1,721,083 research outputs found
Mathematical Modelling of Corleone (Italy) Full-Scale Wastewater Treatment Plant for Estimating the Greenhouse Gas Emissions: A Sensitivity Analysis
Full text linkThis study summarises the sensitivity analysis results using a novel mathematical model. The mathematical model already published represents the modification of the activated sludge model no. 1 (ASM1) in view of including the nitrous oxide (N2O) emission (namely ASM1 + N2O model). The ASM1 + N2O model was applied to a full-scale wastewater treatment plant in Corleone (Italy). Sensitivity analysis was performed by applying a local approach. In view of comparing results obtained for the model outputs taken into account (mixed liquor suspended solids - MLSS, effluent total COD, and effluent NH4-N - SNH concentrations) a normalised sensitivity index (SI) was assessed. Calculated normalised SI for model outputs highlight specific influential parameters, notably YH, fp, μH, bH, and those related to ammonia-oxidizing bacteria (AOBs). For the MLSS model output, only two model parameters were found influential, but 8 significant model parameters (4 for each) were identified for effluent total COD and SNH concentrations. This study provides insights for a more efficient calibration process, laying the groundwork for future research on the ASM1 + N2O mode
Mathematical modelling of greenhouse gas emissions from membrane bioreactors: A comprehensive comparison of two mathematical models
Full text linkThis paper compares two mathematical models (Model I and Model II) to predict greenhouse gases emission from a University Cape Town (UCT) – membrane bioreactor (MBR) plant. Model I considers N2O production only during denitrification. Model II takes into account the ammonia-oxidizing bacteria (AOB) formation pathways for N2O. Both models were calibrated adopting real data. Model comparison was performed in terms of (i) sensitivity analysis (ii) best fit and (iii) model prediction uncertainty. On average 6% of factors of Model I and 9% of Model II resulted to be important. In terms of best fit, Model II had a better capability of reproducing the measured data. The average efficiency related to the N2O model outputs was equal to 0.33 and 0.38 for Model I and Model II, respectively. On average, 73% (Model I) and 86% (Model II) of measured data lay inside the uncertainty bands
Water Reuse and Risk Analysis: The Case Study of Corleone (Italy) Ultrafiltration Plant
No full textThis study summarises the results of two months of monitoring the full-scale ultrafiltration plant in Corleone (Italy). The monitoring has been conducted according to the current regulations on water reuse in Italy (Italian Ministerial Decree 185/2003 and 2020/741/EU). Samples were withdrawn every ten days from three sections: i. treated disinfected wastewater (Section 1); ii. Downstream the sand filtration (Section 2); iii. After the ultrafiltration (Section 3). Data showed the ultrafiltration plant’s excellent capability to remove E.coli, total suspended solids (TSS), and turbidity. For the parameters, the permeate quality can be classified as Class A according to 2020/741/EU. Conversely, in terms of BOD5, the permeate can be categorised as Class B according to 2020/741/EU since the BOB5 value was around 20 mgO2 L-1 on average. Therefore, treated water can be adopted for food crops, processed and non-food crops and all irrigation methods are allowed. The study also has the novelty of providing a first attempt at performing a risk analysis according to 2020/741/EU, which has yet to apply to Sicilian plants
Sewage sludge acidogenic fermentation for organic resource recovery towards carbon neutrality: an experimental survey testing the headspace influence
Full text linkVolatile fatty acids (VFAs) produced by acidogenic digestion of sewage sludge are very interesting bio-products which can contribute to carbon neutrality of wastewater treatment plants. Studies on the production of VFAs from sewage sludge from fermenters with membrane are limited. In view of above, VFAs from a fermenter pilot plant equipped with a membrane bioreactor and fed with real sewage sludge has been monitored. The effect of headspace volume (HdV) on VFA production was studied for the first time to elucidate the optimal operation conditions. Specifically, three fermenter HdV values (namely, 20, 40 and 60% of the total volume) have been investigated. Results revealed that the HdV of 20% ensured the highest sCOD production (900 mgCOD/L) and VFA/COD ratio (45.4%). High value of HdV (namely, 40 and 60%) strongly decreased the acidogenic fermentation performance in terms of VFA production
Nutrient recovery from wastewater treatment by ultrafiltration membrane for water reuse in view of a circular economy perspective
Full text linkThe study aims to recover nitrogen from wastewater by employing ultrafiltration membrane in water reuse for agriculture purpose. To such aim, a new reclaimed water quality index (RWQI) is proposed and applied including an innovative protocol for its assessment. Specifically, the influence of filtration and backwashing times for an ultrafiltration system aimed to nutrient recovery has been analyzed. The final goal was to pin down the trade-off between operation costs and effluent quality. Results show that backwashing time play a crucial role in reducing the operation costs; indeed, low values (i.e., 0.5 min) lead to an increase in the number of required chemical cleanings and consequently operation costs (namely, up to 0.042 euro/m3). The compromise among effluent quality and operation costs has been obtained for 7 min and 1 min, filtration and backwashing, respectively
Volatile fatty acids from sewage sludge by anaerobic membrane bioreactors: Lesson learned from two-year experiments with fouling analysis by the resistance in series model
Full text linkVolatile fatty acid (VFA) production from sewage sludge has become one of the main biotechnologies implemented in view of the circular economy application in wastewater treatment plant (WWTP) management. In this study, domestic sewage sludge collected from three WWTPs over two-year experiments was subjected to acidogenic fermentation. The fermented liquid was recovered through an ultrafiltration membrane. The membrane fouling was analysed in detail by applying the resistance in series model, revealing the major role of the extra polymeric substances in the reversible fouling, accounting for 91.2 % of the total resistance. Finally, the major contribution of the carbon footprint assessment was due to the indirect emissions (1.30 kg CO2eq/m3). The study has the novelty of providing an in-depth understanding of MBR membrane fouling used for solid/liquid separation in a plant aimed at VFA recovery from sewage sludge acidogenic fermentation. Also, the carbon footprint assessment provides insights regarding the environmental impact of VFA recovery through ultrafiltration membrane
Transition to Circular Economy in the Water Sector by Legislative Perspectives for the Sicilian Region (Italy)
No full textWater reuse practices still need to be consistently implemented across Europe and globally, primarily due to insufficient social trust and the complexities of governance surrounding water reuse techniques. Additionally, the need for uniformity in water reuse regulations is a significant factor. To address these challenges, the European Parliament recently passed Regulation 2020/741, which establishes minimum requirements for water reuse to standardise legal obligations for reclaimed wastewater. This regulation also mandates the development of Water Reuse Risk Management Plans (WRRMPs) for all Union reclamation facilities. This manuscript aims to provide an overview of the current regulations on water reuse in Europe, Italy and Sicily. A critical overview has also offered how the regulations changed over time. Moreover, a first attempt at developing WRRMPs for a Sicilian plant (Corleone) has been made. Results showed that the human health risk related to using an agricultural scope is equal to 4 and can be classified as low
Biological Stability of Organic Fraction of Municipal Solid Wastes During Composting Processes
No full textThe article shows results of monitoring of a Sicilian composting plant (southern Italy). In particular, the biological stability of the organic fraction of municipal solid wastes has been monitored. Two experimental periods have been carried out: (1) plant start-up and (2) first operation period. The biological stability has been evaluated throughout the dynamic respiration index (DRI). This index was determined at different stages of process, for each phase. To our knowledge, no work has been previously published on the monitoring of composting plants in southern Italy. This work has the originality of using the DRI measured data for improving operation of a full-scale composting plant, rarely adopted in literature. Results show that storage time of the untreated matrix strongly influences performance of the composting process in terms of biological stability. At high value of storage time (>4 to 5 days) the pH decreased due to acetic acid production. Consequently, inhibition of the aerobic stabilization process takes place. Indeed, after treatment the DRI value was still quite high: 1,709 and 2,650mgO(2)/(kgVS.h) during start-up and start-up and first operation period, respectively. Results also reveal the need of using all operational parameters as reference for regulation of ventilation systems
Treatment and disposal of sewage sludge from wastewater in a circular economy perspective
No full textThe sewage sludge (SS) management represents one of the key issues to be properly addressed in view of achieving resource recovery from wastewater treatment plants and cost effectiveness operations. Several efforts must be performed to overcome the existing bottlenecks: (1) stringent laws on environmental protection, (2) increase production due to the growth of treated civil wastewater production, (3) micropollutants and heavy metals presence in sewage sludge, and (4) improper applied technology for sludge recovery. Europe is adopting a circular economy model, where sludge is a resource to be exploited. However, some European directives are contradictory and/or not adequate to favor the sludge reuse. Furthermore, in the scientific literature there are still doubts about the risks of sludge reusing. The chapter explores the key issues surrounding the sewage sludge management and reuse in view of providing an overview to the current situation on this topic
Trading-off greenhouse gas emissions and 741/2020 European Union water reuse legislation: An experimental MBR study
Full text linkA trade-off between greenhouse emissions (direct and indirect) and operational costs in the water treatment sector is of great importance, although only few literature studies exist. The paper presents a comprehensive experimental study on a Membrane Bioreactor (MBR) pilot plant at the Water Resource Recovery Facility of Palermo University (Italy). The MBR pilot plant was aimed at reducing carbon footprint while producing water suitable for water reuse in agriculture. Multiple scenarios were assessed to unveil the best operational variables including the assessment of the reclaimed water quality index for water reuse. Results showed the lowest operational costs for the MBR of 5.05 euro cent/m3 with Class B according to 741/2020 European legislation. Results revealed optimised values, in terms of airflow rate and backwash frequency, of 0.8 m3/m2/h and 12 times/h, respectively. The highest N2O emission was measured in correspondence of scenario S5 (airflow rate of 1.6 m3/m2/h) with 0.40 mg N2O-N/m2/h in agreement with previous literature studies. The obtained results could effectively address the operators to find a trade-off between operational costs and water quality
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