Abstract
Anaerobic co-digestion technology (AcoD) can be used to process rice straw (RS) and cow manure (CoM) to produce energy and a digestate rich in nutrients, while the improper disposal of RS and CoM causes environmental problems. The overall effectiveness of the anaerobic digestion technology can be improved by utilizing the nutrients available in the digestate. It is also a way to reduce the usage of mineral fertilizer by recycling the nutrients available in the digestate. The co-digestion of RS with CoM was performed in a newly developed digester (F1) and in a mesophilic digester (F2) used as a reference. The mass balance of C, macronutrients (N, P, K, Ca, Mg, and S), and their distribution into a liquid digestate (LD) and a solid digestate (SD) was investigated in both digesters. The mass balance was used to evaluate the carbon available in the biogas and in the digestate. It was also used to investigate the recovery potential of the macronutrients after the AD process. Moreover, the assessment of the resulting digestate was carried out to suggest its potential use in agriculture. The amount of C measured in the biogas was the same in both digesters (41.0% and 38.0% of the initial C). Moreover, the conversion efficiency of C from the substrate into methane was 23.4% for F1 and 21.0% for F2. The Ca, Mg, K, and P were conserved in the digestate because their recovery rates (RR) were close to 100%. However, a relatively low RR was observed for N (84.1% in F1 and 86.8% in F2) and S (87.1% in F1 and 86.5% in F2) in both the digesters. After separation n of the SD, from 79.1 to 83.4% (in F1) and 75.0 to 82.4% (in F2) of the final nutrients were available in the LD. The assessment of the SD suggested its use in agriculture not only for soil amendment but also as a K-providing organic fertilizer.
Highlights
Anaerobic digestion (AD) is a biological process in which the specific microorganisms transform the biomass into biogas in the absence of oxygen [1]
The results of the C balance revealed the presence of the same amount of C in the digestate after the Anaerobic co-digestion technology (AcoD) process in both the digesters, which indicates similar effects of the processes on the input carbon
The Ca, Mg, K, and P were preserved in the digestate after the AcoD process
Summary
Anaerobic digestion (AD) is a biological process in which the specific microorganisms transform the biomass into biogas in the absence of oxygen [1]. In situ incorporation of the RS in the soil and open-field burning are the common practices used by the farmers for its disposal, especially in the parts of the world where there is a short time to make the fields ready for the sowing of the crop [8]. These practices are not environmentally friendly as they contribute to the enhancement of emissions of greenhouse gas [8,9]. Plowing back RS into the soil can potentially increase foliar disease and reduce crop yields [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
