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The application of biochar to agricultural soils can either be beneficial or detrimental, as well as no clear effect to soils and crops. Therefore, the aim of our study was to investigate the effects of biochar addition on soil chemical and biological properties and nutrient leaching in three tropical soils with different types of land-use (forest, non-intensive and intensive farming). The soils were amended with and without 2% coconut shell (CS) and rice husk (RH) biochars by weight and incubated for up to 360 days. To assess the impact of biochar on soil leaching, 27 unplanted soil columns from the same types of land-use were also amended with and without 2% CS and RH biochars by weight. Five leaching experiments were conducted by passing through 100 ml of deionised water via each of the glass columns containing soil. The biochar addition significantly increased (P<0.05) the soil pH and total carbon, but had a marginal effect on CEC and had a limited effect on microbial activity. Biochar treatments reduced ammonium leaching in the forest soil, but had no clear effect on the other two soils. Our data showed that biochar application at a lower rate can ameliorate soil acidic conditions, enhance carbon sequestration and adsorb ammonium ion. However, the success depends on soil and biochar properties and land-use. The biochar samples studied have a limited capacity to reduce nitrate and phosphate leaching due to high biochar phosphate content.

A variety of mathematical models have been developed to simulate the biochemical and physico-chemical aspects of the anaerobic digestion (AD) process to treat organic wastes and generate biogas. However, all these models, including the most widely accepted and implemented Anaerobic Digestion Model No.1, remain incapable of adequately representing the material balance of AD and are therefore inherently incapable of material conservation. The absence of robust mass conservation constrains reliable estimates of any kinetic parameters being estimated by regression of empirical data. To address this issue, the present work involved the development of a “framework” for a mass-conserving atomistic mathematical model which is capable of mass conservation, with a relative error in the range of machine precision value and an atom balance with a relative error of ±0.02% whilst obeying the Henry’s law and electroneutrality principle. Implementing the model in an Excel spreadsheet, the study calibrated the model using the empirical data derived from batch studies. Although the model shows high fidelity as assessed via inspection, considering several constraints including the drawbacks of the model and implementation platform, the study also provides a non-exhaustive list of limitations and further scope for development.

This study aimed to test and refine a new method of mushroom vitamin and mineral enrichment with the use of novel ‘during-growth’ and ‘water-on’ liquid supplements. Through experimental trials, different formulations and dosages, as produced by NutriGain Ltd, were compared along with untreated and UV treated mushrooms, all in commercial conditions, through collaboration with Drinkwater Mushrooms Ltd. This aimed to assess the product in its suitability for providing nutritionally relevant content of Vitamin D, as well as the Bvitamins; B1, B2, B6 and B12, and Selenium. Vitamin D is the most important target of enrichment due to the possibility in replacing the current energyintensive and high associated carbon emitting method of UV enrichment, which comes with many issues such as limited application (only brown mushrooms) and slowed packaging for application after growth. This has great potential benefits and opportunities for novel food products and public health by increasing levels of vitamins to combat deficiencies which are becoming more common in the UK and globally, especially vitamin D deficiencies. The experiment involved commercial growth trials using white button mushrooms conducted at Drinkwater Mushrooms Ltd., with applications of product produced by NutriGain and analysis of vitamins and mineral content at Lancaster Environment Centre using HPLC and ICP-OES methods. A dosage rate in vitamin D of around 125-150 mg/m2 in a calcium-based formulation of the liquid supplement was identified to yield higher vitamin D contents than other formulations tested, such as potassium-based, and was successful in matching UV-produced levels of vitamin D, without discolouration of white mushrooms. Enrichment with the novel MycroNutrient product gave a significant improvement compared to untreated samples, at levels of around 30 µg/g DW, whilst also providing nutritionally relevant levels of B-vitamins. All at a predicted annual carbon emission reduction of 99% in the pr

Lignocellulosic materials possess various features that make them exceptionally attractive as organic substrates in anaerobic bioreactors. Among these substrates, wetland plants such as common reed (Phragmites australis) are highly interesting as a promising feedstock for biogas production due to their vast abundance, sustainable nature, and lack of competition with arable land and food and feed production. However, the main obstacle lies in the recalcitrance of these feedstocks to biological conversion due to their high lignin content, impeding their full-scale adoption for biogas production. Therefore, additional steps are necessary to overcome this challenge and maximize their biodegradability. In the present work, a series of screening assays were conducted using microcosm vessels (125 mL) operating at mesophilic conditions to evaluate the potential of utilising alkaline pre-treatment (using NaOH) and co-digestion with food waste for augmenting the biogas production from P. australis. And determining the parameters that promote P. australis degradation efficiency and anaerobic digestion process stability, such as P. australis particle size, NaOH concentration, incubation time of pre-treatment process, inoculum to substrate ratio, and substrates mixing ratio. Furthermore, two batch experiments were performed using a 1 L bioreactor to investigate the effect of P. australis harvesting time, co-digestion with food waste and mechanical pre-treatment (P. australis biomass grinding to smaller than 0.4 mm) compared to chemical pre-treatment on the chemical composition of P australis and enhancing methane production. The results revealed inverse correlation between the biogas production level and the particle size of P. australis (10, 5, 2, and <1 mm), achieving the highest biogas production at particle size <1mm. As well as it was found that the pre-treatment of P. australis substrate with 0.5, 1, 2, and 4% NaOH positively affected biogas production, causing an increase

The antibacterial effects of a selection of volatile fatty acids (acetic, propionic, butyric, valeric, and caproic acids) relevant to anaerobic digestion were investigated at 1, 2 and 4 g/L. The antibacterial effects were characterised by the dynamics of Enterococcus faecalis NCTC 00775, Escherichia coli JCM 1649 and Klebsiella pneumoniae A17. Mesophilic anaerobic incubation to determine the minimum bactericidal concentration (MBC) and median lethal concentration of the VFAs was carried out in Luria Bertani broth at 37 °C for 48 h. Samples collected at times 0, 3, 6, 24 and 48 h were used to monitor bacterial kinetics and pH. VFAs at 4 g/L demonstrated the highest bactericidal effect (p < 0.05), while 1 g/L supported bacterial growth. The VFA cocktail was the most effective, while propionic acid was the least effective. Enterococcus faecalis NCTC 00775 was the most resistant strain with the VFAs MBC of 4 g/L, while Klebsiella pneumoniae A17 was the least resistant with the VFAs MBC of 2 g/L. Allowing a 48 h incubation period led to more log decline in the bacterial numbers compared to earlier times. The VFA cocktail, valeric, and caproic acids at 4 g/L achieved elimination of the three bacteria strains, with over 7 log10 decrease within 48 h.

The effects of the inoculum (anaerobic digestion effluent) to substrate (simulated food waste) ratio (ISR) 4.00 to 0.25 on putative pathogens and microbial kinetics during batch mesophilic anaerobic digestion were investigated. Red fluorescent protein labelled (RFPAKN132) Escherichia coli JM105 was introduced as a marker species, and together with the indigenous Clostridium sp., Enterococcus sp., Escherichia coli, and total coliforms were used to monitor pathogen death kinetics. Quantitative polymerase chain reaction was also used to estimate the bacterial, fungal, and methanogenic gene copies. All the ISRs eliminated E. coli and other coliforms (4 log10 CFU/mL), but ISR 0.25 achieved this within the shortest time (≤2 days), while ISR 1.00 initially supported pathogen proliferation. Up to 1.5 log10 CFU/mL of Clostridium was reduced by acidogenic conditions (ISR 0.25 and 0.50), while Enterococcus species were resistant to the digestion conditions. Fungal DNA was reduced (≥5 log10 copies/mL) and was undetectable in ISRs 4.00, 2.00, and 0.50 at the end of the incubation period. This study has demonstrated that ISR influenced the pH of the digesters during batch mesophilic anaerobic digestion, and that acidic and alkaline conditions achieved by the lower (0.50 and 0.25) and higher (4.00 and 2.00) ISRs, respectively, were critical to the sanitisation of waste.