Mon Jun 15th, 2009 at 12:37:48 PM EST
Alas, another diary about poo.
But factually, it's about Lumbriculus variegatus. That is the name of a common water-abiding worm. The worm is also the central subject of Tim Hendrickx's PhD thesis which he defends tomorrow at the University of Wageningen.
Hendrickx investigated the problem of waste sludge - that is, the waste product that remains after human sewage has passed through sewage treatment: sludge. Highly concentrated in phosphate, sludge makes good fertilizer (when absent of heavy metals), and this use has been encouraged by the European Commission.
However, with more sludge produced than turned into fertilizer, disposing sludge on dumps or incinerating it is a costly and environmentally unfriendly affair. Who you gonna call? Lumbriculus variegatus!
The Lumbriculus worms actually can feed on the sludge, heads buried while breathing oxygen through their bottom end. What's more: their own excrement is a vast improvement over waste sludge: poo pellets from the worms subside to the bottom because of their increased compactness, and in total the volume of the sludge is reduced by an approximate two thirds.
Hendrickx, who discovered this behaviour of the Lumbricus, dedicated his research to find the optimal conditions (oxygen level, temperature, light exposure) for worms to thrive.
What's more, when the worms are done eating and procreating, their surplus in numbers can serve as fish food: salmon, for instance, eat predominantly meat. And fish farms now need to purchase this for their stock.
The Lumbriculus genus has a specific way of reproducing: adults worms spontaneously split up and both parts grow back into two individual worms, which both can split up again in due time. That means no larvae or egg stages will clutter up the tank. It's pure worm.
Of course, waste treatment worms can only serve as food when it is guaranteed they're "clean" - they shouldn't form a reservoir for, say, hormones of heavy metals by digesting the waste sludge. So far it has been found that heavy metals pass straight through, but for hormones, or medicinal components, this still needs to be determined. Another challenge will be whether it is possible to successfully upscale the worm reactors: so far the gross of the experiments have taken place in laboratory tanks.
My previous poo-diary, Cook on Poop, covered the opposite side of the spectre: instead of massive waster treatment plants, small-scale centralized waste treatment. I'm curious which system will prove to be the optimal recycling scheme.
I thought about including pictures in this diary, but I'm not sure how appetizing it would become.