Enhancement of biogas production from sewage sludge by biofilm pretreatment method /
Various sludge pre-treatment methods are being tested to enhance the yield of biogas production from sewage sludge. In fact, few of these methods have notably improved the solubility of organic floc in the sludge, the biogas production rate as well as the solids reduction. However, there was not an...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
Kuala Lumpur :
Kulliyyah of Engineering, International Islamic University Malaysia,
2018
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| Subjects: | |
| Online Access: | http://studentrepo.iium.edu.my/handle/123456789/4763 |
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| Summary: | Various sludge pre-treatment methods are being tested to enhance the yield of biogas production from sewage sludge. In fact, few of these methods have notably improved the solubility of organic floc in the sludge, the biogas production rate as well as the solids reduction. However, there was not an overall improvement in term of economical production of biogas by using these methods. In order to overcome the low biogas yield and to find an alternative and economically suitable pretreatment method, a biological pretreatment method using a biofilm attached on granular activated carbon was studied. The biofilm constituted of four strains of bacteria producing hydrolases and it was used as an immobilized biocatalyst for the pretreatment of the sludge. The major goals of this study were to develop an efficient biofilm for the pretreatment, to evaluate the improvement of organic material solubility after the pretreatment and to see the effect of this pretreatment method on the biogas production, volatile solids reduction and solids retention time. The optimum time of the immobilization was determined by using One-Factor-At-Time (OFAT) method and the optimization of the mass of carrier and inoculum volume were done by using faced centered central composite design (FCCCD) under the design of response surface method (RSM). The optimization of the pretreatment and anaerobic digestion parameters were carried out by using OFAT method. The attachment of the biofilm and the pretreatment processes were operated in batch mode and the anaerobic digestion was done in a semi-continuous lab-scale reactor. Based on the data obtained during this study, the optimum biofilm formed within 2 days at 37 ⁰C and 150 rpm. The best amount of GAC that has given a good biofilm was 4g as the optimum biofilm carrier for the pretreatment process. An improvement of 16.9% on the chemical oxygen demand solubilization and 28.3% in the volatile solids was observed after 12 hours of pretreatment at room temperature (30 ± 2 ⁰C) and 150 rpm shaking speed. Comparing to the no pretreated sludge (control), a slight increase in the cumulative biogas production was achieved after nine days of digestion with 30% v/v of inoculum (anaerobic sludge) at 37 ⁰C and 25 days of HRT. In addition, for only 14 days of solid retention, the total biogas production was enhanced 15% over the control. However, the control of the anaerobic digestion was higher than the experimental reactors in terms of COD and VS reduction. It can be concluded that the developed pretreatment method can be used for the enhancement of the biogas production from sewage sludge at mesophilic temperature range (37 ⁰C). |
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| Physical Description: | xiv, 100 leaves : illustrations ; 30cm. |
| Bibliography: | Includes bibliographical references (leaves 84-93). |