Column: Dealing with manure in Asia
Big Dutchman became co-owner of our company, Inno+, in March 2016. Since then, I have visited many farms across the globe and thus gain an insight into local challenges and solutions.
One of my first trips was to South Korea and Japan. The greatest surprise there was that all poultry and pig farmers compost their manure on the farm, because all manure to be sold must be free of pathogens. I have not seen a slurry tank there in all those years.
The solid fraction is composted and the liquid fraction is biologically purified, just like in our sewage treatment plant. They let the effluent run off the mountain or into the ditch, but not a drop of it ends up on the land. The compost finds its way to the land or is exported, often to Vietnam.
Societal pushback
The processes used are quite simple. First, the traditional open trench silos, usually with a cover to protect against rain. A so-called chain turner turns the compost every day. This is coming to an end due to social resistance. The enormous emissions and odour trigger people living near to the farms to hang banners on the fence and organise protest marches.
The usual solution is to continue composting in the trench silo and to close the composting hall, ventilate and install a gigantic air washer. The ammonia concentration in the hall is between 200 and 400 ppm. Anyone working in this must wear an astronaut suit with gas bottles on their back. Remember: there are tens of thousands of these facilities in Asia.
The second, a smarter and cheaper method with regard to emissions, are the so-called compost towers, which are closed vertical composting silos with a capacity of 60-200 cubic metres. Only 1,000 cubic metres of polluted air is released per hour (compared to 400,000 cubic metres per hour from the composting halls). A small air scrubber can efficiently capture that. There are now around 15,000 compost towers in Asia.
Composting has an environmental background. It has one major additional advantage: it limits the risk of a pandemic, because all manure is hygienised. We have never thought about that in the Netherlands. Is it time to do that now?
