STUDY ON THE EFFECTS OF CHELATING AGENTS ON HYDRAULIC RETENTION TIME, METHANE AND HYDROGEN SULPHIDE GAS YIELDS FROM SOLID WASTES

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dc.contributor.authorCALVIN, NWOKEM NSIDIBEABASI
dc.date.accessioned2015-03-27T08:43:22Z
dc.date.available2015-03-27T08:43:22Z
dc.date.issued2014-10
dc.descriptionA DISSERTATION WRITTEN IN THE DEPARTMENT OF CHEMISTRY AND SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF DOCTOR OF PHILOSOPHY DEGREE IN ANALYTICAL CHEMISTRY OF AHMADU BELLO UNIVERSITY, ZARIA NIGERIA. OCTOBER, 2014en_US
dc.description.abstractThis research work focused on addition of chelating ligands in order to enhance the overall digestion process; thereby improving methane gas yield, reducing HRT and decreasing concentration of H2S produced within digester systems. In view of this, several experiments and analyses such as metal determination, VFA, and CH4 gas yield were carried out which involved the use of the Atomic Absorption Spectrophotometer (AAS), Biogas 5000 Analyser, and other analytical tools. The results from these analyses showed that, at mesophilic temperature range of 29 – 31oC, four of the different substrates, GU, BL, CH and CD, recorded maximum CH4 gas yield of 8.30 %, 33.30 %, 84.80 % and 67.60 % respectively at an optimum weight of 150 g. The only exception observed was with CM substrate which recorded a CH4 gas yield of 75.40 % at an optimum weight of 250 g. On addition of chelating ligands, EDDA, NTA, EDTA, DTPA, MESYL, PORPH and PENI to the best three performing substrate digesters namely, CM, CD and CH, it was observed that depending on the chelating ligand added and the substrate, an increase in the CH4 yield was recorded which ranged from 1-15 %. This improvement in CH4 gas yield was due to the increased bioavailability of essential nutrients on addition of chelating ligands which invariably promoted the growth and stability of the CH4 producing bacteria; thereby improving CH4 production. Also, the addition of these chelating ligands to the CM CD and CH digester systems reduced the HRT, from 50 days to 25 days, 52 days to 30 days and 57 days to 32 days in the CM CD and CH digester systems respectively. The decrease in HRT was due to the metal chelate catalysis of the hydrolysis stage of the anaerobic digestion process where the metal chelate formation served as the driving force in the solvolysis process. The effect of increasing chelating ligand concentration on production of H2S was also studied. Also, the results showed a general decrease in H2S concentration from 80 % to 30 % on xxii increasing the chelating ligand concentration within the best three performing substrate digesters namely, CM, CD and CH, from 10 μM to 100 μM. This reduction was due to the redox reaction occurring between the various metal chelates and H2S, leading to the formation of elemental Sulphur with the release of H+ ions; thus reducing the concentration of H2S within the digester systems. Generally, addition of ligands to the substrate digesters increased production of CH4, reduced HRT and decreased H2S production greatlyen_US
dc.identifier.urihttp://hdl.handle.net/123456789/6327
dc.language.isoenen_US
dc.subjectEFFECTS,en_US
dc.subjectCHELATING AGENTS,en_US
dc.subjectHYDRAULIC RETENTION,en_US
dc.subjectMETHANE,en_US
dc.subjectHYDROGEN SULPHIDE,en_US
dc.subjectGAS YIELDS,en_US
dc.subjectSOLID WASTES.en_US
dc.titleSTUDY ON THE EFFECTS OF CHELATING AGENTS ON HYDRAULIC RETENTION TIME, METHANE AND HYDROGEN SULPHIDE GAS YIELDS FROM SOLID WASTESen_US
dc.typeThesisen_US
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