Design and development of a high capacity Salvinia Harvester

Abstract

Salvlnla molesta locally known as 'African Payal* ia a noxious floating typo aquatic weed in many parts of the humid tropics. Kerala Agricultural university developed a mechanical device to harvest this menacing weed. An investigation on the performance of the prototype Salvinia Harvester was carried out under various conditions. Prototype ejector E1 with secondary flow straight and primary flow inclined at 900 ejectors E2 and E3 with primary flow straight end secondary flow inclined at 400 and 20° respectively and ejector E4 with secondary flow straight and primary flow inclined at 300 were tested along with circular mouth (M1), adjustable rectangular mouth (M2) and elliptical mouth (M3)• Experiments were also conducted to find out the optimum depth of mouth below the water level. The study revealed that clogging was a serious problem for the prototype Salvinia Harvester, where the weed was in the initial stages of third growth phase. Ejectors E1 and E2 showed clogging when tested with all the different feeding mouths. The E4-M2 and E4-M3 combinations yielded almost identical harvesting capacity of 11 t/hr at one metre static lift mad 12 t/hr at 40 cm static lift without any problem due to clogging. All these experiments conducted revealed that the ejectors E3 and E4 can be used under ell conditions of weed growth without clogging along with mouths M2 and M3. The machine is capable of removing weeds at the rate of 16 t/hr where the spread density value was around 16kq/m2 (160 t/ha) like Kuttanadu area. Hence the machine would be capable of Removing the weeds in one hectare in 10 hours. The estimated cost of operation amounted to Rs. 353/- per hectare which compared favourably with the reported costs of Rs.900/- to Rs.2700/- per hectare for manual collection and disposal.