Multivariate and Multiscale Approaches for Interpreting the Mechanisms of Nitrous Oxide Emission during Pig Manure–Wheat Straw Aerobic Composting

Abstract

Nitrous oxide (NO) emission during composting causes nitrogen loss and air pollution. The interpretation of NO emission mechanisms will help to customize composting strategies that mitigate climate change. At pile and particle scales, this study characterized NO emission-related variables (gases, ions, and microbes) and their correlations during pig manure-wheat straw aerobic composting. Pile-scale results showed that NO emission mainly occurred in mesophilic, thermophilic, and cooling phases; the nitrification by ammonia-oxidizing bacteria ( AOB) and nitrite-oxidizing bacteria ( NOB) coexisted with the denitrification by denitrificans ( DEN); the major NOB and DEN were Nitrobacter ( NOB_Nba) and Thiobacillus denitrificans ( DEN_Tb), respectively. The mechanisms of nitrification, nitrifier denitrification, and anaerobic denitrification in composting particles were initially visualized by confocal laser scanning microscopy: Betaproteobacteria ( AOB_ Beta) sporadically distributed on the outer area of the particles, NOB_Nba internally attached to AOB_ Beta, and Nitrosomonas europea/ Nitrosomonas eutropha ( AOB_eu) and DEN_Tb concentrated in the interior. Correlation analysis of the variables showed that the distribution area of AOB_eu was proportional to NO emission ( R = 0.84); AOB not only participated in nitrification but also nitrifier denitrification, and NO formation was mainly from nitrifier denitrification by AOB_eu during the mesophilic-thermophilic phase and from denitrification by AOB_eu and DEN during the cooling phase.

Effects of Turning Frequency on Ammonia Emission during the Composting of Chicken Manure and Soybean Straw

“…Effects of TF on Ammonia-Oxidizing Bacteria/Ammonia-Oxidizing Archaeal Diversity and Composition during Composting AOB and AOA are ubiquitous in various environments and play crucial roles in the nitrogen cycling process [115][116][117]. AOB and AOA also have been found to be common in the composting of various livestock including chicken [118], cow/cattle [4,51,117], sheep [119], pig [120,121]. Based on the Illumina sequencing data, we obtained an average of 56,022 and 113,491 sequence reads per sample ranging from 15,139-140,517 and 40,925-137,869 reads for AOB and AOA, respectively.…”

N2O emission in full-scale wastewater treatment: Proposing a refined monitoring strategy

“…The necessary information to solve this challenges may be extracted from newer data types, such as microbiological data (Stein, 2018), inorganic carbon measurements (Peng et al, 2016), and concentration of isotopomers (Ostrom and Ostrom, 2017). For example, the measurement of microbial diversity and gene, protein, and metabolites expression has been applied successfully to explain variations in labscale measurements of N2O emissions (Ge et al, 2018;Perez-Garcia et al, 2014).…”

Mechanism and control strategy of ammonia and nitrous oxide during composting of municipal solid wastes

“…The accumulation or compaction of the compost materials will prevent oxygen from entering the inside of the waste pile to form a local anaerobic environment and promote denitrification. Pseudomonas and paracoccus are typical aerobic denitrifying microorganisms, and their abundance is relatively less during the heating-up period of composting, and it will be gradually increased until the high temperature period and the cooling and maturing period [11][12].…”

“…The results show that the SP value of N 2 O emission in the initial stage of composting is 0 to 12, and the N 2 O emission reaches the peak after the turning over the pile, the corresponding SP value is 0 to 5, while the SP value of N 2 O emitted by nitrification is about 33, and the SP value of N 2 O emitted by denitrification is about 0, which indicates that N 2 O can come from both nitrification and denitrification, and denitrification is the main way to produce N 2 O during the composting process. The researches of Ge et al [11] show that, during the compost heating-up period and the high temperature period, N 2 O is mainly emitted through the nitrification process led by ammonia oxidizing bacteria; when entering the cooling and maturing period, N 2 O is mainly emitted through the denitrification process of ammonia oxidizing bacteria and denitrifying bacteria.…”