Enhancement of anaerobic digestion of actual industrial wastewaters : reactor stability and kinetic modeling.

Industrial plants pay disposal costs for discharging their wastewater that can contain pollutants, toxic organics and inorganics, to the sewer based on the Biological Oxygen Demand (BOD) or Chemical Oxygen Demand (COD) of the streams. It has become increasingly expensive for industry to meet stringent regulatory standards. One solution to reduce this cost is to anaerobically degrade the COD content, which in turn generates useful methane gas that can be used to generate useful energy or heat. Anaerobic Digestion (AD) is one of the most suitable renewable resources of conversion of industrial wastewaters to bioenergy, but it is not widely utilized in the US. As a result, this research focused on understanding and improving fundamental technical and economic obstacles such as long residence times, large reactor sizes/footprints and product quality that hamper its industrial applications in the US. Kinetic modeling of these anaerobic digestion processes is important for evaluating experimental results, predicting performance, and optimizing reactor designs, but the modeling can be especially difficult for complex wastewater compositions. Respirometry tests were first conducted to assess the impact of substrate loading on kinetic parameters during AD of three industrial/agricultural wastewaters: soybean processing WW, brewery WW, and recycled beverage WW. Results showed that the rate order statistically increased with increasing initial COD content, demonstrating that conventional kinetic modeling is inadequate for these WW of complex composition. COD degradation models revealed the Monod model gave the best overall fit to experimental data throughout the duration of the AD process, but the reactions were best fit to first-order kinetics during the first 7-9 hours and then best fit to higher order kinetics after about 8-13 hours depending on initial COD load. Expanded granular sludge bed (EGSB) reactors are two-stage continuous systems developed to reduce the residence time and footprint by expanding the sludge bed and escalating hydraulic mixing. However, higher molecular weight and slowly degrading organics, such as crude proteins and fats, cannot efficiently diffuse into the granular biomass to be digested before exiting the reactor, which limits AD efficiency. COD removal efficiency increased by up to 42% and biogas production rate by up to 32% for equivalent organic loading rates by properly manipulating COD load and feed rate. Hydrogen gas, an intermediate product generated during stage-one pre-acidification (PA), escapes the PA tank but theoretically can be captured and sent to the second stage EGSB reactor to enhance the biogas quality by biologically converting the carbon dioxide to methane. Introducing supplemental hydrogen gas in amounts less than theoretically generated in the PA tank increased energy yield by up to 42% and enhanced biogas quality by up to 20%. In addition, COD removal efficiency remained constant at ~98%, indicating that hydrogen injection did not negatively affect overall substrate removal

Emission difference between natural gas usage and digester gas usage.

It is important to burn the air toxics and harmful gases which come from water and wastewater treatment processes. In common practice, instead of natural gas, digester gas is used for economical reasons. This burning process takes place in the Regenerative Thermal Oxidizer (RTO). The current research was conducted to identify if there exists any differences between natural gas and digester gas in outlet emission. The location of the experiment was at Morris Forman Wastewater Treatment Plant of Metropolitan Sewer District (MSD) of Jefferson County, Kentucky, USA. In this experiment, the RTO was run in two cases: one fueling by digester gas and next fueling by natural gas; then samples were obtained from a sampling port during each case. The captured samples were analyzed in the laboratory at the University of Louisville, Kentucky. The resulted data from these two cases showed that there are not much emission differences between these two fuels. Therefore, use of digester gas instead of natural gas is an economical move without causing any harmful emission

A hybrid Kano-fuzzy AHP method for measuring customer satisfaction: A case study of transportation system

An increase competition on today's economy has created motivation for many organizations to look for different alternatives on better serving the customers. There are always some budget limitations on any customer relationship method, which leads us to prioritize different alternatives. In this paper, we present an empirical method based on an integrated Kano and fuzzy analytical hierarchy procedure to rank suitable alternatives. The proposed model of this paper uses a questionnaire survey to gather customer's opinions and implements the method for a real-world case study of transportation planning. The questionnaire includes 37 questions distributed among 976 passengers for two trips in Iran. The results indicate that driver's physical and mental health, buss equipments with GPS functionality and familiarity of drivers with road and road's conditions play important role on choosing a transportation company

The Effect of Different Concentrations of the Thinner Globaryll100 on Chemical Characteristics of Gala Apples

Apple (Malusdomestica) is a plant in the form of short shrub or tree with branches lacking thorns and simple oval obular leaves and small and short head. Apple buds include vegetative or simple buds producing branches and its fertile buds are plain mixed generative buds and produce five flowers and 7-8 leaves when waking up. Apple is of great importance in the world so that in 2011, 75.5 million tons of apples were produced and consumed in the world according to the FAO. It has a lot of properties such as maintaining healthy skin, preventing cancer, and so on. The thinner Globaryll100 at concentrations of 150, 250 and 350 mg were used in the Gala apple varieties with the aim of resolving the problem of alternate fruiting and making coarse and high quality fruits and then traits such as pH, acidity, dry matter content, sugar content, total soluble solids were measured. Globaryll was used when the fruit was 10 mm. Globaryll at a concentration of 350 mg per liter has achieved the first place of Duncan in terms of sugar content, soluble solids, pH, and percentage of dry matter. The results showed that the effect of treatments on all traits was significant except acidity, and also high concentration of both hormones could reduce fruiting percentage compared to the control

An Investigation of the Behaviour of Agricultural Extension and Education Engineering Students in Tehran University Towards Employability

AbstractOne of the most significant aims of universities is to educate experts for entering the business market and applying their knowledge in developing the economy of the country. Accordingly, higher agricultural education has a very colossal role in development of the agricultural and employability skills among the students of this field. Therefore, in the present study, employability of the students of agriculture extension and education of Tehran University has been investigated, based on various observational dimensions of Ajzen's theory of planned behavior, attitude, perceived behavioral control, subjective norm and intention. For this purpose, 42 students of agriculture extension and education of Tehran University reported their information according to the elements of Ajzen's theory. The data supported and reaffirmed Ajzen's theory. The first anticipant of the employability was the control of students’ perceived behavior. In the same way, intention toward employability was the most considerable anticipator of the employability behavior

Effective factors influencing individual’s shared health decision making

This paper investigates the effects of information avoidance, information overload, health literacy on individuals’ shared health decision making. A research model is proposed based on sound theoretical background. Data from 155 respondents was collected via an online survey. Partial Least Squares Structural Equation Modelling (PLS-SEM) was applied to analyse the data. The findings suggest that information overload and information avoidance both exhibit negative effects on an individual’s shared health decision making behaviour, while health literary possess positive effects. We also find that information avoidance has a positive impact on information avoidance. Moreover, health literacy is negatively related to both information overload and information avoidance. The paper enhances both theoretical and empirical understanding of the effects of individuals’ health literacy, information overload and information avoidance on their shared health decision making behaviour. The results indicate that sufficient health literacy enables individuals to engage in their health decision making process and sharing their concerns with their physicians. However, information overload and information avoidance trigger negative effects which lead to individuals less involved in shared health decision making. Our results advocate more efforts to improve individual health literary as the means to mitigate the negative effects of information overload and information avoidance towards shared health decision making.Peer Reviewe

Application of various types of alumina and nano-γ-alumina sulfuric acid in the synthesis of α-aminonitriles derivatives: comparative study

An efficient and green protocol for the synthesis of α-aminonitrile derivatives by one-pot reaction of different aldehydes with amines and trimethylsilyl cyanide has been developed using natural alumina, alumina sulfuric acid (ASA), nano-g-alumina, nano-g-alumina sulfuric acid (nano-g-ASA) under microwave irradiation and solvent-free conditions. The advantages of methods are short reaction times, high yields, milder conditions and easy work up. The catalysts can be recovered for the subsequent reactions and reused without any appreciable loss of efficiency. KEY WORDS: Nano-g-alumina, Nano-g-alumina sulfuric acid, Green synthesis, Microwave irradiation, α-aminonitriles derivatives Bull. Chem. Soc. Ethiop. 2014, 28(3), 441-450.DOI: http://dx.doi.org/10.4314/bcse.v28i3.1