Vibro-thermal disinfestor (VTD) is a simple electrically operated device for disinfestations of food grains. Insects in all their development stage are susceptible to killing by heat when exposed to temperatures of 55 to 60°C for 30 mins. The process is rapid, non-chemical alternative to fumigation and kills all developmental stages of stored grain insects. The system is amenable for scale up and is mobile. The treatment has no effect on germination of seeds as well. Its capacity is of 40 kg/hr.

The system is simple, can be fabricated without much capital investment and useful for farmers, merchants and exporters of food grains.

VTD can be operated by one person and no technical knowledge is needed.

Fumigation as a means of grain disinfestations has its serious limitations. It can leave residues in the food grains that are toxic to humans. Also it is not eco- friendly as fumigants mostly used are ozone depleting substances and are going to be phased out.Therefore, heat/ thermal disinfestations of food grains can be a simple Vibro Thermal Disinfestor (VTD) alternative. Vibro-thermal disinfestor (VTD) is a simple electricity operated device for disinfestations of food grains. Insect infestation i.e. proliferation of insects on stored grains and pulses is a major cause of concern. It causes enormous losses in quantity and degrades the quality of food grains. There is kernel damage, webbing, adding off odours etc. due to infestation. Further, nutritive value of infested grain is adversely affected. The consumption of infested foods has adverse effects on health such as digestive and pulmonary disorders. Insect infestation jeopardizes export and countries may suffer huge economic losses.

Insects in all their development stage are susceptible to killing by heat when exposed to temperatures of 55°C to 60°C for 30 mins. Examples exist where fluidized-bed heating and solar heat are in use for disinfestation on a commercial scale in Australia. BARC has also designed, fabricated and tested a vibro-thermal disinfestor for insect disinfestation of food grains to achieve a shelf life extension upto one year. The system is amenable for scale up and is mobile. The treatment has no effect on germination of seeds as well. The system is simple, can be fabricated without much capital investment and useful for farmers, merchants and exporters of food grains.

VTD SYSTEM

Air Heating System

It consists of an insulated box made up of plywood, a blower, a heating coil and a sensor. The blower, the coil and air circulation are arranged in such a manner so as to achieve maximum air heating. The temperature of food grains is raised by passing hot air over it. Air is blown through heater and circulated through the system using the blower.

Conveyor System

The conveyer unit is housed in the plywood box. It consists of 6 trays and a vibrator. There is one hopper fitted to the box for feeding the grains and an outlet for collecting the treated grains.

OPERATION

Grains are loaded in top hopper and passed at a pre-determined flow rate across six sloping metal trays. The tray system is provided with light vibrations to ensure the flow. During flow the grain is heated to a predetermined temperature by hot air that kills all developmental insect stages including the larval and pupal stages of those species that develop inside grain kernels. The hot air is supplied from the top heating module and passed over the material evenly and uniformly with the help of the blower. For monitoring the temperature inside the box sensors are fitted. The grain is collected at the bottom tray after treatment. The heat treated grains has to be stored in an insect impermeable packaging material or in tight silos for getting a shelf life extension up to one year. The power consumed for processing the grains of 40 kg/hr is one unit of electricity (1kWh).

FABRICATION

The unit has been designed in such a way so that it can be fabricated in any workshop with welding and cutting facilities. The material cost required for VTD fabrication is ~ Rs. 11,000. The other cost involved is fabrication and painting etc. It needs 5 amps single phase 230 V AC supply to operate.

MANPOWER

Vibro-Thermal Disinfestor can be operated by one person and no technical knowledge is needed.