A pilot anaerobic bioreactor requires near-daily monitoring and frequent maintenance. This study aimed to upgrade a pilot bioreactor into a low-cost IoT device via ESP32 microcontrollers. The methodology was based on remote data acquisition and online monitoring of various parameters towards assessing the anaerobic digestion performance. A semi-continuous tank bioreactor with a 60 L total volume was initially inoculated mainly with livestock manure and fed daily with a mixture of glucose, gelatin, and oleic acid, supplemented with a basic anaerobic medium. Under steady-state conditions, the organic loading rate was 2 g VS L_R⁻¹ d⁻¹. Sensors for pH, temperature, REDOX potential, and ammonium concentration, along with devices measuring biogas volume and methane content, were integrated and validated against analytical methods. Biogas production was recorded accurately, enabling the early detection of production declines through ex-situ data analysis. Methane concentration variance was less than 6% compared to gas chromatography, while temperature and pH deviations were 0.15% and 1.67%, respectively. Ammonia ion measurements required frequent recalibration due to larger fluctuations. This IoT-enhanced system effectively demonstrated real-time monitoring of critical bioreactor parameters, with ESP32 enabling advanced control and monitoring capabilities.

The present study focuses on the working volume reduction of anaerobic reactors in biogas plants, which is caused by inorganic material accumulation and inadequate mixing and affects methane production and plant profitability. Precipitation phenomena lead to periodic reactor cleaning processes, which complicate the operation of the plant and increase its operating costs. For this purpose, the bioconversion model (BioModel) was utilized by modifying its conditions to accurately simulate the reduction of the working volume of a biogas plant facing precipitation problems for a study period of 150 days. The modified BioModel exhibited notable results in the prediction of methane production, with an average deviation of 1.97% from the plant’s data. After validation, based on the model results, an equation was set up to predict the optimal reactor cleaning period. Incidentally, the optimal cleaning time was calculated at 5.1 years, which is very close to the period during which the cleaning of the reactors of the studied biogas plant took place (5.5 years). The findings of this research showed that the modified BioModel, along with the developed equation, can be effectively used as a tool for the prediction of the optimal reactor cleaning period.

Anaerobic digestion (AD) of poultry manure often faces ammonia inhibition due to its high nitrogen content. This study investigated a combined strategy involving mild thermal hydrolysis pretreatment and bioaugmentation with ammonia-acclimatised inoculum to enhance methane production and process stability under ammonia-stressed conditions. Batch biomethanation efficiency assays were first conducted to evaluate the effect of different hydrolysis conditions (55–70 °C, 30–60 min) on substrate methane yields and biodegradability. The optimal condition (70 °C for 60 min) increased methane potential by 8.7% compared to the untreated substrate. In addition, a mesophilic continuous stirred-tank reactor (CSTR) experiment was conducted using both non-hydrolysed and thermally hydrolysed poultry manure under hydraulic retention times of 25 and 30 days, across four operational phases: steady-state, ammonia toxicity, bioaugmentation recovery, and increased organic loading rate. CSTRs were subjected to ammonia stress (6500 mg NH₄⁺-N L⁻¹) to assess the effectiveness of an acclimatised bioaugmentation inoculum. Methane yields recovered up to 93% and 100% of pre-inhibition and ammonia-toxicity levels, respectively, accompanied by process stability while reaching 7280 mg NH₄⁺-N L⁻¹. The synergistic application of hydrolysis and bioaugmentation significantly improved substrate conversion and overall AD robustness. This integrated approach provides a viable and scalable strategy for optimising AD performance of nitrogen-rich feedstocks, enabling its future application in AD plants.

Lignocellulose- and ammonia-rich feedstocks are abundant but remain underutilised in anaerobic digestion (AD) due to simultaneous inhibition of hydrolysis and methanogenesis. This study used, for the first time, a composite inoculum of hydrolytic bacteria and ammonia-tolerant methanogenic archaea, acclimatised, lyophilised, and stored long-term. When bioaugmented in an upscale continuous stirred-tank reactor, inhibition from high lignocellulose and ammonia levels was counteracted. Methane production increased by 145.05 ± 8.21 % relative to the inhibited phase, accompanied by stable biochemical conditions and restored methanogenic activity. Overall reactor production rate, before the addition of the biomasses and after bioaugmentation, increased by 46.79 ± 2.71 %. These short communication findings provide proof-of-concept that bioaugmentation with stored long-term composite inocula offers a scalable strategy to overcome lignocellulose and ammonia inhibition and enhance biogas production.

The goal of ALIVE project is to establish a robust, scalable, and efficient system that maximises the potential of anaerobic digestion for bioenergy production and in-situ nutrient recovery. By ensuring the effective employment of thermal hydrolysis and application of specialised anaerobic microbial consortia through bioaugmentation (a process where specific microorganisms are added to a biological system to improve or recover specific functions), followed by a membrane system, the project holds promise for maintaining and enhancing methane production efficiency and nutrient recovery in biogas plants worldwide, that utilise ammonia-rich substrates. This approach supports the generation of renewable energy and contributes to more sustainable waste management practices, aligning with broader environmental and economic goals. The production of biofertilisers and biostimulants from the recovered nutrients can potentially enable the standardisation and commercialisation of the process by scaling up the technology for widespread application.