Namon Nassef's Zero Liquid Discharge system uses engine heat to convert wastewater into water vapor. It's an invention seven years and several hundred thousands dollars in the making that could revolutionize how we dispose of sewage on buses, cruise ships, trains and airplanes.
Nassef has set up a demonstration trailer (pictured below) to show how the eco-friendly sewage elimination system works.
First, sewage moves through a pipe into a small equalization tank. The equalization tank keeps the waste completely mixed. It also starts the grinding process, which reduces solids down into very tiny particles that are about 0.065 inch or less in diameter.
The mixture of liquid and small particles then moves from the receiving tank to the machine's homogenizer (the white plastic cylinder on the right next to the equalization tank). This component dissolves the tiny particles into even smaller particles. Nothing that leaves the homogenizer is larger than the ball in a ball point pen.
The fluid is then sent to an injection pump (the white plastic module on the left). The injection pump pressurizes the fluid and sends it through a nozzle into the hot exhaust stream of the heat source. In the demonstration trailer, a diesel generator is used for the heat source.
In the final stage, the engine's exhaust heat flash evaporates the fluid, killing 99.9 percent of the bacteria without chemicals. What's produced is water vapor and a little bit of mineral ash, which goes out with the exhaust. There's nothing to dump from the holding tank.
The current ZLD unit can eliminate up to 300 gallons of sewage per day, which is more than capable of handling the 20 gallons of waste produced on a 65-passenger bus, says Nassef.
Below is a picture of the current ZLD production unit on its own, equipped for buses.
