The biochemical methane potentials for typical fruit and vegetable waste （FVW） and food waste （FW） from a northern China city were investigated, which were 0.30, 0.56 m3 CH4/kgVS （volatile solids） with biodegrad...The biochemical methane potentials for typical fruit and vegetable waste （FVW） and food waste （FW） from a northern China city were investigated, which were 0.30, 0.56 m3 CH4/kgVS （volatile solids） with biodegradabilities of 59.3% and 83.6%, respectively. Individual anaerobic digestion testes of FVW and FW were conducted at the organic loading rate （OLR） of 3 kg VS/（m3-day） using a lab-scale continuous stirred-tank reactor at 35°C. FVW could be digested stably with the biogas production rate of 2.17 ma/（m3-day） and methane production yield of 0.42 m3 CH4/kg VS. However, anaerobic digestion process for FW was failed due to acids accumulation. The effects of FVW： FW ratio on co-digestion stability and performance were further investigated at the same OLR. At FVW and FW mixing ratios of 2：1 and 1：1, the performance and operation of the digester were maintained stable, with no accumulation of volatile fatty acids （VFA） and ammonia. Changing the feed to a higher FW content in a ratio of FVW to FW 1：2, resulted in an increase in VFAs concentration to 1100-1200 rag/L, and the methanogenesis was slightly inhibited. At the optimum mixture ratio 1：1 for co-digestion of FVW with FW, the methane production yield was 0.49 m3 CH4/kg VS, and the volatile solids and soluble chemical oxygen demand （sCOD） removal efficiencies were 74.9% and 96.1%, respectively.展开更多
针对以往递归神经网络(RNN)训练算法难,连续搅拌反应釜(CSTR)的强非线性等问题,将回声状态网络(echo state network,ESN)方法应用于模型不确定的CSTR系统辨识中.ESN具有较强的非线性逼近能力和良好的短期记忆能力,且只需要训练网络输出...针对以往递归神经网络(RNN)训练算法难,连续搅拌反应釜(CSTR)的强非线性等问题,将回声状态网络(echo state network,ESN)方法应用于模型不确定的CSTR系统辨识中.ESN具有较强的非线性逼近能力和良好的短期记忆能力,且只需要训练网络输出权值,简化了网络训练算法.仿真结果表明,在相同条件下,与带动量的BP(back propagation)神经网络、BP-MLP(back propagation multilayer perceptron)神经网络、最小二乘支持向量机(LS-SVM)、模糊神经网络(FNN)、GAP-RBF神经网络、MGAP-RBF神经网络相比,ESN能给出相当好的性能,表现出较高的辨识精度,ESN比带动量的BP、BP-MLP、LS-SVM神经网络的逼近精度提高了4个数量级,表明了该方法的有效性.展开更多
秸秆厌氧发酵沼气工程中合理的沼液回流可减少沼液排放量,降低后续沼液处置利用成本。以稻秸为底物,采用完全混合搅拌反应器(CSTR)半连续发酵方式,研究沼液全量连续回流对稻秸厌氧发酵特性的影响,旨在为明确沼液全量回流对秸秆厌氧发酵...秸秆厌氧发酵沼气工程中合理的沼液回流可减少沼液排放量,降低后续沼液处置利用成本。以稻秸为底物,采用完全混合搅拌反应器(CSTR)半连续发酵方式,研究沼液全量连续回流对稻秸厌氧发酵特性的影响,旨在为明确沼液全量回流对秸秆厌氧发酵的影响机制、改进沼液全量回流技术提供科学依据。结果表明:在100%沼液回流条件下连续回流50 d时系统运行稳定,总固体(TS)产气率、挥发性固体(VS)产气率及容积产气率分别稳定在245 m L·g-1、300 m L·g-1及0.74 L·L-1·d-1。但随着运行时间延长,回流天数达85 d时,虽然发酵液pH值和沼气中φ(CH4)无明显变化,但系统产气效率明显受到抑制。产气受抑制阶段与产气稳定阶段相比,TS产气率、VS产气率及容积产气率分别下降到186 m L·g-1、226 m L·g-1及0.56 L·L-1·d-1,下降幅度达24%。进一步分析表明,沼液中ρ(NH4+-N)下降到185 mg·L-1,下降幅度为71%;主要金属离子总质量浓度增加到4.13 g·L-1,增加幅度为342%。初步判断沼液全量连续回用会因氮含量严重下降和盐分积累致系统产气量下降,但真实原因还有待进一步研究。展开更多
以人参、赤芍和桂皮等混合中药渣为发酵原料,采用全混式厌氧反应器,在中温(35±1)℃,通过半连续厌氧发酵工艺,研究其发酵过程中不同有机负荷,沼气日产气量、甲烷含量、p H值、挥发性有机酸(VFA)和总无机碳(TIC)等参数变化相互关系...以人参、赤芍和桂皮等混合中药渣为发酵原料,采用全混式厌氧反应器,在中温(35±1)℃,通过半连续厌氧发酵工艺,研究其发酵过程中不同有机负荷,沼气日产气量、甲烷含量、p H值、挥发性有机酸(VFA)和总无机碳(TIC)等参数变化相互关系。结果表明:厌氧消化过程呈现5个阶段,即发酵启动期、增长期、稳定期、超负荷期和恢复期;反应器高效稳定运行可承受的中药渣最大有机负荷为8.0 g TS·(L·d)^(-1),系统p H值稳定在7.0左右,沼气日产气量8.38 L,容积产气率为1.68 L·(d·L)^(-1),原料产沼气能力262 m L·(TS g·d)^(-1),VS去除率为20.69%。有机负荷为10.0 g TS·(L·d)^(-1)时超负荷运行,沼气产量急剧下降,系统运行稳定性被破坏。因此,在中药渣厌氧消化过程中一定要控制有机负荷在最佳数值,实时监测反应器运行过程中的各参数变化,及时做出调整,保证工程的高效稳定运行。展开更多
基金supported by the Ministry of Science and Technology of China (No. 2008BADC4B16, 2008BADC4B18,2008AA062401)
文摘The biochemical methane potentials for typical fruit and vegetable waste （FVW） and food waste （FW） from a northern China city were investigated, which were 0.30, 0.56 m3 CH4/kgVS （volatile solids） with biodegradabilities of 59.3% and 83.6%, respectively. Individual anaerobic digestion testes of FVW and FW were conducted at the organic loading rate （OLR） of 3 kg VS/（m3-day） using a lab-scale continuous stirred-tank reactor at 35°C. FVW could be digested stably with the biogas production rate of 2.17 ma/（m3-day） and methane production yield of 0.42 m3 CH4/kg VS. However, anaerobic digestion process for FW was failed due to acids accumulation. The effects of FVW： FW ratio on co-digestion stability and performance were further investigated at the same OLR. At FVW and FW mixing ratios of 2：1 and 1：1, the performance and operation of the digester were maintained stable, with no accumulation of volatile fatty acids （VFA） and ammonia. Changing the feed to a higher FW content in a ratio of FVW to FW 1：2, resulted in an increase in VFAs concentration to 1100-1200 rag/L, and the methanogenesis was slightly inhibited. At the optimum mixture ratio 1：1 for co-digestion of FVW with FW, the methane production yield was 0.49 m3 CH4/kg VS, and the volatile solids and soluble chemical oxygen demand （sCOD） removal efficiencies were 74.9% and 96.1%, respectively.
文摘秸秆厌氧发酵沼气工程中合理的沼液回流可减少沼液排放量,降低后续沼液处置利用成本。以稻秸为底物,采用完全混合搅拌反应器(CSTR)半连续发酵方式,研究沼液全量连续回流对稻秸厌氧发酵特性的影响,旨在为明确沼液全量回流对秸秆厌氧发酵的影响机制、改进沼液全量回流技术提供科学依据。结果表明:在100%沼液回流条件下连续回流50 d时系统运行稳定,总固体(TS)产气率、挥发性固体(VS)产气率及容积产气率分别稳定在245 m L·g-1、300 m L·g-1及0.74 L·L-1·d-1。但随着运行时间延长,回流天数达85 d时,虽然发酵液pH值和沼气中φ(CH4)无明显变化,但系统产气效率明显受到抑制。产气受抑制阶段与产气稳定阶段相比,TS产气率、VS产气率及容积产气率分别下降到186 m L·g-1、226 m L·g-1及0.56 L·L-1·d-1,下降幅度达24%。进一步分析表明,沼液中ρ(NH4+-N)下降到185 mg·L-1,下降幅度为71%;主要金属离子总质量浓度增加到4.13 g·L-1,增加幅度为342%。初步判断沼液全量连续回用会因氮含量严重下降和盐分积累致系统产气量下降,但真实原因还有待进一步研究。
文摘以人参、赤芍和桂皮等混合中药渣为发酵原料,采用全混式厌氧反应器,在中温(35±1)℃,通过半连续厌氧发酵工艺,研究其发酵过程中不同有机负荷,沼气日产气量、甲烷含量、p H值、挥发性有机酸(VFA)和总无机碳(TIC)等参数变化相互关系。结果表明:厌氧消化过程呈现5个阶段,即发酵启动期、增长期、稳定期、超负荷期和恢复期;反应器高效稳定运行可承受的中药渣最大有机负荷为8.0 g TS·(L·d)^(-1),系统p H值稳定在7.0左右,沼气日产气量8.38 L,容积产气率为1.68 L·(d·L)^(-1),原料产沼气能力262 m L·(TS g·d)^(-1),VS去除率为20.69%。有机负荷为10.0 g TS·(L·d)^(-1)时超负荷运行,沼气产量急剧下降,系统运行稳定性被破坏。因此,在中药渣厌氧消化过程中一定要控制有机负荷在最佳数值,实时监测反应器运行过程中的各参数变化,及时做出调整,保证工程的高效稳定运行。
