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Yang D.,Biogas Institute of Ministry of Agriculture | Yang D.,Laboratory of Development and Application of Rural Renewable Energy | Deng L.,Biogas Institute of Ministry of Agriculture | Deng L.,Laboratory of Development and Application of Rural Renewable Energy | And 8 more authors.
Fuel | Year: 2015

Swine wastewater was separated into a solid fraction and a liquid fraction in a biogas plant using a separator with hydraulic wedge-shaped sieve. The liquid fraction (separated slurry) was further separated into concentrated slurry and dilute liquid by gravity sedimentation in the laboratory. Components and methane production of the solid fraction accounted for about 15% of those of the raw wastewater. The majority of the organic matter and phosphorus (more than 60%) were distributed in the concentrated slurry. The concentrated slurry represented 15% of the volume of initial wastewater but produced more than 70% of the total methane production. The condensation of the pollutants and nutrients in the concentrated slurry can facilitate land application of digestate. The dilute liquid with less organic matter and nutrients can be treated easily using less expensive and easier treatment options. © 2014 Elsevier Ltd. All rights reserved.


Chen C.,Biogas Institute of Ministry of Agriculture | Zheng D.,Biogas Institute of Ministry of Agriculture | Liu G.,Biogas Institute of Ministry of Agriculture | Liu G.,Bioprocess Control AB | And 4 more authors.
Waste Management | Year: 2015

A down plug-flow anaerobic reactor (DPAR) was designed for the feasibility study on continuous dry fermentation of swine manure without any additional stirring. Using fresh swine manure as the feedstock with TS concentration (w/w) of 20%, 25%, 30%, and 35%, stable volumetric biogas production rates of 2.40, 1.92, 0.911, and 0.644L·(Ld)-1 and biogas yields of 0.665, 0.532, 0.252, and 0.178Lg-1VS were obtained respectively, and the TS degradation rates were 46.5%, 45.4%, 53.2%, and 55.6%, respectively. With the increase of feedstock TS concentration, the concentration of ammonia nitrogen grew up to the maximum value of 3500mgL-1. Biogas production was obviously inhibited when the concentration of ammonia nitrogen was above 3000mgL-1. The maximal volumetric biogas production rate of 2.34L·(Ld)-1 and biogas yield of 0.649Lg-1VS were obtained with TS concentration of 25% at 25°C without inhibition. Liquidity experiments showed that TS concentration of digestate could be less than 15.8%, and the flow rate of digestate more than 0.98ms-1 when the feedstock TS concentration was less than 35%, which indicated the digestate could be easily discharged from a DPAR. Therefore, it is feasible to conduct a continuous dry fermentation in a DPAR using fresh swine manure as the feedstock with TS concentration less than 35%, whereas the feedstock TS concentration should not exceed 30% to achieve the maximal biogas production rate and biogas yield. © 2015 Elsevier Ltd.


Zheng D.,Biogas Institute of Ministry of Agriculture | Zheng D.,Laboratory of Development and Application of Rural Renewable Energy | Liu G.,Biogas Institute of Ministry of Agriculture | Liu G.,Bioprocess Control AB | And 15 more authors.
Ecological Engineering | Year: 2016

This research investigated the startup of the partial nitritation (PN) process in a sand filter at ambient room temperature (5.5-27 °C) to produce an effluent suitable for the subsequent anaerobic ammonium oxidation (anammox) process. A naturally ventilated sand filter was used to treat anaerobically digested effluent of swine wastewater. Startup strategy of gradual step increases in the influent ammonium nitrogen concentration and pH successfully achieved the PN process. The principal cause for nitrite accumulation was high free ammonia concentration (up to about 20 mg L-1). An effluent with a nitrite-to-ammonium ratio of 1.02 was obtained, with the optimal influent ammonium nitrogen concentration of 600.0 mg L-1 and pH of 8.09. Overall, the PN process can be maintained in a sand filter without forced aeration, and coupling with the subsequent anammox process to achieve completely unpowered autotrophic nitrogen removal. © 2016 Elsevier B.V.


Yang D.,Biogas Institute of Ministry of Agriculture | Yang D.,Laboratory of Development and Application of Rural Renewable Energy | Deng L.,Biogas Institute of Ministry of Agriculture | Deng L.,Laboratory of Development and Application of Rural Renewable Energy | And 6 more authors.
Journal of Environmental Management | Year: 2016

There are two problems associated with treatment of swine wastewater, low efficiency of anaerobic digestion during winter and poor performance for aerobic treatment of digested effluent. A strategy employing unbalanced distributions of the pollutant mass and wastewater volumes in anaerobic and aerobic units was proposed. To accomplish this, swine wastewater was separated into high content liquid (HCL) and low content liquid (LCL). Three separation ratios of HCL to LCL (v/v), 1:9 (S1), 2:8 (S2), and 3:7 (S3), were evaluated. Anaerobically digestion of the HCL accounted for only 10%, 20% and 30% of the total volume of raw wastewater, but produced 63.38%, 73.79% and 76.61% of the total methane output for S1, S2 and S3, respectively. The mixed liquid of digested effluents of HCL and LCL were treated aerobically using sequencing batch reactors. S2 generated the best performance, with removal efficiencies of 96.98% for COD, 98.95% for NH3-N, 91.69% for TN and 74.71% for TP. The results obtained for S1 were not as good as those for S2, but were better than those for S3. Based on methane output from the anaerobic unit and pollutants removal in the aerobic unit, S2 was the most suitable system for the treatment of swine wastewater. Additionally, the anaerobic digestion efficiency of S2 was 282% higher than that of previous techniques employing balanced distribution. Taken together, these findings indicate that unbalanced distribution could improve the efficiency of the anaerobic unit remarkably, while ensuring good performance of the aerobic unit. © 2015 .


Lan G.,Southwest Petroleum University | Lan G.,Laboratory of Development and Application of Rural Renewable Energy | Fan Q.,Southwest Petroleum University | Liu Y.,University of Southampton | And 4 more authors.
Biochemical Engineering Journal | Year: 2015

The present work aims to produce rhamnolipid from waste cooking oil (WCO) using a newly isolated bacterium named Pseudomonas SWP-4. SWP-4 was a high-yield strain that could accumulate rhamnolipid steadily even in decline phase and gave a maximum rhamnolipid yield of 13.93. g/L and WCO utilization percent around 88%. The critical micelle concentration of the produced rhamnolipid was only 27. mg/L and its emulsification index against n-hexadecane reached around 59%. Moreover, it reduced the surface tension of water from 71.8. mN/m to 24.1. mN/m and the interfacial tension against n-hexadecane from 29.4. mN/m to 0.9. mN/m. Results of biosurfactant stability show the rhamnolipid was effective when the salinity was lower than 8% and pH value ranged from 4 to 10, and it was quite thermostable based on thermal gravity analysis. Furthermore, it maintained high surface activity even after incubation under extreme conditions i.e., pH of 4.0, salinity of 8% and temperature of 80. °C for half a month. Based on free fatty acids metabolism analysis, Pseudomonas SWP-4 consumed palmitic acid, oleic acid and linoleic acid chiefly. All these characteristics demonstrate bioconversion and biodegradation of WCO by Pseudomonas SWP-4 is a promising and commercial way of rhamnolipid production and waste treatment. © 2015 Elsevier B.V.


Wang L.,Biogas Institute of Ministry of Agriculture | Wang L.,Laboratory of Development and Application of Rural Renewable Energy | Zheng P.,Zhejiang University | Abbas G.,Zhejiang University | And 8 more authors.
Process Biochemistry | Year: 2016

Partial nitritation (PN) is the controllable bottleneck of the combined PN-anaerobic ammonium oxidation process, because it has a low nitrogen conversion rate. In this study, a "co-culture and screening" technology was developed to start up PN, and a dual dissolved oxygen-hydraulic retention time (DO-HRT) control strategy was developed to regulate the NH4 +-N/NO2 --N ratio. The results showed that PN could be successfully started up and it had a high nitrogen loading rate and ammonium conversion rate (9.42 kg-N m-3 day-1 and 4.74 kg-N m-3 day-1), respectively. A response surface methodology (RSM) with a central composite design (CCD) was used to optimize the parameters of DO and HRT. When DO and HRT satisfied the relationships 0.66-0.5 × DO ≤ HRT ≤ 0.79-0.53 × DO and 0.5 mg L-1 ≤ DO ≤ 0.75 mg L-1, the performance of PN was excellent with an NH4 +-N/NO2 --N ratio ranging from 1:1.04 to 1:1.47, an ammonium conversion efficiency of 53.6-62.1% and a nitrite accumulation efficiency greater than 90%. The excellent performance of PN process was attributed to the high specific activity of sludge (3.69 g-N g-1 VSS day-1), the predominance of ammonia-oxidizing bacteria, Nitrosomonas, and the inhibition of nitrite-oxidizing bacteria, Nitrospira. © 2015 Elsevier Ltd. All rights reserved.


Yang H.,Biogas Institute of Ministry of Agriculture | Yang H.,Laboratory of Development and Application of Rural Renewable Energy | Deng L.,Biogas Institute of Ministry of Agriculture | Deng L.,Laboratory of Development and Application of Rural Renewable Energy | And 8 more authors.
Water Research | Year: 2016

A study was conducted using a laboratory-scale anaerobic sequencing batch digester to investigate the quantitative influence of organic loading rates (OLRs) on the methane production rate during digestion of swine wastewater at temperatures between 15 °C and 35 °C. The volumetric production rate of methane (Rp) at different OLRs and temperatures was obtained. The maximum volumetric methane production rates (Rpmax) were 0.136, 0.796, 1.294, 1.527 and 1.952 LCH4 L−1 d−1 at corresponding organic loading rates of 1.2, 3.6, 5.6, 5.6 and 7.2 g volatile solids L−1 d−1, respectively, which occurred at 15, 20, 25, 30 and 35 °C, respectively. A new model was developed to describe the quantitative relationship between Rp and OLR. In addition to the maximum volumetric methane production rate (Rpmax) and the half-saturation constant (KLR) commonly used in previous models such as the modified Stover–Kincannon model and Deng model, the new model introduced a new index (KD) that denoted the speed of volumetric methane production rate approaching the maximum as a function of temperature. The new model more satisfactorily described the influence of OLR on the rate of methane production than other models as confirmed by higher determination coefficients (R2) (0.9717–0.9900) and lower bias between the experimental and predicted data in terms of the root mean square error and the Akaike Information Criterion. Data from other published research also validated the applicability and generality of the new kinetic model to different types of wastewater. © 2016 Elsevier Ltd


Abbas G.,Zhejiang University | Abbas G.,University of Gujrat | Wang L.,Biogas Institute | Wang L.,Laboratory of Development and Application of Rural Renewable Energy | And 3 more authors.
Ecological Engineering | Year: 2015

The pilot-scale internal-loop-airlift bio-particle (ILAB) reactor was a novel configuration adopted to study the performance of simultaneous partial nitrification (PN) and anaerobic ammonia oxidation (ANAMMOX). The ILAB reactor was operated at different nitrogen loading rates and hydraulic retention times to investigate the nitrogen removal kinetics. The reactor showed good tolerance to substrate concentration shock while it was significantly affected by hydraulic shock. Five kinetic models including first-order model, Grau second-order model, Stover-Kincannon model, Monod model and Contois model were applied to steady-state experimental data to evaluate the substrate removal in the reactor. The Grau second-order model and Stover-Kincannon model were found to be more appropriate compared with other models to describe and predict the performance of the reactor. Both the models were evaluated by judging the linearity between experimental data and predicted values which confirmed their validity for the process. © 2014 Published by Elsevier B.V.


Wang X.M.,Central China Normal University | Ma S.,Biogas Institute of Ministry of Agriculture | Ma S.,Laboratory of Development and Application of Rural Renewable Energy | Yang S.Y.,Central China Normal University | And 3 more authors.
International Journal of Systematic and Evolutionary Microbiology | Year: 2016

A Gram-stain-positive, non-motile, aerobic and terminal-endospore-forming rod-shaped bacterium, strain P5-1T, was isolated from the hindgut of a wood-feeding higher termite, Nasutitermes sp. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain was closely related to Paenibacillus sepulcri CCM 7311T (97.5% similarity). Growth was observed at 10–40 °C (optimum, 30 °C) and at pH 5.5–9.0 (optimum, pH 7.5). The DNA G+C content of strain P5-1T was 48.9 mol%. Cells contained menaquinone 7 (MK-7) as the sole respiratory quinone and the major fatty acids were anteiso-C15: 0 and iso-C15: 0. The cellular polar lipids comprised phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, one unidentified glycolipid and one unidentified aminophospholipid. The diamino acid of the cell-wall peptidoglycan was mesodiaminopimelic acid. Based on the phylogenetic, chemotaxonomic and phenotypic data obtained within this study, strain P5-1T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus nasutitermitis sp. nov. is proposed. The type strain is P5-1T (=CGMCC 1.15178T=NBRC 111536T). © 2015 IUMS Printed in Great Britain.


Deng L.,Biogas Institute of Ministry of Agriculture | Deng L.,Laboratory of Development and Application of Rural Renewable Energy | Chen C.,Biogas Institute of Ministry of Agriculture | Zheng D.,Biogas Institute of Ministry of Agriculture | And 7 more authors.
Journal of Environmental Management | Year: 2016

Laboratory-scale experiments were performed on the dry digestion of solid swine manure in a semi-continuous mode using 4.5 L down plug-flow anaerobic reactors with an organic loading rate of 3.46 kg volatile solids (VS) m-3 d-1 to evaluate the effects of temperature (15, 25 and 35 °C). At 15 °C, biogas production was the poorest due to organic overload and acidification, with a methane yield of 0.036 L CH4 g-1 VS added and a volumetric methane production rate of 0.125 L CH4 L-1 d-1. The methane yield and volumetric methane production rate at 25 °C (0.226 L CH4 g-1 VS added and 0.783 L CH4 L-1 d-1, respectively) were 6.24 times higher than those at 15 °C. However, the methane yield (0.237 L CH4 g-1 VS added) and the volumetric methane production rate (0.821 L CH4 L-1 d-1) at 35 °C were only 4.86% higher than those at 25 °C, which indicated similar results were obtained at 25 °C and 35 °C. The lower biogas production at 35 °C in dry digestion compared with that in wet digestion could be attributed to ammonia inhibition. For a single pig farm, digestion of solid manure is accomplished in small-scale domestic or small-farm bioreactors, for which operating temperatures of 35 °C are sometimes difficult to achieve. Considering biogas production, ammonia inhibition and net energy recovery, an optimum temperature for dry digestion of solid swine manure is 25 °C. © 2016 Elsevier Ltd.

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