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20202
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Subject: Agricultural Engineering × End date: 2020 × Start date: 2020 × Type: Thesis ×
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    ThesisItemOpen Access
    Investigations on high rate anaerobic bioreactor for energy production from rubber latex processing effluent
    (Department of Farm Machinery and Power Engineering, Kelappaji College of Agricultural Engineering and Technology,Tavanur, 2020) Megha, A S; KAU; Shaji James, P
    Agro-processing industries often contribute significantly in pollution due to discharge of untreated effluents. By anaerobic digestion of these organic effluents, methane rich gas can be produced which is suitable to generate electricity and process heat. But conventional biogas plants are slow in operation with long hydraulic retention times of 35 to 40 days which necessitates large digester volumes. So, anaerobic digestion of high volume agro-processing effluents is feasible only through high rate bioreactors which can reduce hydraulic retention time to few hours. Rubber latex processing effluent (RLPE) is a dilute waste water for which high rate anaerobic treatment can be an affordable technology. Hence, an investigation was taken up to study the performance of Up-flow Anaerobic Hybrid Bioreactor for energy conversion of rubber latex processing effluent (RLPE). Physico-chemical characteristics of RLPE samples were tested and found that RLPE was a dilute waste water with pH in the acidic range. BOD: COD ratio of 0.44 obtained in this study showed good biodegradability of RLPE. A batch anaerobic digestion study was conducted as a preliminary experiment to investigate the biomethanation characteristics of RLPE. The experiment consisted of four treatments having different composition of RLPE with inoculums replicated thrice. This study could prove that RLPE could be subjected to biomethanation and cow dung slurry can be used as inoculum. Even at a lower inoculum: substrate ratio of 1:2, the system could be started up yielding substantial amount of biogas coupled with good TS reduction. Performance of field scale Up-flow Anaerobic Hybrid Bioreactors (UAHBR) was assessed by operating them at different HRTs of 10, 7, 5, 3 and 2 day. During the study an interruption of 2 months in operation occurred due to shut down of the processing unit due to Covid 19. After interruption of 2 months reactor recovered within one month and it proved that hybrid bioreactor could be restarted easily after a shutdown for few months. Reactor was stable in operation during 10, 7, 5, 3 and 2 day HRTs and exhibited good process efficiency with better pollutant reduction and biogas production. Performance was seen deteriorated beyond 5 day HRT. The bioreactors were operated successively at reduced loading rates corresponding to the longer HRTs after reaching the shortest HRT of 2 day. It was observed that there was no considerable difference in daily biogas production with the earlier values obtained during the progressive decrease in HRT. This revealed that the bioreactors would have achieved the maximum possible microbial population already and there was no further improvement in performance on further passage of time. The performance parameters obtained in the investigations with field scale reactors were used for evolving guidelines to design a full scale anaerobic bioreactor. The UAHBR performance was quite satisfactory at 5 day HRT with respect to pollutant reduction as well as energy production. Hence as criteria, full scale plant was proposed to be operated at 5 day and the corresponding reactor volume was 27 m 3 with 7.2 m 3 gas holder volume. The biogas expected to be produced from the full scale plant can be used in a biogas fired rubber sheet dryer which can save about 500 kg of fire wood per day currently used for drying rubber sheets.
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    ThesisItemOpen Access
    Investigations on soil crop and machine parameters towards the development of a root crop harvester
    (Department of Farm Machinery and Power Engineering, Kelappaji College of Agricultural Engineering and Technology,Tavanur, 2020) Basavaraj; KAU; Jayan, P R
    The tractor drawn root harvester was designed and developed by considering soil, crop and machine parameters and performance evaluation of the machine was carried out in the experimental area at KCAET, Tavanur and different farmers’ fields at Palakkad and Thrissur districts. The developed machine mainly consists of main frame, power transmission system, digging and soil separator units. The effect of three blade geometries viz., straight edge, V-type and crescent blades at three rake angles of 15, 20 and 25 deg. and at three forward speeds of 1.5, 2.0 and 2.5 km h-1 for the digging unit of the harvester were evaluated in terms of draft, digging efficiency, per cent damage of tuber/rhizome and fuel consumption of tractor mounted harvester for harvesting coleus, ginger and turmeric. The best optimal condition was observed at a forward speed of 2.0 km h-1 with 20 deg. rake angle for V-type blade. The soil separator unit of the harvester was evaluated along the digging operation. The soil separator unit was tested with different operational parameters viz., diameter of crank 40, 60 and 80 mm and spring tension 800, 1200 and 1600 N m-1. The best optimal operational conditions were observed at a spring tension of 1600 N m-1 with 80 mm diameter of crank. The maximum draft of 2009.52 N was recorded in straight blade while the minimum of 1418.66 N was observed in V-type blade. The maximum digging efficiency of 99.89 per cent was noticed in V-type blade, whereas the lowest of 84.15 per cent in straight edge blade. The least damage coleus of 0.59 per cent was observed in V-type blade whereas highest of 5.5 per cent was obtained in crescent blade. Among the different type of blades tested, the less fuel consumption of 3.80 l h-1 was noticed for V-type blade, whereas the maximum of 4.98 l h-1 for straight edge blade. In the case of harvesting ginger, the maximum draft of 2176.33 N was recorded in straight edge blade while the minimum of 1374.31 N was observed in V- type blade. The maximum digging efficiency of 99.57 per cent was noticed in V-type blade, whereas the lowest of 80.40 per cent in straight edge blade. The least damage coleus of 0.86 per cent was observed in V-type blade whereas highest of 6.05 per cent was obtained in crescent blade. Among the different type of blades, the less fuel consumption of 3.74 l h-1 was noticed for V-type blade, whereas the maximum of 5.19 l h-1 for straight edge blade. In the case of harvesting of turmeric, the maximum draft of 2192.08 N was recorded in straight edge blade while the minimum of 1390.06 N was observed in V-type blade. The maximum digging efficiency of 99.50 per cent was noticed in V-type blade, whereas the lowest of 81.91 per cent was recorded with the straight edge blade. The least per cent damage coleus of 0.74 per cent was observed in V-type blade whereas highest of 7.3 per cent was obtained in crescent blade. Among the different type of blades, the less fuel consumption of 4.0 l h-1 was noticed for V- type blade, whereas the maximum of 5.57 l h-1 for straight edge blade. The field capacity of the machine for coleus, ginger and turmeric were 0.15, 0.16 and 0.16 ha h-1 respectively and the field efficiencies were 86.11, 88.89 and 88.89 per cent respectively. The soil separation indices of root crop harvester for coleus, ginger and turmeric were found out as 82.71, 73.22 and 68.82 per cent respectively where as the conveying efficiencies were 90.70, 87.55 and 89.71 per cent respectively. The estimated cost of the prototype tractor drawn root crop harvester was as Rs. 60,000. The cost of operation was found out as Rs. 767.57 per hour. The saving in cost over root crop harvester for three root crops was 89 per cent. The machine has BEP of 40 h, PBP as 1.5 years and BCR as 10.7.