Production of bio-fertilizer from Jatropha cake blended

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1 Production of bio-fertilizer from Jatropha cake blended M. M. Manyuchi * and M. Nyamunokora Department of Chemical and Process Systems Engineering, Harare Institute of Technology, Ganges Rd, Belvedere, Harare, Zimbabwe *mmanyuchi@hit.ac.zw ABSTRACT This study aimed at assessing the feasibility of producing a bio-fertilizer from jatropha cake blended with vermicompost and vermiwash. Experiments were done to determine the optimum temperature and ph for digestion, as well as the optimum drying temperature for the bio-fertilizer. Further tests were carried out to determine the moisture content and the nitrogen, phosphorus and potassium content (NPK) of the biofertilizer. Vermicompost and vermiwash with an NPK content of 2.32%, 1.92% and 1.56% respectively was blended with jatropha cake and pelletized to a bio-fertilizer. The resultant pellets had an NPK content of 11.62%, 4.20% and 3.15% respectively with a moisture content of 3.49% and a ph of 7. This assessment indicated the feasibility of blending jatropha cake and vermi-products to bio-fertilizer pellets. Keywords: Bio-fertilizers, jatropha cake, pellets, vermicompost, vermiwash 1. INTRODUCTION The rapid increase in the Zimbabwean population has contributed largely to the gradual increase in crop production. Hence the development of the fertilizer industry is very important in order to improve agricultural productivity and enhance food production to feed the increasing population. Zimbabwe has also been focusing on alleviating potential fuel shortages through the production of bio-diesel. As this industry continues to grow, an excess of jatropha cake is bound to be created and means to dispose of it will be required. This cake can be used as stock feed, in biogas production and also in bio-fertilizer production. Also since agricultural production is rapidly expanding, the rampant use of chemical or inorganic fertilizer is contributing largely to the deterioration of the environment through 1 P a g e

2 depletion of fossil fuels, emission of toxic gases such as carbon dioxide and contamination of water resources. It is also contributing to the deterioration of the ecological system due to the leaching of nitrates. These are giving rise to environmental problems both locally and globally. The imbalanced use of chemical fertilizers has adversely impacted agricultural productivity and caused soil degradation. Meanwhile the rejuvenation of degraded soils is a major concern. At the same time, the production of vermi-products i.e. vermicompost and vermiwash has also increased in a bid to promote sustainability in the agricultural sector. Environmental degradation has become the major threat confronting the world therefore there is a need for the replacement of synthetic fertilizers with bio-fertilizers. This study therefore focused on assessing the potential to produce bio-fertilizer pellets from jatropha cake blended with vermicompost and vermiwash. 2. MATERIALS AND METHODS 2.1 Materials The jatropha cake (Figure 1) was collected from Finealt Engineering and vermicompost and vermiwash was collected at the Harare Institute of Technology laboratory vermicompost research group. Preliminary characterization of the Jatropha cake was carried out and a summary of the specifications is shown in Table 1. Determination of the nitrogen content in jatropha cake and the final product required the use of sodium hydroxide, chlorine, hydrochloric acid was used. Figure 1: Jatropha cake used in this study 2 P a g e

3 Table 1: Jatropha cake specification Element Amount Moisture content 1.42% Nitrogen content 4.44% Phosphorus content 2.09% Potassium 1.68% Carbon content 47.75% 2.2 Experimental Determination of the optimum temperature for digestion A sample of 10g of jatropha cake was weighed out and pulverized using a pestle and motor. The pulverized cake was weighed and the mass was noted. The jatropha cake was then mixed with water in a 1:2 ratio. Approximately 5g of vermicompost was mixed with vermiwash in a ratio of 1:2. The mixture was then added to the mixture of jatropha cake and water. Four samples were prepared and the ph each sample was measured and regulated. A water bath at set at different temperatures ranging between 25 C and 65 C were used to heat up the mixture Determination of the ph of jatropha cake Mixtures of jatropha cake, vermicompost and vermiwash prepared in a similar manner as that in were thoroughly mixed. The feed mixture was placed in a water bath at 30 C for 10 minutes. The ph of the mixture was measured using a ph meter. The procedure was repeated for three samples Determination of the optimum ph for digestion The ph of the mixture of the jatropha cake, water, vermicompost and vermiwash was measured and recorded. A known amount of hydrochloric acid was added to reduce the ph to 6, 6.5, 7 and 8. The ph of 8 was the control for the experiment. The sample was left for 14 days for digestion. After 14 days the mass of the solids that remained was 3 P a g e

4 determined. The mass of the solids consumed was determined and was recorded in a tabular form Determination of the moisture content of the dry and wet bio fertilizer The mass of the empty beaker was firstly measured (M c ).The sample of digested cake placed in the beaker. Mass of the beaker together with the granules (M CW ) was determined and recorded. The beaker was placed in a drying oven that was set at 105 C and left in an oven for overnight. The beaker was removed and allowed to cool to room temperature. The mass of the beaker together with the granules (M CD ) was determined and recorded. From the results mass of dry granules (W solid ) and the mass of free water (W Water ) was calculated. Also the percentage water content will be determined using the following equation: %water content = (W water / W solid ) 100% Determination of the optimum temperature for drying 50g of the wet bio fertilizer from jatropha cake blended with vermicompost and vermiwash was firstly measured and put in a beaker. Six samples were prepared for the same mass of wet bio-fertilizer. The beaker was placed in a drying oven and the drying time for each sample was approximately 6hrs. Each sample was dried at a different temperature but the drying time was kept constant. The drying was performed at a temperature of 90 C, 95 C, 100 C, 105 C, 110 C, 115 C and 120 C. After drying the moisture content for each sample was determined using a moisture content analyzer. The results were recorded in a tabular form Determination of the feasibility of producing bio-fertilizer pellets 40g of jatropha was firstly weighed using an electronic balance and the mass was recorded. The weighed jatropha cake was then crushed using a pestle and motor to powder form (pulverized). The crushed sample was weighed to determine any mass loss and the mass was also recorded. The pulverized cake was put in a conical flask. Water was added to the cake in the ratio of 1:2 (cake: water). Approximately 34g of vermicompost was mixed with vermiwash in the ratio 1:2 respectively. The mixture was then added to the mixture of jatropha cake and water. 2 ml of hydrochloric was then 4 P a g e

5 added to the mixture and mixed in thoroughly. The conical flask was left open in order to allow aerobic digestion to take place. The conical flask was put in a water bath controlled at a steady temperature of 45 C. The mixture was left for 14 days. After fourteen days digested cake was separated from the liquid using a filter cloth or a wire mesh. The digested cake was composted using forced air for one day. Pelletizing of the composted cake was done. The moist granules were dried in an oven at a temperature of 110 C. 2.3 Analyses tests Determination of the carbon content in the jatropha cake The carbon content in the sample was measured by evaporating water from a sample of jatropha cake. The sample was burnt to obtain ash. The ash obtained is the carbon content. The composition of carbon in jatropha cake was calculated Determination of NPK content of jatropha cake and the bio-fertilizer The nitrogen, phosphorous and potassium content were determined by standard procedures (APHA, 2005). 3. RESULTS AND DISCUSSION 3.1 Determining the optimum temperature during digestion In order to determine the best optimum temperature, a series of experiments were carried out by varying the temperature of reactants from 25 C to 65 C. The experimental results show that the optimum temperature for maximum rate of digestion is 45⁰C as it resulted in more solids being consumed. At temperatures lower than 45⁰C the activity of the micro-organisms was low and lower volumes of solids were consumed. As the temperature increases to 45 C, the yield of bio fertilizer increased. However, at operating temperatures above 45 C the volume of gas produced decreased. This was attributed to denaturing of micro-organisms 3.2 Results for determining the optimum ph during digestion The optimum ph was determined by measuring the amount of slurry that remained at different ph. From the results obtained, the decomposition rate increases ph moves to 5 P a g e

6 neutral. At a ph 7 a lot of solids were consumed indicating that that the process of digestion favors a ph of 7. Therefore it shows that the bacteria favor a ph of 7. But however as ph becomes acidic or basic, the volume of gas produced decreases. Hence acidic and basic condition affects the activities of bacteria. Therefore at neutral ph the yield of bio fertilizer is at its maximum. 3.3 Determination of moisture content of wet and dry bio fertilizer The average moisture content of dry bio-fertiliser is 3.49%. From the literature the average moisture content required by a particle to avoid dusting and also for easy dissolution is between %.From the experimental results the average moisture content was obtained as 3.49% which is between %. 3.4 Results for determining the optimum temperature for drying Several experiments were done to determine the optimum temperature for drying biofertilizer. From the experimental results above, a temperature of 110 C is required for the optimum removal of moisture in the bio-fertiliser. After 110 C the mass of water removed remained constant. 3.5 Bio fertilizer quality tests results The bio fertilizer pellets were obtained by blending the vermi-products, vermiwash and vermicompost then blending with the jatropha cake. From Table 2 pelletized bio-fertilizer has more nutrient content as compared to the liquid fertilizer. Table 2: Results for NPK of the materials Sample Nitrogen (%) Phosphorus (%) Potassium (%) Jatropha cake Liquid bio-fertiliser Pelletized bio-fertiliser P a g e

7 4. INDUSTRIAL PROCESS DESIGN Process design establishes the sequence of chemical and physical operations, operating conditions, the major specifications and the general arrangement of equipment needed to ensure proper functioning of the process. 4.1 Process synthesis and selection The selection of an appropriate bio-fertilizer manufacturing process was based on a number of factors which included: cost of setting up the system, pollution level, and product yield and energy consumption. As an analysis of selection criteria, a decision matrix was made which sums up the individual mark values of each method such that a method that ends up with the greatest number of marks become the suitable chosen method. 4.2 Process description The detailed process description is given in Figure 1. The raw materials required are jatropha cake and water blended with vermicompost and vermiwash. The jatropha cake is firstly crushed to powder form since it is in the form of flakes. This is done to facilitate the rate of digestion or decomposition. Crushing was carried out using a hammer mill. The cake is broken down into smaller pieces then it is rubbed into powder by a set of swing hammers pinned to a rotor disc. From the crusher the pulverized cake is pumped to the thermal hydrolysis reactor using a high density solid pump. The cake is heated at a temperature of 60 C for 30 minutes. This is done to remove excess oils in the cake and trypsin inhibitors. After thermal hydrolysis the cake is pumped to the mixing tank. Water from the reservoir is added to cake in the ratio 2:1 respectively. Hydrochloric acid is also added in order to reduce the ph of the jatropha cake. This parameter is very important and it needs to be controlled during aerobic digestion. Vermicompost and vermiwash are added in the ratio 1:2 respectively. Blending with vermicompost and vermiwash is done to increase the nutrient content of the bio fertilizer. Internal screw mixtures are used for mixing the mixture. The mixture is then pumped using a centrifugal pump into a batch flow aerobic digester. The temperature inside the digester is maintained at 45 C. 7 P a g e

8 Gas is also produced during aerobic digestion, the main constituent of this gas is carbon dioxide, this can be used for preservation in beverage manufacturing companies. After a retention time of 14 days the mixture is moved to filtration centrifugal separators. The liquids and the solids are separated by the use of centrifugal force. Liquid fertilizer filters through the wall of the centrifuge basket. The slurry remains in the centrifugal basket. The slurry is then pelletized using an extruder. The slurry is compressed and spherical pellets are produced. The pellets are dried at a temperature of 110 C to a moisture content of approximately 4% using a rotary drier. The dried cake is then cooled to 30 C. The pellets are lifted to a screening section using a conveyor belt. They are screened using vibrating screeners. The fine particles are recycled back directly to the mixing section whilst the course particles are firstly crushed before being sent to the mixing section. The required sizes are then moved to the storage vessel and the bio-fertilizer is packed according to customer requirements. excess oils Trypsin inhibitor Water HCl Biogas Liquid fertiliser Jatropha cake crusher Thermal hydrolysis reactor mixer Biodigester Filtration centrifugal separator Heat Heat vermicompost vermiwash air fines Pelletised biofertiliser Hot air Screener Cooler Dryer Extrusion (Pelletiser) Mixer Water Starch Figure 1: Bio fertilizer pellets production process 8 P a g e

9 5. CONCLUSION Pelletized bio fertilizer from jatropha cake is beneficial to the environment keeping it clean and green. A pelletized bio fertilizer with NPK content of 11.62%, 4.20% and 3.15% respectively was obtained and moisture content of 4.32% was also obtained. REFERENCES Bhatttacharyya P. and Kumar R. (2000), Liquid bio fertilizer current Knowledge and future prospect, National seminar on development and use of bio-fertilizers, biopesticides and organic manures, pp Chivandi E, Fushai F. (2005), A comparison of the nutrient and anti-nutrient composition of industrially processed Zimbabwean Jatropha curcas and Glycine max meals, Pakistan Journal of Biological Sciences, pp El-Yazeid A. A, Mady M.A. (2007), Enhancing growth, productivity and quality of squash plants using phosphate dissolving microorganisms International Annual Symposium on Sustainability Science and Management, pp Khosro M, Yousef S. (2012), Bacterial bio-fertilizer for sustainable crop production, ARPN journal of agricultural and biological sciences, pp Manzanilla D. O. (2006), Overview of Organic Agriculture: Definition, Scope, Principles, and History, Paper presented at the Trainers Training Program for the Promotion of Organic, pp Ososanya E, Mahmoud W, Adebayo A. (2008), The Design of an experimental anaerobic digester for organic waste processing, Proceedings of the 2008 ASEE Annual Conference& Exposition, pp Palsania J, Sharma R, Srivastava J.K, Sharma D. (2008), Effect of moisture content variation over kinetic reaction rate during vermicomposting process, Applied Ecology and Environmental Research, pp Singh R. N. Vyas D.K. (2008), Experience on holistic approach to utilize all parts of Jatropha curcas fruit for energy Renewable Energy, pp P a g e

10 Spets J. P, Ahtila P. (2004), Reduction of organic emissions by using a multistage drying system for wood based biomass, Drying Technology, pp Subba N. S. (2001), An appraisal of bio-fertilizers in India, The biotechnology of biofertilizers, Narosa Pub. House, New Venkatashwarlu B, (2008), Role of bio-fertilizers in organic farming, Organic farming in rain fed agriculture: Central institute for dry land agriculture, pp P a g e