Search results for "Digestion"
showing 10 items of 357 documents
Effects of biochar addition on anaerobic digestion and comparison of different biochar qualities
2017
Tässä pro gradu -työssä tutkittiin, voidaanko anaerobisen mädätyksen toimintaa parantaa lisäämällä mädätysprosessiin pieniä määriä biohiiltä. Anaerobista mädätystä tutkittiin laboratoriomittakaavan biokaasukokeilla, joissa biokaasureaktoreita käsiteltiin sekä pyrolyyttisesti että hydrodermaalisesti tuotetulla biohiilellä. Biohiilen mahdolliseen kykyyn lievittää ammoniakki-inhibitiota kiinnitettiin huomiota. Seitsemän pyrolyyttisen ja yhden hydrodermaalisen hiilen ominaisuuksia vertailtiin, jotta voitaisiin määrittää soveltuvia biohiiliä anaerobiseen mädätykseen. Biohiilistä analysoitiin ammonium-adsorptiokapasiteetti, irtoavan liukoisen orgaanisen kokonaishiilen (DOC) ja liukoisen kokonaist…
Alkaline pretreatment to enhance one-stage CH4 and two-stage H2/CH4 production from sunflower stalks: Mass, energy and economical balances
2015
Abstract Biological production of second generation biofuels such as biohydrogen (H2) or methane (CH4) represents a promising alternative to fossils fuels. Alkaline pretreatments of lignocellulosic biomass are known to enhance the accessibility and the bioconversion of hollocelluloses during anaerobic digestion and dark fermentation processes. In the present study, four different configurations were investigated: one-stage CH4 continuous and two-stage H2 batch/CH4 continuous process with and without alkaline pretreatment of sunflower stalks (55 °C, 24 h, 4 g NaOH/100 g TS). The results showed that two stage H2/CH4 (150 ± 3.5 mL CH4 g−1 VS) did not improve methane yields compared to one stag…
Development and pilot-scale validation of a fuzzy-logic control system for optimization of methane production in fixed-bed reactors
2018
International audience; The objective of this study was to develop an advanced control system for optimizing the performance of fixed-bed anaerobic reactors. The controller aimed at maximizing the bio-methane production whilst controlling the volatile fatty acids content in the effluent. For this purpose, a fuzzy-logic controller was developed, tuned and validated in an anaerobic fixed-bed reactor at pilot scale (350 L) treating raw winery wastewater. The results showed that the controller was able to adequately optimize the process performance, maximizing the methane production in terms of methane flow rate, resulting in an average methane yield of about 0.29 LCH4 g−1 COD. On the other han…
Biogas production from meat and pulp and paper industry by-products
2014
Chemically Stressed Bacterial Communities in Anaerobic Digesters Exhibit Resilience and Ecological Flexibility
2020
Anaerobic digestion is a technology known for its potential in terms of methane production. During the digestion process, multiple metabolites of high value are synthesized. However, recent works have demonstrated the high robustness and resilience of the involved microbiomes; these attributes make it difficult to manipulate them in such a way that a specific metabolite is predominantly produced. Therefore, an exact understanding of the manipulability of anaerobic microbiomes may open up a treasure box for bio-based industries. In the present work, the effect of nalidixic acid, γ-aminobutyric acid (GABA), and sodium phosphate on the microbiome of digested sewage sludge from a water treatmen…
Aerobic composting and anaerobic digestion of pulp and paper mill sludges
1997
The feasibility of aerobic vessel composting and anaerobic digestion for the treatment of pulp and paper mill sludges were studied. The composting studies made use of primary and secondary sludge from a de-inking and paper mill. In six parallely aerated 500 1 vessels with various carbon : nitrogen (C:N) -ratios, the most optimal performance was obtained with C:N -ratios of c. 22–35, while higher and lower ratios delayed the temperature increase. With the optimal ratios, the thermophilic stage was reached within 36 h, and the stage lasted for about seven days. In the scale-up study (18 m3 compost vessel), the thermophilic stage was reached within 24 h. An effective dehydratation of the mass …
Biogas measurement techniques and the associated errors
2011
There are several techniques for the measurement of laboratory scale biogas production. This thesis describes the study and evaluation of the most significant and commonly used biogas measurement techniques and analyzes the source of errors associated with the measurement of biogas production. Firstly, inaccuracy mainly due to biogas carbon dioxide (CO₂) dilution in displaceable liquids and losses to atmosphere of dissolved CO₂ was evaluated by testing solubility of CO₂ in different barrier solutions. Saturated acidified brine solution showed lower CO₂ solubility among the tested solutions. An accurate, simple, automated and easy to calibrate laboratory scale liquid displacement gas measuri…
Biochemical methane potential (BMP) of solid organic substrates: evaluation of anaerobic biodegradability using data from an international interlabor…
2011
Background: This paper describes results obtained for different participating research groups in an interlaboratory study related to biochemical methane potential (BMP). In this research work, all experimental conditions influencing the test such as inoculum, substrate characteristics and experimental conditions were investigated. The study was performed using four substrates: three positive control substrates (starch, cellulose and gelatine), and one raw biomass material (mung bean) at two different inoculum to substrate ratios (ISR). Results: The average methane yields for starch, cellulose, gelatine and mung bean at ISR of 2 and 1 were 350 ± 33, 350 ± 29, 380 ± 42, 370 ± 36 and 370 ± 35 …
Influence of the Oxic-Settling-Anaerobic (OSA) Process on Methane Production by Anaerobic Digestion of Sewage Sludge
2023
The present study evaluated different sludge-reduction mechanisms in the oxic-settling-anaerobic (OSA) process in terms of their effects on methane productivity by anaerobic digestion of sewage sludge. Two different layouts were investigated for the sludge return from an anaerobic side-stream reactor (ASSR) to the anoxic (scheme A) or the aerobic (scheme B) reactor of a pre-denitrification plant. Biochemical methane-potential (BMP) assays performed on the excess sludge revealed that scheme A promoted an overall increase of methane production in the OSA (20 mLCH4 gVSS−1d−1, +19%), although compared with a control CAS plant a significant decrease in the excess sludge production (3…