Browsing by Author "Solera, Rosario"
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Item Anaerobic digestion of slaughterhouse waste in batch and anaerobic sequential batch reactors.(Biomass Conversion and Biorefinery, 2022) Ripoll Morales, Vanessa; Agabo‑García, Cristina; Solera, Rosario; Perez, MontserratThis work focuses on the design of an effective treatment process for slaughterhouse waste management. Four different treatment sequences were proposed, based on aerobic and anaerobic technologies, as well as thermal and centrifugation pre-treatments. Biochemical methane potential tests were carried out to assess the viability in terms of biodegradability and biogas production of the anaerobic digestion units, which involved different substrates for each proposed process (raw slaughterhouse wastewater, thermal pre-treated slaughterhouse activated sludge, supernatant of thermal pre-treated slaughterhouse sludge, and co-digestion mixture of slaughterhouse wastewater and supernatant of thermal pre-treated slaughterhouse sludge). The obtained results showed that thermal pre-treatment is not effective by itself. However, if it is followed by centrifugation, organic matter removal is importantly improved. In addition, removal efficiency reached 76.0% when employing a codigestion mixture. Kinetic analyses showed that the specific constant rate of the mixture was 1.5 times higher than with the sole supernatant. Afterwards, the co-digestion mixture was employed as a substrate for an anaerobic sequencing batch reactor working under a semi-continuous operational mode. The influence of organic load rate (OLR) on organic matter removal and biogas production was studied. The best operational OLR range was 1.16–2.16 kg/m3•d, achieving 87.8% of chemical oxygen demand removal and 0.23 LCH4/ Ldigester·d of methane production rate. A faster organic load rate than 2.88 kg/m3•d led to bioreactor destabilisation. The obtained results were competitive against published studies that employed different anaerobic technologies and made progress towards the industrial implementation of effective technology in slaughterhouse facilities.Item Improvement of biomethane potential of sewage sludge anaerobic co-digestion by addition of “sherry-wine” distillery wastewater.(Journal of Cleaner Production, 2020) Ripoll Morales, Vanessa; Agabo-García, Cristina; Perez, Montserrat; Solera, RosarioCo-digestion of sewage sludge (SS) with other unusually treated residues has been reported as an efficient method to improve biomethane production. In this work, Sherry-wine distillery wastewater (SW-DW) has been proposed as co-substrate in order to increase biomethane production and as a breakthrough solution in the management of both types of waste. In order to achieve this goal, different SS:SW-DW mixtures were employed as substrates in Biomethane Potential (BMP) tests. The biodegradability and biomethane potential of each mixture was determined selecting the optimal co-substrate ratio. Results showed that the addition of SW-DW as a co-substrate improves the anaerobic digestion of SS in a proportionally way in terms of CODs and biomethane production The optimal co-substrates ratio was 50:50 of SS:SW-DW obtaining %VSremoval = 54.5%; YCH4 = 225.1 L CH4/kgsv or 154 L CH4/kgCODt and microbial population of 5.5 times higher than sole SS. In this case, %VSremoval = 48.1%; YCH4 = 183 L CH4/kgsv or 135 L CH4/kgCODt. The modified Gompertz equation was used for the kinetic modelling of biogas production with successful fitting results (r2 = 0.99). In this sense, at optimal conditions, the maximum productivity reached at an infinite digestion time was () = 229 ± 5.0 NL/kgSV; the specific constant was K = 25.0 ± 2.3 NL/kgSV·d and the lag phase time constant was (λ) = 2.49 ± 0.19.Item Kinetic modelling of anaerobic co-digestion of sewage sludge and Sherry-wine distillery wastewater: Effect of substrate composition in batch bioreactor.(Fuel, 2022) Ripoll Morales, Vanessa; Solera, Rosario; Pérez, MontserratBatch thermophilic anaerobic co-digestion of sewage sludge (SS) and Sherry-wine distillery wastewater (SW-DW) was investigated through biochemical methane potential tests (BMP). The results pointed out that biodegradability and biomethane potential were enhanced proportionally to the percentage of SW-DW of the feedstock, whose soluble biodegradability fraction is 10-fold higher than SS. Specifically, organic matter removal increases from 37 % (employing sole SS as feedstock) to 60 % (employing sole SW-DW as feedstock). SW-DW almost doubles methane yield in comparison to SS (302 ± 15 and 175 ± 9 NL/kg, respectively). A structured kinetic model was developed considering hydrolysis, acidogenic and methanogenic steps of anaerobic digestion. A non-linear multiple-response regression was employed to estimate the kinetic parameters for each feedstock (0%(v/v) SW-DW, 25%(v/v) SW-DW, 50%(v/v) SW-DW, 75%(v/v) SW-DW, and 100%(v/v) SW-DW). The first-order kinetic parameter estimated of the hydrolysis step varies inversely proportional to the percentage of SW-DW content in the feedstock. Whereas, there is no significant influence of feedstock composition on kinetic parameters value regarding acidogenesis and methanogenesis. These results showed that rate–limiting step switched during the fermentation and the addition of SW–DW favours acidogenic and methanogenic steps. In summary, the proposed kinetic model was able to predict batch experimental data, supporting the application of biogas production from anaerobic co-digestion of SS and DW-DW.Item Modelling of the anaerobic semi-continuous co-digestion of sewage sludge and wine distillery wastewater.(Environmental Science: Water Research & Technology, 2020) Ripoll Morales, Vanessa; Agabo García, Cristina; Solera, Rosario; Pérez, MontserratThe semi-continuous mesophilic anaerobic co-digestion of sewage sludge and wine distillery wastewater was investigated. In this sense, the effects of reducing the hydraulic retention time (HRT, from 20 d to 8 d) on the degradation of organic matter and methane production were determined. The experimental results showed that anaerobic co-digestion enhanced the biodegradability of the mixture in terms of VS and CODT (7–8% higher) for HRT = 8 d. The methane productivity at HRT = 8 d (18.0 LCH4 kgVS−1 d−1) was also enhanced (30% higher) compared to that obtained in the control experiment. In addition, a mathematical kinetic model was proposed to determine the rate-limiting step of the process. Stoichiometric parameters obtained for SS : WDW (0.115 kgCH4 kgCOD−1) was higher than SS (0.094 kgCH4 kgCOD−1), which means that co-digestion increased the rate of consumption because of the higher amount of biodegradable compounds. The kinetic study showed that anaerobic co-digestion favoured the methane production rate enhancing the acetate consumption step and making methanogenesis the rate-limiting step in this process.