Sign In. Skip Nav Destination. Mata-Alvarez J. This Site. Google Scholar. Publication date:. Cite Icon Cite. Buy This Book. In general, these Fig. Evolution of gas composition within the three cells. The sludge resulting from the MSW presents an high ammonia content.
The metal fraction which has been dissolved is partially retained in the sludge. When an- aerobic treatment was carried out in only one stage, the leachate formed had high amounts of volatile fatty acids; butyric and acetic acids being the most Fig.
Accumulative gas production for the three cells. Longer times were required for reaching low concentrations of volatile acids. When a new cell is placed on top of another, already digested cell, the leachate generated has a lower pollutants content. This behaviour is a result of the anaerobic producing a high quantity of CO2 and in practice digestion produced in the old digested cell when the no methane. After that, an acidic period began leachate passes through it.
The behaviour of these where the CO2 predominated due to the reaction old cells with respect to the leachate formed in the between the VFA and the bicarbonate ions. It must The accumulated volume of biogas produced in be emphasised that in order to obtain degradation the third cell expressed in normal litres is rep- of the leachates, the distribution of the leachate resented in Fig. The generation of gas increases formed in each cell must pass through the cell im- until day approximately, passing through a mediately below in the most homogenous way poss- phase of constant production until day and ible so as to avoid preferential paths.
Company for Solid Waste Management dation velocity, was around 2. Andreottola G. Christensen, R. Stegman, pp. Elsevier Applied Science, Lema J. A Review. Water Air Soil Pollut. American Public Health Association, Washington, DC. Pohland F. Analysis and optimisation of the anaerobic digestion of the organicfraction of municipal solid waste 4.
Anaerobic digestion of the organic fraction of municipal solid waste:a perspective 5. Types of anaerobic digester for solid wastes 6. Co-digestion of the organic fraction of… Expand. View via Publisher. Save to Library Save. Create Alert Alert. Share This Paper. Background Citations. Methods Citations. Results Citations. Citation Type. Has PDF. Publication Type. More Filters. Analysis of the biogas productivity from dry anaerobic digestion of organic fraction of municipal solid waste.
Worldwide there is an increasing trend for the study and use of new sources of renewable energy. Municipal solid wastes are becoming increasingly used as an energy source in waste-to-energy projects. RESULTS The monitoring of the thermophilic and mesophilic anaerobic degradation processes involved the determi- nation of the following control parameters: pH, soluble chemical oxygen demand CODs , dissolved organic carbon DOC , total acidity, alkalinity, and daily pro- duction of biogas, accumulated methane and biogas Figure 2.
The pH evolution in the mesophilic M and ther- mophilic T reactors Table 1. Figure 3 The hydrolysis and acidogenesis phases result in Although this parameter 60 and For the same time of operation, for heterogeneity of the waste, we can observe an increase approximately 22 days, both systems achieve similar in the early days due to the solubilisation of organic removal rates, but the rates are slightly higher in the matter in the solid waste.
The duration of this increase mesophilic system. The value of this parameter increases until day process. The removal in crease of In the T the M reactor was If we consider the same is noted that the operating time was different for both operation time, the percentage of removal is in the same systems.
Thus, for the same time of the operation, the order in both processes. It declines until day 60, coinciding respect to this parameter. From that time, all of the Figure 3. The total acidity evolution in mesophilic M and mophilic T reactors thermophilic T reactors Figure 4. With the onset of methanogenesis day 10 , the ratio begins to decrease to values below 0. Monitoring of biogas The daily production of biogas shows a different evolu- tion depending on the operating temperature Fig.
In the mesophilic process, the methanogenic phase starts on day 15, coinciding with the degradation of organic matter in the system as seen by the DOC and CODs levels. The me- Figure 9. Accumulated methane in the systems M and T thane production in the M reactor is delayed until day 10 Fig. For the T reactor, the methane production takes place from a better understanding of the results, the two stages of the 2nd or 3rd day.
The methanogenic phase lasts for 29 days in M and 18 days in T. The values for the methanogenic Overview of the processes stage were calculated based on the overall duration of Table 2 shows a summary of the main results obtained the process until the end of the consumption of the in this study regarding the anaerobic degradation of biodegradable organic matter. This implies that the ope- rating time was different for the two systems, T and M.
The generation of hydrogen was 1. Summary of the main results of the batch anaerobic Analysing the hydrolysis step reactors for the degradation of the OFMSW under the The evolution of the hydrolysis and acidogenesis stages two temperature ranges, mesophilic and thermophilic is used to characterise these stages and to predict the behaviour of systems in successive stages.
The difference between the start of both processes is distinguished, and the detailed study of the hydrolysis provides information on the anaerobic digestion in both of the temperature ranges. The duration of the hydrolysis and acidogenesis sta- ges together has shown to be between 7 and 9 days in the thermophilic range, from the starting time of the methanogenesis stage, in which the products generated in the previous stages are consumed to form methane and carbon dioxide. Figure 10 shows a histogram with the percentage increases obtained for the parameters related to the organic content in the reactor: CODs, DOC and VFA measured as the total acidity.
These values have been calculated as the percentage increase over the value of the initial day. The CODs progressively increase until day 11 of the experiment. From day 7, we can see that the hydrolysis rate decreases.
The DOC and VFA increase up to day 7, but from this time we can see a decrease, which involves the progressive con- sumption of the organic matter measured as the DOC process compared to that used in the mesophilic process, and volatile acidity. This difference The hydrolysis-acidogenesis period in the mesophilic determines the evolution of the pH values. Furthermore, the heterogeneity of the waste fractions of different biodegradability19 can explain the evolution of the solubility of the organic matter that would war- rant the extra time needed for solubilisation of certain fractions contained in the solid waste to liquid waste.
In this sense, there is a fraction that is highly refractory cellulose, hemicelluloses and lignin which come from vegetables waste and paper Therefore, the acclimati- sation of inoculum-substrate and the rapid growth of the microbial hydrolytic in thermophilic conditions lead to rapid waste hydrolysis. But, also, it should be noted that the real evolution of organic matter parameters may not have been recorded with the sampling conditions that were established at the beginning of the experiment.
Figure Percentage increases over the initial values for the The data suggest that the generation of volatile fatty CODs, DOC and VFA measured as volatile acidity acids in this case is attached, at least in part. In any case, it is likely that with an increased These parameters show the highest rate of increase sampling frequency more pronounced changes could have between 14 and 21 days.
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