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Featured researches published by Nina Duan.


Bioresource Technology | 2012

High-solid anaerobic digestion of sewage sludge under mesophilic conditions: Feasibility study

Nina Duan; Bin Dong; Bing Wu; Xiaohu Dai

Feasibility of high-solid anaerobic digestion of sewage sludge was investigated in single-stage completely stirred tank reactors at 35±1 °C. System stability and the effect of organic loading rate (OLR), sludge retention time (SRT) and total solid (TS) content on the performance of high-solid system was examined. Experimental results showed that, with the concentration of free ammonia nitrogen (FAN) lower than 600 mg l(-1), high-solid anaerobic digestion of sewage sludge could maintain satisfactory stability. Slight, moderate and significant inhibition was found with FAN concentration ranging from 250 to 400, 400 to 600 and 600 to 800 mg l(-1), respectively. The VFA/TA criteria could not foresee system instability in significant ammonia inhibition system by its traditional ratio grades. High-solid system could support higher OLR (4-6 times as high) and obtain similar methane yield and VS reduction as conventional low-solid system at the same SRT, thus reach much higher volumetric methane production rate.


Waste Management | 2013

High-solids anaerobic co-digestion of sewage sludge and food waste in comparison with mono digestions: stability and performance.

Xiaohu Dai; Nina Duan; Bin Dong; Lingling Dai

System stability and performance of high-solids anaerobic co-digestion of dewatered sludge (DS) and food waste (FW) in comparison with mono digestions were investigated. System stability was improved in co-digestion systems with co-substrate acting as a diluting agent to toxic chemicals like ammonia or Na(+). For high-solids digestion of DS, the addition of FW not only improved system stability but also greatly enhanced volumetric biogas production. For high-solids digestion of FW, the addition of DS could reduce Na(+) concentration and help maintain satisfactory stability during the conversion of FW into biogas. System performances of co-digestion systems were mainly determined by the mixing ratios of DS and FW. Biogas production and volatile solids (VSs) reduction in digestion of the co-mixture of DS and FW increased linearly with higher ratios of FW. A kinetic model, which aimed to forecast the performance of co-digestion and to assist reactor design, was developed from long-term semi-continuous experiments. Maximum VS reduction for DS and FW was estimated to be 44.3% and 90.3%, respectively, and first order constant k was found to be 0.17d(-1) and 0.50 d(-1), respectively. Experimental data of co-digestion were in good conformity to the predictions of the model.


Bioresource Technology | 2017

Impact of a high ammonia-ammonium-pH system on methane-producing archaea and sulfate-reducing bacteria in mesophilic anaerobic digestion

Xiaohu Dai; Chongliang Hu; Dong Zhang; Lingling Dai; Nina Duan

A novel strategy for acclimation to ammonia stress was implemented by stimulating a high ammonia-ammonium-pH environment in a high-solid anaerobic digestion (AD) system in this study. Three semi-continuously stirred anaerobic reactors performed well over the whole study period under mesophilic conditions, especially in experimental group (R-2) when accommodated from acclimation period which the maximum total ammonia nitrogen (TAN) and free ammonia nitrogen (FAN) increased to 4921 and 2996mg/L, respectively. Moreover, when it accommodated the high ammonia-ammonium-pH system, the daily biogas production and methane content were similar to those in R-1 (the blank control to R-2), but the hydrogen sulfide (H2S) content lower than the blank control. Moreover, mechanistic studies showed that high ammonia stress enhanced the activity of coenzyme F420. The results of real-time fluorescent quantitative polymerase chain reaction (PCR) showed that ammonia stress decreased the abundance of sulfate-reducing bacteria and increased the abundance of methane-producing archaea.


Archive | 2011

Method for improving fermentation capability of slurry dry process

Bin Dong; Nina Duan; Qunbiao He; Xiaohu Dai


Archive | 2011

Method for producing mash gas from municipal sludge through dry method anaerobic fermentation

Bin Dong; Nina Duan; Xiaohu Dai


Archive | 2011

Advanced dry anaerobic digestion method based on sludge modification pretreatment

Bin Dong; Nina Duan; Lingling Zhou; Xiaohu Dai


Archive | 2012

Method for enhancing dry-process fermentation stability of sludge by adding kitchen waste

Bin Dong; Nina Duan; Qunbiao He; Xiaohu Dai


Archive | 2012

Quick starting method for producing biogas through anaerobic fermentation of municipal sludge

Bin Dong; Chao Sha; Nina Duan; Lingling Dai; Xiaohu Dai


Water Science and Technology | 2016

Anaerobic digestion of sludge differing in inorganic solids content: performance comparison and the effect of inorganic suspended solids content on degradation

Nina Duan; Xiaohu Dai; Bin Dong; Lingling Dai


Archive | 2011

Circular inoculation method used for accelerating fermentation process of municipal sludge dry method

Bin Dong; Nina Duan; Lingling Zhou; Yuanyuan Yan; Xiaohu Dai

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