Misha's Blog

My installation at the TONY 2012 is a ship for traveling to parallel universes. The entry point and centerpiece of this shipping container installation is the aquaponics toilet farming I call Toiletponics. I outfitted a pink 1950s American Standard toilet with all the requirements for sustaining life. In this alchemical self-sustained ecosystem, shit is transmuted into food.

I’ve been doing research on using urine as fertilizer. However, for the installation downtown the food toilet is running in aquaponics mode. A half pound tilapia fish (rescued from a science experiment) is living in the bowl.

It’s waste is pumped out of the bowl and into the tank where it mixes into the growing medium containing several strains of nitrifying bacteria which convert waste into nitrogen fertilizer. Edible plants grow in the medium and absorb the nutrients made available by said bacteria. As the plants thrive, the tilapia enjoyes naturally cleaned water trickling back into the toilet bowl. But the container doesn’t let in much natural light which the plants require. I created a special LED-based grow light out of a matching pink sink. The LEDs are water cooled, and the waste heat is captured to heat the water for the fish.

Fluorescent lights are marketed as a ‘green’ technology. But even though they are more energy efficient than incandescent bulbs they contain mercury which is a poison. I like LEDs better. I used a combination of high powered red and red green blue (RGB) LEDs to achieve the right balance of light. Plants, it turns out, don’t like green light. They appear green to us because they are bouncing all of the sun’s green rays right back away from themselves. I used high frequency red light (it penetrates the plant’s bodies) and RGB LEDs with the blue light turned on to satisfy plants’ taste for the blues. I also dialed in some green to balance out the light for human enjoyment as well. These high powered LEDs produce a ton of heat and if the heat is not dissipated the LEDs grow dim and can even burn out.

Enter the heat sink! The matching pink sink is cast iron and serves as a great heat sink for the LEDs. But it becomes even better with water cooling and heat recycling!

I’m stopping it up and pumping the toiletponics water through it. The water cools the heat sink and in turn heats up. When it finally flows out back into the toilet bowl through the white hose it is warmer to please the tilapia (a species hailing from balmy Egypt).

I used some handy Instructables tutorials for my LED work. Here is a very basic tutorial describing how to drive an LED with a Voltage Regulator IC. Here is a comprehensive tutorial iterating over several driver circuit designs integrating capacitors for smoothing power spikes. I didn’t end up using capacitors as I didn’t notice any real spikes in my power supply (the city’s holiday light socket in the park pole).

This next one is what I found after deciding to do tunable RGB LED lights in our sauna project. It also describes an overload protection circuit for preventing what is called Thermal Runaway which I haven’t found happening with my system. I measured voltage and current after hours of operation and didn’t see it.

I’m looking forward to finishing the installation and opening it for the public.