Anaerobic slurry co-digestion of poultry manure and straw: effect of organic loading and temperature

In order to obtain basic design criteria for anaerobic digestion of a mixture of poultry manure and wheat straw, the effects of different temperatures and organic loading rates on the biogas yield and methane contents were evaluated. Since poultry manure is a poor substrate, in term of the availability of the nutrients, external supplementation of carbon has to be regularly performed, in order to achieve a stable and efficient process. The complete-mix, pilot-scale digester with working volume of 70 L was used. The digestion operated at 25°C, 30°C and 35°C with organic loading rates of 1.0, 2.0, 2.5, 3.0, 3.5 and 4.0 kg Volatile solid/m(3)d and a HRT of 15 days. At a temperature of 35°C, the methane yield was increased by 43% compared to 25°C. Anaerobic co-digestion appeared feasible with a loading rate of 3.0 kg VS/m(3)d at 35°C. At this state, the specific methane yield was calculated about 0.12 m(3)/kg VS with a methane content of 53–70.2% in the biogas. The volatile solid (VS) removal was 72%. As a result of volatile fatty acid accumulation and decrease in pH, when the loading rate was less than 1 or greater than 4 kg VS/m(3)d, the process was inhibited or overloaded, respectively. Both the lower and higher loading rates resulted in a decline in the methane yield

Study of the First Isolated Fungus Capable of Heavy Crude Oil Biodesulfurization [abstract]

Track II: Transportation and BiofuelsOnly abstract of poster available.To meet stringent emission standards stipulated by regulatory agencies, the oil industry is required to bring down the sulfur content of fuels. Oil supplies 38% of the worldwide energy, and as the light oil is limited and meanwhile the energy demand is increasing, it is a must to use heavy crude oil and therefore desulfurize it to meet environmental standards. As it is not feasible to desulfurize all the sulfur containing compounds of heavy crude oil by the existing methods (such as hydro-desulfurization) we have focused on biodesulfurization of heavy crude oil. We have isolated the first native fungus which has been identified as Stachybotrys sp. and is able to remove sulfur and nitrogen from heavy crude oil selectively at 30 °C. This fungus is able to desulfurize 76% and 64.8% of the sulfur content of heavy crude oil of Soroush oil field and Kuhemond oil field (with the initial sulfur contents of 5 wt % and 7.6 wt %, respectively) in 72 and 144 h, respectively. We have studied the impacts of several parameters on heavy crude oil biodesulfurization efficiency of our fungus strain such as initial pH of the medium, water−oil ratio, and number of spores in the suspension used for inoculation. This fungus strain has been isolated as a part of the heavy crude oil biodesulfurization project initiated by Petroleum Engineering Development Company (PEDEC), a subsidiary of National Iranian Oil Company

Effective Parameters on Increasing Filamentous Bacteria and Their Effects on Membrane Fouling in MBR

Over 90 percent of the wastewater treatment plants in Iran use activated sludge process. Due to increase in organic loading rates, most of these plants do not have appropriate performance. For upgrading these systems and decreasing production of the excess sludge, a UASB reactor can be used as pretreatment for decreasing the organic loading prior to the activated sludge system. Also for improving the effluent quality, a membrane can be replaced for secondary sedimentation tank, i.e. changing activated sludge to membrane bioreactor. In this study, the effect of significant changes in feed composition, due to the introduction of UASB reactor; have been investigated on the population of filamentous bacteria, COD and TS removal efficiency and membrane fouling. The results showed that the population of filamentous bacteria increased rapidly from 5 to 100 Count/µL. However, this increase does not have considerable effect on membrane fouling. With increasing MLSS concentration, the number of filamentous bacteria increased from 100 to 400Count/µL. As a result, the trans membrane pressure was raised from 1.5 to 3kpa and overall membrane resistance was increased against the effluent flux. For reducing the filamentous bacteria, a dose of 20 g Cl2 /Kg MLSS was added in few intervals for two days. It was also found the number of filamentous bacteria decreased from 400 to 100 after 5 days without decreasing the other microorganisms’ population significantly. The trans membrane pressure was also retained without any further increase

Adsorption of violet B by agricultural waste of soft pistachio shells

In this study, inexpensive agricultural waste pistachio sells was used for adsorption of violet B. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) were used to characterize the pistachio shells. The morphology of pistachio shell was studied by SEM and it showed the porous structure of pistachio shells. Different parameters like contact time, pH and mass of sorbent were investigated. The adsorption is dependent on pH of the medium where the removal efficiency increases as the pH turns to 11. The contact time studies showed that 45 min shaking time was sufficient to achieve the equilibrium. The reaction kinetics data were analyzed using two reactions kinetic of pseudo-first-order reaction model and pseudo-second-order reaction model, and it was found that the removal of violet B followed the pseudo-second order reaction model.Keywords: Adsorption, violet B, agricultural waste, pistachio shell. Afr. J. Biotechnol. Vol. 12 No. 5

Economic assessment of hydrogen fueling station, a case study for Iran

In recent years there have been many efforts to develop a hydrogen energy system in Iran. For instance, the Iranian fuel cell steering committee conducted a project and determined some targets to implement hydrogen in different sectors, especially transportation. In this paper, the costs of building stations and the levelized cost of hydrogen for two types of stations, SMR and electrolysis, with various sizes and capacity factors have been investigated. Also, in the case of electrolysis, hydrogen cost sensitivity to the price of electricity has been examined. According to the cost analysis conducted here, it is understandable that hydrogen costs ($/kg) vary considerably based on station type, size, and capacity factor. Hydrogen production from natural gas results in lower costs ($3–7/kg H2) in comparison to electrolysis ($6–10/kg H2). Hydrogen cost would decrease by increasing the capacity factor, but in the case of electrolysis, from a specific capacity factor, hydrogen cost begins to rise; this is due to the trade off between the capacity factor and the price of electricity in various load zones. In general, hydrogen costs in Iran are estimated from 3 to 10.5$/kg, however a strategy for producing even lower cost hydrogen in the early years of hydrogen implementation, is proposed, which all together indicates that hydrogen could be an economical alternative fuel to substitute gasoline in the Iran's transportation secto

A Survey of Sludge Granulation Theories Under Anaerobic Conditions

This paper surveys the different theories developed on anaerobic sludge granulation. The theories are generally categorized as physical, microbial, and thermodynamic approaches. In the physical approach to the granulation process, granulation is described by such physical conditions of the reactor as upflow velocity of gas and liquid streams, suspended solids in the effluent flow, and excess sludge removal. Microbial theories are based on the properties of specific organisms and on granule properties (granule structure and its microbiology). The thermodynamic approach studies such factors as hydrophobia, electrophoretic mobility, effective energy in granule adhesion process, and effect of proton transferring activities on bacterial membrane surfaces

Risk assessment of industrial hydrocarbon release and transport in the vadose zone as it travels to groundwater table: A case study

In this paper, a modeling tool for risk assessment analysis of the movement of hydrocarbon contaminants in the vadose zone and mass flux of contamination release into the groundwater table was developed. Also, advection-diffusion-reaction equations in combination with a three-phase equilibrium state between trapped air, soil humidity, and solid particles of unsaturated soil matrix were numerically solved to obtain a one dimensional concentration change in respect to depth of soil and total mass loading rate of hydrocarbons into the groundwater table. The developed model calibrations by means of sensitivity analysis and model validation via data from a site contaminated with BTEX were performed. Subsequently, the introduced model was applied on the collected hydrocarbon concentration data from a contaminated region of a gas refinery plant in Booshehr, Iran. Four different scenarios representing the role of different risk management policies and natural bio-degradation effects were defined to predict the future contaminant profile as well as the risk of the mass flux of contaminant components seeping into the groundwater table. The comparison between different scenarios showed that bio-degradation plays an important role in the contaminant attenuation rate; where in the scenarios including bio-degradation, the contaminant flux into the ground water table lasted for 50 years with the maximum release rate of around 20 gr per year while in the scenarios without including bio-degradation, 300 years of contaminant release into groundwater table with the maximum rate of 100 gr per year is obtained. Risk assessment analysis strongly suggests a need for bioremediation enhancement in the contaminated zones to reduce the contaminant influx to groundwater

Biokinetic coefficients determination of a MBR for styrene and ethylbenzene as substrate base on Andrews model

In this study, a lab-scale membrane bioreactor (MBR) was operated for a period of more than 10 months to determine the biokinetic coefficients of the system under the hydraulic retention times (HRT) of 20, 15 and 10 hrs and sludge retention times (SRT) of 5-20 days. The results revealed that the biological removal efficiency of styrene and ethylbenzene at a solid retention time of 20 day and a hydraulic retention time of 15 hr was higher compared to a SRT of 10 day and at the same HRT. The results also showed that the yield (Y), the endogenous decay coefficient (kd), the maximum specific growth rate (μmax), and the saturation constant (Ks) for styrene and ethylbenzene as substrate were 0.60 and 0.60 mg/mg, 0.25 and 0.25 day−1, 0.188 and 0.363 h-1, and 0.146 and 2.82 mg /l, respectively. Furthermore, ethylbenzene was more appropriate as a source of carbon to activated sludge in the membrane bioreactor than the styrene which had a lower μmax than ethylbenzene

Factors Involved in Sludge Granulation under Anaerobic Conditions

This paper investigates the effects of factors involved in sludge anaerobic granulation. Granulated sludge formation is the main parameter contributing to the success of UASB reactors. Anaerobic granulation leads to reduced reactor size, space requirement, and investment costs. Operation costs are also greatly reduced due to lack of aeration. An important parameter affecting process performance is the size of sludge granules; the factors involved in granule size will be investigated. Some of the important parameters of anaerobic sludge granulation are: existence of growth cores as inert particles or granulated sludge, process operational conditions (Sludge Loading Rate and Organic Loading Rate, Loading rate increase and …), and environment conditions (nutrients, temperature, pH, combination and …)

Developing an integrated model for allocating resources and assessing technologies based on the watergy optimal point (water-energy nexus), case study: a greenhouse

Water-energy nexus approach analyses water and energy interactions to provide sustainable usage of resources. This study incorporates a comprehensive bottom-up optimization model to assess the combination of technologies based on the water-energy nexus (watergy) optimal point. To achieve this goal, the watergy reference system is introduced according to six principles of watergy system. In this study, a new method is developed by adding an integration layer to the optimizing model with the objective function of the minimum total cost. In this layer, the demands for water and energy, for supplying the water and energy services, are calculated endogenously. A sensitivity analysis is performed by presenting six scenarios for greenhouse case study. Results indicate that the drainage recycling, combined heat and power, and photovoltaic were chosen at the watergy optimal point. Compared to the base case scenario, the maximum achievable reduction in the total cost of production is 31% in the most cost-effective scenario (Scenario B). Also, among the modelled scenarios, the optimal combination of technologies could result in reducing the use of water, electricity, and fertilizer by 18%, 31%, and 25% respectively