Succession of bacteria communities during production and application of dairy bedding by membrane-covered aerobic fermentation

The cost of dairy manure treatment and bedding material purchase increases the operating cost of the dairy farm.Membrane-covered aerobic fermentation system has been widely used for dealing with dairy manure and recycling the final product as bedding material.However,the microbial safety in each processing step is still uncertain.To better understand the bacterial community dynamics during the whole bedding conversion process,a full-chain and large-scale experiment including 16-day membrane-covered aerobic fermentation and 11-day bedding material application was conducted.The results showed that the pile temperatures in the fermentation stage rapidly increased to 80°C and maintained>50°C for more than 11 days and the use of fermentation product as bedding material provided cows with a stable and comfortable bedding environment.The Chao1 and Shannon index decreased at the end of the fermentation stage and remained stable in the application stage,indicating that membrane-covered aerobic fermentation effectively killed some pathogenic bacteria and guaranteed both the maturity and stability of the final product.The dominant bacteria in the fermentation stage were Acinetobacter,Thermus,and Rhodothermus at genus level.Seven common potential pathogens of mastitis(Staphylococcus,Enterococcus,Serratia,Pseudomonas,Corynebacterium,Mycobacterium,and Bacillus)were found at the end of fermentation stage but the relative abundance was low(0.0025%-0.2727%).The dominant bacteria in the application stage mainly included Acinetobacter,Pseudomonas,and Flavobacterium at the genus level.The relative abundance of Pseudomonas increased in the application stage,which was a reminder to the dairy farm to pay attention to the disinfection and timely replacement of bedding material to prevent the occurrence of dairy mastitis.The results of this study contributed deep understanding of the microorganism-driven bedding conversion process and provide practical guidance and cautions for the bedding materials application.

The use of Phanerochaete chrysosporium,Trichoderma harzianum and Trichoderma viride for biogas production

The expanding cost of ordinary fuel in urban zones requires the investigation of other vitality sources.The exploitation of agricultural wastes for biogas production could protect our environment and can also solve emerging energy crises problems.Phanerochaete chrysosporium,Trichoderma virdie and Trichoderma harzianum were used to ferment rice straw and cattle dung for production of compost and biogas.Biogas yield was determined using displacement technique,using acidified water(1 N H_(2)SO_(4))to prevent solubilization of carbon dioxide contained in the biogas.Current results showed that the highest rate of biogas and methane were recorded with treated rice straw mixed with cattle dung where the amount of production from the total gas was 51.84 of biogas and 37.86 of methane per Liter(L)/Kilogram(Kg)of fermented material.Also,the results showed that the consumed biogas and methane related to volatile solids gave the highest amount with untreated rice straw(86.32 and 56.72 L/Kg respectively)followed by treated rice straw and untreated and treated mixtures of rice straw and cattle dung respectively.The results also showed that the highest bacterial count was obtained from fungi treated rice straw mixed with cattle dung(125×10^(3)cells/g)followed by treated rice straw(32×10^(3)cells/g).This study confirms that P.chrysosporium,T.virdie and T.harzianum significantly speed up the process of aerobic and anaerobic fermentation of rice straw in respect to biogas and methane production.

Effect of airflow on biodrying of gardening wastes in reactors

Biodrying consists of reducing moisture by using the heat from aerobic bio-degradation.The parameters that control the process are：aeration,temperature during the process,initial moisture of biowaste,and temperature and relative humidity of the input air.Lawn mowing and garden waste from the gardens of the University Jaume I,Castellón（Spain）were used as a substrate.Biodrying was performed in 10 reactors with known air volumes from 0.88 to 6.42 L/（min·kg dry weight）.To promote aeration,5 of the reactors had 15% of a bulking agent added.The experiment lasted 20 days.After the experiments it was found that the bulking agent led to greater weight loss.However,the increased airflow rate was not linearly proportional to the weight loss.