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Featured researches published by Wanqin Zhang.


Bioresource Technology | 2015

Performance and kinetic evaluation of semi-continuously fed anaerobic digesters treating food waste: Role of trace elements

Wanqin Zhang; Shubiao Wu; Jianbin Guo; Jie Zhou; Renjie Dong

This study investigated the effects of trace elements (TEs) on the anaerobic digestion (AD) of food waste (FW) in laboratory-scale semi-continuously fed anaerobic digesters. The duration of digesters operation was approximately 400 days. Organic loading rates (OLRs) ranged from 1.0 to 5.5 g VS L(-1) d(-1) at 37 °C. Results showed that methane production of the digester was severely inhibited at a volatile fatty acid (VFA) concentration of 30,000 mg L(-1) at OLR of 4.0 g VS L(-1) d(-1) in the absence of TEs. Contrary to the failed digesters, a stable performance was achieved in the TEs added digesters. High methane yield (approximately 465.4 mL CH4 g(-1)VSadded) was obtained, and no significant accumulation of VFA was observed in the TEs added digesters at OLR of 1.0-5.0 g VS L(-1) d(-1) and HRT of 40 days. These findings strongly indicated that the addition of TEs has an important impact on the operation stability of AD of FW.


Bioresource Technology | 2013

Effects of organic loading rate and effluent recirculation on the performance of two-stage anaerobic digestion of vegetable waste.

Zhuang Zuo; Shubiao Wu; Wanqin Zhang; Renjie Dong

The effects of organic loading rates (OLR) and effluent recirculation on dynamics of acidogenic and methanogenic processes in two-stage anaerobic digestion of vegetable waste were investigated. Two systems were performed at OLRs of 1.3, 1.7, 2.1 and 2.6 g VS/L/d. One system recirculated the effluent from the methanogenic reactor to acidogenic reactor. With increasing OLRs, total volatile fatty acid (VFA) concentration increased to approximately 8500 mg/L in acidogenic digester, where pH decreased from 6.4 to 5.2. Daily biogas production and methane content in methanogenic reactor increased from 1.2 to 4.4 L/d and from 27.4% to 60.5%, respectively. However, inhibition of hydrolysis in acidogenic reactor was demonstrated under the OLR of 2.6 g VS/L/d without recirculation, thus indicating system overloading. Effluent recirculation shown a considerable positive effect on alleviating VFA inhibition and improving biogas production in acidogenic reactor because of the effect of dilution and pH adjustment, particularly at high OLRs.


Bioresource Technology | 2014

Anaerobic digestion characteristics of pig manures depending on various growth stages and initial substrate concentrations in a scaled pig farm in Southern China

Wanqin Zhang; Qianqian Lang; Shubiao Wu; Wei Li; Hamidou Bah; Renjie Dong

The characteristics of anaerobic digestion of pig manure from different growth stages were investigated. According to growth stage, batch experiments were performed using gestating sow manure (GSM), swine nursery with post-weaned piglet manure (SNM), growing fattening manure (GFM) and mixed manure (MM) as substrates at four substrate concentrations (40, 50, 65 and 80gVS/L) under mesophilic conditions. The maximum methane yields of MM, SNM, GSM and GFM were 354.7, 328.7, 282.4 and 263.5mLCH4/gVSadded, respectively. Volatile fatty acids/total inorganic carbon (VFA/TIC) ratio increased from 0.10 to 0.89 when loading increased from 40 to 80gVS/L for GFM. The modified Gompertz model shows a better fit to the experimental results than the first order model with a lower difference between measured and predicted methane yields. The kinetic parameters indicated that the methane production curve on the basis of differences in biodegradability of the pig manure at different growth stages.


Science of The Total Environment | 2016

Properties of plant nutrient: Comparison of two nutrient recovery techniques using liquid fraction of digestate from anaerobic digester treating pig manure

Xin Li; Jianbin Guo; Renjie Dong; Birgitte Kiær Ahring; Wanqin Zhang

Anaerobic digestate has valuable potential as organic fertilizer or soil amendment, given that it typically contains high amounts of plant nutrients, such as nitrogen, phosphate and plant hormones. In this study, ammonia stripping and vacuum evaporation were tested to compare their technical feasibilities and their effects on plant nutrient properties in the liquid fraction of digestate. Results of the batch experiments showed that the nutrient characteristics of liquid digestate, including total ammonia nitrogen (TAN), soluble P, gibberellic acid (GA), indoleacetic acid (IAA) and abscisic acid (ABA), were strongly dependent on the initial pH in both ammonia stripping and vacuum evaporation processes. A low plant nutrient concentration (TAN 137 mg · L(-1), soluble P 1.5 mg · L(-1), GA3/ABA 0.04) in the liquid digestate was achieved in the ammonia stripping process with Ca(OH)2 addition of 12 g · L(-1), whereas a high nutrient concentration (TAN 2998 mg · L(-1), soluble P 178.3 mg · L(-1), IAA 60.9 mg · L(-1) and GA3/ABA 0.4) was achieved in vacuum evaporation at a pH level of 6. According to the results, both ammonia stripping and vacuum evaporation can be used as an alternative of nutrient recovery techniques, which should be chosen based on the potential different applications of liquid digestate (e.g., soaking seed, increasing plant tolerance, and nutrients transportation).


Chemosphere | 2014

Performance and kinetic evaluation of a semi-continuously fed anaerobic digester treating food waste: Effect of trace elements on the digester recovery and stability

Quanyuan Wei; Wanqin Zhang; Jianbin Guo; Shubiao Wu; Tianwei Tan; Fang Wang; Renjie Dong

This study investigated the effects of trace elements (TEs: Fe, Co, and Ni) on the anaerobic digestion of food waste in laboratory scale semi-continuously fed anaerobic digesters. The digesters were operated for approximately 460 d at organic loading rates (OLRs) ranging from 1.0 to 5.0 g VS L(-1)d(-1) at 37°C. Results showed that methane production was severely inhibited when volatile fatty acids (VFAs) concentration was 30,000 mg L(-1) at OLR of 4.0 g VS L(-1)d(-1) without the addition of TEs. However, the inhibition was gradually decreased and the methane production increased from 0.13 up to 0.44 L g(-1)VS added when the TEs was added. Fe was proved to be the essential element in maintaining the stability of the digester. The conversion coefficient of substrate into biogas (YS/G) was 1.00 and 1.26 gVS removedL(-1) biogas with and without TEs addition, respectively. The estimated biomass yield with feeding TEs (0.06 g VSS g(-1)COD removed) was higher three times than that without TEs (0.02 gVSS g(-1)COD removed).


Bioresource Technology | 2014

Performance of two-stage vegetable waste anaerobic digestion depending on varying recirculation rates.

Zhuang Zuo; Shubiao Wu; Wanqin Zhang; Renjie Dong

Vegetable waste, which characterized by high moisture content, was evaluated as a substrate for biogas production. The effects of recirculation rate (RR) on the performance of two-stage anaerobic digestion were investigated. The system was operated at an organic loading rate of 1.7 g VS/L/d with varying RRs (0, 0.6, 1, and 1.4). Results demonstrated that volumetric biogas production rates in acidogenic reactor increased from approximately 0.2 7 L/L/d to 0.97 L/L/d, when pH is increased from approximately 5.1 to 6.7. These indicate that recirculation of alkaline effluent from the methanogenic reactor helps create a favorable condition for biogas production in the acidogenic reactor. The decrease in chemical oxygen demand (COD) concentrations from approximately 21,000 mg/L to 6800 mg/L was also observed in the acidogenic reactor. This condition may be attributed to dilution under recirculation. The dynamics between hydrolysis and methanogenesis under recirculation indicated that mass transfer capacity between two-stage reactors improved.


Bioresource Technology | 2017

Combined effect of crude fat content and initial substrate concentration on batch anaerobic digestion characteristics of food waste

Wanqin Zhang; Qianqian Lang; Ming Fang; Xin Li; Hamidou Bah; Hongmin Dong; Renjie Dong

The mesophilic anaerobic digestion (AD) characteristics of food waste (FW) with different crude fat (CF) contents and four initial substrate concentrations (4, 6, 8, and 10gVS/L) were investigated. The maximum methane yields of FW with CF contents of 15%, 20%, 25%, 30%, and 35% were 565.0, 580.2, 606.0, 630.2 and 573.0mLCH4/gVSadded, respectively. An acidification trend with a drop in pH (<6.80) and increase in the volatile fatty acids/total inorganic carbon (VFAs/TIC) ratio (>0.4) were found for CF contents of 30% (10gVS/L) and 35% (8 and 10gVS/L). A 35% CF content in FW led to decrease in the first-order degradation constant of approximately by 40%. The modified Gompertz model showed that the lag phase (λ) was prolonged from 0.4 to 7.1days when the CF content in FW and initial substrate concentration were increased to 35% and 10gVS/L.


Waste Management | 2014

Evaluation of batch anaerobic co-digestion of palm pressed fiber and cattle manure under mesophilic conditions.

Hamidou Bah; Wanqin Zhang; Shubiao Wu; Dandan Qi; Simon Kizito; Renjie Dong

Palm pressed fiber (PPF) and cattle manure (CM) are the waste which can be managed properly by anaerobic co-digestion. The biogas production in co-digested PPF and CM at three volatile solids (VS) ratios of 3:1, 1:1, and 1:3 was investigated in a series of batch experiments at an organic loading rate of 30.0 g VS/L under mesophilic (37±1°C) conditions. The highest daily biogas yield of PPF and CM only, was 90.0 mL/g VS(added) at day 12 and 23.4 mL/g VS(added) at day 7. For co-digestion of PPF/CM at mixing ratios of 3:1, 1:1 and 1:3, there were 93.6 mL/g VS(added) at day 11, 86.8 and 26.4 mL/g VS(added) at day 8. VS removal rate for PPF, CM, and co-digestion at mixing ratio of 3:1, 1:1, and 1:3 were 91.1%, 86.0% and 71.0%, respectively. The anaerobic digestion of PPF and CM and their co-digestion systems were stable in operation with low range of volatile fatty acids (VFA)/TIC (total inorganic carbon) of (0.035-0.091). The main volatile fatty acids were propionic, and iso-butyric acids for PPF, iso-butyric and n-butyric acids for CM. The VFAs and ammonium inhibition were not occurred. The modified Gompertz model can be used to perform a better prediction with a lower difference between the measured and predicted biogas yields. A VS ratio of 3:1 is recommended for practice.


Waste Management | 2017

Performance evaluation of a novel anaerobic digestion operation process for treating high-solids content chicken manure: Effect of reduction of the hydraulic retention time at a constant organic loading rate

Wanqin Zhang; Qianqian Lang; Zhendong Pan; Yingqing Jiang; Jan Liebetrau; Michael Nelles; Hongmin Dong; Renjie Dong

A novel feeding strategy was adopted in this study and the effect of reduction in hydraulic retention time (HRT) on the anaerobic digestion of chicken manure (CM) with a constant organic loading rate of 6.0gVS/L/d was investigated. The lab-scale CSTR was operated at 38°C and HRTCM was reduced from 52days to 5days. At HRTCM of 20-45days, the reactor was relatively stable in terms of the volumetric biogas production rates and specific biogas production (SBP), which were 2.2-2.4L/L/d and 338.3-418.7mL/gVSadded, respectively. However, process instability and VFA accumulation occurred when the HRTCM was reduced to 10days due to excess microbes washout. The reduction in HRTCM to 5days caused SBP to decrease to 198.7mL/gVSadded and the acetic acid content to exceed 6000mg/L. The biomass balance model showed that the biomass concentration at HRTCM of 20-52days (0.473-0.615gVSS/L) was notably higher than that at HRTCM of 5-10days (0.173gVSS/L).


Applied Energy | 2014

Batch anaerobic co-digestion of pig manure with dewatered sewage sludge under mesophilic conditions

Wanqin Zhang; Quanyuan Wei; Shubiao Wu; Dandan Qi; Wei Li; Zhuang Zuo; Renjie Dong

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Renjie Dong

China Agricultural University

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Shubiao Wu

China Agricultural University

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Jianbin Guo

China Agricultural University

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Hamidou Bah

China Agricultural University

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Qianqian Lang

Chinese Academy of Sciences

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Xin Li

China Agricultural University

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Zhuang Zuo

China Agricultural University

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Dandan Qi

China Agricultural University

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Jie Zhou

China Agricultural University

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Quanyuan Wei

Beijing University of Chemical Technology

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