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The wastewater treatment process is based on complex chemical, physical and biological mechanisms that are closely interconnected. The efficiency of the system (which depends on compliance with national regulations on wastewater quality)... more
The wastewater treatment process is based on complex chemical, physical and biological mechanisms that are closely interconnected. The efficiency of the system (which depends on compliance with national regulations on wastewater quality) can be achieved through the use of tools such as monitoring, that is the detection of parameters that allow the continuous interpretation of the current situation, and experimental tests, which allow the measurement of real performance (of a sector, a single treatment or equipment) and comparison with the following ones. Experimental tests have a particular relevance in the case of municipal wastewater treatment plants fed with a strong industrial component and especially in the case of plants authorized to treat aqueous waste. In this paper a case study is presented where the application of management tools such as careful monitoring and experimental tests led to the technical and economic optimization of the plant: the main results obtained were t...
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Two advanced control strategies were applied in the secondary and tertiary stages, respectively, of a full scale wastewater treatment plant (WWTP). This has a nominal capacity of 330,000 population equivalent (PE), a complex configuration... more
Two advanced control strategies were applied in the secondary and tertiary stages, respectively, of a full scale wastewater treatment plant (WWTP). This has a nominal capacity of 330,000 population equivalent (PE), a complex configuration (having been upgraded several times through the years), and it faces significant seasonal load fluctuations (being located in a touristic area, in Northern Italy). The lifting station of the tertiary treatments (devoted to phosphorus precipitation and UV disinfection) was optimized by adjusting the pumped flowrate, depending on influent phosphorus concentration. A preliminary simulation showed that a 15% reduction of pumping energy could be achieved. This result was confirmed by field measurements. Moreover, a fuzzy control system was designed and applied to one of the six parallel nitrification reactors, yielding a reduction of more than 25% of the power requirement for aeration. Overall, the combined application of the two controllers led to a 7%...
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Northern Italy was the most affected by CoViD-19 compared to other Italian areas and comprises zones where air pollutants concentration was higher than in the rest of Italy. The aim of the research is to determine if particulate matter... more
Northern Italy was the most affected by CoViD-19 compared to other Italian areas and comprises zones where air pollutants concentration was higher than in the rest of Italy. The aim of the research is to determine if particulate matter (PM) has been the primary cause of the high CoViD-19 spread rapidity in some areas of Northern Italy. Data of PM for all the 41 studied cities were collected from the local environmental protection agencies. To compare air quality data with epidemiological data, a statistical analysis was conducted identifying the correlation matrices of Pearson and Spearman, considering also the possible incubation period of the disease. Moreover, a model for the evaluation of the epidemic risk, already proposed in literature, was used to evaluate a possible influence of PM on CoViD-19 spread rapidity. The results exclude that PM alone was the primary cause of the high CoVid-19 spread rapidity in some areas of Northern Italy. Further developments are necessary for a ...
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Recently, among AOPs, photoelectrocatalysis (PEC) on TiO2 is gaining interest. In this study, five different real waters sampled in four different points of the integrated urban water management (IUWM) system were tested with PEC and UV... more
Recently, among AOPs, photoelectrocatalysis (PEC) on TiO2 is gaining interest. In this study, five different real waters sampled in four different points of the integrated urban water management (IUWM) system were tested with PEC and UV alone, for comparison. This work aims to verify the effect of the PEC suggesting the optimal position in IUWM system where the PEC should be located to obtain the best performance. In groundwaters (GWs), PEC effectively removed atrazine-based compounds (> 99%), trichloroethylene, and perchloroethylene (96%), after 15 min of reaction time. However, given the low concentrations of emerging compounds, the synergistic effect of UV radiation with the catalyst and with the polarization of the mesh was not visible, with very few differences compared with the results obtained with UV alone. Pharmaceutical industrial wastewater (IWW) showed a significant increase in biodegradability after 2 h, both if subjected to PEC or UV (200%), despite the absence of C...
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Nitrogen dioxide (NO2) can have harmful effects on human health and can act as a precursor for the formation of other air pollutants in urban environment such as secondary PM2.5 and ozone. The lockdown measures for CoViD-19 allowed to... more
Nitrogen dioxide (NO2) can have harmful effects on human health and can act as a precursor for the formation of other air pollutants in urban environment such as secondary PM2.5 and ozone. The lockdown measures for CoViD-19 allowed to simulate on a large scale the massive and prolonged reduction of road traffic (the main source for NO2 in urban environment). This work aims to selectively assess the maximum impact that total traffic blocking measures can have on NO2. For this reason, three megacities (London, Milan and Paris) were chosen that had similar characteristics in terms of climatic conditions, population, policies of urban traffic management and lockdown measures. 52 air quality control units have been used to compare data measured in lockdown and in the same periods of previous years, highlighting a significant decrease in NO2 concentration due to traffic (London: 71.1 % - 80.8 %; Milan: 8.6 % - 42.4%; Paris: 65.7 % - 79.8 %). In 2020 the contribution of traffic in London, Milan and Paris was dropped to 3.3 ± 1.3 µg m-3, 6.1 ± 0.8 µg m-3, and 13.4 ± 1.5 µg m-3, respectively. Despite the significant reduction in the NO2 concentration, in UT stations average NO2 concentrations higher than 40 µg m-3 were registered for several days. In order to reduce the pollution, the limitation of road traffic could be not enough, but a vision also aimed at rethink the vehicles and their polluting effects should be developed.
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An unconventional cascade control system, for the regulation of air supply in activated sludge wastewater treatment plants (WWTPs), was tested. The dissolved oxygen (DO) set point in the aeration tank was dynamically calculated based on... more
An unconventional cascade control system, for the regulation of air supply in activated sludge wastewater treatment plants (WWTPs), was tested. The dissolved oxygen (DO) set point in the aeration tank was dynamically calculated based on effluent ammonia concentration, following a fuzzy logic based approach. First, simulations were conducted, according to the BSM2 protocol, for a general comparison with more conventional control strategies. It turned out that the effluent quality could be improved by 7–8%, based on the EQI parameter. Moreover, the aeration energy requirement could be reduced up to 13%. Subsequently, the system was installed in a full-scale WWTP. While stably complying with the ammonia effluent standard (10 mg/L), excess air supply was prevented, and a reduction of the specific power consumption (kWh/kgCODremoved) of 40–50% was recorded with respect to the previously installed PID controller (fixed DO set point).
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As for the SARS coronavirus in the 2003 epidemic, the presence of SARS-CoV-2 has been demonstrated in faeces and, in some cases, urine of infected people, as well as in wastewater. This paper proposes a critical review of the state of the... more
As for the SARS coronavirus in the 2003 epidemic, the presence of SARS-CoV-2 has been demonstrated in faeces and, in some cases, urine of infected people, as well as in wastewater. This paper proposes a critical review of the state of the art regarding studies on the presence of SARS-CoV-2 in wastewater and sewage sludge, the factors affecting its inactivation and the main proposed treatments, with the aim to provide useful information at operative level in order to better and safer manage wastewater and sewage sludge. Given the lack of literature on SARS-CoV-2, studies involving other HCoVs such as SARS-CoV and HCoV-229E have been also considered. In wastewater, the resistance of SARS-CoV has proven to be very limited, especially at temperatures above 20 °C, and the virus has been easily removed with the use of chlorine (> 0.5 mg L-1 for 30 min). For sewage sludge, based on in vitro experiments, it is suggested to increase the retention times before a possible reuse in agricultu...
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Northern Italian regions have been the most affected from CoViD-19 compared to other Italian areas and are also the zones where air pollutants concentration has been higher than in the rest of Italy. The aim of the research is analysing... more
Northern Italian regions have been the most affected from CoViD-19 compared to other Italian areas and are also the zones where air pollutants concentration has been higher than in the rest of Italy. The aim of the research is analysing possible correlations between air pollutants PM10 and PM2.5 and the rapidity of the spread of the infection caused by CoViD-19 in Northern Italy. PM10 and PM2.5 data for all the 41 studied cities were collected from the local environmental protection agencies. In order to compare air quality data with epidemiological data (Td), a statistical analysis was conducted identifying the correlation matrices of Pearson and Spearman, considering the possible incubation period of the disease. The results exclude a strong direct correlation between PM in the air and the diffusion rate of CoViD-19. Further developments are necessary for a better comprehension of the influence of atmospheric pollution parameters on the rapidity of spread of the virus SARS-CoV-2, ...
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An adequate access to water supply systems is crucial for a sustainable future. Climate change is expected to increase water shortage problems worldwide. Reuse/recycling of treated wastewater for domestic and/or agricultural purposes can... more
An adequate access to water supply systems is crucial for a sustainable future. Climate change is expected to increase water shortage problems worldwide. Reuse/recycling of treated wastewater for domestic and/or agricultural purposes can be considered an interesting water supply: it is independent from seasonal drought and meteorological variability and able to cover the peak of water demand. In the case of direct reuse, the parameter of treated water must comply with the reuse limits for biological oxygen demand, chemical oxygen demand and suspended solids. In case of indirect reuse, the regulatory approach changes as the dilution ratio between discharge and flow of the irrigation canal is taken into account too. There are many interventions that are considered useful for the purpose of promoting the development of an enhanced water recovery and recycling: legislation improvements, modification in the water storage management, prevention in pollution discharged into sewerage system...
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AbstractThis work is aimed at assessing the effects of pretreated aqueous wastes stream-fed to a biological nutrient removal (BNR)–activated sludge plant. Aqueous wastes (mainly landfill leachate a...
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The authors regret that, despite thoroughly reviewing the manuscript, the content of a paragraph has been duplicated and has to be ignored .
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A holistic assessment procedure has been used in this study for comparing conventional activated sludge (CAS) and membrane bioreactor (MBR) processes for the treatment of municipal wastewater. Technical, social, administrative, economic... more
A holistic assessment procedure has been used in this study for comparing conventional activated sludge (CAS) and membrane bioreactor (MBR) processes for the treatment of municipal wastewater. Technical, social, administrative, economic and environmental impacts have been evaluated based on 1 year of operational data from three full-scale lines (one MBR and two CAS) working in parallel in a large municipal treatment plant. The comparative assessment evidences a slight advantage of the conventional process in the studied case, essentially due to lower costs, complexity and energy consumption. On the other hand, the MBR technology has a better social acceptance and similar overall environmental footprint. Although these results are influenced by site-specific parameters and cannot be generalized, the assessment procedure allowed identifying the most important factors affecting the final scores for each technology and the main differences between the compared technologies. Local conditions can affect the relative importance of the assessed impacts, and the use of weighting factors is proposed for better tailoring the comparative assessment to the local needs and circumstances. A sensitivity analysis on the weighted final scores demonstrated how local factors are very important and must be carefully evaluated in the decision making process.
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Abstract Wastewater treatment facilities are increasingly being considered as centralized installations where various resources can be recovered from the sewage. Novel technological solutions are already available for achieving this goal.... more
Abstract Wastewater treatment facilities are increasingly being considered as centralized installations where various resources can be recovered from the sewage. Novel technological solutions are already available for achieving this goal. However, their application to upgrade existing plants can be far more challenging than building new dedicated plants. While the scientific literature is generally focused on testing and comparing the recovery options, this work was aimed at giving a holistic evaluation of the actual impacts of upgrading existing facilities. Commercially available systems were considered for retrofitting two plants of different size (50,000 and 500,000 population equivalents) and achieving either energy self-sufficiency or material recovery. Based on mass and energy balances, a detailed evaluation of technical, social, economic, and administrative aspects was carried out. Environmental aspects were also included, adopting a simplified approach. It turned out that energy self-sufficiency (external energy supply reduced down to about 10% of the total need) is not far away to be achieved, with moderate techno-economic implications, especially when the plant is already equipped with primary sedimentation and anaerobic digestion. Integral recovery of treated effluent, sludge and nitrogen can also be pursued in large facilities, while several potential criticalities arise for medium-sized plants. The adopted procedure evidenced critical aspects that are often disregarded in the decision process: this may suggest where to address efforts in evaluating real situations.
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This paper presents the results of a broad-scale survey of resource recovery implementation in Italian wastewater treatment plants (WWTPs). To the best of our knowledge, this is the first survey comprising a large number of WWTPs done in... more
This paper presents the results of a broad-scale survey of resource recovery implementation in Italian wastewater treatment plants (WWTPs). To the best of our knowledge, this is the first survey comprising a large number of WWTPs done in Europe: more than 600 plants were investigated, representing a treated load of around 20 million population equivalent (≈25% of the total in Italy). Conventional and innovative options for both material and energy recovery along the water and sludge line were surveyed, in order to i) offer a real and complete picture of the current state of resource recovery in WWTPs, and ii) underline key aspects and potential areas for improvements, as a baseline for future developments in the direction of more sustainable plants. Survey outcomes showed that resource recovery is just in its infancy in sewage treatment: only 40% of plants perform at least one option for material/energy recovery. The action most often implemented is recovery of material from surplus...
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A combination of thermophilic aerobic membrane reactor (TAMR) and conventional activated sludge (CAS) was studied by means of two pilot plants at semi-industrial scale in order to simulate the new configuration adopted in a full-scale... more
A combination of thermophilic aerobic membrane reactor (TAMR) and conventional activated sludge (CAS) was studied by means of two pilot plants at semi-industrial scale in order to simulate the new configuration adopted in a full-scale facility for the treatment of high strength aqueous wastes. Aqueous wastes with high contents of organic pollutants were treated by means of the TAMR technology, progressively increasing the organic load (3-12 kg m d). A mixture of municipal wastewater and thermophilic permeate was fed to the CAS plant. The main results are the following: achievement of a high COD removal yield by both the TAMR (78%) and the CAS (85%) plants; ammonification of the organic nitrogen under thermophilic conditions and subsequent mesophilic nitrification; capacity of the downstream mesophilic process to complete the degradation of the organic matter partially obtained by the TAMR process and precipitation of phosphorus as vivianite and carbonatehydroxylapatite in the TAMR p...
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Proper strategies for reducing the sludge production are a key factor for a correct wastewater treatment plant (WWTP) management. This paper describes an experimental study on sludge thermal alkaline hydrolysis under mild conditions... more
Proper strategies for reducing the sludge production are a key factor for a correct wastewater treatment plant (WWTP) management. This paper describes an experimental study on sludge thermal alkaline hydrolysis under mild conditions (temperatures from 40 to 70 °C and pH up to 11.5), aimed at sludge minimisation. Tested biological sludge derived from two different WWTPs that treat urban and mixed urban/industrial wastewater, respectively. The experimental results showed: 1) an increase of soluble COD in sludge supernatants; 2) very good biodegradability of the supernatants; 3) improved settleability and dewaterability of treated sludge. The best results were obtained under the following conditions, using lime milk: 70°C, pH 10.0-10.5, contact time 3h.
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Foam formation in the excess sludge treatment facilities of biological wastewater treatment plants (WWTPs) may represent a critical issue as it could lead to several operative problems and reduce the overall plant performance. This... more
Foam formation in the excess sludge treatment facilities of biological wastewater treatment plants (WWTPs) may represent a critical issue as it could lead to several operative problems and reduce the overall plant performance. This trouble also affects a novel technology recently proposed for sludge minimization, the thermophilic membrane reactor (TMR), operating with alternate aeration/non-aeration cycles. This technology, which has proven to be extremely resilient and suitable for treating industrial wastewater of different nature, demonstrated a high potential also as a solution for integrating existing WWTPs, aiming at the “zero sludge production.” In this work, an experimental study was conducted with a TMR pilot plant (fed daily with thickened sewage sludge) by adjusting the duration of aeration/non-aeration alternate cycles. Extracellular polymeric substance (EPS) concentration (and its soluble and bound fractions) has been monitored along with foaming power indices. The results highlight that foaming can be correlated to the presence of soluble protein fraction of EPS. Moreover, EPS production seems to be reduced by increasing the duration of the non-aeration cycles: optimal operating conditions resulted 2 h of aeration followed by 6 h of non-aeration. These conditions allow to obtain an EPS concentration of 500 mg L−1 with respect to 2300 mg L−1 measured at the beginning of experimental work.
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Abstract The increase of sewage sludge production together with the high treatment and disposal costs in the last years has pushed to study different solutions aimed at sludge minimization. In this paper, the thermophilic membrane... more
Abstract The increase of sewage sludge production together with the high treatment and disposal costs in the last years has pushed to study different solutions aimed at sludge minimization. In this paper, the thermophilic membrane technology was evaluated as an alternative for municipal sewage sludge reduction. The experimentation (carried out by means of a pilot scale plant, 1 m 3 volume) was divided into two steps: the first one was aimed at confirming the results obtained in a previous research focused on industrial sludge treatment; the second step was devoted to define the best process conditions (in particular the optimization of the aeration phases) and to the chemical permeate characterization. The results of the experiments highlight that the hydraulic retention time (HRT) and aeration conditions play a crucial role on the overall process performance. The volatile suspended solids removal efficiency was greater than 80% under the following conditions: HRT even lower than 15 d; 2 h of aeration - 6 h of non aeration cycles; and organic loading rate of 2.0 kgCOD m −3 d −1 . The permeate showed a good biodegradability under mesophilic conditions thus being treatable by means of conventional biological processes. Moreover, ammonia (the permeate presenting high concentrations) could be recovered as a fertilizer (stripping and subsequent washing of the exhausted gas is an established technique). Finally, the ammonia-free permeate can be valorised as a carbon source in denitrification processes.
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ABSTRACT Existing wastewater/aqueous waste treatment plants often need to be upgraded in order to improve their performance. The satisfactory operation of biological treatment plants requires appropriate monitoring, and respirometric... more
ABSTRACT Existing wastewater/aqueous waste treatment plants often need to be upgraded in order to improve their performance. The satisfactory operation of biological treatment plants requires appropriate monitoring, and respirometric techniques are needed to determine the kinetic parameters that regulate biological processes. Innovative technologies are treating industrial wastewater/aqueous waste, such as thermophilic aerobic treatments. Thermophilic aerobic biological systems operate at temperatures higher than 45°C. Such temperature levels can be reached, at a reasonable cost, using wastewater with a high organic loading and reactors, which are appropriately thermally insulated. This kind of treatment shows high removal kinetics of biodegradable substrates and a very low sludge production. This paper describes the application of respirometric tests in thermophilic conditions on the biomass derived from a thermophilic aerobic membrane reactor in order to model the process, with a particular focus on the rapidly biodegradable chemical oxygen demand (rbCOD). The utility of rbCOD determination is related to the optimal treatment that the aqueous waste should undergo. Calculating the kinetic parameters is critical to the biological modelling used in the management and control of wastewater treatment plants.
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This paper is aimed at evaluating, from a techno-economic and environmental point of view, the performance of an existing wastewater treatment plant in which the traditional biological section is upgraded with an innovative Sequencing... more
This paper is aimed at evaluating, from a techno-economic and environmental point of view, the performance of an existing wastewater treatment plant in which the traditional biological section is upgraded with an innovative Sequencing Batch Biofilter Granular Reactor. Two scenarios were simulated in order to model and assess the performances of conventional (CAS, Conventional Activated Sludge) and innovative solutions, based on mass balances, techno-economic evaluation and environmental assessment. The results showed that converting the activated sludge process into an SBBGR allows to achieve a drastic reduction in sludge production (up to 75% as volatile suspended solids). Furthermore, the secondary sedimentation and sludge stabilization units can be dismissed, reducing the area requirement (up to 50%). The technical assessment is mainly positive, with the electric energy consumption being the only critical item. The higher energy demand of the upgraded plant (about 25% more than the conventional treatment) is mainly associated with the recycle flow in the SBBGR system. Although the economic sustainability of the upgraded plant depends on local conditions, it can be considered to be likely favourable: sludge disposal and materials & reagents costs, together with the investment for plant reconstruction are those items that should be carefully evaluated before upgrading the CAS plant with SBBGR technology. The environmental assessment shows also mostly positive results, although it points to the increased phosphorus concentration in the effluent as a potentially critical issue and it highlights the electricity use and the increased nitrous oxide generation as other matters that need to be carefully checked in real case application.
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A thermophilic aerobic membrane reactor (TAMR) treating high-strength COD liquid wastes was submitted to an integrated investigation, with the aim of characterizing the biomass and its rheological behaviour. These processes are still... more
A thermophilic aerobic membrane reactor (TAMR) treating high-strength COD liquid wastes was submitted to an integrated investigation, with the aim of characterizing the biomass and its rheological behaviour. These processes are still scarcely adopted, also because the knowledge of their biology as well as of the physical-chemical properties of the sludge needs to be improved. In this paper, samples of mixed liquor were taken from a TAMR and submitted to fluorescent in situ hybridization for the identification and quantification of main bacterial groups. Measurements were also targeted at flocs features, filamentous bacteria, and microfauna, in order to characterize the sludge. The studied rheological properties were selected as they influence significantly the performances of membrane bioreactors (MBR) and, in particular, of the TAMR systems that operate under thermophilic conditions (i.e., around 50°C) with high MLSS concentrations (up to 200 gTS L−1). The proper description of the...
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In the present work, the thermophilic aerobic membrane reactor technology was studied for the treatment of high strength aqueous wastes mainly containing dyes, surfactants and solvents. The thermophilic biomass resilience and the process... more
In the present work, the thermophilic aerobic membrane reactor technology was studied for the treatment of high strength aqueous wastes mainly containing dyes, surfactants and solvents. The thermophilic biomass resilience and the process stability under critical conditions (such as rapid rise of the mixed liquor pH, oxygen supply interruption, etc.) were also evaluated. The experimental work was carried out with the use of a pilot plant at semi-industrial scale, which was managed throughout for 14 months; the operation temperature was 49 °C and the organic loading rate was increased from 3 to 12 kgCOD m−3 d−1. Critical conditions, especially the interruption of oxygen supply, affected the pilot plant performance but did not cause a complete system break down. After the temporary reduction of process performance, also proven by the decrease in the oxygen consumption, the normal working conditions were restored. Moreover, the longer non-aerated phase involved a significant reduction (...
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Abstract Wet Oxidation (WO) models are generally employed for reactor design, thus WO modeling is a topic of great interest. Indeed, WO is one of the different technologies studied for sludge minimization and treatment, which represent... more
Abstract Wet Oxidation (WO) models are generally employed for reactor design, thus WO modeling is a topic of great interest. Indeed, WO is one of the different technologies studied for sludge minimization and treatment, which represent crucial aspects in the management of wastewater treatment plants (WWTP). Different Generalized Lumped Kinetic Models (GLKM) for sewage sludge WO were proposed in the literature for describing the complex transformations occurring in the process. Usually, works are related to a single type of sludge and, consequently, kinetic constants cannot be used for different case studies. In the present paper an alternative approach has been followed. A mathematical model was proposed and identified on a set of six different types of sludge (primary, secondary and mixed sludge from both urban and industrial WWTP). Kinetic parameters were determined for the different types of sludge with the non-linear least-squares method. In general, the predicted COD values obtained with the estimated kinetic constants closely fit experimental data: the mean absolute error associated with total (dissolved) COD is 3.2% (3.7%) and 10% (17%), respectively for the best and worst case. Kinetic constants values were finally correlated to the sludge VSS/TSS ratio (VSS = Volatile Suspended Solids; TSS = Total Suspended Solids) in order to provide a tool for a gross estimation of WO kinetic parameters, for a given sludge, relying on simple analytical measurement (VSS and TSS), commonly available at every WWTP.
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This work deals with the treatment of wastewaters containing not biodegradable and/or inhibitory compounds by means of chemical oxidation. Both well-known processes and those which are still under research and which are not yet employed... more
This work deals with the treatment of wastewaters containing not biodegradable and/or inhibitory compounds by means of chemical oxidation. Both well-known processes and those which are still under research and which are not yet employed on the full scale are described in the first parts of the work; in particular, process principles and treatment applicability are discussed. The results of specific experiences (some of which carried out directly by the authors) are reported in the other two parts of the work (which will be published in the next numbers of the journal): they deal with the pre-treatment or post-treatment of industrial wastewaters and landfill leachate by means of wet oxidation, Fenton oxidation, ozonization, combined oxidation with hydrogen peroxide and ozone.
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Piggery slaughterhouse wastewater poses serious issues in terms of disposal feasibility and environmental impact, due to its huge organic load and variability. It is commonly treated by means of activated sludge processes, whose... more
Piggery slaughterhouse wastewater poses serious issues in terms of disposal feasibility and environmental impact, due to its huge organic load and variability. It is commonly treated by means of activated sludge processes, whose performance, in case of municipal wastewater, can be monitored by means of specific analyses, such as Sludge Biotic Index (SBI), Sludge Index (SI) and floc and filamentous bacteria observation. Therefore, this paper was aimed at assessing the applicability of these techniques to piggery slaughterhouse sewage. A plant located in Northern Italy was monitored for 1 year. Physical, chemical and operation parameters were measured; the activated sludge community (ciliates, flagellates, amoebae and small metazoa) was analysed for calculating SBI and SI. Floc and filamentous bacteria were examined and described accordingly with internationally adopted criteria. The results showed the full applicability of the studied techniques for optimizing the operation of a pigg...
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Abstract Waste management planning is a complex task involving a variety factors and professional skills. In order to avoid oversimplification leading to the risk of adopting inappropriate solution the relevant decision problems should be... more
Abstract Waste management planning is a complex task involving a variety factors and professional skills. In order to avoid oversimplification leading to the risk of adopting inappropriate solution the relevant decision problems should be tackled with: (a) a comprehensive decision model (including technical, environmental, economic, social, etc. factors) and (b) a suitable decision supporting tool. In this work as far as (a) is concerned we propose a model based on more than 30 parameters for the evaluation of sewage sludge management strategies. As to (b) we implemented this model by employing both a worksheet (“home made” option) and a DSS commercially available (“buy” option). As a case study, we considered the selection of the sewage sludge management strategy in a 500,000 inhabitants area comparing the following alternatives: Agricultural use, Incineration, Wet Oxidation and recovery in Cement Kiln. The assessment of the four alternatives led to the following preference order: Agricultural use ≫ Incineration > Cement Kiln ≅ Wet Oxidation. Finally, a discussion on the make-or-buy dilemma and on pros and cons of decision support methods is reported. As a result, a paradigm shift defined make-and-buy approach is proposed.
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A chemical and bio-analytical protocol is proposed as a holistic monitoring framework for the assessment of WWTPs (Wastewater Treatment Plants) performance. This combination of tests consists of: i) an analysis of emerging contaminants,... more
A chemical and bio-analytical protocol is proposed as a holistic monitoring framework for the assessment of WWTPs (Wastewater Treatment Plants) performance. This combination of tests consists of: i) an analysis of emerging contaminants, to be added to the established physico-chemical parameters in order to understand the causes of (new) pollution phenomena and ii) some of the bio-analytical tools most widely applied in the field of wastewater research, which provide information on groups of chemicals with a common mode of toxic action (baseline toxicity, estrogenicity and mutagenicity/genotoxicity, selected as the most representative for human health). The negative effects of the discharge can thus be highlighted directly and used to assess the global environmental impact of WWTPs. As a validation, this multi-tiered approach was applied to a full-scale WWTP (150,000 p.e.), where different measurements were carried out: EDCs (Endocrine Disrupting Compounds) detection; algal growth inhibition, bioluminescence inhibition and acute toxicity test (for baseline toxicity); an E-Screen-like assay (for estrogenic activity); Ames, Allium cepa and Comet tests (for mutagenic/genotoxic activity). As a result, the WWTP showed good performance for all these issues, displaying its ability to enhance effluent quality, except for residual mutagenic behaviour, probably due to the by-products generated by the tertiary ozonation.
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ABSTRACT
The management of sewage sludge is becoming a more and more important issue, both at national and international level, in particular due to the uncertain recovery/disposal future options. Therefore, it is clear that the development of new... more
The management of sewage sludge is becoming a more and more important issue, both at national and international level, in particular due to the uncertain recovery/disposal future options. Therefore, it is clear that the development of new technologies that can mitigate the problem at the source by reducing sludge production is necessary, such as the European Directive 2008/98/EC prescribes. This work shows the results obtained with a thermophilic membrane reactor, for processing a biological sludge derived from a wastewater treatment plant (WWTP) that treats urban and industrial wastewater. Sewage sludge was treated in a thermophilic membrane reactor (TMR), at pilot-scale (1 m(3) volume), with alternate aeration cycles. The experimentation was divided into two phases: a "startup phase" during which, starting with a psychrophilic/mesophilic biomass, thermophilic conditions were progressively reached, while feeding a highly biodegradable substrate; the obtained thermophilic biomass was then used, in the "regime phase", to digest biological sludge which was fed to the plant. Good removal yields were observed: 64% and 57% for volatile solids (VS) and total COD (CODtot), respectively, with an average hydraulic retention time (HRT) equal to 20 d, an organic loading rate (OLR) of about 1.4-1.8 kg COD m(-3) d(-1) and aeration/non aeration cycles alternated every 4 h.
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ABSTRACT In this paper the effectiveness of an advanced sludge treatment technology (Wet Oxidation, WO) is presented, by analyzing experimental studies at the lab-scale and data collected during years of industrial-scale activities. The... more
ABSTRACT In this paper the effectiveness of an advanced sludge treatment technology (Wet Oxidation, WO) is presented, by analyzing experimental studies at the lab-scale and data collected during years of industrial-scale activities. The data showed good performances of WO on COD and VSS removal efficiencies -about 65-70% and 95-98% respectively- and the effect of operating parameters (i.e., temperature and reaction time) on process efficiencies was highlighted. The energy balance of the WO systems indicated that about 90% of the energy entering the system may be recovered. Finally, a techno-economic assessment showed that WO can be a suitable solution for sludge treatment and minimization.
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This work presents a study of the ammonia air stripping pro cess in a semi-flow batch bubble reactor as a pre-treatment for municipal solid waste (MSW) landfill leachate. In order to assess the optimum treatment conditions from a... more
This work presents a study of the ammonia air stripping pro cess in a semi-flow batch bubble reactor as a pre-treatment for municipal solid waste (MSW) landfill leachate. In order to assess the optimum treatment conditions from a technical and an economic point of view, the research was carried out in the following steps: 1) experimentation in a pilot plant; 2) mathematical model development; and 3) economic analysis. The experimentation showed that it is possible to achieve high ammonia removal efficiencies even without basificant dosage, if temperature is maintained between approximately 60 and 70°C. The development and calibration of a mathe matical model permitted the study to determine the treat ment efficiency of the process under several operating condi tions. The economic analysis has shown that, with a removal efficiency of approximately 70%, it is convenient to work without basificant dosage and at a temperature of 70°C. These conditions can also be considered optimal from...
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Ammonia stripping from MSW landfill leachate in ... Carlo Collivignarelli Giorgio Bertanza Department of Civil Engineering, University of Brescia, Brescia, Italy ... Marco Baldi Department of Hydraulic and Environmental Engineering,... more
Ammonia stripping from MSW landfill leachate in ... Carlo Collivignarelli Giorgio Bertanza Department of Civil Engineering, University of Brescia, Brescia, Italy ... Marco Baldi Department of Hydraulic and Environmental Engineering, University of Pavia, Pavia, Italy
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This paper presents a novel argumentation framework to support design debates in an IBIS-based style, by providing an automatic evaluation of the positions put forwards in the debates. It also describes the integration of the proposed... more
This paper presents a novel argumentation framework to support design debates in an IBIS-based style, by providing an automatic evaluation of the positions put forwards in the debates. It also describes the integration of the proposed approach within the designVUE software tool along with two case studies in engineering design and their initial evaluation by domain experts.