Biogas production from different substrates in an experimental Continuously Stirred Tank Reactor anaerobic digester

Different mixtures were digested in a single-stage, batch, mixed, laboratory scale mesophilic anaerobic digester at the Biomass Research Centre Laboratory (University of Perugia). The yield and the composition of biogas from the different substrates were evaluated and the cumulative curves were estimated. Two experimental campaigns were carried out, the first on three mixtures (chicken, pig and bovine manures), the second on animal and vegetal biomasses (chicken and cow manure, olive husk) with different inocula (rumen fluid and digested sludge). In the first campaign pig manure mixture showed the maximum biogas production (0.35 Nm³/kg) and energy content (1.35 kWh/kg VS); in the second one the differences in produced biogas from the different inocula were analyzed: olive husk with piggery manure anaerobically digested as inoculum showed the higher biogas (0.28 Nm³/kg VS) and methane yield (0.11 Nm³/kg VS), corresponding to an energetic content of 1.07 kWh/kg VS. All data obtained from the laboratory scale anaerobic digester are comparable to the values in literature for several biomass and in particular for olive husk, dairy manure and chicken manure.     

Methane from cattle waste: Effects of temperature, hydraulic retention time, and influent substrate concentration on kinetic parameter (k)

The effects of temperature (35 and 55 degrees C), influent volatile solids (VS) concentration (S(0) = 43, 64, 82, 100, and 128 kg VS/m(3)) and hydraulic retention time (HRT = 4, 5, 8, 10, 15, and 25 days) on methane (CH(4)) production from cattle waste were evaluated using 3-dm(3) laboratoryscale fermentors. The highest CH(4) production rate achieved was 6.11 m(3) CH(4) m(-3) fermentor day(-1) at 55 degrees C, four days HRT, and S(0) = 100 kg VS/m(3). Batch fermentations showed an ultimate CH(4) yield (B(0)) of 0.42 m(3) CH(4)/kg VS fed. The maximum loading rates for unstressed fermentation were 7 kg VS m(-3) day(-1) at 35 degrees C and 20 kg VS m(-3) day(-1) at 55 degrees C. The kinetic parameter (K, an increasing K indicates inhibition of fermentation) increased exponentially as S(0) increased, and was described by: K = 0.8 + 0.0016 e(0.06S(0) ). Temperature had no significant effect on K for S(0) between 40 and 100 kg VS/m(3). The above equation predicted published K values for cattle waste within a mean standard error of 7%.     

Experiences with the dual digestion of municipal sewage sludge

The dual digestion process was investigated using sludge samples collected at the WWTP of Tomaszow Mazowiecki (Poland). Mixed sludge was treated in a laboratory setup under batch and semi-continuous conditions. Dual digestion with a 1d SRT aerobic thermophilic pretreatment followed by an anaerobic step with 20 d of SRT turned out to be optimal, since a 44-46% VS reduction and a biogas yield of 480 dm(3)/kg VS fed were achieved. In the course of the process, the concentration of nitrogen in supernatant increased over 5 times and its major portion was converted into ammonia. Phosphorus also entered the supernatant, reaching over 200 g/m(3). The dual digestion noticeably deteriorated the sludge dewaterability. Following completion of the process, capillary suction time measurements averaged 64 s for the raw sludge, 400 s for aerobically pretreated sludge and 310-360 for the anaerobically digested sludge. Aerobic pretreatment consistently reduced Enterobacteriaceae content to below detectable limits.     

Co-digestion of intermediate landfill leachate and sewage sludge as a method of leachate utilization

This study examines the co-digestion of intermediate landfill leachate and sewage sludge from a municipal wastewater treatment plant. Application of leachate as a co-fermentation component increased the concentrations of soluble organic compounds (expressed as total organic carbon), ammonium nitrogen, and alkalinity in the digester influents.The biogas yield obtained from the co-fermentation of a 20:1 sewage sludge: intermediate leachate mixture was 1.30 m³ per kg of removed volatile solids (VS), while that from a 10:1 mixture was 1.24 m³ per kg of removed VS. These values exceeded the biogas yield for the sludge alone by 13% and 8%, respectively. The leachate addition influenced the proportion of methane to a minor extent. Increased methane yields of 16.9% and 6.2% per kg of removed VS were found for the two sewage sluge:intermediate leachate mixtures, respectively.     

Adaptive neuro-fuzzy modelling of anaerobic digestion of primary sedimentation sludge

Modelling of anaerobic digestion systems is difficult because their performance is complex and varies significantly with influent characteristics and operational conditions. In this study, Adaptive Neuro-Fuzzy Inference System (ANFIS) were used for modelling of anaerobic digestion system of primary sludge of Kayseri municipal WasteWater Treatment Plant (WWTP). Effluent Volatile Solid (VS) and methane yield were predicted by the ANFIS. Two stage models were performed. In the first stage, effluent VS concentration was predicted using pH, VS concentration, flowrate of pre-thickened sludge and temperature of the influent as input parameters. In the second stage, effluent VS concentration in addition to first stage input parameters were used as input parameters to predict methane yield. The low Root Mean Square Error (RMSE) and high Index of agreement (IA) values were obtained with subtractive clustering method of a first order Sugeno type inference. The model performance was evaluated with statistical parameters. According to statistical evaluations, the models satisfactorily predict effluent VS concentration and methane yield.     

Anaerobic digestion of grass silage in batch leach bed processes for methane production

Anaerobic digestion of grass silage in batch leach bed reactors, with and without a second stage upflow anaerobic sludge blanket (UASB) reactor, was evaluated. Sixty six percent of the methane potential in grass was obtained within the 55 days solids retention time in the leach bed-UASB process without pH adjustment, whereas in the one-stage leach bed process 20% of the methane potential in grass was extracted. In two-stage operation, adjustment of the pH of influent to the leach bed reactor to 6 with HCl led to inhibition of both hydrolysis/acidogenesis and methanogenesis. In the leach bed-UASB process 39% of the carbohydrates and 58% of the acid soluble lignin were solubilised within the 49 days of operation, whereas Klason lignin was most recalcitrant. The methane potential of the digestates varied from 0.141 to 0.204 m3 CH4 kg(-1) added volatile solids.     

Ultrasonic sludge disintegration for enhanced methane production in anaerobic digestion: effects of sludge hydrolysis efficiency and hydraulic retention time

Hydrolysis of waste activated sludge (WAS) has been regarded as the rate limiting step of anaerobic sludge digestion. Therefore, in this study, the effect of ultrasound and hydraulic residence time during sludge hydrolysis was investigated with the goal of enhancing methane production from anaerobic digestion (AD). WAS was ultrasonically disintegrated for hydrolysis, and it was semi-continuously fed to an anaerobic digesters at various hydraulic retention times (HRTs). The results of these experiments showed that the solids and chemical oxygen demand (COD) removal efficiencies when using ultrasonically disintegrated sludge were higher during AD than the control sludge. The longer the HRT, the higher the removal efficiencies of solids and COD, while methane production increased with lower HRT. Sludge with 30% hydrolysis produced 7 × more methane production than the control sludge. The highest methane yields were 0.350 m(3)/kg volatile solids (VS)(add) and 0.301 m(3)/kg COD(con) for 16 and 30% hydrolyzed sludge, respectively. In addition, we found that excess ultrasound irradiation may inhibit AD since the 50% hydrolyzed sludge produced lower methane yields than 16 and 30% hydrolyzed sludge.     

Effect of ultrasound and addition of bacterial product on hydrolysis of by-products from the meat-processing industry

The hydrolysis efficiency of ultrasound (US) and bacterial product (BP; Liquid Certizyme 5™) was studied as a pre-treatment for anaerobic digestion (AD) of four animal by-products (ABP) from the meat-processing industry (digestive tract content + drumsieve waste, dissolved air flotation (DAF) sludge, grease trap sludge and the mixture of these). The change in volatile solids (VS) based hydrolysis parameters was screened using different specific US energy (Es) inputs (1000-14,000 kJ/kg of total solids (TS)) and durations of BP treatment (3-48 h). The Es of 6000-8500 kJ/kg TS increased most extensively the soluble chemical oxygen demand (COD_sol) and VS ratio, by 45-290%, and soluble nitrogen (N_sol) by 44-99%. Simultaneously, the average particle size (APS) decreased by 45-75%, from the original value. With BP, the highest increases in COD_sol/VS (29-130%), N_sol (35-63%) and decline in APS (40-70%) depended on the raw material (digestive tract content + drumsieve waste: 3 and 24 h; DAF sludge: 3 and 6 h, mixture: 12 and 48 h). BP apparently was more effective at hydrolyzing smaller cellulose particles, while US appeared to enhance the degradation of grease-containing cells.     

Influence of inoculum activity on the bio-methanization of a kitchen waste under different waste/inoculum ratios

The use of a granular inoculum prevented acidification during the anaerobic batch biodegradation of a kitchen waste for waste/inoculum ratios in the range of 0.5–2.3 g VS/g VS, when the alkalinity/COD ratio was 37 mg NaHCO₃/g COD. In similar experiments but using a suspended sludge with a significantly lower activity, the methane production rates and the biodegradability were significantly lower and the pH decreased below 5.5 at the waste/inoculum ratio of 2.3 g VS/g VS. When the added alkalinity was decreased to 2 mg NaHCO₃/g COD, the ratio waste/inoculum was clearly more important than the inoculum activity, since, irrespective of the sludge used, acidification occurred at waste/inoculum ratios higher than 0.5 g VS/g VS. The advantage of using granular sludge was further investigated in order to define reasonable condition of waste/inoculum ratio and added alkalinity that could be applied in practice. For a waste/inoculum ratio of 1.35, there were no significant differences between the results obtained for the biodegradability and maximum methane production rate (MMPR), when the alkalinity decreased from 44 to 22 mg NaHCO₃/g COD.     

侧脑室注射肾上腺髓质素增加大鼠心血管相关核团中c-fos的表达并激活脑内一氧化氮神经元

本研究利用Fos蛋白和一氧化氮合酶(nNOS)双重免疫组化方法,观察侧腑脑室注射肾上腺髓质素(adrenomedullin,ADM)对大鼠心血管相关核中c-fos表达及一氧化氮神经元的影响,以探讨ADM在中枢的作用部位并研究其在中枢的作用是否有NO神经元参与。侧脑室注射ADM(1nmol／kg,3nmol／kg)诱发脑干的孤束核、最后区、蓝斑核、臂旁核和外侧巨细胞旁核,下丘脑的室旁核、视上核才腹内侧核以及前脑的中央杏仁核和外侧缰核等多个部位的心血管中枢出现大量Fos样免疫反应神经元。侧脑室注射ADM(3nmol／kg),引起脑干的孤束核、外侧巨细胞旁核,下丘脑的室旁核、视上核内的Fos-nNOS双标神经元增加;ADM(1nmol／kg)亦可引起室旁核、视上核内的Fos-nNOS双标神经元增加,而对孤束核、外侧巨细胞旁核内的Fos-nNOS双标神经元无影响。降钙素基因相关肽(calcitonin gene—related peptide,CGRP)受体拈抗剂CGRP8-37(30nmol／kg)可明显减弱此效应。以上结果表明,ADM可兴奋脑内多个心血管相关核闭的神经元并激活室旁核、视上核、孤束核及外侧巨细胞核内一氧化氮神经元,此效应可能部分山CGRP受体介导。     

Some adverse effects of soil amendment with organic Materials—The case of soils polluted by copper industry phytostabilized with red fescue

The study was aimed to examine the effects of soil amendment with organic waste materials on the growth of red fescue and the uptake of Cu and Zn by this grass, in view of its potential usage for phytostabilization of Cu-polluted soils. Five soils, containing 301–5180 mg/kg Cu, were collected from the surroundings of copper smelter Legnica, and amended with lignite (LG) and limed sewage sludge (SS). Plant growth and the concentrations of Cu and Zn in the shoots and roots of grass were measured in a pot experiment and related to the results of Pytotoxkit and Microtox® tests performed on soil solution. The effects of soil amendment with LG and SS differed greatly, and depended on soil properties. In some cases, the application of alkaline SS resulted in dramatic increase of Cu phytotoxicity and its enhanced uptake by plants, while application of LG to slightly acidic soil caused increased accumulation of Zn in plants, particularly in their roots. The study confirmed good suitability of red fescue for phytostabilization of Cu-contaminated soils except for those extremely polluted. Organic amendments to be used for metal immobilization should be thoroughly examined prior to application.     

Thermochemical liquidization and anaerobic treatment of dewatered sewage sludge

Dewatered sewage sludge was thermochemically liquidized at 175°C and the liquidized sludge was separated by centrifugation to 57.7% (w/w) supernatant [moisture, 92.3%; volatile solid (VS), 7.0%] and 42.3% precipitate (moisture, 71.6%; VS, 18.9%). The supernatant was successfully anaerobically digested. Biogas yield from the supernatant at organic loading concentrations of 1.9–2.2 g VS/l during 9 days' incubation was 440 ml/g-added VS and digestion ratio was 66% (w/w). Biogas yield in the case of dewatered sewage sludge was 257% ml/g-added VS and digestion ratio was 45%. Digestion of the supernatant resulted in high biogas productivity and a high digestion ratio compared with that of the dewatered sewage sludge. Moreover, it was suggested that the precipitate can be incinerated without the need for any supplemental fuel.     

Biodistribution and Antitumor Effect of Adriamycin Encapsulated in Long-Circulating Liposomes Containing Amphipathic Polyethylene Glycol or Ganglioside GM1

Abstract

Biodistribution and antitumor effect of adriamycin (ADM) encapsulated in liposomes with reduced uptake by reticuloendothelial system (RES) and prolonged circulation time were investigated in mice. Two different types of long-circulating liposomes, ganglioside GMI (GMl)/distearoyl phosphatidyl choline (DSPC) /cholesterol (CH) (0.13:1:1, m/m) and amphipathic polyethylene glycol (PEG)/DSPC/CH (0.13:1:1, m/m) were used. They were sized to 180-200 nm in mean diameter. In the case of amphipathic PEG, distearoyl phosphatidylethanolamine (DSPE) derivatives of PEG with various molecular weight (1000-12000 in mean molecular weight) were used. ADM was encapsulated by transmembrane pH gradient method. GM~DSPC /CH     

Effect of high dose alpha-tocopherol and alpha-tocopherol acetate pretreatment on adriamycin (doxorubicin) induced toxicity and tissue distribution

When two doses (15 mg/kg) of adriamycin (ADM) were administered to ICR mice pretreated with 500 mg/kg/day of alpha-tocopherol (VE) and alpha-tocopherol acetate (VE-AC) respectively, both the VE and the VE-AC pretreatment groups showed a significant shortening of survival time compared to control group. The concentration of ADM and of total aglycone (AD-NE) was determined in the tissue of mice given a single dose of 15 mg/kg of ADM after pretreatment with 500 mg/kg of VE and VE-AC, respectively, high values were found in liver, kidney and heart tissue compared to the control group. And, particularly the heart tissue of the group pretreated with VE showed significantly higher values of ADM and AD-NE. High AD-NE levels were noted in mouse liver mitochondria (Mt), after pretreatment with both VE and VE-AC, with a significantly higher concentration in the VE-pretreated group. A comparison of the uptake of ADM and AD-NE into mouse Mt pretreated with VE or VE-AC in vitro, showed no difference in the ADM value from that of the control group, but both the VE- and the VE-AC-pretreated groups had significantly higher in AD-NE concentrations compared to the control group.     

Sequential anaerobic/aerobic digestion of waste activated sludge: analysis of the process performance and kinetic study

Sequential anaerobic-aerobic digestion was applied to waste activated sludge (WAS) of a full scale wastewater treatment plant. The study was performed with the objective of testing the sequential digestion process on WAS, which is characterized by worse digestibility in comparison with the mixed sludge. Process performance was evaluated in terms of biogas production, volatile solids (VS) and COD reduction, and patterns of biopolymers (proteins and polysaccharides) in the subsequent digestion stages. VS removal efficiency of 40%, in the anaerobic phase, and an additional removal of 26%, in the aerobic one, were observed. For total COD removal efficiencies of 35% and 25% for anaerobic and aerobic stage respectively, were obtained. Kinetics of VS degradation process was analyzed by assuming a first order equation with respect to VS concentration. Evaluated kinetic parameters were 0.44 ± 0.20 d(-1) and 0.25 ± 0.15 d(-1) for the anaerobic stage and aerobic stage, respectively. With regard to biopolymers, in the anaerobic phase the content of proteins and polysaccharides increased to 50% and 69%, respectively, whereas in the subsequent aerobic phase, a decrease of 71% for proteins and 67% for polysaccharides was observed. The average specific biogas production 0.74 m(3)/(kg VS destroyed), was in the range of values reported in the specialized literature for conventional anaerobic mesophilic WAS digestion.     

Adrenomedullin(27-52) inhibits vascular calcification in rats

Adrenomedullin (ADM) has the vasodilatory properties and involves in the pathogenesis of vascular calcification. ADM could be degraded into more than six fragments in the body, including ADM(27-52), and we suppose the degrading fragments from ADM do the same bioactivities as derived peptides from pro-adrenomedullin. The present study carries forward by assessing the effects on vascular calcification of the systemic administration of ADM(27-52). The rat vascular calcific model was replicated with vitamin D3 and nicotine. ADM or/and ADM(27-52) were systemically administrated with mini-osmotic pump beginning at seventh day after the model replication for 25 days. Vascular calcific nodules histomorphometry, vascular calcium content, vascular calcium uptake, alkaline phosphatase activity, and osteopontin-mRNA quantification in aorta were assessed. ADM limited 40.2% vascular calcific nodules (P<0.01), did not effect on calcium content (P>0.05), reduced 44.4% calcium uptake (P<0.01), lowered 21.1% alkaline phosphatase activity (P<0.01), and regulated 40.9% downwards osteopontin-mRNA expression (P<0.01) in the aorta of rats with vascular calcification. ADM(27-52) receded 32.0% vascular calcific nodules (P<0.01), taken from 55.5% calcium content (P<0.01), did not affect calcium uptake (P>0.05), inhibited 22.5% alkaline phosphatase activity (P<0.01), and restrained 21.9% osteopontin-mRNA expression (P<0.01) in the aorta of rats with vascular calcification. Both of ADM and ADM(27-52) did interact on vascular calcification each other. ADM could partially antagonize the effects of ADM(27-52) in taking from calcium content (17.5%, P<0.01) and in receding vascular calcific nodules (18.6%, P<0.01). ADM could obviously enhance the action of ADM(27-52) in inhibiting alkaline phosphatase activity (14.4%, P<0.01) and in reducing calcium uptake (11.4%, P<0.01). ADM(27-52) could partially antagonize the effects of ADM on regulating downwards osteopontin-mRNA expression (17.0%, P<0.01). It is concluded that ADM(27-52) derived from ADM acts as an inhibitory agent on vascular calcification, with special mechanisms different from ADM derived from ADM progenitor molecule.     

肾上腺髓质素对豚鼠心室肌细胞L-型钙通道的调制

应用全细胞膜片钳技术研究了肾上腺髓质素 (ADM )对豚鼠心室肌细胞L 型钙电流 (ICa ,L)的影响及其信号传导机制。结果发现 :ADM ( 1～ 10 0nmol/L)浓度依赖性抑制ICa,L(P <0 0 5 ) ,并可被ADM特异受体阻断剂ADM2 2 52 ( 10 0nmol/L)完全阻断。用蛋白激酶A特异拮抗剂H 89( 10 μmol/L)预处理 ,对ADM抑制ICa ,L的作用无影响。但用蛋白激酶C (PKC)特异性拮抗剂PKC19 36 预处理 ,可完全阻断ADM的抑制效应 ;而PKC特异性激动剂PMA则可以模仿ADM的抑制效应 (P <0 0 5 )。上述结果提示 :ADM作用于特异性ADM受体可浓度依赖性地抑制豚鼠心室肌细胞ICa ,L,而此作用可能是PKC介导的。     

Detailed study of anaerobic digestion of Spirulina maxima algal biomass

Biomass of the blue-green alga Spirulina maxima was converted to methane using continuous stirred tank digesters with an energy conversion efficiency of 59%. Digesters were operated using once-a-day feeding with a retention time (theta) between 5 and 40 days, volatile solid concentrations (S(to)) between 20 and 100 kg VS/m(3), and temperatures between 15 and 52 degrees C. The results indicated a maximum methane yield of 0.35 m(3) (STP)/kg VS added at theta 30 days and S(to) 20 kg VS/m(3). Under such conditions, the energy conversion of the algal biomass to methane was 59%. The maximum methane production rate of 0.80 m(3) (STP)/m(3) day was obtained with theta= 20 days and S = 100 kg VS/m(3). The mesophilic condition at 35 degrees C produced the maximum methane yield and production rate. The process was stable and characterized by a high production of volatile acids (up to 23, 200 mg/L), alkalinity (up to 20, 000 mg/L), and ammonia (up to 7000 mg/L), and the high protein content of the biomass produced a well buffered environment which reduced inhibitory effects. At higher loading rates, the inhibition of methanogenic bacteria was observed, but there was no clear-cut evidence that such a phenomenon was due to nonionized volatile acids or gaseous ammonia. The kinetic analysis using the model proposed by Chen and Hashimoto indicated that the minimum retention time was seven days. The optimum retention time increased gradually from 11 to 16 days with an increase in the initial volatile solid concentration. The kinetic constant K decreased with the improvement in the digester performance and increased in parallel with the ammonia concentration in the culture media.     

Anaerobic co-digestion of algal sludge and waste paper to produce methane

The unbalanced nutrients of algal sludge (low C/N ratio) were regarded as an important limitation factor to anaerobic digestion process. Adding high carbon content of waste paper in algal sludge feedstock to have a balanced C/N ratio was undertaken in this study. The results showed adding 50% (based on volatile solid) of waste paper in algal sludge feedstock increased the methane production rate to 1170+/-75 ml/l day, as compared to 573+/-28 ml/l day of algal sludge digestion alone, both operated at 4 g VS/l day, 35 degrees C and 10 days HRT. The maximum methane production rate of 1607+/-17 ml/l day was observed at a combined 5 g VS/l day loading rate with 60% (VS based) of paper adding in algal sludge feedstock. Results suggested an optimum C/N ratio for co-digestion of algal sludge and waste paper was in the range of 20-25/1.