Bioremediation through the use of Biochar

Biochar is becoming an innovative step towards addressing soil deterioration that occurs through over-farming and unsustainable chemical fertilisation.

Biochar can increase soil fertility, agricultural productivity and protect against foliar and soilbourne diseases. It is a stable solid, rich in carbon and can endure in soil for thousands of years.

‘Biochar’ is a term used for charcoal when it is used for particular purposes, namely as a soil amendment. Biochar is created by the pyrolysis of biomass (firing biomass without oxygen). In this context, we have used refused tea as biomass. Biochar can increase soil fertility, increase agricultural productivity and provide protection against some foliar and soil-bourne diseases. Biochar is a stable solid, rich in carbon and can endure in soil for thousands of years. Biochar is also under investigation as an approach towards carbon sequestration, to produce negative carbon dioxide emissions. Thus, Biochar has the potential to help mitigate climate change by way of carbon sequestration.

As part of Dilmah Conservation’s Biomediation Programme, a new machine was invented to convert waste tea generated from our own factories into Biochar. With the creation of a prototype, the tea waste was successfully and efficiently converted and Dilmah will place these machines in some of our plantations and main agriculture hubs to improve productivity. This machine can additionally convert paddy husk and sawmill waste into Biochar.

This machine uses Dilmah’s waste oil (a by-product of tea bagging machines) to ignite the process and to produce the energy required for the conversion. We have installed suction methods to forcibly take the toxic syn gas out of the machine, in order to reduce airpollution at this stage and purify the gas using a few layers of water screens. At a later stage, this gas is used to fuel the machine and dry the biomass.

We have seen visible results; not only in the yield, but also in the quality of the texture of the leaf. The leaf is succulent with good colour. We are continuing to see progress in terms of tasting and identifying contents.

- Jeevanthe Senaratne,

Manager, Pelmadulla Tea Estate