KOURA Windékpè Tatiana (2015). Analysis of the mode and utilization technologies of palm oil mill wastes and its application for the production of three tropical vegetables (Lycopersicon esculentum, Amaranthus cruentus, Corchorus olitorius) in Southern Benin. Department of Natural Resources Management, Faculty of Agronomic Sciences, University of Abomey Calavi, Benin republic, 252p.
Promotor: Prof. Dr. Ir. SINSIN A. Brice.
Abstract: Owing to the revitalization of the palm oil manufacturing sector in South Benin, some mills are confronted to the problems of waste management although there are many ways these wastes can be reused. To assess how these wastes are managed, waste production systems were determined by numerical classification and considering palm oil production factors and quantities of waste, and characterized through aprincipal component analysis. A semi-structured survey was conducted among 335 oil mills. Four extraction methods (EM) had been identified: traditional (T), improved (I), modern (M) and semi industialized (SI). The amount of wastes generated by each category of oil mill was determined by evaluating that generated by 7 T, 4 I, 4 M and 9 SI oil mills randomly chosen. The study identified four classes of waste production systems: small, medium, large and very large. They produced on average per year 12.4 ± 22 t; 31.3 ± 52.8 t; 132.7 ± 59.1 t and 800.7 ± 418.1t empty fruit bunches; 5.6 ± 10.3 t; 13.6 ± 23.1 t; 135.2 t ± 95.2and 637 ±312.6 t fibers and 15.1 ± 23.7 t; 40.9 ± 28 t; 233.4 ± 172.1 t and 572.6 ± 90.3 t sludge respectively. They were discriminated by the nature and size of plantations, the financial capacity of the mills owners to hirelaborers and the quantities of waste produced. The use of all the amount of generated bunches and fibers did not depend on the quantity produced. Thus, the relationship between the EM improvement andthese wastes management was analyzed. The effect of the EM, the type of waste and their interaction on the calculated indices (user’s percentage, the commercial value, the Rejection Rate, the Importance Value, and the Use Value) were assessed using the log linearly analysis. The fidelity level of each use for each mill was calculated. However, within categories, all mills considered each use at the same level. Whatever theEM, the surplus waste was eliminated either by discharging into the environment or selling. These options were more observed when the EM was improved. Ethnobotanical indexes were used to evaluate the importance and value of palm oil mill wastes in palm oil production areas. A Two Principal Component Analyses was performed to characterize palm oil mill waste uses in link with the production areas. The results showed that the sludge has no importance for mills ‘owners. Oil mills that used the whole amount of bunch and fibers produced were those for which the waste was important for a unique use. The palm oil mill waste contributed more to environmental pollution in Plateau, Couffo and Mono. In order to find immediate solutions to mills facing waste management problems, we proposed solid wastes co-composting and the use of this compost in vegetables production. The analysis of the sustainability of agricultural practices implemented by producers in relation to their knowledge revealed that the use of empty fruits, bunches and fibers depends on producers’ knowledge. These wastes were spread by local application (76.5%) or mulching (33.3%) in plantations or indirectly after composting. Composting is made either by heaping, in combination with pigs breeding or in pits. Composting is a process unknown by 67.5% of mills’ owners. The difference between those who know about it and use it, and those who know about it but do not use it is based on their knowledge of composting advantages. The physico-chemical composition of these wastes were assessed using an ion chromatograph and revealed that these wastes are relatively rich in nutrients except in phosphorus. The co composting of empty fruits bunches and fibers was tested in eighteen bins installed in a split plot design not repeated. Composting method (No shelters (NS) andunder shelter (US)) was the main factor and the type of manure (No manure (NM), poultry manure (PM) and cow dung (CD)) was the secondary factor. As results, the decomposition of wastes and the compost quality obtained varied significantly (p <0.05) with the method of composting and type of manure used. The lowest ratio Carbon/Nitrogen (C/N) 18.38 was obtained in compost where FV were used and made without shelter. The FV had improved the quality of composts in phosphorus content. However, the analysis of leachate revealed high loss of total nitrogen (88.3 ± 12.6mg / l to 146.2 ± 16.4mg / l), potassium (37.2 ± 0.8 to 53.3 ± 1.2 mg / l) and phosphorus (107.9 ± 23.7 to 187.4 ± 65.8mg / L). The high levels of chloride (1301.3 ± 195.8 to 1656.7 ± 147.8 mg / l), biological oxygen demand (3499 ± 425.8 to 6370.7 ±1031.7) shows the need to avoid making the compost heap directly on the ground. The effectiveness of composts was tested with the production of Lycopersicon esculentum, Amaranthus hybridus and Corchorusolitorius were evaluated through a split-split plot design with composting method as the main factor and the types of manure and composts application rates (0t / ha 5t / ha to 10t / ha and 20t / ha) as secondaryfactors. There were 24 treatments and 4 replicates per vegetable. The PM-based compost produced with no shelter (NS) increased amaranth growth and yield (19,2t / ha) compared to others composts. However,in the case of Corchorus olitorius, composts made from waste and CD performed US was recommended. The application of composts increased the yield of Corchorus olitorius and Lycopersicon esculentum from10t / ha.
Keywords: Palm oil mill wastes, waste management, extraction method, type of manure, composting method, vegetables production