April 9, 2011
School of Engineering, Coimbatore
 

For quite some time now, all organic waste at the Amrita campuses is composted. A layer of vegetable peels and other food waste is covered with cow dung; dry leaves and soil are also placed on top.
 

For about six weeks, the pile is manually mixed and turned using spades and pickaxes, as the aerobic bacteria go to work, converting the waste into nutrient-rich compost.
 

Now a new compost aerator designed and fabricated by a team of final-year students of B.Tech. (Mechanical Engineering) at our Coimbatore campus may well obviate the need for this labor-intensive mixing and turning.
 

Initial tests conducted using this new device also showed a dramatic reduction in the time taken for composting from six weeks to three and a half weeks.
 

“There weren’t any standard designs for such a mechanism,” stated Dr. Thirumalini who guided the student team of Ashwin Kumar C. S., Gowtham G., Vignesh V. and Viswanath A. V. “But the team improvised. The idea was to serve the purpose of compost agitation with a robust device built with the least possible cost.”
 

The design is elegant and simple. A drum with blades aligned on its surface, at calculated angles, is mounted towards the rear of a general purpose tractor. This drum-blade setup, is supported on a frame attached to the tractor and overhangs on the left side. When it rotates, in a direction opposite to that of the rotation of the wheels, it mixes and aerates the compost pile.
 

“The drive to the drum is taken from the 55bhp engine of the tractor itself, through a heavy-duty differential,” explained the students. “A speed of about 100 rpm is attained at the drum. A hydraulic jack is installed to lift the overhanging drum to an angle of about 65 degrees for ease of transportation.”
 

“Our compost turner helps churn the compost; as a result, good aeration and mixing is achieved.”
 

Why is this important?
 

“When the compost is compacted, air does not reach the core of the compost pile. The aerobic bacteria cannot work in the absence of air. Hence mixing and turning are very important. Our compost aerator mechanizes the process of compost aeration.”
 

The device can also potentially be of immense help to farmers, as they begin to turn to organic farming techniques and make their own compost.
 

“We are very happy to have had the opportunity to make this useful contribution to our college before we bid goodbye next month,” stated the students. “The team from the fabrication workshop and automobile engineering workshop were of great help and we thank them for their support. Most of all, we thank our guide Dr. Thirumalini.”
 

“In light of the ongoing Amala Bharatam Campaign (ABC) initiated by the Mata Amritanandamayi Math, such projects by budding engineers will go a long way in shaping a greener tomorrow,” added Dr. Thirumalini. “We will continue to work on the compost aerator to improve its effectiveness; we want to investigate the use of better and lighter materials also.”