沼气工程罐装工艺的控制设计

沼气是一种可再生的生物质能源,对沼气进行工程收集灌装,将是扩大生产应用的重要途径。首先分析了沼气工程收集灌装的工艺,明确了控制要求,确定采用PLC对工艺过程及初级压缩机和高级压缩机的电机进行控制,完成了控制设计。     

沼气池在农村污水处理中的应用

简述了农村排水的现状,介绍了污水处理的方法,探讨了沼气在农村污水处理中的应用,指出厌氧净化污水池迎合了我国小城镇建设和发展的需要,在不断对其研究和改进的同时应大力推广应用。     

Anaerobic digestion of Aegean olive mill effluents with and without pretreatment

BACKGROUND: Olive oil production is an important economical activity in the Aegean region of Turkey. However, the effluents of the olive oil producing mills with their high organic loads and toxic compounds are causing serious environmental problems. The anaerobic biological treatment of olive mill wastewater (OMWW) using the treatment plants of the regional industries could be a method of choice and within the scope of this study floccular and granular sludges were investigated in batch mode for their success in the treatment of OMWW while producing biogas. The major limitation of this treatment is the inhibition of methanogenic bacteria by the phenolic compounds in OMWW. Thus an integrated solution was suggested in which a pre‐treatment step (dephenolization) was also introduced before biological step. RESULTS: The effluents of 27 olive mills out of 47 were found to have total phenolics (TP) less than 3 g L^?1 and could be treated anaerobically after simple dilution. The biogas production for the untreated OMWW was higher for floccular sludge than for the granular sludge (68.5 mL and 45.7 mL respectively). Combined pre‐treatment experiments, first coagulation with polyaluminum chloride, followed by flocculation with cationic polyelectrolyte and finally Fenton's oxidation, could remove 80% of TP and 95% of the total suspended solids. CONCLUSION: OMWW having TP values less than 3 g L^?1 can be treated anaerobically using floccular sludge after simple dilution and biogas can be produced. For OMWW samples having higher TP values pre‐treatment is necessary and the pre‐treatment given in this study may be used effectively. Copyright © 2010 Society of Chemical Industry     

沼液预处理最优混凝搅拌条件的研究

通过混凝法对沼液进行预处理最优条件的研究,为沼液预处理提供参考。在实验室条件下,对COD、TN、TP、色度和SS的去除率综合评价混凝工艺效果。实验中依次进行混凝剂投加量、助凝剂投加量、pH和搅拌强度的单因素实验,进而通过正交实验确定沼液预处理最优的混凝搅拌条件。试验结果表明:PAC投加量为4 g/L、PAM投加量为50 mg/L、搅拌速度为200 r/min、混凝阶段同时投加PAC和PAM,处理后的水样COD、TN、TP、色度和SS分别为216.20、181.99、0.18、11.77和71.67 mg/L,去除率分别达到92.51%、88.85%、99.75%、98.37%和89.46%,达到畜禽养殖业污染物排放标准(GB18596-2001),减轻了后续污水处理的负荷,为沼液实际处理提供了理论支持。     

Anaerobic biogas generation from sugar industry wastewaters in three‐phase fluidized‐bed bioreactor

In the present study, attempts are made to optimize digestion time, initial feed pH, feed temperature, and feed flow rate (organic loading rate, OLR) for maximum yield of methane gas and maximum removal of chemical oxygen demand (COD) and biological oxygen demand (BOD) of sugar industry wastewaters in three‐phase fluidized‐bed bioreactor. Methane gas is analysed by using flame‐ionisation detector (FID). The optimum digestion time is 8 h and optimum initial pH of feed is observed as 7.5. The optimum temperature of feed is 40°C and optimum feed flow rate is 14 L/min with OLR 39.513 kg COD/m³ h. OLR is calculated on the basis of COD inlet in the bioreactor at different flow rates. The maximum methane gas concentration is 61.56% (v/v) of the total biogas generation at optimum biomethanation process parameters. The maximum biogas yield rate is 0.835 m³/kg COD/m³ h with maximum methane gas yield rate (61.56%, v/v) of 0.503 m³/kg COD/m³ h at optimum parameters. The maximum COD and BOD reduction of the sugar industry wastewaters are 76.82% (w/w) and 81.65% (w/w) at optimum biomethanation parameters, respectively.     

Effects of chemical and thermochemical pretreatments on sunflower oil cake in biochemical methane potential assays

BACKGROUND: The effects of chemical and thermochemical pretreatments on the composition and anaerobic biodegradability of sunflower oil cake were studied to compare these pretreatments and to assess their effectiveness. Four reagents (lime, sodium hydroxide, sulphuric acid, and sodium bicarbonate) at concentrations of 25% (w/w) of dry weight of substrate and 20 g L^?1 substrate concentration were used for the chemical pretreatment for 4 h. The same conditions were used for thermochemical pretreatment with heating at 75°C. After the pretreatments, the solid and liquid fractions were separated and subjected to biochemical methane potential tests. RESULTS: The methane yields of the solid fraction obtained with lime, sodium hydroxide, sulphuric acid and bicarbonate were 130±9, 54±4, 61±6 and 88±7 mL CH₄ g^‐1COD_added, respectively, and after thermochemical pretreatment were 26±2, 84±7, 74±7, and 77±6 mL CH₄ g^‐1COD_added, respectively. The methane yields for liquids were 152±13, 2±0, 0±0, 249±19 mL CH₄ g^‐1COD_added, for the chemical pre‐treatment, respectively, and after the thermochemical pretreatment were 273±13, 58±5, 0±0 and 145±12 mL CH₄ g^‐1COD_added, respectively. CONCLUSION: Only the solid fraction obtained after the chemical pretreatment with lime gave a methane yield higher (130 mL CH₄ g^‐1COD_added) than the obtained for the untreated solid material (114 mL CH₄ g^‐1COD_add). No thermochemical pretreatment enhanced the methane yield of the solid or liquid fractions of the untreated material. © 2012 Society of Chemical Industry     

厌氧反应器中沼气泄漏扩散模拟研究

基于FDS建立沼气泄漏扩散模型,分别模拟管道接头破损、导凝管阀门破损和沼气突破水封,探究厌氧反应器中沼气泄漏扩散的基本规律。结果表明：当管道接头破损、导凝管阀门破损时,沼气泄漏后的危险范围为下风向处距离泄漏口约5 m;当沼气突破水封时,沼气泄漏后的危险范围为下风向处距离泄漏口约60 m;沼气突破水封的危险性最大;泄漏后的甲烷会向下风向膨胀扩散,但遇到障碍物时,窝风位置会出现甲烷积聚;当沼气发生类似突破水封的大面积泄漏时,固定桩式可燃气报警仪的预警作用非常重要。     

钢渣微粉对牛粪厌氧发酵产沼气的影响

为提高沼气发酵效率和沼气产量,以不同钢渣微粉作为沼气发酵的功能促进剂,探讨其对牛粪厌氧发酵的沼气产量、发酵前后pH值和发酵前后COD值的影响。结果表明：钢渣微粉对牛粪厌氧发酵产沼气具有显著的促进作用,不仅能够提高原料的累积产气量和产气速率,而且能使产气高峰期大幅提前,其中0.5% ZHB钢渣微粉对牛粪厌氧发酵产沼气效果最佳;钢渣微粉明显提高发酵前各处理组的pH值;钢渣微粉有助于提高厌氧发酵的COD值降低率,其中0.5%的ZHB钢渣微粉总COD值降低率达到64.74%,同时可以促使发酵启动最快,效率最高,周期最短。