Methane eating bacteria key to greenhouse gas reduction? 


Dr Rashad Syed


Seven years ago, Dr Rashad Syed was living in India, last week he graduated with a PhD having made great strides to tackle one of his new home country’s leading climate change challenges.

In New Zealand, the majority of methane emissions are from the agriculture sector (enteric fermentation, manure management) and the remainder from solid waste disposal, coal mining and natural gas leaks.

Mr Syed says he felt the strong desire to help tackle a big problem in New Zealand and decided upon the environmental cost of agriculture’s methane emissions.

“Greenhouses gases keep heat in the atmosphere and carbon dioxide, methane, nitrous oxide, and fluorinated gases all contribute, but methane is especially relevant with New Zealand’s high agricultural output. Biofilters offer much promise for mitigating methane emissions from dairy effluent ponds.

“These open ponds contribute more than 50 per cent of total on-farm methane emissions and are likely to increase in future. I wanted to pursue a popular possible solution - the use of soil biofilters seeded with methanotrophs, which are essentially methane eating bacteria, which have the capability to remove greenhouse gas methane emissions.’

Earlier and current New Zealand studies looked at using volcanic pumice soil as biofilter. However, the limited availability of volcanic pumice soil and associated transportation costs limited the wider application of this technology within New Zealand and internationally. 

“We want to make biofilters as cost-effective as possible, find a material that we can introduce and sustain active methanotroph populations in that can operate in all weathers for prolonged periods with little or no maintenance,” says Dr Syed.

To do this there was a need to fill a knowledge gap around the characteristics of these populations using molecular approaches and how they respond to different conditions.

Dr Syed’s research sought to understand the activity of these bacteria and how they might be employed in other materials. Several cheap and widely available materials were tested to assess their efficacy to remove methane and support active growth of methanotrophs. The potential biofilter materials included on-farm soil, pine biochar, garden waste compost, and weathered pine bark mulch.

The new materials were assessed with and without a small amount of volcanic pumice soil to boost the population and all materials supported the growth and activity of methanotrophs. However, the removal was high and consistent in the farm soil and biochar and enhanced by up to 99 per cent by the addition of nutrient solution. Field evaluations of these potential materials are now needed to confirm the viability of these materials for recommending them for use on farms.

Methanotroph characteristics in two biofilter prototypes were studied at Massey No.4 dairy farm. Acidic column biofilters tend to have acidophilic methanotrophs that enabled it to perform effectively under extremely acidic conditions when sufficient moisture was available and floating biofilters had a right mix of two major groups of methanotrophs that driven the ability to remove large amounts of methane under changing field conditions. Dr Syed published the research in three peer-reviewed international journals and has spoken to it at national conferences and workshops.

Dr Syed wished to thank the many people who helped him get to where he is, “I would like to express my greatest appreciation to my supervisor’s Drs Surinder Saggar, Kevin Tate and Bernd Rehm for their tireless support, inspiration, encouragement and constructive advice in making this Thesis happen.”

He now works for Callaghan Innovation in Wellington and is currently collaborating with Landcare Research in the process of driving the work further.

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