Energy and Process Engineering

This research work evaluates the impact of stormwater infiltration on the removal of organics, solids, nitrogen and phosphorus in a LECA-based horizontal subsurface flow constructed wetland. Stormwater runoff for the period between January 2008 and June 2010 (30 months) was estimated for the drainage basin of the Vila Fernando wastewater treatment plant (constructed wetland system) and it was observed proportionality between the increase in surface runoff and the infiltration flow rate that reached the plant. The average stormwater infiltration rate that reached the plant was 67.4 m(3) d(-1) (77% of the influent flow rate into the plant). The 30 month monitoring campaign set up at one of the reed beds showed that stormwater infiltration led to a high variation of the hydraulic loading rate (HLR) throughout the bed, which affected its performance in the removal of organic matter, suspended solids and nitrogen. For a HLR below 20 cm d-1 the removal efficiencies for BOD5, COD and TSS doubled. The removal of nitrogen was too low and was associated with the weak development of nitrifying biofilm and the poor growth of reeds. However, it was observed a good relationship between the applied and removed loads for most of the parameters, which seems to indicate that the organic, solid, nitrogen and phosphorus loading rates influenced the respective removal rates. The use of a bed material with high specific surface area, such as LECA, can only improve the treatment capacity of horizontal subsurface flow systems if the organic and solid loading rates, as well as the HLR, can be effectively controlled.

A strategy for adaptive control and energetic optimization of aerobic fermentors was implemented, with both air flow and agitation speed as manipulated variables. This strategy is separable in its components: control, optimization, estimation. We optimized parameter’s estimation (from the usual KLa correlation) using sinusoidal excitation of air flow and agitation speed. We have implemented parameter’s estimation trough recursive least squares algorithm with forgetting factor. We carried separate essays on control, optimization and estimation algorithms. We carried our essays using an original computational simulation environment, with noise and delay generating facilities for data sampling and filtering.

Our results show the convergence and robustness of the estimation algorithm used, improved with use of both forgetting factor and KLa dead-band facilities. Control algorithm used in our work compares favorably with PID using the integrated area criteria for deviation between oxygen molarity and critical molarity (set point). Optimization algorithm clearly reduces energetic consumption, respecting critical molarity. Integration of control, optimization and adaptive algorithms was implemented, but future work is needed for stability. Methods were defined and implemented for stability improvement. We have implemented data acquisition and computer manipulation of air flow and agitation speed for actual fermentors.

Nitrogen (N) cycle involves a complex set of potential biochemical pathways with reactions catalyzed by different microorganisms. Elementary mass balances for COD, DO, NH4-N and alkalinity were conducted and stoichiometric relationships were investigated to explain possible pathways of the nitrogen removal mechanisms in a lab-scale submerged down flow biological packed bed (BPB) reactor. Four sets of experiments were performed by modifying the organic loading and C/N ratio in comparison with steady-state conditions. Approximately 90% of COD and NH4-N removal occurred in two upper sections occupying 1/5 of the reactor height. The elementary
mass balances could not explain all the experimental results with respect to nitrogen removal and oxygen consumption by known mechanisms. The mass balance calculations, excluding the possibility of nitrification, were in general in accordance with the observations indicating no or minimal NO3-N production. The theoretical stoichiometric requirements for nitrification reaction
were satisfied in 6 experiments and in another 8 experiments nitrification may have occurred, but stoichiometry was not satisfied. Using C/N ratio as the variable, only at C/N ratio = 10, the predictions confirmed the possibility of nitrification in the same 3 (out of 4) assays as observed in practice. The results of this study reveal that the nitrogen transformations occurring in the studied reactor are complex and cannot be explained by simple mechanisms of microbial assimilation and nitrification.

The formulation of policies requires the selection and configuration of effective and acceptable courses of action to reach explicit goals. A one-size-fits-all policy is unlikely to achieve the desired goals; as a result, the identification of a suite of alternative policies, together with clear indications of their trade-offs, is crucial to accommodate the diversity of stakeholders’ preferences. At present, the formulation of transport policies is done manually; this fact, together with the size of the space of possible policies, results in a large part of that space being left unexplored. A six-step framework to explore the space of alternative transport policies in order to achieve environmental targets is proposed. The process starts with a user-defined set of specific policy measures, using them as building blocks in the generation of alternative policy packages, clusters and future images according to the user's preferences and goals.The analysis framework is based on the visioning and backcasting approach used in the VIBAT report [Banister, D., & Hickman, R. (2006a). Visioning and backcasting for UK transport policy (VIBAT) project. Department for Transport's Horizons Research Programme 2004/06. The Bartlett school of planning and Halcrow Group Ltd. Retrieved 1/18/2008 http://www.ucl.ac.uk/∼ucft696/vibat2.html]. The framework is being implemented as a prototype decision support system around a case study: the formulation and analysis of policies required to achieve CO2 emission targets for the transport sector in the UK. Important insights on how to develop the framework have also been elicited from engineering design. The goal is to accelerate the task of policy-making and improve the effectiveness of the resulting policies.The proposed method and computer implementation is fundamentally different from the tools commonly used in the transport sector and is intended to assist (not replace) transport policy makers, and complement (not substitute nor compete with) existing mathematical modelling tools. This research constitutes the first step towards the development of a general family of computer-based systems that support the design of policies to achieve environmental targets—not only for transport, but also for other sectors such as energy and water.

The paper intended to enhancement of energy and product quality by installing Vortex mixture in urea Reactor. This is the new approaches to convert reactant to useful product. In urea plant Carbon dioxide & ammonia are the reactants, in which the ammonia in liquid form and carbon dioxide is in gas form. The Carbon Dioxide is the limiting reactant. The percentage conversion calculated how much carbon dioxide converted to urea. The ammonia is excess reactant. For enhancement of conversion different process technique are used e.g. high efficiency trays etc. The Vortex mixture also the same function like CSTR. Efficiency enhancement of the synthesis section not only improves process parameters, but also increases final product output. The contact surface is increased by 1.5-2.0 times compared to conventional mixing arrangements. Efficient operation of synthesis section greatly depends on the amount of ammonia and Carbon Dioxide recycle. The worldwide Russian company M/S. NIIK is supplied the Vortex mixture at reasonable cost. The energy saving reported 0.03 to 0.08 G.cal. /ton of Urea as depends upon plant capacity and process.

Biogas typically refers to an odourless gas produced by anaerobic digestion (AD) of biomass using microorganisms. It has an approximate composition of 70-50% Methane (a combustible gas), 30-50% Carbon dioxide and other trace gases depending on the nature of the biomass. The idea of using the organic fraction of municipal solid waste (OFMSW) or simply municipal biowaste as feedstock for biogas production represents an environmentally sustainable energy source since it improves solid waste management while simultaneously providing an alternative clean energy source. Among other applications, the gas can be used for heating, cooking and electricity generation. However, notwithstanding, OFMSW as a feedstock for AD comes with its own unique challenges compared to other forms of biomass. This paper therefore reviews the specific opportunities, challenges and techno-economics of using OFMSW as sole feedstock supply for biogas production.

A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1–8 to weeks 9–14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient loads.

Water has a precious value and each drop must be accounted-for in water scarce regions such as the Middle East and North Africa. Therefore, wastewater has to be reclassified as a renewable water resource rather than waste. This helps in augmenting water availability, and at the same time in preventing environmental pollution. Utilization of this resource requires collection, treatment, and use of all generated wastewater. Although reuse of wastewater is recognized in most water-scarce countries, the reuse of wastewater is still very low. This paper analyzes the major components of a sustainable wastewater reuse scheme. It also reviews the different methods that are frequently used to quantify and report progress and achievements in wastewater reuse. The paper also introduces an alternative yardstick named by the author as the wastewater Reuse Index (WRI) that has a value between 0-100; WRI is calculated by dividing the amounts of wastewater being actually reused by the total amounts of wastewater generated at country level. WRI enables water resource managers and policy-makers to put a figure on the gap between achievements at different junctures. Moreover, WRI recognizes water saving efforts such as low water consumption and reducing losses; thus, highlights the way forward for improving the reuse efficiency as an integral part of water resources management. The paper highlights the major barriers to extensive reuse of the reclaimed wastewater in the MNEA countries.

Biogas typically refers to an odourless gas produced by anaerobic digestion (AD) of biomass using microorganisms. It has an approximate composition of 70-50% Methane (a combustible gas), 30-50% Carbon dioxide and other trace gases depending on the nature of the biomass. The idea of using the organic fraction of municipal solid waste (OFMSW) or simply municipal biowaste as feedstock for biogas production represents an environmentally sustainable energy source since it improves solid waste management while simultaneously providing an alternative clean energy source. Among other applications, the gas can be used for heating, cooking and electricity generation. However, notwithstanding, OFMSW as a feedstock for AD comes with its own unique challenges compared to other forms of biomass. This paper therefore reviews the specific opportunities, challenges and techno-economics of using OFMSW as sole feedstock supply for biogas production.

Scholarly Abstract Water has a precious value and each drop must be accounted-for in water scarce regions such as the Middle East and North Africa. Therefore, wastewater has to be reclassified as a renewable water resource rather than waste. This helps in augmenting water availability, and at the same time in preventing environmental pollution. Utilization of this resource requires collection, treatment, and use of all generated wastewater. Although reuse of wastewater is recognized in most water-scarce countries, the reuse of wastewater is still very low. This paper analyzes the major components of a sustainable wastewater reuse scheme. It also reviews the different methods that are frequently used to quantify and report progress and achievements in wastewater reuse. The paper also introduces an alternative yardstick named by the author as the Wastewater Reuse Index (WRI) that has a value between 0-100; WRI is calculated by dividing the amounts of wastewater being actually reused b...

The removal of Volatile Fatty Acids (VFA) , from wastewater deriving from numerous sources such as chemical plants has been an area of research interest for more than a century. With the global petroleum resources facing scarcity and the constantly rising awareness of the environmental impact the carbon based economy has created , research has been focused in developing alternative methods of their production, such as biofermentation. In biofermentation, the hydrolysis of target solid wastes followed by the microbial conversion of them to biodegradable organic content results in the production of intermediate organic acids, specifically VFA. VFA are detected at high concentrations in the effluent streams and mixed liquors of anaerobic membrane reactor systems, because of sudden variations in hydraulic and organic loading rates. Several studies have shown possible environmental and commercial benefits using filtration as a source separation process in comparison to integral wastewater treatment. These benefits include the relief of municipal treatment plants, the use of favourable nutrients and the composition of urine free wastewater for biotreatment. and insufficient capacity of microfiltration and ultrafiltration systems for their rejection, mainly due to their low molecular weight. Anaerobic effluents need to be treated with a more advanced treatment process such as nanofiltration and reverse osmosis.

Biogas typically refers to an odourless gas produced by anaerobic digestion (AD) of biomass using microorganisms. It has an approximate composition of 70-50% Methane (a combustible gas), 30-50% Carbon dioxide and other trace gases depending on the nature of the biomass. The idea of using the organic fraction of municipal solid waste (OFMSW) or simply municipal biowaste as feedstock for biogas production represents an environmentally sustainable energy source since it improves solid waste management while simultaneously providing an alternative clean energy source. Among other applications, the gas can be used for heating, cooking and electricity generation. However, notwithstanding, OFMSW as a feedstock for AD comes with its own unique challenges compared to other forms of biomass. This paper therefore reviews the specific opportunities, challenges and techno-economics of using OFMSW as sole feedstock supply for biogas production.

A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1-8 to weeks 9 -14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient loads.

Nitrogen (N) cycle involves a complex set of potential biochemical pathways with reactions catalyzed by different microorganisms. Elementary mass balances for COD, DO, NH 4 -N and alkalinity were conducted and stoichiometric relationships were investigated to explain possible pathways of the nitrogen removal mechanisms in a lab-scale submerged down flow biological packed bed (BPB) reactor. Four sets of experiments were performed by modifying the organic loading and C/N ratio in comparison with steady-state conditions. Approximately 90% of COD and NH 4 -N removal occurred in two upper sections occupying 1/5 of the reactor height. The elementary mass balances could not explain all the experimental results with respect to nitrogen removal and oxygen consumption by known mechanisms. The mass balance calculations, excluding the possibility of nitrification, were in general in accordance with the observations indicating no or minimal NO 3 -N production. The theoretical stoichiometric requirements for nitrification reaction were satisfied in 6 experiments and in another 8 experiments nitrification may have occurred, but stoichiometry was not satisfied. Using C/N ratio as the variable, only at C/N ratio = 10, the predictions confirmed the possibility of nitrification in the same 3 (out of 4) assays as observed in practice. The results of this study reveal that the nitrogen transformations occurring in the studied reactor are complex and cannot be explained by simple mechanisms of microbial assimilation and nitrification.

A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1-8 to weeks 9 -14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient loads.

This research work evaluates the impact of stormwater infiltration on the removal of organics, solids, nitrogen and phosphorus in a LECA-based horizontal subsurface flow constructed wetland. Stormwater runoff for the period between January 2008 and June 2010 (30 months) was estimated for the drainage basin of the Vila Fernando wastewater treatment plant (constructed wetland system) and it was observed proportionality between the increase in surface runoff and the infiltration flow rate that reached the plant. The average stormwater infiltration rate that reached the plant was 67.4 m 3 d −1 (77% of the influent flow rate into the plant). The 30 month monitoring campaign set up at one of the reed beds showed that stormwater infiltration led to a high variation of the hydraulic loading rate (HLR) throughout the bed, which affected its performance in the removal of organic matter, suspended solids and nitrogen. For a HLR below 20 cm d −1 the removal efficiencies for BOD 5 , COD and TSS doubled. The removal of nitrogen was too low and was associated with the weak development of nitrifying biofilm and the poor growth of reeds. However, it was observed a good relationship between the applied and removed loads for most of the parameters, which seems to indicate that the organic, solid, nitrogen and phosphorus loading rates influenced the respective removal rates. The use of a bed material with high specific surface area, such as LECA, can only improve the treatment capacity of horizontal subsurface flow systems if the organic and solid loading rates, as well as the HLR, can be effectively controlled.

This study was on the technical and biological characteristics of a partial-SHARON submerged-filter bioreactor of 3 L. The main focus was the influence of the hydraulic retention time (HRT) on biofilms. For this purpose, we used molecular tools based on the partial 16S rRNA genes. The results showed that the HRT may affect the nitrification processes of a bioreactor using synthetic
wastewater containing 600 mg/L of ammonia. It was found
that an HRT of 0.5 day transformed 100 % of the ammonium
into nitrite. However, when the HRT was decreased to 0.4 day, there was a significant reduction (35 %) in the quantity of ammonia transformed, which confirmed the complexity of the system operation. Moreover, a PCRTGGE approach highlighted the differences observed. The results obtained showed that an HRT of 0.5 day reduced bacterial biodiversity in the biofilms, which were mainly formed by Nitrosomonas and Diaphorobacter. In contrast, an HRT of 0.4 day facilitated the formation of heterogeneous biofilms formed by nitrifying bacteria, such as Nitrosomonas sp., Nitrosospira sp., and Nitrosovibrio sp.).