Energetic and economic assessment of sludge thermal hydrolysis in novel wastewater treatment plant configurations

Novel wastewater treatment plants (WWTPs) are aimed to be more energetically efficient than conventional ones. Their first step is a chemical oxygen demand (COD) preconcentration stage with different alternatives, such as rotating belt filters (RBF), chemically enhanced primary treatment (CEPT), high-rate activated sludge (HRAS), or combinations thereof, in which energy requirements are substantially reduced. The COD recovered as sludge allows a noticeable increase of biogas production in anaerobic digestion (AD). In conventional WWTPs, sludge anaerobic biodegradability can be significantly enhanced by applying sludge pretreatment methods, such as thermal hydrolysis (TH), before AD. However, considering that novel-sludges are more anaerobically biodegradable than conventional ones, the impact of TH on their methane production is expected to result significantly lower. In this study, an energetic and economic assessment of applying TH in novel WWTPs was performed. We found that TH is only justified to reduce operational costs as long as sludge TS concentration in the feeding to the TH unit is higher than 1-2%. The HRAS is the scenario that leads to the lowest treatment costs (below 1 c€/m3 wastewater if sludge is thickened over 10% of TS). However, the WWTP based on CEPT for COD preconcentration leads to the lowest electricity consumption (below 0.01 kWh/m3 of wastewater), but even in the most favourable conditions the energy autarky was not achievable. Results show that the main impact of TH is mainly due to sludge disposal savings (270,000-430,000 €/year for a 500,000 inhabitants WWTP) rather than the increase of energy production (achieves maximum savings of 35,000-60,000 €/year). Payback time is very dependent on the WWTP size, ranging from 15 to 30 years for a 100,000 inhabitants WWTP and from 2 to 4 years for a 1,000,000 inhabitants WWTPThe authors would like to thank the EU (ID199) and AEI (PCIN-2015-22) for funding, in the frame of the collaborative international Consortium Pioneer_STP financed under Water Joint Programming Initiative. The authors belong to the Gali- cian Competitive Research Group ED431C 2017/029 and the CRETUS Strategic Partnership (ED431E 2018/01). These programmers are co-funded by FEDER (EU)S

Thermal hydrolysis pre-treatment has no positive influence on volatile fatty acids production from sewage sludge

The study compares the potential to produce volatile fatty acids (VFA) from sewage sludge, both raw and thermally pre-treated in two modes of operation. In batch mode, raw sludge at pH 8 obtained the highest maximum VFA yield (0.41 g COD-VFA/g CODfed) whereas pre-treated sludge achieved a lower value (0.27 g COD-VFA/g CODfed). The operation of 5-L continuous reactors showed that thermal hydrolysis pre-treatment (THP) did not have any significant influence on VFA yields, averaging 15.1 % g COD-VFA/g COD with raw sludge and 16.6 % g COD-VFA/g COD with pre-treated one. Microbial community analysis showed that phylum Firmicutes was predominant in both reactors and that the enzymatic profiles involved in VFA production were very similar regardless of the substrate fedThis work is part of the ECOVAL and CIGAT CIRCULAR projects, which are funded by Interreg Sudoe (SOE4/P1/E1104) and by the Xunta de Galicia and Viaqua (IN853C2022/03), respectively. Juan M. Lema belongs to the Galician competitive research group ED431C-2021/37 co-funded by Xunta de Galicia and ERDF (EU)S

An optimised control system to steer the transition from anaerobic mono- to co-digestion in full-scale plants

Despite the rapid increase of anaerobic co-digestion works over the last years, the very small number of pilot- and full-scale studies available in the literature is a major barrier to its full-scale implementation. In this paper, a control strategy methodology was applied in a full-scale sludge digester to safely steer the transition from anaerobic mono- to co-digestion and to maximize methane production.Traditional wastewater treatment plants (WWTPs) are electrical consumers, with a usual high demand in the range of 0.3 to 0.6 kWh/m3 of wastewater treated. Their digesters are commonly oversized, and consequently operated at low organic loading rates (OLRs). This opens a great opportunity for anaerobic co-digestion (AcoD) as an interesting technology to increase methane productivity and the electrical self-production in WWTPs. However, there is a quite limited implementation of AcoD at full-scale plants, since the transition from mono- to co-digestion and the further AcoD optimisation is a crucial and delicate step that could lead to the inhibition of the process if not thoroughly controlled. In this study, a methodology based on an optimum control strategy is explained in detail and it was applied to safely and optimally steer the transition from mono- to co-digestion and to maximize methane production during AcoD. A lab-scale anaerobic digester of 14 L mimicking the full-scale one (3,500 m3) was operated 30 days in advance to anticipate and if needed correct any operational destabilization that might occurr. As a result, the treatment of sewage sludge with two co-substrates (coming from a pig slaughterhouse and from a frying industry), which accounted for just 11% of the feeding flowrate, at a hydraulic retention time of 20 days allowed to raise the OLR and the methane production by 2-fold and 3-fold, respectively, increasing the self-produced electricity from 25% to 75% of the total demand of the WWTP. The diagnosis indicators proved to be accurate to take decisions concerning wastes blending and the strategy of increasing OLR. Besides, the proposed control system provides the steps to ensure a safe transition from anaerobic mono- to co-digestion and further optimisation at full-scale plantsThis work was supported by SmartGreenGas project (Spanish Government, AEI, 2014-CE224). The authors from Universidade de Santiago de Compostela belong to the Galician Competitive Research Group ED431C 2017/029 and to the CRETUS Strategic Partnership (AGRUP2017/01). All these programs are co-funded by FEDER (EU)S

Assessment of the fate of organic micropollutants in novel wastewater treatment plant configurations through an empirical mechanistic model

Novel wastewater treatment plants (WWTPs) are expected to be less energetically demanding than conventional ones. However, scarce information is available about the fate of organic micropollutants (OMPs) in these novel configurations. Therefore, the objective of this work is to assess the fate of OMPs in three novel WWTP configurations by using a plant-wide simulation that integrates multiple units. The difference among the three configurations is the organic carbon preconcentration technology: chemically enhanced primary treatment (CEPT), high-rate activated sludge (HRAS) combined or not with a rotating belt filter (RBF); followed by a partial-nitritation (PN-AMX) unit. The simulation results show that the three selected novel configurations lead mainly to comparable OMPs removal efficiencies from wastewater, which were similar or lower, depending on the OMP, than those obtained in conventional WWTPs. However, the presence of hydrophobic OMPs in the digested sludge noticeably differs among the three configurations. Whereas the configuration based on sole HRAS to recover organic carbon leads to a lower presence of OMPs in digested sludge than the conventional WWTP, in the other two novel configurations this presence is noticeable higher. In conclusion, novel WWTP configurations do not improve the OMPs elimination from wastewater achieved in conventional ones, but the HRAS-based WWTP configuration leads to the lowest presence in digested sludge so it becomes the most efficient alternativeThe authors would like to thank the EU (ID199) and AEI (PCIN-2015-22) for funding, in the frame of the collaborative international Consortium Pioneer_STP financed under Water Joint Programming Initiative. The authors from Universidade de Santiago de Compostela belong to the Galician Competitive Research Group ED431C 2017/029 and the CRETUS Strategic Partnership (AGRUP2017/01). These programmers are co-funded by FEDER (EU)S

Lee, imagina y juega con la literatura infantil y juvenil

Memoria ID-0030. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2014-2015

A comparison of novel and conventional sewage treatment plants in terms of energy requirements, operational costs and organic micropollutants removal

The goal of this Thesis is to evaluate the energy requirements, the operational costs and the organic micropollutants (OMPs) removal in different novel sewage treatment plant (STP) configurations based on rotating belt filters, chemically enhanced primary treatment and high-rate activated sludge or combinations for organic matter recovery followed by a partial nitritation-anammox unit and to compare the results with those of a conventional STP configuration. The different novel STP configurations evaluated significantly decrease the energy requirements in comparison with conventional STPs. The alternative based on high-rate activated sludge reaches comparable energy demand and also considerably lower operational costs than the other evaluated configurations. In terms of OMPs, all the studied novel STP configurations reach similar removal efficiencies from wastewater for most them, However, among the studied alternatives, the novel STP configurations based on the high-rate activated sludge reactor achieve the lowest presence of OMPs in digested sludge. In conclusion, the STP configurations based on high-rate activated sludge become the preferable option from a holistic point of view

Opportunities for rotating belt filters in novel wastewater treatment plants configurations

Novel wastewater treatment plants (WWTPs), which are based on a partial nitritation-anammox (PN-anammox) process, enable higher chemical oxygen demand (COD) recovery to produce biogas and lower treatment costs. In this study, rotating belt filters (RBFs) were examined in different configurations to identify the opportunities for RBFs to be included in novel WWTP configurations. RBFs enable recovery of 22-37% of the influent COD and removal of 34-56% of hydrophobic organic micropollutants (OMPs). However, the effluent was not suitable for treatment in a PN-anammox process due to its high COD. Chemically enhanced settling (CES) enabled these limitations to be overcome and caused an increase in OMP removal to 73-94%. However, a dose of 300 mg/L of ferric chloride was required to produce a suitable effluent for a PN-anammox reactor. The combination of RBF and CES not only derived effluents suitable for treatment in PN-anammox units but also decreased the alkalinity consumption and the required chemical dose 3-fold to achieve comparable COD recovery and OMP removal. The methane yield of the combined sludges that were produced (184 L(N) CH4/kg CODinfluent) was 75% higher than that obtained in conventional wastewater treatment (105 L(N) CH4/kg CODinfluent), and the electricity requirements decreased from 0.54 to 0.41 kWh/m3 of treated wastewater. The energetic calculations showed that a WWTP incorporating this combined treatment could attain energy autarky with 29% lower operational costs than that of conventional treatment (0.022 vs 0.031 €/m3) as long as a minimum alkalinity-to-ammonium ratio of 1-1.25 g IC to g NH4+-N was ensured in the effluent of the combined treatmentThis work is part of the PIONEER STP project, which is funded by the Water Joint Programming Initiative, a water challenge for a changing world waterworks 2014 cofund call. The authors belong to the Galician Competitive Research Group ED43C 2017/029 and the CRETUS Strategic Partnership (AGRUP2017/01). These programmes are co-funded by FEDER (EU)S

Clinical Characteristics and Risk Factors of Respiratory Failure in a Cohort of Young Patients Requiring Hospital Admission with SARS-CoV2 Infection in Spain: Results of the Multicenter SEMI-COVID-19 Registry.

Age is a risk factor for COVID severity. Most studies performed in hospitalized patients with SARS-CoV2 infection have shown an over-representation of older patients and consequently few have properly defined COVID-19 in younger patients who require hospital admission. The aim of the present study was to analyze the clinical characteristics and risk factors for the development of respiratory failure among young (18 to 50 years) hospitalized patients with COVID-19. This retrospective nationwide cohort study included hospitalized patients from 18 to 50 years old with confirmed COVID-19 between March 1, 2020, and July 2, 2020. All patient data were obtained from the SEMI-COVID Registry. Respiratory failure was defined as the ratio of partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2 ratio) ≤200 mmHg or the need for mechanical ventilation and/or high-flow nasal cannula or the presence of acute respiratory distress syndrome. During the recruitment period, 15,034 patients were included in the SEMI-COVID-19 Registry, of whom 2327 (15.4%) were younger than 50 years. Respiratory failure developed in 343 (14.7%), while mortality occurred in 2.3%. Patients with respiratory failure showed a higher incidence of major adverse cardiac events (44 (13%) vs 14 (0.8%), p320 U/I (OR, 1.69; 95% CI, 1.18 to 2.42; p=0.0039), AST >35 mg/dL (OR, 1.74; 95% CI, 1.2 to 2.52; p=0.003), sodium 35 mg/dL (OR, 1.74; 95% CI, 1.2 to 2.52; p=0.003), sodium 8 mg/dL (OR, 2.42; 95% CI, 1.72 to 3.41; p Young patients with COVID-19 requiring hospital admission showed a notable incidence of respiratory failure. Obesity, SAHS, alcohol abuse, and certain laboratory parameters were independently associated with the development of this complication. Patients who suffered respiratory failure had a higher mortality and a higher incidence of major cardiac events, venous thrombosis, and hospital stay

Influencia de la historia de tabaquismo en la evolución de la hospitalización en pacientes COVID-19 positivos: datos del registro SEMI-COVID-19.

Smoking can play a key role in SARS-CoV-2 infection and in the course of the disease. Previous studies have conflicting or inconclusive results on the prevalence of smoking and the severity of the coronavirus disease (COVID-19). Observational, multicenter, retrospective cohort study of 14,260 patients admitted for COVID-19 in Spanish hospitals between February and September 2020. Their clinical characteristics were recorded and the patients were classified into a smoking group (active or former smokers) or a non-smoking group (never smokers). The patients were followed up to one month after discharge. Differences between groups were analyzed. A multivariate logistic regression and Kapplan Meier curves analyzed the relationship between smoking and in-hospital mortality. The median age was 68.6 (55.8-79.1) years, with 57.7% of males. Smoking patients were older (69.9 [59.6-78.0 years]), more frequently male (80.3%) and with higher Charlson index (4 [2-6]) than non-smoking patients. Smoking patients presented a worse evolution, with a higher rate of admission to the intensive care unit (ICU) (10.4 vs 8.1%), higher in-hospital mortality (22.5 vs. 16.4%) and readmission at one month (5.8 vs. 4.0%) than in non-smoking patients. After multivariate analysis, smoking remained associated with these events. Active or past smoking is an independent predictor of poor prognosis in patients with COVID-19. It is associated with higher ICU admissions and in-hospital mortality