China
Africa
Explore chapters and articles related to this topic
Anaerobic Digestion of Aqueous Waste for Methane and Hydrogen
Published in Yatish T. Shah, Water for Energy and Fuel Production, 2014
Besides temperature and pH, the availability of several macro- and micronutrients is also very important for the growth and survival of specific groups of microorgan-isms. Very low amount of macronutrients such as carbon, nitrogen, phosphorus, and sulfur is needed (C:N:P:S = 600:15:5:1) because only a small amount of biomass is developed [5]. Micronutrients such as iron, nickel, cobalt, selenium, molybdenum, and tungsten are important for the growth rate of microorganisms, and they must be added, particularly if the energy crops are the only substrate for biogas production [5]. Nickel is important for all methanogenic bacteria because it is necessary for the cell component cofactor F430, which is involved in the methane formation [5]. For optimum growth, the cell requires cobalt to build up the Co-containing corrinoid factor III [5]. The growth of only few methanogens depends on the trace elements such as selenium, molybdenum and tungsten. The required concentration is only 0.05-0.06 mg/l [5]. The iron is, however, necessary in higher concentration of 1-10 mg/l [50]. These micronutrients are very important for the stable process and high loading for energy crops [51]. While the addition of manure reduces the need for micronutrients addition, even with 50% manure in the reaction medium, the addition of micronutrients can increase the biogas production rate [5].
Optimization of cobalt, nickel, and iron supplement for mesophilic and thermophilic anaerobic digestion treating high-solid food waste
Published in Environmental Technology, 2022
Trace metals that are considered the most essential in AD are transition metals, e.g. cobalt (Co), nickel (Ni), and iron (Fe) [10]. Co is a core trace metal of vitamin B12 and is involved in methyltransferase activity required for methyl group transfer from methanol-containing compounds in methanogenesis [6, 11]. Ni is a key component of carbon monoxide dehydrogenase and in cofactor F430 in methyl-coenzyme M reductase [6]. Ni addition has been extremely important for increasing uptake of volatile fatty acids (VFAs) and production of biogas [6]. CH4-forming bacteria and anaerobic digesters have often been reported to require Ni [12]. Fe supplementation can increase acetate utilization by methanogens and promote conversion of CO2 to CH4 [13, 14]. However, excessive trace metal concentrations cause inhibition of methanogenesis [8].