大型奶牛场粪便厌氧消化工程的研究

本文报导了大型牛场粪便厌氧消化工程研究的概况。该工程针对牛粪草多、浮渣多的特点设计了除长草、除浮渣装置。以保证了厌氧消化的稳定运行。工程每天可处理奶牛粪便８０余吨、鸡粪及工业发酵废渣２０余吨,生产沼气供应２８６８户职工家庭作燃气使用,平均沼气率为１．２ｍ＾３／ｍ＾３．ｄ。经后处理的发酵残留物被充分利用,制成肥料、绿色营养土和鱼饵,这样既免除了二次污染,又提高了工程的经济效益。该工程为我国大中型沼气     

Anaerobic filter treatment of fishery wastewater

Anaerobic treatment of wastewater from a selected seafood processing plant was conducted at organic loading rates (OLR) ranging from 0.3 to 1.8 kg chemical oxygen demand (COD)/m³.day and hydraulic retention times (HRT) ranging from 36 to 6 days. COD reduction decreased with increasing OLR. More than 75% COD reduction could be maintained up to an OLR of about 1 kg COD/m³.day with an HRT of 11 days. An OLR of 1.3 kg COD/m³.day corresponding to an HRT of 6.6 days gave maximal biogas productivity of 1.5 m³/m³.day or 1.3 m³ biogas/kg COD with a 65% COD reduction. If the HRT was kept constant at 11 days, an OLR of 1.3 kg COD/m³.day achieved maximal biogas productivity (1.1 m³/m³.day) and yield (0.75 m³/kg COD) and a 60% COD reduction for treatment of tuna condensate.P. Prasertsan and S. Jung are with the Department of Agro-Industry, Faculty of Natural Resources, Prince of Songkla University, Hatyai 90110, Thailand. K.A. Buckle is with the Department of Food Science and Technology, University of New South Wales, Kensington, NSW 2033, Australia.     

Microbial Community Dynamics of a Continuous Mesophilic Anaerobic Biogas Digester Fed with Sugar Beet Silage

The aim of the study was to investigate the long‐term fermentation of an extremely sour substrate without any addition of manure. In the future, the limitation of manure and therefore the anaerobic digestion of silage with a very low buffering capacity will be an increasing general bottleneck for energy production from renewable biomass. During the mesophilic anaerobic digestion of sugar beet silage (without top and leaves) as the sole substrate (without any addition of manure), which had an extreme low pH of around 3.3, the highest specific gas production rate (spec. GPR) of 0.72 L/g volatile solids (VS) d was achieved at a hydraulic retention time (HRT) of 25 days compared to an organic loading rate (OLR) of 3.97 g VS/L d at a pH of around 6.80. The methane (CH₄) content of the digester ranged between 58 and 67 %, with an average of 63 %. The use of a new charge of substrate (a new harvest of the same substrate) with higher phosphate content improved the performance of the biogas digester significantly. The change of the substrate charge also seemed to affect the methanogenic population dynamics positively, thus improving the reactor performance. Using a new substrate charge, a further decrease in the HRT from 25 to 15 days did not influence the digester performance and did not seem to affect the structure of the methanogenic population significantly. However, a decrease in the HRT affected the size of the methanogenic population adversely. The lower spec. GPR of 0.54 L/g VS d attained on day 15 of the HRT could be attributed to a lower size of methanogenic population present in the anaerobic digester during this stage of the process. Furthermore, since sugar beet silage is a relatively poor substrate, in terms of the buffering capacity and the availability of nutrients, an external supply of buffering agents and nutrients is a prerequisite for a safe and stable digester operation.     

厌氧反应器中颗粒污泥的培育及应用研究进展*

厌氧生物处理技术因其具有有机负荷高、污泥产量低、能耗低等优点被广泛应用于各种废水处理中。厌氧颗粒污泥具有沉降性能好、微生物浓度高、有机负荷高等优点,极大地提高了废水处理效率。尤其在处理含高氨氮废水中,厌氧颗粒污泥的形成对反应器的高效生物脱氮至关重要。但到目前为止,厌氧反应器中的颗粒污泥形成及废水处理效果还缺乏系统的认识。鉴于此,总结了厌氧反应器中颗粒污泥的形成机制,分析了影响厌氧反应器中颗粒污泥形成的因素,论述了厌氧反应器中厌氧颗粒污泥生长的模拟,最后介绍了厌氧颗粒污泥在国内外的主流应用。厌氧反应器中颗粒污泥的形成是综合因素影响的结果,对影响厌氧颗粒污泥形成的每个因素都需要认真对待,可为在厌氧反应器中颗粒污泥的培育和应用提供理论指导和技术支撑。     

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.     

Impact of chlortetracycline on sequencing batch reactor performance for swine manure treatment

Treatment of aged (500 day, 4 °C stored) chlortetracycline (CTC; 0, 20, 40, 80 mg/L CTC)-amended swine manure using two cycle, 22 day stage anaerobic sequencing batch reactors (SBR) was assessed. Eighty milligrams per liter CTC treatment inhibited SBR treatment efficiencies, although total gas production was enhanced compared to the no-CTC treatment. The 20 and 40 mg/L CTC treatments resulted in either slight or no differences to SBR treatment efficiencies and microbial diversities compared to the no-CTC treatment, and were generally similar to no-CTC treatments upon completion of the first 22 day SBR cycle. All CTC treatments enhanced SBR gas generation, however CH₄ yields were lowest for the 80 mg/L CTC treatment (0.111 L CH₄/g tCOD) upon completion of the second SBR react cycle. After a 22 day acclimation period, the 80 mg/L CTC treatment inhibited methanogenesis due to acetate accumulation, and decreased microbial diversity and CH₄ yield compared to the no-CTC treatment.     

Anaerobic biodegradation of diesel fuel-contaminated wastewater in a fluidized bed reactor

Diesel fuel spills have a major impact on the quality of groundwater. In this work, the performance of an Anaerobic Fluidized Bed Reactor (AFBR) treating synthetic wastewater is experimentally evaluated. The wastewater comprises tap water containing 100, 200 and 300 mg/L of diesel fuel and nutrients. Granular, inert, activated carbon particles are employed to provide support for biomass inside the reactor where diesel fuel is the sole source of carbon for anaerobic microorganisms. For different rates of organic loading, the AFBR performance is evaluated in terms of the removal of diesel fuel as well as chemical oxygen demand (COD) from wastewater. For the aforementioned diesel fuel concentrations and a wastewater flow rate of 1,200 L/day, the COD removal ranges between 61.9 and 84.1%. The concentration of diesel fuel in the effluent is less than 50 mg/L, and meets the Level II groundwater standards of the MUST guidelines of Alberta.     

Biogas manufacture from co-digestion of untreated primary sludge with raw chicken manure under anaerobic mesophilic environmental conditions

This work aimed to co-digest various wastes to assess the best combination of all mixing ratio, also at choosing the best ratio between untreated primary sludge (UPS) singly from two sources, (South valley University (SUPS) and Abu tesht wastewater station (AUPS) and raw chicken manure (RCM) and comparing the results in either case. The co-digestions of untreated primary sludge from Abu tesht wastewater treatment stations with different levels of raw chicken manure (0:100, 10:90, 30:70, 50:50, 90:10, and 100:0) to obtain the best mixtures. Also, co-digestion of untreated primary sludge from south valley university with different levels of raw chicken manure at the same ratios, to obtain the best mixtures. Batch digestion tests were applied in 2.5 L digester with a working volume of 2.0 L. The samples in triplicates were separately loaded into the digesters locally fabricated and kept for 20 days as a retention period and diluted with the same amount of water. Mesophilic under 35 °C was adopted for untreated primary sludge as well as mixtures with raw chicken manure based on total solids (TS) and volatile solid (VS) proportions. The average biogas yields from AUPS/RCM mixture obtained ranged from 8570 to 5600 ml, by the following descending order, 10: 90 > 90:10 and so on >100:0, and the average biogas yields from SUPS/RCM obtained ranged from 6330 to 5635 ml, in the order of 90: 10 > 10:90 and so on >100:0. The results showed highest biogas yield from AUPS/RCM and SUPS/RCM mixtures with mixing ratio of 10:90 and 90:10, respectively, however, the lowest biogas production detected in separate digestion of AUPS and SUPS. The results indicated that co-digestion between the sludge and raw chicken manure could increase total biogas production volume, enhance sludge treatment process, and produce eco-friendly sludge because of co-digestion process than separate processing of each feedstock.     

厌氧发酵过程中温度对甲烷产量的影响

厌氧发酵是对有机废弃物进行无害化和资源化处理的有效方法之一。目前已知有许多微生物菌群参与此过程,许多环境因素都直接或间接地影响着微生物的生长,这其中温度对其影响很大。实验用序批次反应器测定不同温度条件下,乙酸和丙酸分别作为底物时产生甲烷的潜力。在108mL的反应器中加入8mL嗜热性微生物菌群和0.5mL的底物以及31.5mL 的营养液,然后放置在9个不同处理温度的生化培养箱中进行适应性培养。二周后,重新加入0.5mL底物和0.5mL维生素混合液。反应器中甲烷的产量用气相色谱(Shimadzu GC-8A)分析和测定。实验结果表明,当处理温度为25℃和30℃时乙酸和丙酸作为底物它们产甲烷的能力几乎没有差异;当处理温度为37℃和50℃时产甲烷的能力丙酸作为底物要大于乙酸作为底物;在其余的试验组中乙酸产甲烷的能力都要高于丙酸。同时发现在40℃和55℃试验组乙酸产甲烷的能力为最大,而丙酸作为底物时其最大产甲烷能力发现在37℃和50℃试验组。导致这一实验结果的原因在于试验所使用的微生物菌群不是单一的品种,尽管它们在各自的试验温度中都进行了先期适应性培养。     

Biogas from dedicated energy crops in Northern Italy: electric energy generation costs

Agricultural anaerobic digestion facilities are increasing in many EU member States and biomass supply is sometimes an issue. Dedicated energy crops (DEC) (mainly Maize, Triticale and Sorghum) are often used to integrate other substrates, such as agricultural residues, manure and organic waste. However, DEC production includes onerous agricultural operations (soil preparation, harvest, transport and storage) and may result in high unit costs (UC) of electric energy (EE, € kWhe⁻¹), compared to other renewable sources. In this work, seven different types of DEC (4 different combinations of crop successions) were cultivated in 30 different parcels, distributed along the Po Valley (northern Italy), using different varieties of seeds for each crop type. All agricultural operations were accounted for their costs (988–3346 € ha⁻¹). Biomass production was measured and reported as average of different parcels for each type of crop (31.2–187 Mg ha⁻¹). Biomass dry matter content and biogas potential were measured on representative samples and the EE obtainable was calculated (7.9–35.3 MWhe ha⁻¹), by assuming conservative factors (CH₄ contents in biogas and electric generation yields). The costs of ensiled biomass sensibly varied (13.8–40 € Mg⁻¹) among crop solutions, as well as the same UC of EE (0.068–0.150 € kWhe⁻¹). These costs were considered together with typical plant management and investment costs (plant size: 0.5–1 MWe): total UC of EE generation through anaerobic digestion (considering 100% DEC) varied in a relatively wide range (0.143–0.279 € kWhe⁻¹). When the biomass mix is ‘blended’ with low-cost residues or organic waste, this range could be lowered to 0.096–187 € kWhe⁻¹. Only this strategy and strong efforts in reducing technological investment/management costs can candidate biogas-based EE as a really competitive renewable alternative to traditional sources, in the next future.     

Conversion of cereal residues into biogas in a rumen-derived process

A recently developed high-rate, two-phase process, which employs rumen microorganisms for efficient acidogenesis, was tested for anaerobic degradation of barley straw, rye straw, and maize stover. Under conditions similar to those of the rumen and loading rates varying between 9.8 and 26.0 g of organic matter/I/day in the first phase (acidogenic reactor), total fibre degradation efficiencies ranged between 42% and 57%, irrespective of the loading rate applied. Average specific production of volatile fatty acids and biogas/g volatile solid digested in the acidogenic reactor varied between 6.9 and 11.2 mmol and 0.10 and 0.25 l, respectively.The effect of varying solid retention times on the extent of degradation of barley straw was examined. Changing of retention times in the range of 60 to 156 h had no effect on degradation efficiency, but a decrease in efficiency was observed at retention times below 60 h.By connecting the acidogenic reactor in series to an Upflow Anaerobic Sludge Blanket (UASB) methanogenic reactor the volatile fatty acids were converted into biogas. Average methane contents of the gases produced in the acidogenic reactor and in the UASB reactor were 30±3% and 78±3%, respectively.     

Anaerobic Immobilized Yeast Cell Fermentation and Anaerobic Remediation in Hybrid Reactor for Mineralization of Dicarboxylic Acid Solid Waste

Summary The solid resinous product (SRP) containing unsaturated/saturated dicarboxylic acid residues, phthalic acid and maleic acid is discharged as a solid waste during cracking of benzene over vanadium at temperatures above 500°C in the dicarboxylic acid manufacturing industry. In the present study the solid waste was diluted with water to a concentration of 0.5% w/v for microbial degradation. The waste was fermented in a reactor containing mesoporous activated carbon on which was immobilized Saccharomyces cerevisiae at an optimum residence time of 24 h at pH 6.5. The immobilized-yeast-treated samples were further treated in an upflow anaerobic reactor at an hydraulic retention time (HRT) of 0.1038 days at a hydraulic flow rate of 7.34 × 10⁻³ m³/day and chemical oxygen demand (COD) loading rate of 2.19 kg/m³/day. The pathway followed in the degradation of dicarboxylic acid into end products by anaerobic metabolism in the yeast cell fermentor and in the upflow anaerobic reactor was confirmed through HPLC, Fourier transform infra red spectroscopy and proton and ¹³C NMR spectroscopy.     

Anaerobic digestion of microalgal biomass with ultrasonic disintegration

The use of photosynthetic microalgae for nutrient removal and biofuel production has been widely discussed. Anaerobic digestion of waste microalgal biomass to produce biogas is a promising technology for bioenergy production. However, the methane yield from this anaerobic process was limited because of the hard cell wall of Chlorella vulgaris. The use of ultrasound has proven to be successful at improving the disintegration and anaerobic biodegradability of Chlorella vulgaris. Ultrasonic pretreatment in the range of 5–200 J ml⁻¹ was applied to waste microalgal biomass, which was then used for batch digestion. Ultrasound techniques were successful and showed higher soluble COD at higher applied energy. During batch digestion, cell disintegration due to ultrasound increased in terms of specific biogas production and the degradation rate. Compared to the untreated sample, the specific biogas production was increased in the ultrasound-treated sample by 90% at an energy dose of 200 J ml⁻¹. For the disintegrated samples, volatile solids reduction was also increased according to the energy input and degradation. These results indicate that the hydrolysis of microalgal cells is the rate-limiting step in the anaerobic digestion of microalgal biomass.     

Characterization of the methanogenic Archaea within two-phase biogas reactor systems operated with plant biomass

The two-phase leach-bed system is a biogas reactor system optimized for the utilization of energy crop silages at maximized loading rates under maintenance of an optimal microbial activity. In this study, a characterization of the methanogenic microbial community within this reactor system was conducted for the first time. Accordingly, effluent samples from the anaerobic filter and the silage digesting leach-bed reactors of both a laboratory-scale two-phase biogas reactor system and a scaled-up commercial on-farm pilot plant were investigated. In total, five Archaea-specific 16S rDNA libraries were constructed and analyzed by amplified rDNA restriction analysis (ARDRA), with subsequent phylogenetic analysis of nucleotide sequences for individual ARDRA patterns. A quantification of major methanogenic Archaea groups was conducted by real-time PCR. A total of 663 clones were analyzed and 45 operational taxonomic units (OTUs) related to methanogenic Archaea were detected. These OTUs were related to the orders Methanosarcinales, Methanomicrobiales and Methanobacteriales, as well as the hitherto uncultured CA-11 and ARC-I groups, and most of them occurred throughout all the compartments of both two-phase biogas reactors. The proportion of acetotrophic to hydrogenotrophic methanogens differed between the laboratory and the pilot scale system. A total of 56% of the clones from the 16S rDNA library derived from the laboratory biogas system were assigned to presumably acetotrophic members of Methanosarcinales. In contrast, these OTUs were less abundant in the 16S rDNA library derived from samples of the pilot plant. Therein, the most dominant OTUs were Methanoculleus-related OTUs, which presumably indicated the predominant presence of hydrogenotrophic methanogens. These findings were confirmed by group-specific quantitative real-time PCR assays. The results indicated that the fraction of acetotrophic and hydrogenotrophic methanogens within a biogas reactor caused certain variations, which may reflect varying substrate utilization during methanogenesis.     

Comparative evaluation of biogas production from dairy manure and co‐digestion with maize silage by CSTR and new anaerobic hybrid reactor

This study aimed to investigate potential methane production through anaerobic digestion of dairy manure and co‐digestion with maize silage. Two different anaerobic reactor configurations (single‐stage continuously stirred tank reactor [CSTR] and hybrid anaerobic digester) were used and biogas production performances for each reactor were compared. The HR was planned to enable phase separation in order to improve process stability and biogas production under higher total solids loadings (≥4%). The systems were tested under six different organic loading rates increased steadily from 1.1 to 5.4 g VS/L.d. The CSTR exhibited lower system stability and biomass conversion efficiency than the HR. The specific biogas production of the hybrid system was between 440 and 320 mL/gVS with 81–65% volatile solids (VS) destruction. The hybrid system provided 116% increase in specific biogas production and VS destruction improved by more than 14%. When MS was co‐digested together with dairy manure, specific biogas production rates increased about 1.2‐fold. Co‐digestion was more beneficial than mono‐material digestion. The hybrid system allowed for generating methane enriched biogas (>75% methane) by enabling phase separation in the reactor. It was observed that acidogenic conditions prevailed in the first two compartments and the following two segments as methanogenic conditions were observed. The pH of the acidogenic part ranged between 4.7 and 5.5 and the methanogenic part was between 6.8 and 7.2.     

Anaerobic digestion of food waste in a hybrid anaerobic solid–liquid system with leachate recirculation in an acidogenic reactor

Recirculation of the leachate in the acidogenic reactor was proposed to enhance anaerobic digestion of food waste in the hybrid anaerobic solid–liquid (HASL) system. Recirculation of the leachate in the acidogenic reactor provided better conditions for extraction of organic matter from the treated food waste and buffering capacity to prevent excessive acidification in the acidogenic reactor. It ensured faster supply of nutrients in the methanogenic reactor in experiment. The highest dissolved COD and VFA concentrations in the leachate from the acidogenic reactor were reached for shorter time and were 16,670 mg/l and 9450 mg/l in control and 18,614 mg/l and 11,094 mg/l in experiment, respectively. Recycling of the leachate in the acidogenic reactor intensified anaerobic digestion of food waste and diminished time needed to produce the same quantity of methane by 40% in comparison with anaerobic digestion of food waste without recirculation.     

Development of a pilot scale anaerobic digester for biogas production from cow manure and whey mix

This paper presents results from anaerobic digestion of cow manure and whey mix. A pilot scale anaerobic digester, 128 l in volume, has been developed, to operate under batch and fed-batch conditions. The versatile and unique characteristics of the instrument allowed testing the methane production directly in the farm. The digester performance was evaluated with two calibration tests, the main for a period of 56 days. The study test was divided into three phases, one for each type of feeding operation (batch, fed-batch, batch). The initial phase of digestion resulted in 57 l-CH₄/kg-VS, the second phase had a yield of 86.6 l-CH₄/kg-VS and the third one had a production of 67 l-CH₄/kg-VS. The total methane yield was equal to 211.4 l-CH₄/kg-VS. Using the obtained pilot plant results to a real scale diary production cycle, it was possible to evaluate an electricity production equal to 8.86 kwh per 1 t/d. The conducted tests did show that there is a good potential to the use of a cow manure and whey biomass mix for biogas production.     

Fate of bacterial pathogens in cattle dung slurry subjected to anaerobic digestion

The survival of certain pathogenic bacteria was studied in anaerobic batch digesters at room temperature (18–25 °C) as well as at 35 °C under laboratory conditions. The survival of Escherichia coli and Salmonella typhi at room temperature was upto 20 days whereas at 35 °C it was only upto 10 days. Shigella dysenteriae was found to be the most sensitive organism which could survive upto 10 days at room temperature and upto 5 days at 35 °C. The longest survival was observed in case of Streptococcus faecalis which could survive upto 35 days at room temperature and 15 days at 35 °C. The survival time of Salmonella typhi increased when the solid contents of the digester were elevated from 9% to 15%.     

Anaerobic digestion of secondary residuals from an anaerobic bioreactor at a brewery to enhance bioenergy generation

Many beer breweries use high-rate anaerobic digestion (AD) systems to treat their soluble high-strength wastewater. Biogas from these AD systems is used to offset nonrenewable energy utilization in the brewery. With increasing nonrenewable energy costs, interest has mounted to also digest secondary residuals from the high-rate digester effluent, which consists of yeast cells, bacteria, methanogens, and small (hemi)cellulosic particles. Mesophilic (37 °C) and thermophilic (55 °C) lab-scale, low-rate continuously-stirred anaerobic digestion (CSAD) bioreactors were operated for 258 days by feeding secondary residuals at a volatile solids (VS) concentration of ∼40 g l⁻¹. At a hydraulic retention time (HRT) of 15 days and a VS loading rate of 2.7 g VS l⁻¹ day⁻¹, the mesophilic bioreactor showed an average specific volumetric biogas production rate of 0.88 l CH₄ l⁻¹ day⁻¹ and an effluent VS concentration of 22.2 g VS l⁻¹ (43.0% VS removal efficiency) while the thermophilic bioreactor displayed similar performances. The overall methane yield for both systems was 0.21 l CH₄ g⁻¹ VS fed and 0.47–0.48 l CH₄ g⁻¹ VS removed. A primary limitation of thermophilic digestion of this protein-rich waste is the inhibition of methanogens due to higher nondissociated (free) ammonia (NH₃) concentrations under similar total ammonium (NH₄ ⁺) concentrations at equilibrium. Since thermophilic AD did not result in advantageous methane production rates or yields, mesophilic AD was, therefore, superior in treating secondary residuals from high-rate AD effluent. An additional digester to convert secondary residuals to methane may increase the total biogas generation at the brewery by 8% compared to just conventional high-rate digestion of brewery wastewater alone. JIMB-2008: BioEnergy—Special issue.     

Anaerobic co-digestion of desugared molasses with cow manure; focusing on sodium and potassium inhibition

Desugared molasses (DM), a syrup residue from beet-molasses, was investigated for biogas production in both batch and in continuously-stirred tank reactor (CSTR) experiments. DM contained 2-3 times higher concentration of ions than normal molasses, which could inhibit the biogas process. The effect of sodium and potassium concentration on biogas production from manure was also investigated. Fifty percent inhibition occurred at sodium and potassium concentration of 11 and 28 g/L, respectively. The reactor experiments were carried out to investigate the biogas production from DM under different dilutions with water and co-digestion with manure. Stable operation at maximum methane yield of 300 mL-CH₄/gVS-added was obtained at a mixture of 5% DM in cow manure. The biogas process was inhibited at DM concentrations higher than 15%. Manure was a good base substrate for co-digestion, and a stable anaerobic digestion could be achieved by co-digesting DM with manure at the concentration below 15% DM.