ABSTRACT
In Nigeria Arable land covers approximately 745,000km2 of the total land area and at present organic farming is not prevalent, encouraged or facilitated despite its sustainability advantages. The outputs (Biogas and digestate). The digestate when properly harnessed can be used as a substitute for inorganic fertilizer.
Preliminary studies (methodology) were undertaken to determine the liquid absorbability of non-shredded grass vise-visa dry shredded grass, the mineral content of digestate and to determine the moisture content of fresh elephant and spear grass which are commonly available. After these process we concluded an internal combustion powered machine was designed and fabricated to shred dry and steve crushed grasses to be used as absorbent of digestate.
The machine was evaluated (results) for performance using different samples of properly dried elephant and spear grass for shredding and sieving using 3mm hole, the shredded grasses samples were mixed with discharge digestate collected from a biodigester to produce organic fertilizer as nitrogen (N), Phosphorous (p) and potassium (k) as well as a range of other macro-and micronutrients, calcium (ca), magnesium (mg), iron (Fe) etc.
The shredding time, machine throughout capacity efficiency, mass of fibre and liquor were determined. T he results obtained reveal that a shredding fore and power of 197N and 2hp were required by the machine. Also, a torgue of 2.4625Nm, volume of feeder hopper of 0.026m3, volume of sieve compartment of 0.0567m3 and area of sieve compartment of 0.1134m2 were established. For the elephant grass samples used, an average value of efficiency (90.97%), machine through put capacity (1.225g/sec), shredding time (126.54seconds), percentage loss (8.393%), Fibre (288.58g) and liquor (119.83g) were established.
Similar result were obtained with spear grass; efficiency (90.50%), machine through-put capacity (1.225g/sec), shredding time 126.54 seconds), percentage loss (8.32%),fibre (294.12g), and liquor (118.85g). the outcome of the results revealed that both solid fertilizer (fibre and liquid fertilizer (liquor) were extracted from the digestate, and an average mass of 138.86g can absorb 269.55g of liquid digestate to produce NPK organic fertilizer
