Jared Onyango Nyang’au, Jihane El Mahdi, Henrik Bjarne Møller, Peter Sørensen
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引用次数: 0
Abstract
Background
There is an increasing interest in using lignocellulosic feedstocks for biogas production. Treatment of these feedstocks prior to anaerobic digestion (AD) can enhance their accessibility to microorganisms involved in the process. To improve the digestion of recalcitrant feedstocks and boost biogas yields, many biogas plants now employ two-step AD systems, extending substrate residence times. However, the combined effect of feedstock treatment and two-step AD on methane yield and fertiliser value of digestates are underexplored. This study, therefore, evaluated the effectiveness of thermal treatment (TT) of pre-digested agricultural feedstocks before a secondary AD step on the carbon (C) and nitrogen (N) dynamics of digestates following application to soil. It also investigated the effects of TT on methane yields. Pre-digested feedstock (PDF) was treated at three different temperatures (70 °C, 120 °C and 180 °C) for 60 min, followed by parallel secondary AD steps using lab-scale continuous stirred-tank reactors (CSTR) and a batch test. Thermally treated feedstocks with and without a secondary AD step were applied to soil to study C and N dynamics and turnover for 2 months.
Results
TT at 180 °C increased ultimate CH4 yields by 7.2%; however, it decreased the net mineral N release in soil from 42 to 34% (of N input). Adding a secondary AD step increased the net mineral N release in soil from an average of 39% to 47% (of N input), with the effect of TT levelling off. Moreover, the secondary AD step significantly reduced C mineralisation rates from an average of 37% to 26% (of C applied).
Conclusions
Overall, TT at 120–180 °C can improve biogas yields of recalcitrant feedstocks, but it may lead to the formation of refractory nitrogen compounds resistant to further degradation during AD, potentially resulting in a lower N fertiliser value of digestates.
期刊介绍：
Chemical and Biological Technologies in Agriculture is an international, interdisciplinary, peer-reviewed forum for the advancement and application to all fields of agriculture of modern chemical, biochemical and molecular technologies. The scope of this journal includes chemical and biochemical processes aimed to increase sustainable agricultural and food production, the evaluation of quality and origin of raw primary products and their transformation into foods and chemicals, as well as environmental monitoring and remediation. Of special interest are the effects of chemical and biochemical technologies, also at the nano and supramolecular scale, on the relationships between soil, plants, microorganisms and their environment, with the help of modern bioinformatics. Another special focus is the use of modern bioorganic and biological chemistry to develop new technologies for plant nutrition and bio-stimulation, advancement of biorefineries from biomasses, safe and traceable food products, carbon storage in soil and plants and restoration of contaminated soils to agriculture.
This journal presents the first opportunity to bring together researchers from a wide number of disciplines within the agricultural chemical and biological sciences, from both industry and academia. The principle aim of Chemical and Biological Technologies in Agriculture is to allow the exchange of the most advanced chemical and biochemical knowledge to develop technologies which address one of the most pressing challenges of our times - sustaining a growing world population.
Chemical and Biological Technologies in Agriculture publishes original research articles, short letters and invited reviews. Articles from scientists in industry, academia as well as private research institutes, non-governmental and environmental organizations are encouraged.
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