Search results for "Sludge"
showing 10 items of 320 documents
Expert control of DO in the aerobic reactor of an activated sludge process
2001
Abstract An expert control structure is proposed for the control of dissolved oxygen (DO) in a Nitrification Denitrification Biological Excess Phosphorus Removal (NDBEPR) plant to account for the several processes that are influenced by the DO concentration in the aerator. In the scheme a supervisory fuzzy controller determines the set point of an inner DO control loop where an Adaptive Robust Generic Model Control (ARGMC) controller is used. The fuzzy supervisory control has a hierarchical structure. Off-line measurements of biological parameters of influent and effluent streams can be used to periodically update the set points of the fuzzy controllers. The complete control scheme has been…
Cost modeling for sludge and waste management from wastewater treatment plants: an empirical approach for Spain
2013
Abstract Wastewater treatment involves the generation of large volumes of sludge and other waste. Managing this waste in an economical and environmentally acceptable way has become a matter of increasing importance over the last few years. While the technologies and processes to reduce sludge generation are being widely studied, research on the economic aspects is much more limited. This study applies a cost-modeling methodology that uses statistical information from a sample of Spanish wastewater treatment plants (WWTPs) to generate a sewage sludge and waste management cost function with the aim of contributing to a better understanding of the cost structure and predicting the cost savings…
Modelling and dynamic simulation of hybrid moving bed biofilm reactors: model concepts and application to a pilot plant.
2011
In the recent years, there has been an increasing interest in the development of hybrid reactors, especially in the up-grading of existing activated sludge plants that are no longer able to comply with concentration limits established by regulatory agencies. In such systems the biomass grows both as suspended flocs and as biofilm. In this way, it is possible to obtain a higher biomass concentration in the reactor, but without any significant increase of the load to the final clarifier. The paper presents the setting-up of a dynamic mathematical model aimed at quantitatively describing the biokinetic processes occurring in a hybrid moving bed biofilm reactor (HMBBR), and, more in general, in…
comparing two start-up strategies for MBRs: experimental study and mathematical modelling
2012
Abstract The performance of a membrane bioreactor (MBR), and mechanisms of fouling formation, may differ due to the start-up. Therefore, the start-up can constitute an aspect that critically influences MBR performance during its lifespan. Indeed, the start-up can influence the mechanisms of membrane fouling, which is of paramount importance in an MBR. In order to gain insights on the effects of the start-up, both experimental and mathematical modelling studies were carried out on an MBR pilot plant. The MBR pilot plant constituted of a hollow fibre membrane module, in a submerged configuration, was fed by real wastewater. Two experimental periods were carried out, lasting 65 days each, char…
Variance-based sensitivity analysis for wastewater treatment plant modelling.
2014
Global sensitivity analysis (GSA) is a valuable tool to support the use of mathematical models that characterise technical or natural systems. In the field of wastewater modelling, most of the recent applications of GSA use either regression-based methods, which require close to linear relationships between the model outputs and model factors, or screening methods, which only yield qualitative results. However, due to the characteristics of membrane bioreactors (MBR) (non-linear kinetics, complexity, etc.) there is an interest to adequately quantify the effects of non-linearity and interactions. This can be achieved with variance-based sensitivity analysis methods. In this paper, the Extend…
Modelling of hybrid moving bed biofilm reactors: a pilot plant experiment.
2007
In recent years there has been an increasing interest in the development of hybrid biofilm reactors, especially in the upgrading of existing WWTP that are no longer able to respect concentration limits. In fact, today's challenge is the achievement of a good aquatic state for the receiving water bodies according to the Water Framework Directive requirements, which indeed limit even more the continuous emissions, i.e. coming from WWTP. This paper presents the setting up of a mathematical model for the simulation of a hybrid MBBR system; the model calibration/validation has been carried out considering a field gathering campaign on an experimental pilot plant. The main goal is to gain insight…
Parameter subset selection for the dynamic calibration of activated sludge models (ASMs): experience versus systems analysis.
2007
In this work we address the issue of parameter subset selection within the scope of activated sludge model calibration. To this end, we evaluate two approaches: (i) systems analysis and (ii) experience-based approach. The evaluation has been carried out using a dynamic model (ASM2d) calibrated to describe nitrogen and phosphorus removal in the Haaren WWTP (The Netherlands). The parameter significance ranking shows that the temperature correction coefficients are among the most influential parameters on the model output. This outcome confronts the previous identifiability studies and the experience based approaches which excluded them from their analysis. Systems analysis reveals that parame…
SCREENING OF CHEMICAL SPILL RISKS TO MUNICIPAL SEWAGE TREA TMENT PLANTS
1994
Seven operational mishaps were specified on the basis of a questionnaire on wastewater treatment plants, some of them large. In this study a process was developed for screening the chemical spill risks to municipal biological sewage treatment plant. Data on wastewater treatment processes, potential spill sources and chemical properties were combined to determine the threshold chemical quantities which may inhibit the removal of carbonaceous material, prevent nitrification and methanogenesis, cause sludge contamination or lead to the aeration capacity being exceeded. Two sewage treatment plants and eleven industrial sites were chosen for field studies. The influence of spill duration and mai…
Uncertainty assessment of a model for biological nitrogen and phosphorus removal: Application to a large wastewater treatment plant
2012
Abstract In the last few years, the use of mathematical models in WasteWater Treatment Plant (WWTP) processes has become a common way to predict WWTP behaviour. However, mathematical models generally demand advanced input for their implementation that must be evaluated by an extensive data-gathering campaign, which cannot always be carried out. This fact, together with the intrinsic complexity of the model structure, leads to model results that may be very uncertain. Quantification of the uncertainty is imperative. However, despite the importance of uncertainty quantification, only few studies have been carried out in the wastewater treatment field, and those studies only included a few of …
Comparing the efficiency of wastewater treatment technologies through a DEA metafrontier model
2011
Abstract The assessment of economic and technical efficiency is a useful tool to select the most appropriate technology for wastewater treatment. However, traditional models require that the units being assessed operate with the same technology. To overcome this limitation, we investigate the viability of using a non-concave metafrontier approach that is based on data envelopment analysis (DEA) to calculate the techno-economic efficiency and technological gap ratios (TGRs) of wastewater treatment plants (WWTPs) operating with non-homogeneous technologies. The model is applied to a sample of 99 Spanish WWTPs, encompassing four alternative technologies: activated sludge; aerated lagoon; trick…