Biogeochemistry of trace elements in anaerobic digesters

Abstract

Essential trace elements (TE) are a prerequisite that ensures optimal performance of the anaerobic digestion (AD) process. However, finding the proper way to deliver these micronutrients to microbial communities is not an easy task. The chemical speciation of TE and the complex environment characterizing AD play a critical role in their mobility, bioavailability, and toxicity. These aspects are particularly

Rheology, Micronutrients, and Process Disturbance in Continuous Stirred-Tank Biogas Reactors

“… , The extent of this effect is primarily regulated by the hydraulic retention time (HRT) and organic loading rate (OLR) (interactions 2 and 3 in Figure ). − The substrate composition and loading rate (interaction 32 in Figure ) ,, also define the supply of macro- and micronutrients, potential inhibitory compounds, and the chemical speciation of micronutrients/trace elements (TE) due to complexation and/or precipitation with metal-binding ligands . Through these mechanisms, a suboptimal substrate composition can contribute to microbial toxicity and nutrient deficiency, triggering process deterioration (interactions 27 and 33 in Figure ).…”

“…The substrate fed to an AD reactor is the primary source of nutrients for the microbial activity in AD. Commonly used substrates include mixtures of primary and activated wastewater sludge, manure, agricultural residues, energy crops, food waste, and different organic industrial wastes. , The substrate serves as an electron source for the energy metabolism of the microbial community, as well as a source of macronutrients (i.e., C, N, P, K, Na, S, Ca, and Mg) and micronutrients, also known as trace elements (TE; i.e., Co, Ni, Fe, Zn, Mo, W, and Se). , All are vital for cell growth and function . TE mainly play a role in AD as enzyme cofactors and are thus essential for the correct functioning of specific metabolic pathways. − The available concentration of individual TE that can be integrated in the enzymes is vital for their normal functioning: Too low, and not enough enzymes can be built; too high, and the TE begin to bind nonspecifically and disrupt enzymatic functioning .…”

“…In the following section we will introduce and briefly list the different interactions in our proposed conceptual model, and in the subsequent sections we will examine in greater detail how well the individual interactions, related to either rheology, process disturbance, or micronutrient dynamics, match existing evidence in the literature. As this article does not delve deeply into the fundamental aspects of AD rheology and micronutrients, readers are encouraged to consult specific reviews, such as those by Schnenider and Gerber and Staicu et al for comprehensive coverage of common terminology, concepts, and theories within each of these fields.…”