Anaerobic Digestion: Factors Affecting Anaerobic Digestion Process

Abstract

Anaerobic digestion (AD) is a biological decomposition process that occurs in the absence of oxygen. The decomposition of organic matter is a multi-step process of series and parallel reactions that occurs in four stages namely hydrolysis, acidogenesis, acetogenesis and methanogene. Most of the control in anaerobic digestion is undertaken directly by the micro-organisms themselves, however, the operational conditions such as temperature, pH, essential trace nutrients and toxicants can play a major role in modifying reaction rates of individual sub-processes. The energy performance of the anaerobic digestion is depending mainly on the biogas production technology (wet or dry technology, mesophilic or thermophilic), raw materials and geographic location (ambient temperature). Since the feedstocks coming to anaerobic digestion have usually lower heating value as received and the usual energy efficiency calculation used for incineration plant is not useful. Most commonly used method is the input-output method and the estimation is dependent upon the chosen system boundary.

Effect of Engineered Biomaterials and Magnetite on Wastewater Treatment: Biogas and Kinetic Evaluation

“…When the bioreactor is run at optimal conditions, production of the bioenergy such as methane (60-70%) and stabilised digestate by AD creates economic opportunities and eases pollution [8,11,12]. The AD process utilizes microorganism degradation potential in an ecologically sustainable [13][14][15], odour-reducing, and pathogenic organism-degrading process, especially in reactors running at mesophilic (25-45 • C) and thermophilic (>45 • C) temperatures [14,15]. Furthermore, produced biogas often contains impurities such as H 2 S and CO 2 , which lower the calorific value of biogas and are detrimental to equipment like pipes and combustion engines [3,16].…”

Performance of Anaerobic Digestion of Chicken Manure Under Gradually Elevated Organic Loading Rates

“…It is estimated that a total quantity of 4 × 10 8 t/year of chicken manure is being produced in China, and most of it will be transferred into the natural environment directly, causing serious environmental problems [1]. Using energy conversion technologies such as anaerobic digestion (AD) to deal with various bio-wastes like chicken manure, cow dung, and other various agricultural residues has been an efficient and popular approach for many years because it produces clean energy without polluting the environment [2,3]. However, it is common for ammonia inhibition to have a negative impact on the stability of AD systems [4] and to even cause AD failure when the ammonia concentration increases to a certain range [5,6].…”

Enhanced Biogas Production from Winery Solid Waste through Application of Iron oxide Nanoparticles

“…Hence it gives a Carbon/ Nitrogen ratio of 28.63, which is acceptable. For high methane yield a Carbon/Nitrogen ratio between 20:1-30:1 is considered appropriate [17]. A protein content of 11% was also found.…”