes

Microalgae (MA) and purple phototrophic bacteria (PPB) have the ability to remove and recover nutrients from digestate (anaerobic digestion effluent) and pre-settled pig manure that can be utilized as a bio-fertilizer. The objective of this study was to compare the effect of biologically recovered nutrients from MA and PPB in relation to plant growth and soil biological processes involved in nitrogen & carbon cycling

Response of Wheat to a Multiple Species Microbial Inoculant Compared to Fertilizer Application

Microbial inoculants, including those formed from multiple species, may have dual functions as biostimulants and/or biocontrol agents, and claimed agricultural benefits are instrumental for regulatory categorisation. Biostimulants include commercial products containing substances or microorganisms that stimulate plant growth. Biostimulant microbes can be involved in a range of processes that affect N and P transformations in soil and thus influence nutrient availability, and N and P fertilizers can influence soil microbial diversity and function. A glasshouse experiment was conducted to investigate the effect of a multiple species microbial inoculant relative to a rock-based mineral fertilizer and a chemical fertilizer on wheat growth and yield, and on microbial diversity in the rhizosphere. The microbial inoculant was compared to the mineral fertilizer (equivalent to 5.6 kg N ha-1 and 5.6 kg P ha-1), and to the chemical fertilizer applied at three rates equivalent to: (i) 7.3 kg N ha-1 and 8.4 kg P ha-1 as recommended for on-farm use, (ii) 5.6 kg N ha-1 and 6.5 kg P ha-1 which matched the N in the mineral fertilizer, and (iii) 4.9 kg N ha-1 and 5.6 kg P ha-1 which matched P content in the mineral fertilizer. Despite an early reduction in plant growth, the microbial inoculant treatment increased shoot growth at maturity compared to the control. Similarly, grain yield was higher after application of the microbial inoculant when compared to control, and it was similar to that of plants receiving the fertilizer treatments. Using 16S rRNA sequencing, the microbial inoculant and fertilizer treatments were shown to influence the diversity of rhizosphere bacteria. The microbial inoculant increased the relative abundance of the phylum Actinobacteria. At tillering, the proportion of roots colonized by arbuscular mycorrhizal (AM) fungi increased with the microbial inoculant and mineral fertilizer treatments, but decreased with the chemical fertilizer treatments. At maturity, there were no treatment effects on the proportion of wheat roots colonized by AM fungi. Overall, the multiple species microbial inoculant had beneficial effects in terms of wheat yield relative to the commercial mineral and chemical fertilizers applied at the level recommended for on-farm use in south-western Australia

Lactic acid production from food waste at an anaerobic digestion biorefinery: effect of digestate recirculation and sucrose supplementation

Low lactic acid (LA) yields from direct food waste (FW) fermentation restrict this production pathway. However, nitrogen and other nutrients within FW digestate, in combination with sucrose supplementation, may enhance LA production and improve feasibility of fermentation. Therefore, this work aimed to improve LA fermentation from FWs by supplementing nitrogen (0–400 mgN·L−1) as NH4Cl or digestate and dosing sucrose (0–150 g·L−1) as a low-cost carbohydrate. Overall, NH4Cl and digestate led to similar improvements in the rate of LA formation (0.03 ± 0.02 and 0.04 ± 0.02 h−1 for NH4Cl and digestate, respectively), but NH4Cl also improved the final concentration, though effects varied between treatments (5.2 ± 4.6 g·L−1). While digestate altered the community composition and increased diversity, sucrose minimised community diversion from LA, promoted Lactobacillus growth at all dosages, and enhanced the final LA concentration from 25 to 30 g·L−1 to 59–68 g·L−1, depending on nitrogen dosage and source. Overall, the results highlighted the value of digestate as a nutrient source and sucrose as both community controller and means to enhance the LA concentration in future LA biorefinery concepts

Developing a food waste biorefinery: Lactic acid extraction using anionic resin and impacts on downstream biogas production

Coupling lactic acid (LA) production with food waste (FW) anaerobic digestion (AD) can facilitate the next generation biorefinery to increase revenue and economic viability of FW AD. For this, LA should be effectively extracted from complex fermentation broths with minimal adverse effects on subsequent AD to maximise economic benefit. This study evaluated LA recovery by adsorption using a polymeric resin (BA765), not previously tested for LA, to explore adsorption capacity and kinetics. Furthermore, biochemical methane potential (BMP) tests were utilised to assess the effect of LA extraction on subsequent AD by measuring biogas production from the solid and liquid extraction residues. Optimal adsorption conditions yielded a maximum capacity of 0.21 gLA·g−1resin from pure solutions at pH 2–4, which was insensitive to temperature. However, real mixed fermentation broth impurities reduced LA uptake by 37%. BMP tests showed that the solid and liquid extraction residues had significant methane potential, with only a 21% reduction in overall methane yield compared to the raw fermentation broth prior to LA extraction. LA production outweighed the loss in methane energy in terms of relative value and indicated a FW biorefinery concept could be commercially attractive and technically feasible

Alterations to arbuscular mycorrhizal fungal community composition is driven by warming at specific elevations

Background Global warming can alter plant productivity, and community composition which has consequences for soil-plant associated microorganisms. Arbuscular mycorrhizal fungi (AMF) are distributed widely and form symbiotic relationships with more than 80% of vascular plants and play a key role in nutrient cycling processes at the ecosystem scale. Methods A simulated warming experiment at multiple elevations (3,000, 3,500, 3,800, and 4,170 m) was conducted utilizing an in-situ open-top chamber (OTC) for exploring the effect of global warming on AMF community structure in the Qinghai-Tibet Plateau (QTP). This region has been identified as one of the most sensitive areas to climatic changes. Soil DNA was extracted and sequenced using next the Mi-Seq platform for diversity profiling. Results AMF richness was higher under the simulated warming chamber, however this only occurred in the elevation of 3,500 m. Warming did not alter other AMF alpha diversity indices (e.g. Shannon, Ace, and Simpson evenness index). Glomus and Acaulospora were the dominate AMF genera as assessed through their relative abundance and occurrence in control and warming treatments at the different elevations. Conclusion Warming changed significantly AMF community. The effects of warming on AMF community structure varied depend on elevations. Moreover, the occurrences of AMF in different genera were also presented the different responses to warming in four elevations

Nutrient Recovery Via Anaerobic Digestion Of Supermarket Food Waste And Re-Use As Fertiliser In Potting Media For The Urban Retail Market; A Proof Of Concept Using Digestate And Biochar

Food waste can be diverted from landfill and utilised via anaerobic digestion (AD) to produce biogas. The liquid by-product of AD is commonly referred to as digestate, and this can be an organic certifiable biofertilizer. Digestate in Europe is frequently used in agriculture, though is not commonly used in the urban retail market. Biochar is another organic matter which can adsorb and retain the nutrients, and also could decrease the adverse effects of high nitrogen content of soil

Lactic acid from mixed food wastes at a commercial biogas facility: Effect of feedstock and process conditions

Anaerobic digestion facilities can become biorefineries to produce higher-value products together with biogas energy and nutrient-rich digestate. To inform future biorefinery concepts with lactic acid recovery, the current study monitored organic acids in a pre-fermentation stage at a commercial anaerobic digestion facility. The study assessed lactic acid production performance and the impact of mixed food waste feedstocks and process conditions. Feed rate and feedstock composition varied weekly with waste availability. Normal operating conditions of the pre-fermentation stage included warm ambient conditions (24–35 °C), low pH (3.45 ± 0.03), a short hydraulic retention time (1–3.5 days) and stable organic loading rate (12 ± 2 kgVS.m−3.day−1). These conditions favoured lactic acid, being dominant at an encouraging average concentration of 21.70 g L−1, notably without any process optimisation or control. Lactobacillus constituted the majority of the microbial community in the pre-fermentation stage (98.1 %–99.1 % relative abundance) with an unknown Lactobacillus species and L. reuteri being the major species present. Grain processing waste and milk paste were positive influencers of LA concentration. The monitoring results, together with a simple economic evaluation, indicated that lactic acid recovery from a commercial food waste anaerobic digestion facility had baseline feasibility. In addition, there would be significant opportunities to increase economic performance by targeted process control and optimisation

Response of Arbuscular Mycorrhizal Fungi to Simulated Climate Changes by Reciprocal Translocation in Tibetan Plateau

Arbuscular mycorrhiza (AM) fungi are considered as an important factor in predicting plants and ecosystem responses to climate changes on a global scale. The Tibetan Plateau is the highest region on Earth with abundant natural resources and one of the most sensitive region to climate changes. To evaluate the complex response of arbuscular mycorrhizal fungi colonization and spore density to climate changes, a reciprocal translocation experiment was employed in Tibetan Plateau. The reciprocal translocation of quadrats to AM colonization and spore density were dynamic. Mycorrhizal colonization frequency presented contrary changed trend with elevations of quadrat translocation. Colonization frequency reduced or increased in majority quadrats translocated from low to high or from high to low elevation. Responses of colonization intensity to translocation of quadrats were more sensitive than colonization frequency. Arbuscular colonization showed inconsistent trend in increased or decreased quadrat. Vesicle colonization decreased with changed of quadrat from low to high elevations. However, no significant trend was observed. Although spore density was dynamic with signs of decreasing or increasing in translocated quadrats, the majority enhanced and declined respectively in descent and ascent quadrat treatments. It is crucial to understand the interactions between AM fungi and prairie grasses to accurately predict effects of climate change on these diverse and sensitive ecosystems. This study provided an opportunity for understanding the effect of climate changes on AM fungi