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
Most of the processes in the industry have nonlinear behavior. Control of such processes with conventional control methods could lead to unstable, suboptimal, etc., results. On the other hand, the adaptive control is ...Most of the processes in the industry have nonlinear behavior. Control of such processes with conventional control methods could lead to unstable, suboptimal, etc., results. On the other hand, the adaptive control is a technique widely used for controlling of nonlinear systems. The approach here is based on the recursive identification of the external linear model as a linear representation of the originally nonlinear system. The controller then reacts to the change of the working point or disturbances which could occur by the change of the parameters, structure, etc. The polynomial synthesis together with the linear quadratic(LQ) approach is employed here for the controller synthesis. These techniques satisfy basic control requirements such as the stability, the reference signal tracking and the disturbance attenuation. Resulted controller could be tuned with the choice of weighting factors in LQ approach. This work investigates the effect of these factors on control results. Proposed methods are tested on the mathematical model of the isothermal continuous stirred-tank reactor and simulated results are also verified on the real model of the continuous stirred tank reactor.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Most of the processes in the industry have nonlinear behavior. Control of such processes with conventional control methods could lead to unstable, suboptimal, etc., results. On the other hand, the adaptive control is a technique widely used for controlling of nonlinear systems. The approach here is based on the recursive identification of the external linear model as a linear representation of the originally nonlinear system. The controller then reacts to the change of the working point or disturbances which could occur by the change of the parameters, structure, etc. The polynomial synthesis together with the linear quadratic(LQ) approach is employed here for the controller synthesis. These techniques satisfy basic control requirements such as the stability, the reference signal tracking and the disturbance attenuation. Resulted controller could be tuned with the choice of weighting factors in LQ approach. This work investigates the effect of these factors on control results. Proposed methods are tested on the mathematical model of the isothermal continuous stirred-tank reactor and simulated results are also verified on the real model of the continuous stirred tank reactor.
