Pulping production process produces a large amount of wastewater and pollutant emitted, which has become one of the main pollution sources in pulp and paper industry. To solve this problem, it is necessary to implemen...Pulping production process produces a large amount of wastewater and pollutant emitted, which has become one of the main pollution sources in pulp and paper industry. To solve this problem, it is necessary to implement cleaner production by using modeling and optimization technology. This paper studies the modeling and multi\|objective genetic algorithms for continuous digester process. First, model is established, in which environmental pollution and saving energy factors are considered. Then hybrid genetic algorithm based on Pareto stratum\|niche count is designed for finding near\|Pareto or Pareto optimal solutions in the problem and a new genetic evaluation and selection mechanism is proposed. Finally using the real data from a pulp mill shows the results of computer simulation. Through comparing with the practical curve of digester,this method can reduce the pollutant effectively and increase the profit while keeping the pulp quality unchanged.展开更多
Five types of food wastes were investigated as feedstock for a potential centralized anaerobic digester system in the area of Sacramento,California to produce biogas energy.The wastes were from a soup processing plant...Five types of food wastes were investigated as feedstock for a potential centralized anaerobic digester system in the area of Sacramento,California to produce biogas energy.The wastes were from a soup processing plant,a cafeteria,a commercial kitchen,a fish farm,and grease trap collection service.Digestibilities of the food wastes,individually and in mixtures,were conducted at mesophilic(35℃)and thermophilic(50℃)temperatures and at two food to microorganism ratios(F/M)of 0.5 and 1.0,for 28 days.A continuously fed mesophilic single-stage anaerobic digester was evaluated using a mixture of the five food wastes at organic loading rates of 0.5 to 1.0 g VS/L/d.In the batch digestion tests,fish and grease trap wastes required longer time to complete the digestion and had higher biogas yields than the other wastes.The continuously-fed digester required the addition of sodium hydroxide to maintain pH at proper levels in the digester.Alkalinity of about 2,500 mg CaCO3/L and pH above 7 was maintained by adding 0.2 g NaOH/g VS.The results of this study indicated that it was necessary to use the chemicals,such as NaOH,to control the pH of the single-stage anaerobic digester treating the food waste.For commercial applications,the cost of chemicals and proper management of additional salts in the digester effluent need to be carefully considered.展开更多
基金TheNationNaturalScienceFoundationofChina (No .6 9974 0 34)
文摘Pulping production process produces a large amount of wastewater and pollutant emitted, which has become one of the main pollution sources in pulp and paper industry. To solve this problem, it is necessary to implement cleaner production by using modeling and optimization technology. This paper studies the modeling and multi\|objective genetic algorithms for continuous digester process. First, model is established, in which environmental pollution and saving energy factors are considered. Then hybrid genetic algorithm based on Pareto stratum\|niche count is designed for finding near\|Pareto or Pareto optimal solutions in the problem and a new genetic evaluation and selection mechanism is proposed. Finally using the real data from a pulp mill shows the results of computer simulation. Through comparing with the practical curve of digester,this method can reduce the pollutant effectively and increase the profit while keeping the pulp quality unchanged.
文摘Five types of food wastes were investigated as feedstock for a potential centralized anaerobic digester system in the area of Sacramento,California to produce biogas energy.The wastes were from a soup processing plant,a cafeteria,a commercial kitchen,a fish farm,and grease trap collection service.Digestibilities of the food wastes,individually and in mixtures,were conducted at mesophilic(35℃)and thermophilic(50℃)temperatures and at two food to microorganism ratios(F/M)of 0.5 and 1.0,for 28 days.A continuously fed mesophilic single-stage anaerobic digester was evaluated using a mixture of the five food wastes at organic loading rates of 0.5 to 1.0 g VS/L/d.In the batch digestion tests,fish and grease trap wastes required longer time to complete the digestion and had higher biogas yields than the other wastes.The continuously-fed digester required the addition of sodium hydroxide to maintain pH at proper levels in the digester.Alkalinity of about 2,500 mg CaCO3/L and pH above 7 was maintained by adding 0.2 g NaOH/g VS.The results of this study indicated that it was necessary to use the chemicals,such as NaOH,to control the pH of the single-stage anaerobic digester treating the food waste.For commercial applications,the cost of chemicals and proper management of additional salts in the digester effluent need to be carefully considered.
