Effect of Sludge from Different Sources on Solid Anaerobic Digestion of Corn Straw

[Objective] The aim was to study on effect of sludge from different sources on biogas yield efficiency through anaerobic digestion of corn straw. [Method] The present research studied on daily biogas yield and the accumulated biogas amount through anaerobic digestion of corn straw and sludges from four sources. [Result] The accumulated biogas yields produced from sludges in four sources from high to low were granular sludge, river sediments, concentrated sludge and filtered sludge. The first one proved the highest at 3.73 and 56.29 L/kg VS in daily biogas yield and the accumulated biogas. [Conclusion] The research laid foundation for full utilization of straw, improvement of energy utilization and sustainable development.

Research on the Nature of Thermophilic Anaerobic Ethanol Producer Thermo anaerobacter sp DF3 in Petroleum Reservoirs

[Objective] The aim was to study the physiological and biochemical char- acteristics of Thermoanaerobacter sp DF3 in petroleum reservoirs and optimize the culture plan of producing ethanol from xylose. [Method] DF3, an anaerobic bacillus producing ethanol, was isolated from produced liquid from oil layer of Dagang oil field with anaerobic isolation technique. The phylogenetic position was analyzed by physiological and biochemical identification and phylogeny of 16S rDNA sequence. The metabolites were analyzed by gas chromatograph. [Result] The strain DF3 was a strict anaerobic thermophilic bacterium, which was straight in rod shape,and gram negative. Besides, it was 0.42 μmx（1.60-5.20） iJm in length. The strains can be soli- tary,in pairs or string and apical spore usually produced. Its growth temperature was 45-78 and 65 ℃ was the optimum. Many substances could be used as carbon sources, including glucose, xylose, fructose, ribose, mannose, arabinose, sucrose, galactose, lactose, cellobiose, melizitose, raffinose-, and starch. The similarity between strain DF3 and T. pseudoethanolicus achieved 99.7%. The main product of glucose and xylose fermentation was ethanol. After the culture plan was optimized,the final concentration of ethanol was 2.0 g/L. [Conclusion] It was proved through experiments that the strain DF3 was one of the strains with higher activity to produce ethanol at present and it could produce 2.0 g/L ethanol from xylose metabolization at 65 ℃. It has been demonstrated that DF3 is one of the known strains with high-production to produce ethanol,for example, 2.0 g/L ethano at 65℃. Presently, all the high-yield ethanol can be produced from metabolic xylose strains of metabolic xylose were isolat- ed by foreign countries, therefore, isolation of strain DF3 has provided an excellent original strain for studying ethanol production from lignocellulose in China.

CHARACTERISTICS OF THERMOPHILIC ANAEROBIC ACIDOGENESIS OF STARCH WASTEWATER

Acidogenic dissimilation of synthetic starch wastewater (1 000～10 000 mg COD·L -1 ) was studied in a thermophilic (55 ℃) upflow anaerobic sludge blanket (UASB) reactor.The production of volatile fatty acids (VFA) was proportional to the chemical oxygen demand (COD) loading rate.The yield of VFA was around 0.28 g VFA/g COD over the COD loading rate from 1.25 to 30 g COD·L -1 ·d -1 and the hydraulic retention time from 8.8 h to 24 h.Distribution of organic acids,the contents of propionic and butyric acids in the effluent in particular were also dependent on the COD loading rate.The thermophilic UASB reactor showed a stable performance on hydrolysis and acidogenesis of starch as well as suspended solid removal at short hydraulic retention times and high influent pH(10～11),during the operation of 110 d.

Stable Control of Influence Factor during Two-phase Anaerobic Digestion for Agricultural Organic Waste

Two-phase anaerobic digestion process is influenced by acid control for hydrogen production, reaction temperature, substrate detention time, sludge activity, and granular formation. Al of these technological parameters are directly related to success or failure of the system operation and treatment effect.

Application Effect of Cassava Starch Anaerobic Fermentation Liquid on Watermelon Production

In order to find out a new way for environment-friendly and resourcelized utilization of cassava starch processing wastewater, the cassava starch anaerobic fermentation liquid was applied in watermelon production, and its effects on the growth and development, yield and fruit quality of watermelon were investigated. The results showed that the cassava starch anaerobic fermentation liquid significant- ly promoted the vegetative and reproductive growth and improved the yield and fruit quality of watermelon. Compared with conventional fertilization, the application of cassava starch anaerobic fermentation both with COD concentration of 1 200 mg/L according to the amount of 150 t/hm2 promoted the growth of vines and leaves of watermelon plants, brought forward the flowering, fruiting and harvest of watermelon and significantly increased the fruit number, fruit weight, yield, fruit size, fruit shape index, soluble solid content, soluble sugar content, soluble protein content and Vita- min C content of watermelon. At the same time of improving the yield and quality of watermelon, cassava starch anaerobic fermentation liquid was turned into treasure as a liquid fertilizer. This study provides a new ideal for the yield and quality im- provement of watermelon and the wastewater treating of starch factories.

Characteristics of high-sulfate wastewater treatment by two-phase anaerobic digestion process with Jet-loop anaerobic fluidized bed

A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and sulfide inhibition in reactors, were discussed for a JLAFB and a general anaerobic fiuidized bed （AFB） reactor used as sulfate-reducing phase and methane-producing phase, respectively, in two-phase anaerobic digestion process. The formation of granules in the two reactors was also examined. The results indicated that COD and sulfate removal had different demand of influent COD/SO4^2- ratios. When total COD removal was up to 85%, the ratio was only required up to 1.2, whereas, total sulfate removal up to 95% required it exceeding 3.0. The alkalinity in the two reactors increased linearly with the growth of influent alkalinity. Moreover, the change of influent alkalinity had no significant effect on pH and volatile fatty acids （VFA） in the two reactors. Influent alkalinity kept at 400-500 mg/L could meet the requirement of the treating process. The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms. When sulfate loading rate was up to 8. 1 kg/（m^3.d）, the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L, respectively. Furthermore, the granules, with offwhite color, ellipse shape and diameters of 1.0-3.0 mm, could be developed in JLAFB reactor. In granules, different groups of bacteria were distributed in different layers, and some inorganic metal compounds such as Fe, Ca, Mg etc. were found.

Start-up performances of dry anaerobic mesophilic and thermophilic digestions of organic solid wastes

Two dry anaerobic digestions of organic solid wastes were conducted for 6 weeks in a lab-scale batch experiment for investigating the start-up performances under mesophilic and thermophilic conditions. The enzymatic activities, i.e., β-glucosidase, N-α-benzoyl-Largininamide （BAA）-hydrolysing protease, urease and phosphatase activities were analysed. The BAA-hydrolysing protease activity during the first 2-3 weeks was low with low pH, but was enhanced later with the pH increase. β-Glucosidase activity showed the lowest values in weeks 1-2, and recovered with the increase of BAA-hydrolysing protease activity. Acetic acid dominated most of the total VFAs in thermophilic digestion, while propionate and butyrate dominated in mesophilic digestion. Thermophilic digestion was confirmed more feasible for achieving better performance against misbalance, especially during the start-up period in a dry anaerobic digestion process.

Effects of ultrasonic pretreatment on sludge dewaterability and extracellular polymeric substances distribution in mesophilic anaerobic digestion

Effect of ultrasonic pretreatment on sludge dewaterability was determined and the fate of extracellular polymeric substances （EPS） matrix in mesophilic anaerobic digestion after ultrasonic pretreatment was studied. Characteristics of proteins （PN）, polysaccharides （PS）, excitation-emission matrix （EEM） fluorescence spectroscopy and molecular weight （MW） distribution of dissolved organic matters （DOM） in different EPS fractions were evaluated. The results showed that after ultrasonic pretreatment, the normalized capillary suction time （CST） decreased from 44.4 to 11.1 （sec·L）/g total suspended solids （TSS） during anaerobic digestion, indicating that sludge dewaterability was greatly improved. The normalized CST was significantly correlated with PN concentration （R2 = 0.92, p 〈 0.01） and the PN/PS ratio （R2 = 0.84, p 〈 0.01） in the loosely bound EPS （LB-EPS） fraction. Meanwhile, the average MW of DOM in the LB- EPS and tightly bound EPS （TB-EPS） fractions also had a good correlation with the normalized CST （R2 〉 0.66, p 〈 0.01）. According to EEM fluorescence spectroscopy, tryptophan-like substances intensities in the slime, LB-EPS and TB-EPS fractions were correlated with the normalized CST. The organic matters in the EPS matrix played an important role in influencing sludge dewaterability.

Role of live microbial feed supplements with reference to anaerobic fungi in ruminant productivity: A review

To keep the concept of a safe food supply to the consumers, animal feed industries world over are showing an increasing interest in the direct-fed microbials（DFM） for improved animal performance in terms of growth or productivity. This becomes all the more essential in a situation, where a number of the residues of antibiotics and/or other growth stimulants reach in milk and meat with a number of associated potential risks for the consumers. Hence, in the absence of growth stimulants, a positive manipulation of the rumen microbial ecosystem to enhance the feedstuff utilization for improved production efficiency by ruminants has become of much interest to the researchers and entrepreneurs. A few genera of live microbes（i.e., bacteria, fungi and yeasts in different types of formulations from paste to powder） are infrequently used as DFM for the domestic ruminants. These DFM products are live microbial feed supplements containing naturally occurring microbes in the rumen. Among different DFM possibilities, anaerobic rumen fungi（ARF） based additives have been found to improve ruminant productivity consistently during feeding trials. Administration of ARF during the few trials conducted, led to the increased weight gain, milk production, and total tract digestibility of feed components in ruminants. Anaerobic fungi in the rumen display very strong cell-wall degrading cellulolytic and xylanolytic activities through rhizoid development, resulting in the physical disruption of feed structure paving the way for bacterial action. Significant improvements in the fiber digestibility were found to coincide with increases in ARF in the rumen indicating their role. Most of the researches based on DFM have indicated a positive response in nutrient digestion and methane reducing potential during in vivo and/or in vitro supplementation of ARF as DFM. Therefore, DFM especially ARF will gain popularity but it is necessary that all the strains are thoroughly studied for their beneficial properties to have a confirmed ‘generally regarded as safe＇ status for ruminants.

Influence of lactic acid on the two-phase anaerobic digestion of kitchen wastes

To evaluate the influence of lactic acid on the methanogenesis, anaerobic digestion of kitchen wastes was firstly conducted in a two-phase anaerobic digestion process, and performance of two digesters fed with lactic acid and glucose was subsequently compared. The results showed that the lactic acid was the main fermentation products of hydrolysis-acidification stage in the two-phase anaerobic digestion process for kitchen wastes. The lactic acid concentration constituted approximately 50% of the chemical oxygen demand （COD） concentration in the hydrolysis-acidification liquid. The maximum organic loading rate was lower in the digester fed with lactic acid than that fed with glucose. Volatile fatty acids （VFAs） and COD removal were deteriorated in the methanogenic reactor fed with lactic acid compared to that fed with glucose. The specific methanogenic activity （SMA） declined to 0.343 g COD/（gVSS-d） when the COD loading were designated as 18.8 g/（L-d） in the digester fed with lactic acid. The propionic acid accumulation occurred due to the high concentration of lactic acid fed. It could be concluded that avoiding the presence of the lactic acid is necessary in the hydrolysis-acidification process for the improvement of the two-phase anaerobic digestion process of kitchen wastes.

Startup and operation of anaerobic EGSB reactor treating palm oil mill effluent

A bench-scale expanded granular sludge bed （EGSB） reactor was applied to the treatment of palm oil mill effluent （POME）. The reactor had been operated continuously at 35℃ for 514 d, with organic loading rate （OLR） increased from 1.45 to 17.5 kg COD/（m^3·d）. The results showed that the EGSB reactor had good performance in terms of COD removal on the one hand, high COD removal of 91% was obtained at two days＇ of hydraulic retention time （HRT）, and the highest OLR of 17.5 kg COD/（m^3·d）. On the other hand, only 46% COD in raw POME was transformed into biogas in which the methane content was about 70% （V/V）. A 30-d intermittent experiment indicated that the maximum transformation potential of organic matter in raw POME into methane was 56%. Volatile fatty acid （VFA） accumulation was observed in the later operation stage, and this was settled by supplementing trace metal elements. On the whole, the system exhibited good stability in terms of acidity and alkalinity. Finally, the operational problems inherent in the laboratory scale experiment and the corresponding countermeasures were also discussed.

Hydrodynamic characteristics of a four-compartment periodic anaerobic baffled reactor

Periodic anaerobic baffled reactor （PABR） is a novel reactor based on the design concept of anaerobic baffled reactor （ABR）. Residence time distribution （RTD） studies on both clean and working reactors at the same hydraulic residence time （HRT） of 2 d were carded out to investigate the dead spaces and mixing patterns in PABRs at different organic loading rates （OLRs） in various switching manners and frequencies. The results showed that the fraction of dead space in PABR was similar to that in ABR, which was low in comparison with other reactor designs. Dead space may be divided into two categories, hydraulic and biological. In RTD studies without biomass, the hydraulic dead space in the PABR run in an ＂every second＂ switching manner with T = 2 d was the lowest whereas that in the PABR run in a T = ∞ （ABR） switching manner was the highest. The same trend was obtained with the total dead space in RTD studies with biomass no matter what the OLR was. Biological dead space was the major contributor to dead space but affected decreasingly at higher OLR whichever switching manner the PABR run in. The flow patterns within the PABRs were intermediate between plug-flow and perfectly mixed under all the conditions tested,

Effect of inorganic carbon on anaerobic ammonium oxidation enriched in sequencing batch reactor

The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon(sodium bicarbonate)on anaerobic ammonium oxidation.The enrichment of anammox bacteria was carried out in a 7.0-L sequencing batch reactor(SBR)and the effect of bicarbonate on anammox was conducted in a 3.0-L SBR.Research results,especially the biomass,showed first signs of anammox activity after 54 d cultivation with synthetic wast...

Thermogenic protein UCP1 and UCP3 expression in non- small cell lung cancer： relation with glycolysis and anaerobic metabolism

Uncoupling protein 1(UCP1)is a proton transporter/channel residing on the inner mitochondrial membrane and is involved in cellular heat production.Using immunohistochemistry,we investigated the expression of UCP1 and UCP3 in a series of 98 patients with non-small cell lung cancer(NSCLC)treated with surgery.Expression patterns were correlated with histopathological variables,prognosis,and the expression of enzymes/proteins related to cell metabolism.Bronchial epithelium did not express UCP1 or UCP3,while alveolar cells strongly expressed UCP1.In tumors,strong expression of UCP1 and UCP3 was recorded in43/98(43.8%)and 27/98(27.6%)cases,respectively.UCP1 was significantly associated with squamous cell histology(P=0.05),whilst UCP3 was more frequently overexpressed in large cell carcinomas(P=0.08),and was inversely related to necrosis(P=0.009).In linear regression analysis,UCP1 was directly related to markers of glycolysis[hexokinase(HXKII)and phosphofructokinase(PFK1)]and anaerobic glucose metabolism[pyruvate dehydrogenase kinase(PDK1)and lactate dehydrogenase(LDH5)].UCP3 was directly linked with a glucose transporter(GLUT2),monocarboxylate transporter(MCT2),glycolysis markers(PFK1 and aldolase),and with the phosphorylation of pyruvate dehydrogenase(p PDH).Kaplan-Meier survival analysis showed that UCP3 was significantly related to poor prognosis in squamous cell carcinomas(P=0.04).UCP1 and UCP3 are overexpressed in a large subgroup of non-small cell lung tumors and their expression coincides with increased glucose absorption,intensified glycolysis,and anaerobic glucose usage.Whether UCPs are targets for therapeutic interventions in lung cancer is a hypothesis that demands further investigation.

Occurrence and removal of organic micropollutants in the treatment of landfill leachate by combined anaerobic-membrane bioreactor technology

Organic micropollutants,with high toxicity and environmental concern,are present in the landfill leachate at much lower levels than total organic constituents (chemical oxygen demand (COD),biochemical oxygen demand (BOD),or total organic carbon (TOC)),and few has been known for their behaviors in different treatment processes.In this study,occurrence and removal of 17 organochlorine pesticides (OCPs),16 polycyclic aromatic hydrocarbons (PAHs),and technical 4-nonylphenol (4-NP) in landfill leachate in a comb...

Influence of Chemical Oxygen Demand Concentrations on Anaerobic Ammonium Oxidation by Granular Sludge From EGSB Reactor

Objective To investigate the effect of chemical oxygen demand （COD） concentrations on the anaerobic ammonium oxidation （ANAMMOX）. Methods An Expanded Granular Sludge Bed （EGSB） reactor was used to cultivate the granular sludge and to perform the ANAMMOX reaction in the bench scale experiment. NH4^＋-N and NO2^--N were measured by using colorimetric method. NO3^＋-N was analyzed by using the UV spectrophotometric method. COD measurement was based on digestion with potassium dichromate in concentrated sulphuric acid. Results When the COD concentrations in the reactors were 0 mg/L, 200 mg/L, 350 mg/L, and 550 mg/L, respectively, the NH4^＋-N removal efficiency was 12.5%, 14.2%, 14.3%, and 23.7%; the removal amount of NO2-N was almost the same; the nitrate removal efficiency was 16.8%, 94.5%, 86.6%, and 84.2% and TN removal efficiency was 16.3%, 50.7%, 46.9%, and 50.4%, moreover, the COD removal efficiency was 85%, 65.7%, and 60%; the COD removal rate was 27.42, 61.88, and 97.8 mg COD/（h·L）. Conclusion COD concentrations have a significant influence on anaerobic ammonium oxidation by granular sludge.

Anaerobic BTEX degradation in soil bioaugmented with mixed consortia under nitrate reducing conditions

Different concentrations of BTEX, including benzene, toluene, ethylbenzene, and three xylene isomers, were added into soil samples to investigate the anaerobic degradation potential by the augmented BTEX-adapted consortia under nitrate reducing conditions. All the BTEX substrates could be anaerobically biodegraded to non-detectable levels within 70 d when the initial concentrations were below 100 mg/kg in soil. Toluene was degraded faster than any other BTEX compounds, and the high-to-low order of degradation rates were toluene 〉 ethylbenzene 〉 m-xylene 〉 o-xylene 〉 benzene 〉 p-xylene. Nitrite was accumulated with nitrate reduction, but the accumulation of nitrite had no inhibitory effect on the degradation of BTEX throughout the whole incubation. Indigenous bacteria in the soil could enhance the BTEX biodegradation ability of the enriched mixed bacteria. When the six BTEX compounds were simultaneously present in soil, there was no apparent inhibitory effect on their degradation with lower initial concentrations. Alternatively, benzene, o-xylene, and p-xylene degradation were inhibited with higher initial concentrations of 300 mg/kg. Higher BTEX biodegradation rates were observed in soil samples with the addition of sodium acetate compared to the presence of a single BTEX substrate, and the hypothesis of primary-substrate stimulation or cometabolic enhancement of BTEX biodegradation seems likely.

Biodegradation of 4-Chlorophenol by Candida albicans PDY-07 under Anaerobic Conditions

Candida albicans PDY-07 was isolated from activated sludge under anaerobic conditions and identified as a member belonging to the genus Candida. Pure culture of C. albicans PDY-07, biodegradation of 4-chlorophenol (4-CP) was carried out under anaerobic conditions in Erlenmeyer flasks at 35°C, with an initial pH of 7.0–7.2 and a starting inoculum of 10%(by volume). The results showed that, under the above-mentioned conditions, C. albicans PDY-07 could thoroughly biodegrade 4-CP up to a concentration of 300mg·L?1 within 244h and that it had a high tolerance potential of up to 440mg·L?1 for 4-CP. With the increase in the initial concentrations of 4-CP, substrate inhibition was obviously enhanced. There was increased consumption of 4-CP, which was not assimilated by the cell for growth but was used to counteract the strong substrate inhibition. In addition, the cell growth and substrate-degradation kinetics of 4-CP as the sole source of carbon and energy for the strain in batch cultures were also investigated over a wide range of substrate concentrations (2.2–350mg·L?1), using the proposed cell growth and degradation kinetic models. The results recorded from these experiments showed that the proposed kinetic models adequately described the dynamic behavior of 4-CP biodegradation by C. albicans PDY-07.

Anaerobic soil disinfestation:A chemical-independent approach to pre-plant control of plant pathogens

Due to increasing regulations and restrictions, there is an urgent need to develop effective alternatives to chemical-dependent fumigation control of soilborne pests and pathogens. Anaerobic soil disinfestation （ASD） is one such alternative showing great promise for use in the control of soilborne pathogens and pests. This method involves the application of a carbon source, irrigation to field capacity, and covering the soil with a plastic tarp. While the mechanisms of ASD are not completely understood, they appear to be a combination of changes in the soil microbial community composition, production of volatile organic compounds, and the generation of lethal anaerobic conditions. The variety of materials and options for ASD application, including carbon sources, soil temperature, and plastic tarp type, influence the efficacy of pathogen sup- pression and disease control. Currently, both dry （e.g., rice bran） and liquid （e.g., ethanol） carbon sources are commonly used, but with different results depending on environmental conditions. While solarization is not an essential component of ASD, it can enhance efficacy. Understanding the mechanisms that mediate biological changes occurring in the soil during ASD will facilitate our ability to increase ASD efficacy while enhancing its commercial viability.

Anaerobic benzene biodegradation by a pure bacterial culture of Bacillus cereus under nitrate reducing conditions

A pure culture using benzene as sole carbon and energy sources was isolated by screening procedure from gasoline contaminated soil.The analysis of the 16S rDNA gene sequence,morphological and physiological characteristics showed that the isolated strain was a member of genus Bacillus cereus.The biodegradation performance of benzene by B.cereus was evaluated,and the results showed that benzene could be efficiently biodegraded when the initial benzene concentration was below 150 mg/L.The metabolites of anaerobic nitrate-dependent benzene oxidation by strain B.cereus were identified as phenol and benzoate.The results of substrate interaction between binary combinations for benzene,phenol and benzoate showed that the simultaneous presence of benzene stimulated the degradation of benzoate,whereas the addition of benzene inhibited the degradation of phenol.Benzene degradation by B.cereus was enhanced by the addition of phenol and benzoate,the enhanced effects were more pronounced at higher concentration.To our knowledge,this is the first report that the isolated bacterial culture of B.cereus can efficiently degraded benzene under nitrate reducing conditions.