Zhangying Ye

Co-liquefaction of swine manure and crude glycerol to bio-oil: Model compound studies and reaction pathways

The reaction pathways of co-liquefaction of swine manure and crude glycerol to bio-oil (ester compounds) were investigated. Swine manure was hydrothermal treated (340 °C, 27.5 MPa, 15 min) with a number of model compounds in a high pressure batch reactor under inert atmosphere. The compounds were methanol, pure glycerol, mixture of pure glycerol, pure methanol and H(2)O, and commercial fatty acids (linoleic acid). The chemical composition of the bio-oil was analyzed by GC/MS. Glycerol, methanol and water showed synergistic effects on manure liquefaction, increasing the oil yield as high as 65%. A maximum oil yield of 79.96% was obtained when linoleic acid reacted with swine manure. Based on the results, the reaction pathways were proposed. Esterification reactions occurred not only because the crude glycerol have methanol, but also because methanol can be produced from hydrothermal reactions of glycerol.

Ammonia Emissions Affected by Airflow in a Model Pig House: Effects of Ventilation Rate, Floor Slat Opening, and Headspace Height in a Manure Storage Pit

Laboratory experiments were performed to study the influence of airflow on ammonia emissions from pig house slurry in a model growing/finishing pig house with slurry in the pit and a clean slatted floor with various opening areas, 100%, 33.3%, and 16.7%. The 100% opening area meant that the headspace was an integral part of the room air space, and this configuration was used as the reference treatment. The pig house model had two sidewall inlets and exhaust in the middle of the ceiling. The liquid slurry used was from a growing/finishing pig building and consisted of 1% to 2% dry matter, had pH of 8.05, and TAN (total ammonia nitrogen) of 2.38 g/L. Experiments in a model growing/finishing swine barn were conducted to determine the effects of room ventilation rate, slurry pit air exchange rates, slatted floor openings, and pit headspace on ammonia emissions. The results showed that ammonia emission rate increased as ventilation rate increased with a constant inlet opening. Increase in the slatted floor opening ratio increased the air exchange rate in the slurry pit, resulting in a higher ammonia emission rate. Different correlations between the ammonia emission rate and the air headspace height in the slurry pit caused by the type of flow in the boundary layer influenced the ammonia transport from the slurry surface to the ventilation air. A statistical model was developed to calculate the ammonia emission rate as a function of ventilation rate, slatted floor opening ratio, and slurry pit headspace (R2 = 0.93). It was found that the NH3 emission rate was more sensitive to the ventilation rate than to the slatted floor opening ratio and air headspace height in the pit. In addition, the NH3 emission rate was much more sensitive to variations in the ventilation rate at low ventilation rates than at high ventilation rates. Similar sensitivity responses were obtained for both slatted floor opening ratio and air headspace height.

Simultaneous ammonia and nitrate removal in an airlift reactor using poly(butylene succinate) as carbon source and biofilm carrier.

In this study, an airlift inner-loop sequencing batch reactor using poly(butylene succinate) as the biofilm carrier and carbon source was operated under an alternant aerobic/anoxic strategy for nitrogen removal in recirculating aquaculture system. The average TAN and nitrate removal rates of 47.35±15.62gNH4-Nm(-3)d(-1) and 0.64±0.14kgNO3-Nm(-3)d(-1) were achieved with no obvious nitrite accumulation (0.70±0.76mg/L) and the dissolved organic carbon in effluents was maintained at 148.38±39.06mg/L. Besides, the activities of dissimilatory nitrate reduction to ammonium and sulfate reduction activities were successfully inhibited. The proteome KEGG analysis illustrated that ammonia might be removed through heterotrophic nitrification, while the activities of nitrate and nitrite reductases were enhanced through aeration treatment. The microbial community analysis revealed that denitrifiers of Azoarcus and Simplicispira occupied the dominate abundance which accounted for the high nitrate removal performance. Overall, this study broadened our understanding of simultaneous nitrification and denitrification using biodegradable material as biofilm carrier.

Effects of stocking density of the white shrimp Litopenaeus vannamei (Boone) on immunities, antioxidant status, and resistance against Vibrio harveyi in a biofloc system

Abstract Determining optimum stocking density of the white shrimp Litopenaeus vannamei (Boone) is a big concern for shrimp farmers. However, few studies have assessed the influence of stocking density on the antioxidant status, immunology, digestive enzyme activities, and growth performance of white shrimp in biofloc systems. In this study, these parameters of white shrimp in a biofloc system were compared at three stocking densities: 300 orgs m−3 as low stocking density (LD), 400 orgs m−3 as medium stocking density (MD), and 500 orgs m−3 as high stocking density (HD). The feed conversion ratio in the LD group was significantly lower than that in the MD and HD groups (P < 0.05), and the ultimate individual weight in the LD group was significantly higher than that in the other two groups (P < 0.05). The antioxidant status and immunology parameters, including complement 3, complement 4, lysozyme, superoxide dismutase, glutathione peroxidase and malondialdehyde were all depressed in the HD groups. Furthermore, activities of the digestive enzymes, amylase, trypsin, and lipase were lower in the MD and HD groups than that in the LD group. The highest relative percentage survival was observed in the LD group 10 days after challenge with the pathogen Vibrio harveyi. Results of this study indicated that the immune status and welfare of white shrimp can be seriously impaired in the HD condition (i.e., ≥500 m−3) in biofloc systems. These findings can be used to determine suitable stocking densities in the white shrimp farming industry using the biofloc system. HighlightsHigh stocking density had effects on the culture of Litopenaeus vannamei in a biofloc‐based system.High stocking density stress reduced shrimp growth performance in the biofloc system.Choosing a suitable stocking density can obtain a high yield of Litopenaeus vannameiHigh stocking density had a bad influence on the shrimp immune parameters in the biofloc system.

Spatial behavioral characteristics and statistics-based kinetic energy modeling in special behaviors detection of a shoal of fish in a recirculating aquaculture system

A modified kinetic energy model was proposed to detect special behaviors of the shoal instead tracking.Two alternative methods were applied to the extraction of behavioral characteristics.Optical flow, entropy and statistics were adopted to measure spatial behavioral characteristics of the shoal. In global aquaculture, fish welfare is attached increasing importance to. Fish behavior holds important information of its living welfare. Thus, in order to detect special behaviors concerned with fish welfare in a recirculating aquaculture system (RAS), a modified kinetic energy model of the whole shoal instead tracking individuals inside a shoal was proposed in this study. The dispersion, velocity and turning angle of the shoal were regarded as the key factors in this model. First, with the reflective regions of the water surface taken into account, two alternative ways were presented to extract the necessary spatial behavioral characteristics of the shoal. Then, optical flow, entropy and statistics were adopted to measure the dispersion status (dispersion of individuals in space) and the changing magnitude of the motion (behavioral characteristics) of the shoal. Finally, the modified kinetic energy model was obtained by combining the dispersion measurement with the changing magnitude of the behavioral characteristics. Referring to the human observation and the evacuation of the gastro-intestine contents-based long experiment of Nile tilapia (Oreochromis niloticus) in RAS, the proposed model shows good performance in detection of the emergent gathering and scattering behaviors with 97.20ź1.23% success rate at least and 0.61ź0.08% missing report rate at most.

Bacterial Community Analysis of Different Sections of a Biofilter in a Full-Scale Marine Recirculating Aquaculture System

AbstractThe indoor recirculating aquaculture system (RAS) is a sustainable alternative to traditional aquaculture systems, and a biofilter is a crucial component for the stable operation of this system. In this study, the bacterial communities within different sections of the biofilter in a full-scale RAS for the culture of Tongue Sole Cynoglossus semilaevis were investigated using polymerase chain reaction–based 454 pyrosequencing. A total of 67,368 effective sequences of the 16S rRNA gene with V1–V3 regions were obtained from samples collected from the front section, rear section, and sludge of the biofilter. Using a 3% cut-off level and sufficient sequencing depth, a total of 5,185 operational taxonomic units (OTUs) were identified in these sequences across all samples. However, a low shared richness of 570 OTUs (11.0% of the reads) was found in all samples, indicating a high diversity of bacterial profiles even in a single biofilter. Based on the SILVA database classifier of phylogenetic taxa, Proteob...

Inactivation Mechanism of Escherichia coli Induced by Slightly Acidic Electrolyzed Water

Foodborne disease outbreak caused by food microbiological contamination is a serious public health problem. Slightly acidic electrolyzed water (SAEW), a new ultra-high effect and wide-spectrum disinfectant that is colourless, odourless, and harmless to humans and the environment, is directly used on food surfaces in Japan and America. However, the underlying inactivation mechanism remains unknown. In this study, biochemical and cellular changes were observed to investigate the bactericidal mechanism of SAEW against Escherichia coli (E. coli). The results indicated that SAEW with a pH of 6.40, an oxidation-reduction potential (ORP) of 910 mV, an available chlorine concentration (ACC) of 60 mg/L, and a volume ratio of 20:1, produced the most effective sterilization action. A fluorescence-based live-dead assay was further used to demonstrate the sterilized effect and the cell esterase activity damage caused by SAEW. During the observation period, within 10 min, the cell morphology changed, which was characterized by cell expansion, cell elongation and increased membrane permeability. Meanwhile, reactive oxygen substances (ROS) were released in the bacterial cells. E. coli inactivation and apoptosis induced by SAEW were observed. Our findings illustrate that the bactericidal effects of SAEW against E. coli occurred through cellular and biochemical mechanisms of cell necrosis and apoptosis.

Synergistic Effects of Micro-electrolysis-Photocatalysis on Water Treatment and Fish Performance in Saline Recirculating Aquaculture System

A new physico-chemical process for TAN (total ammonia nitrogen) removal and disinfection is introduced in saline recirculating aquaculture system (RAS), in which the biofilter is replaced with an integrated electrolysis cell and an activated carbon filter. The electrolysis cell which is based on micro current electrolysis combined with UV-light was self-designed. After the fundamental research, a small pilot scale RAS was operated for 30 days to verify the technical feasibility. The system was stocked by 42 GIFT tilapia (Oreochromis niloticus) fish with the rearing density of 13 kg/m3. During the experiments, the TAN concentration remained below 1.0 mg/L. The nitrite concentration was lower than 0.2 mg/L and the nitrate concentration had increased continuously to 12.79 mg/L at the end. Furthermore, the concentration of residual chlorine in culture ponds remained below 0.3 mg/L, ORP maintained slight fluctuations in the range of 190~240 mV, and pH of the water showed the downtrend. Tilapia weight increased constantly to 339.3 ± 10 g. For disinfection, the active chlorine generated by electrochemical treatment caused Escherichia coli inactivation. Enzyme activity assay indicated that the activity of glutamate dehydrogenase, carbonic anhydrase and glutamic pyruvic transaminase increased within the normal range. The preliminary feasibility was verified by using this physico-chemical technology in the RAS.

The impact of DO and salinity on microbial community in poly(butylene succinate) denitrification reactors for recirculating aquaculture system wastewater treatment

The interactions between environmental factors and bacterial community shift in solid-phase denitrification are crucial for optimum operation of a reactor and to achieve maximum treatment efficiency. In this study, Illumina high-throughput sequencing was applied to reveal the effects of different operational conditions on bacterial community distribution of three continuous operated poly(butylene succinate) biological denitrification reactors used for recirculating aquaculture system (RAS) wastewater treatment. The results indicated that salinity decreased OTU numbers and diversity while dissolved oxygen (DO) had no obvious influence on OTU numbers. Significant microbial community composition differences were observed among and between three denitrification reactors under varied operation conditions. This result was also demonstrated by cluster analysis (CA) and detrended correspondence analysis (DCA). Hierarchical clustering and redundancy analysis (RDA) was performed to test the relationship between environmental factors and bacterial community compositions and result indicated that salinity, DO and hydraulic retention time (HRT) were the three key factors in microbial community formation. Besides, Simplicispira was detected under all operational conditions, which worth drawing more attention for nitrate removal. Moreover, the abundance of nosZ gene and 16S rRNA were analyzed by real-time PCR, which suggested that salinity decreased the proportion of denitrifiers among whole bacterial community while DO had little influence on marine reactors. This study provides an overview of microbial community shift dynamics in solid-phase denitrification reactors when operation parameters changed and proved the feasibility to apply interval aeration for denitrification process based on microbial level, which may shed light on improving the performance of RAS treatment units.

Optimization of Local Ventilation System for Gaseous Pollutants Removal in Broiler House Using CFD Simulation

Gaseous pollutants in broiler house may cause negative effects to the production performance and health of broilers. Ventilation is an effective and simple way to improve air quality in broiler house. For the purpose of heat preservation, there is little ventilation in broiler house in winter season for small-scale broiler production in China, which leads to serious air quality issues. This paper proposes an optimization of a local ventilation system which could be used for gaseous pollutants removal in winter.