Optimization Of Anaerobic Digestion Research Articles

Optimization of anaerobic digestion and solubilization of biosludges from the kraft cellulose industry using thermal hydrolysis as pretreatment

The management of secondary sludge from aerobic treatment of effluents from the cellulose industry is a current problem. The usual ways of disposal do not provide added value to the waste as they assume an economy based on “take-make-waste” (linear economy). In this work, thermal hydrolysis (TH) and anaerobic digestion (AD) are proposed to valorize this biosludge. Based on a Doehlert experimental plan, a response surface methodology (RSM) defined by seven different TH conditions is proposed. After TH, biomethanation potential (BMP) tests were performed to evaluate the AD possibilities. The TH conditions cover a temperature range between 125 °C and 205 °C and a reaction time from 15 min to 45 min. The TH process was successful in enhancing the bioavailability of the waste, increasing the concentration of soluble organic matter quantified by chemical oxygen demand of the soluble fraction (CODs), and decreasing the concentration of volatile suspended solids (VSS). However, response surfaces performed for CODs and VSS revealed the existence of optimums, which demonstrated the adverse effects of the more severe TH conditions. Organic matter solubilization was confirmed by microscopic observations. The amount of suspended organic matter after TH is reduced by two to three times compared to the untreated value. The subsequent BMP of the hydrolyzed waste increases between 100% and 220% compared to the untreated condition, wich had a BMP value of 84 NmL CH4 gVS−1. The response surface determined for the BMP reveals the presence of a maximum point of methane production at 202 °C for 31 min, which differs from the maximum CODs value observed at 196 °C for 40 min.

Biogas Production Using Codigestion of Organic Residues with Malt Bagasse

This study evaluated the use of two anaerobic bioreactors in the production of biogas from malt bagasse waste. Bioreactor B1 was loaded with a mixture of 600mL of anaerobic sludge, 300g of organic waste, taken from an upflow anaerobic sludge blanket (UASB) reactor, and 300g of malt bagasse residue. Bioreactor B2 was loaded with a mixture of 600g of organic waste and 600mL of anaerobic sludge taken from an UASB reactor. The anaerobic digestion processes lasted for 10 weeks and the produced methane fraction was measured in 5 occasions. Bioreactor B1 presented low methane production (7.2%) but Bioreactor B2 showed a much more signif- icant percentage, reaching up to 48.3%. The experiments were capable of reproducing largescale operational conditions, enabling increased results in biogas capturing and processing, strengthening sustainability and energy efficiency. The experiment also showed the importance of studying different types of organic waste, seeking optimization of anaerobic digestion pro- cesses.

Modeling and Optimization of Anaerobic Digestion: A Review

Anaerobic digestion is recognized as being an advantageous waste management technique representing a source of clean and renewable energy. However, biogas production through such practice is complex and it relies on the interaction of several factors including changes in operating and monitoring parameters. Enormous researchers have focused and gave their full attention to mathematical modeling of anaerobic digestion to get good insights about process dynamics, aiming to optimize its efficiency. This paper gives an overview of the different approaches applied to tackle this challenge including mechanistic and data-driven models. This review has led us to conclude that neural networks combined with metaheuristic techniques has the potential to outperform mechanistic and classical machine learning models.

A Review of the Role of Critical Parameters in the Design and Operation of Biogas Production Plants

Many operating parameters, individually or together, may influence the performance of anaerobic digestion towards biogas or digestate yield and quality maximization. The most preferred method of optimizing an anaerobic digestion plant often relies on how carefully the crucial parameters, such as pH, temperature, organic loading rate, hydraulic retention time, and pressure, are chosen. There is a large amount of literature available on optimization of anaerobic digestion; however, given the continued development and implementation of innovative technologies, together with the introduction of increasingly complex systems, it is necessary to update present knowledge on process parameters and their role on operational ranges and flexibilities in real-life anaerobic digestion system. Accordingly, the present review discusses the importance of the selection of operational parameters in existing technologies and their impact on biogas yield. Notably, the four broad areas of feedstock utilization (substrate, inoculum, codigestion and pretreatment), process condition (pH, temperature, pressure, and reactor design), reactor control (HRT and OLR) and inhibition (Ammonia and VFAs) are covered in this review. In addition, particular emphasis is placed on the most recent innovations that have been or may be implemented in current or future biogas plants.

A Review of the Processes, Parameters, and Optimization of Anaerobic Digestion.

Anaerobic digestion is a technology that has been used by humans for centuries. Anaerobic digestion is considered to be a useful tool that can generate renewable energy and significant research interest has arisen recently. The underlying theory of anaerobic digestion has been established for decades; however, a great deal of current research is directed towards the optimization of anaerobic digestion under diverse digestion conditions. This review provides a summary of the processes underlying anaerobic digestion, commonly-utilized measurements of anaerobic sludge, operating parameters of anaerobic digesters, and methods of acceleration and optimization used to improve process efficiency. Recent developments in addition to older research are considered to provide a general but comprehensive summary of accumulated knowledge in the theory of anaerobic digestion, as well as considerations in the efficient operation of digesters. We have determined that the numerous factors pertinent to the design and operation of batch-based anaerobic digesters must each be considered to ensure the maximum efficiency and cost-effectiveness of a digester provided its respective operating conditions.

Review on the Mechanisms of the optimization of Anaerobic Digestion (AD) for Waste Water Treatment: from Economic and Environmental Perspective

Review on the Mechanisms of the optimization of Anaerobic Digestion (AD) for Waste Water Treatment: from Economic and Environmental Perspective

Optimization of Anaerobic Digestion for Resource Recovery

Optimization of Anaerobic Digestion for Resource Recovery

Modeling and optimization of anaerobic digestion of corn stover on biogas production: Initial pH and carbon to nitrogen ratio

ABSTRACTAnaerobic digestion is a reliable technology for obtaining biogas from corn stover, and it is significantly affected by the initial pH and carbon to nitrogen ratio. Batch tests were carried out to define the critical factors and determine the cumulative methane yield, and the kinetics of methane production was researched. The results showed that the maximum methane content and yield were obtained under the condition of initial pH 7.5 and carbon to nitrogen ratio of 25. The Gompertz model was suitable for describing the digestion process. The ultimate methane production and corresponding digestion rate could be expressed through the methane production kinetic model.

Evaluation of chlorophyll and anti-oxidative components harvested from the anaerobic digestion of fruit and vegetable waste

Abstract Two-phase up-flow sludge blanket filter (TUBF) digestion process of fruit and vegetable waste homogenate generated anaerobic sludge with concentrated pigments and reducing compounds. In the 5–50 L scale-up daily batch and semi-batch operations, the organic loading rate attained was over 6 kg COD/m 3 .day. A comparative study indicated that Minox polyethylene ring packing was critical for optimization of anaerobic digestion. The biogas production in terms of the volatile fatty acid pattern with a C 2 –C 6 level of 600 mg/L through liquefaction and acidification (LA) maintained the alkalinity over 3500 mg/L and stabilized the pH of the LA phase at 5.2–6.8 according to the loading status. In the semi-batch operation of 50 L, pigments gradually condensed in the sludge layer were concentrated by a factor of at least ten fold, and a high level of reducing activity was retained by the chlorophyll and anti-oxidative components.

Optimization of anaerobic digestion of municipal solid waste in combined process and sequential staging

The optimization of anaerobic digestion aims to maximize organic waste stabilization after a short digestion period. This paper presents the optimization performance of the combined anaerobic digestion and sequential staging concept in a thermophilic, solid-state batch system as a treatment technology prior to landfill. The former involves enhanced pre-stage flushing with the addition of microaeration and inoculum in the methane phase. The latter involves leachate cross-recirculation between the mature and fresh waste reactors without conducting a pre-stage operation. The optimized process for combined anaerobic digestion showed that reducing the pre-stage operation with the maximum removal of organics from the waste bed is beneficial. Moreover, the sequential staging concept offers an improved process over the combined anaerobic digestion wherein the specific methane yield of 11.9 and 7.2 L CH4 kg(-1) volatile solids (VS) per day was achieved, respectively. After 28 days of operation, the sequential staging process showed an improved waste stabilization with 86 and 79% mass and volume reduction, respectively. A higher methane yield of 334 L CH4 kg(-1) VS with 86% VS reduction, which is equivalent to 84% process efficiency was obtained.

97/00491 Mathematical modeling and optimization of anaerobic digestion of animal husbandry wastes

97/00491 Mathematical modeling and optimization of anaerobic digestion of animal husbandry wastes