Hongyang Cui

Relationship between bacterial diversity and environmental parameters during composting of different raw materials

The aim of this study was to compare the bacterial structure of seven different composts. The primary environmental factors affecting bacterial species were identified, and a strategy to enhance the abundance of uncultured bacteria through controlling relevant environmental parameters was proposed. The results showed that the physical-chemical parameters of each different pile changed in its own manner during composting, which affected the structure and succession of bacteria in different ways. DGGE profiles showed that there were 10 prominent species during composting. Among them, four species existed in all compost types, two species existed in several piles and four species were detected in a single material. Redundancy analysis results showed that bacterial species compositions were significantly influenced by C/N and moisture (p<0.05). The optimal range of C/N was 14-27. Based on these results, the primary environmental factors affecting a certain species were further identified as a potential control of bacterial diversity.

Effect of actinobacteria agent inoculation methods on cellulose degradation during composting based on redundancy analysis

In this study, actinobacteria agent including Streptomyces sp. and Micromonospora sp. were inoculated during chicken manure composting by different inoculation methods. The effect of different treatments on cellulose degradation and the relationship between inoculants and indigenous actinobacteria were investigated during composting. The results showed that inoculation in different stages of composting all improved the actinobacteria community diversity particularly in the cooling stage of composting (M3). Moreover, inoculation could distinctly accelerate the degradation of organic matters (OM) especially celluloses. Redundancy analysis indicated that the correlation between indigenous actinobacteria and degradation of OM and cellulose were regulated by inoculants and there were significant differences between different inoculation methods. Furthermore, synergy between indigenous actinobacteria and inoculants for degradation of OM and cellulose in M3 was better than other treatments. Conclusively, we suggested an inoculation method to regulate the indigenous actinobacteria based on the relationship between inoculants and indigenous actinobacteria and degradation content.

Effect of precursors combined with bacteria communities on the formation of humic substances during different materials composting

The aim of this work was to put forward a method to improve HS amount by studying the formation regularity of HS. Five precursors have been detected and few researches combined them with bacteria to study HS formation. During composting, the polyphenols, carboxyl and amino acids concentration decreased by 75.8%, 63.2% and 68.3% on average, respectively. However, the polysaccharides, reducing sugars and HS concentration increased by 61.2%, 47.1% and 37.33% on average. Relationships between precursors and HS concentration showed that the HS formation were significantly affected (p<0.05). The key bacteria community and physical-chemical parameters which affected HS formation have also been identified by redundancy analysis. Twelve key bacteria communities have been selected, which were significantly affected by physical-chemical parameters (p<0.05). Accordingly, we proposed an adjusting method to promote HS amount during composting based on the relationship between the key bacteria communities and the precursors as well as physical-chemical parameters.

An optimized regulating method for composting phosphorus fractions transformation based on biochar addition and phosphate-solubilizing bacteria inoculation

The study was conducted to investigate the influence of biochar and/or phosphate-solubilizing bacteria (PSB) inoculants on microbial biomass, bacterial community composition and phosphorus (P) fractions during kitchen waste composting amended with rock phosphate (RP). There were distinct differences in the physic-chemical parameters, the proportion of P fractions and bacterial diversity in different treatments. The contribution of available P fractions increased during composting especially in the treatment with the addition of PSB and biochar. Redundancy analysis showed that bacterial compositions were significantly influenced by P content, inoculation and biochar. Variance partitioning further showed that synergy of inoculated PSB and indigenous bacterial communities and the joint effect between biochar and bacteria explained the largest two proportion of the variation in P fractions. Therefore, the combined application of PSB and biochar to improve the inoculation effect and an optimized regulating method were suggested based on the distribution of P fractions.

Assessment of phytotoxicity grade during composting based on EEM/PARAFAC combined with projection pursuit regression

Improper treatment of organic waste may result in environmental pollution and harm to plant growth due to the high concentration of phytotoxin. Composting has widely been used for recycling organic waste and reducing phytotoxin to improve soil properties. Assessing the phytotoxicity grades of compost products is essential for achieving high quality compost to guarantee its marketability. In this study, a technique combined parallel factor (PARAFAC) of excitation-emission matrices (EEMs) spectroscopy with projection pursuit regression (PPR) was applied to improve the sensitivity of phytotoxicity assessment during composting. Results showed that composting reduced the concentration of phytotoxin, and increased the germination index (GI). Composts were divided into four grades based on GI values. Five components containing simple DOM (component C1 and C2) and complex DOM (component C3-C5) were successfully developed by PARAFAC. Correlation analysis between phytotoxicity, chemical indices and fluorescence components demonstrated that C1, C4, complex DOM, and the ratio of simple/complex DOM components were more suitable to assess phytotoxicity of composting products. These results revealed that PARAFAC/PPR enabled a rapid and accurate method to assess the phytotoxicity of compost materials for composting plant.

Reducing nitrogen loss and phytotoxicity during beer vinasse composting with biochar addition

The aim of this study was to investigate the feasibility of composting of beer vinasse generated from brewing industry, the effect of biochar amendment on beer vinasse composting was also evaluated based on the changes of different physicochemical parameters, phytotoxicity and final compost quality. Four different treatments were performed of beer vinasse with biochar addition at 0, 5%, 10%, 15% (w/w dry basis). The final product obtained from beer vinasse composting was phytotoxicity-free (GI: 120.8%), mature (C/N: 19.88, NH4+-N: 295.0mg/kg, DOC: 9.76g/kg) and nutrient-rich (especially for P: 1.92%) compost except high N loss (60.76%), which had the potential to be as soil amendment or fertilizer. Biochar addition contributed to decomposition of DOC indicating higher microbial activity and attain phytotoxicity-free standard rapidly. N loss significantly reduced by 27% with biochar at 15% addition. And 15% biochar addition ensured all parameters, which was involved in composts quality, to attain the mature standard. Therefore, it was suggested that biochar addition at 15% was optimal.

A novel method for contributing to composting start-up at low temperature by inoculating cold-adapted microbial consortium

Low temperature climate presented a technical challenge to start-up composting in northern region of China. This study investigated if the cold-adapted microbial consortium (CAMC) could promote composting start-up at low temperature. In this work, the CAMC was inoculated when food waste was composted at 10°C. The results showed that inoculating CAMC accelerated the piles temperature effectively, the piles passed through the start-up period within 37h. Moreover, the inoculants could enhance the abundances of dominant strains related to organic matters degradation rate. Redundancy analysis (RDA) indicated that the relationships among indigenous bacteria, organic substrates degradation and temperature evolution were influenced by the inoculants. Furthermore, the heat generation value and degradation rate of the hydrolysable carbohydrate, lipids and protein were significantly enhanced with CAMC inoculated. This work demonstrated that inoculating CAMC was beneficial to composting self-heating, it provided a novel biotechnology support to ensure the normal start-up of winter composting.

Snowmelt-driven changes in dissolved organic matter and bacterioplankton communities in the Heilongjiang watershed of China

Bacterioplankton plays a significant role in the circulation of materials and ecosystem function in the biosphere. Dissolved organic matter (DOM) from dead plant material and surface soil leaches into water bodies when snow melts. In our study, water samples from nine sampling sites along the Heilongjiang watershed were collected in February and June 2014 during which period snowmelt occurred. The goal of this study was to characterize changes in DOM and bacterioplankton community composition (BCC) associated with snowmelt, the effects of DOM, environmental and geographical factors on the distribution of BCC and interactions of aquatic bacterioplankton populations with different sources of DOM in the Heilongjiang watershed. BCC was measured by denaturing gradient gel electrophoresis (DGGE). DOM was measured by excitation-emission matrix (EEM) fluorescence spectroscopy. Bacterioplankton exhibited a distinct seasonal change in community composition due to snowmelt at all sampling points except for EG. Redundancy analysis (RDA) indicated that BCC was more closely related to DOM (Components 1 and 4, dissolved organic carbon, biochemical oxygen demand and chlorophyll a) and environmental factors (water temperature and nitrate nitrogen) than geographical factors. Furthermore, DOM had a greater impact on BCC than environmental factors (29.80 vs. 15.90% of the variation). Overall, spring snowmelt played an important role in altering the quality and quantity of DOM and BCC in the Heilongjiang watershed.

Characterization of chromophoric dissolved organic matter and relationships among PARAFAC components and water quality parameters in Heilongjiang, China

Chromophoric dissolved organic matter (CDOM) is an important optically active substance that can transports nutrients and pollutants from terrestrial to aquatic systems. Additionally, it is used as a measure of water quality. To investigate the source and composition of CDOM, we used chemical and fluorescent analyses to characterize CDOM in Heilongjiang. The composition of CDOM can be investigated by excitation-emission matrix (EEM) fluorescence and parallel factor analysis (PARAFAC). PARAFAC identified four individual components that were attributed to microbial humic-like (C1) and terrestrial humic-like (C2–4) in water samples collected from the Heilongjiang River. The relationships between the maximum fluorescence intensities of the four PARAFAC components and the water quality parameters indicate that the dynamic of the four components is related to nutrients in the Heilongjiang River. The relationships between the fluorescence component C3 and the biochemical oxygen demand (BOD5) indicates that component C3 makes a great contribution to BOD5 and it can be used as a carbon source for microbes in the Heilongjiang River. Furthermore, the relationships between component C3, the particulate organic carbon (POC), and the chemical oxygen demand (CODMn) show that component C3 and POC make great contributions to BOD5 and CODMn. The use of these indexes along with PARAFAC results would be of help to characterize the co-variation between the CDOM and water quality parameters in the Heilongjiang River.

Characterization of atrazine binding to dissolved organic matter of soil under different types of land use

Atrazine is widely used in agriculture. In this study, dissolved organic matter (DOM) from soils under four types of land use (forest (F), meadow (M), cropland (C) and wetland (W)) was used to investigate the binding characteristics of atrazine. Fluorescence excitation-emission matrix-parallel factor (EEM-PARAFAC) analysis, two-dimensional correlation spectroscopy (2D-COS) and Stern-Volmer model were combined to explore the complexation between DOM and atrazine. The EEM-PARAFAC indicated that DOM from different sources had different structures, and humic-like components had more obvious quenching effects than protein-like components. The Stern-Volmer model combined with correlation analysis showed that log K values of PARAFAC components had a significant correlation with the humification of DOM, especially for C3 component, and they were all in the same order as follows: meadow soil (5.68)>wetland soil (5.44)>cropland soil (5.35)>forest soil (5.04). The 2D-COS further confirmed that humic-like components firstly combined with atrazine followed by protein-like components. These findings suggest that DOM components can significantly influence the bioavailability, mobility and migration of atrazine in different land uses.