Two Phase Anaerobic Digestion System of Municipal Solid Waste by Utilizing Microaeration and Granular Activated Carbon

Microaerobic condition as pretreatment for improving anaerobic digestion: A review

Pretreatment of waste before anaerobic digestion (AD) has been extensively studied during the last decades. One of the biological pretreatments studied is the microaeration. This review examines this process, including parameters and applications to different substrates at the lab, pilot and industrial scales, to guide further improvement in large-scale applications. The underlying mechanisms of accelerating hydrolysis and its effects on microbial diversity and enzymatic production were reviewed. In addition, modelling of the process and energetic and financial analysis is presented, showing that microaerobic pretreatment is commercially attractive under certain conditions. Finally, challenges and future perspectives were also highlighted to promote the development of microaeration as a pretreatment before AD.

A review on biological methodologies in municipal solid waste management and landfilling: Resource and energy recovery

Rapid industrialization and urbanization growth combined with increased population has aggravated the issue of municipal solid waste generation. MSW has been accounted for contributing tremendously to the improvement of sustainable sources and safe environment. Biological processing of MSW followed by biogas and biomethane generation is one of the innumerable sustainable energy source choices. In the treatment of MSW, biological treatment has some attractive benefits such as reduced volume in the waste material, adjustment of the waste, economic aspects, obliteration of microorganisms in the waste material, and creation of biogas for energy use. In the anaerobic process the utilizable product is energy recovery. The current review discusses about the system for approaching conversion of MSW to energy and waste derived circular bioeconomy to address the zero waste society and sustainable development goals. Biological treatment process adopted with aerobic and anaerobic processes. In the aerobic process the utilizable product is compost. These techniques are used to convert MSW into a reasonable hotspot for resource and energy recovery that produces biogas, biofuel and bioelectricity and different results in without risk and harmless to the ecosystem. This review examines the suitability of biological treatment technologies for energy production, giving modern data about it. It likewise covers difficulties and points of view in this field of exploration.

The Measurement, Application and Effect of Oxygen in Microbial Fermentations: Focusing on Methane and Carboxylate Production

Oxygen is considered detrimental to anaerobic fermentation processes by many practitioners. However, deliberate oxygen sparging has been used successfully for decades to remove H2S in anaerobic digestion (AD) systems. Moreover, microaeration techniques during AD have shown that small doses of oxygen may enhance process performance and promote the in situ degradation of recalcitrant compounds. However, existing oxygen dosing techniques are imprecise, which has led to inconsistent results between studies. At the same time, real-time oxygen fluxes cannot be reliably quantified due to the complexity of most bioreactor systems. Thus, there is a pressing need for robust monitoring and process control in applications where oxygen serves as an operating parameter or an experimental variable. This review summarizes and evaluates the available methodologies for oxygen measurement and dosing as they pertain to anaerobic microbiomes. The historical use of (micro-)aeration in anaerobic digestion and its potential role in other anaerobic fermentation processes are critiqued in detail. This critique also provides insights into the effects of oxygen on these microbiomes. Our assessment suggests that oxygen dosing, when implemented in a controlled and quantifiable manner, could serve as an effective tool for bioprocess engineers to further manipulate anaerobic microbiomes for either bioenergy or biochemical production.

Diversifying the products from the organic fraction of municipal solid waste (OFMSW) by producing polyhydroxyalkanoates from the liquid fraction and biomethane from the residual solid fraction

This study describes the diversification of products obtainable from the organic fraction of municipal solid waste (OFMSW) by producing polyhydroxyalkanoates (PHA) from the liquid fraction and biomethane from the residual solid fraction. OFMSW samples were taken during the 2021 season from two full field scale plants treating wastes. After solid/liquid (S/L) separation, 80% of initial organic acids (OAs) were released in the liquid stream. OAs were then used as feed for PHA production and residual solid cakes were tested for biomethane production. Complete mass balance and energy balance were calculated. PHAs production was of 115 ± 23 (n = 6) g kg^{- 1} OFMSW (TS) and residual biomethane of 219 ± 3 g kg^{- 1} OFMSW TS, (n = 6). Energy balance indicated that nearly 40% of OFMSW energy was recovered as products. This value was lower than that obtained previously when AD was performed before OAs separation (i.e. 64%).

Recent advances in valorization of organic municipal waste into energy using biorefinery approach, environment and economic analysis

Researcher's all around works on a copious technique to lessen waste production and superintend the waste management for long-term socio-economic and environmental benefits. Value-added products can be produced from municipal waste by using holistic and integrated approaches. In this review, a detail about the superiority of the different methods like anaerobic digestion, biofuel production, incineration, pyrolysis and gasification were used for the conversion of municipal waste to feedstock for alternate energy and its economic- environmental impacts were consolidated. Most conversion techniques were environmentally friendly to manage municipal waste. The biological process was more economically feasible compare to the thermal process, for the reason thermal process required a large amount of capital investment and energy utilization. In the thermal process, gasification shows low emission, and pyrolysis shows low capital investment and economically feasible compare to other thermal processes. Waste to energy technology significantly reduced the emission and energy demand.

High-Solid Anaerobic Digestion: Reviewing Strategies for Increasing Reactor Performance

High-solid and solid-state anaerobic digestion are technologies capable of achieving high reactor productivity. The high organic load admissible for this type of configuration makes these technologies an ideal ally in the conversion of waste into bioenergy. However, there are still several factors associated with these technologies that result in low performance. The economic model based on a linear approach is unsustainable, and changes leading to the development of a low-carbon model with a high degree of circularity are necessary. Digestion technology may represent a key driver leading these changes but it is undeniable that the profitability of these plants needs to be increased. In the present review, the digestion process under high-solid-content configurations is analyzed and the different strategies for increasing reactor productivity that have been studied in recent years are described. Percolating reactor configurations and the use of low-cost adsorbents, nanoparticles and micro-aeration seem the most suitable approaches to increase volumetric production and reduce initial capital investment costs.