Aquatic plants like Eichhornia crassipes, Pistia stratiotes, and Lemna gibba can help clean up heavy metals from waste water produced by flashlight manufacturing. These plants were tested with different concentrations of the waste water for 5 weeks. The results showed that Eichhornia crassipes was the most effective at removing mercury, lead, zinc, and manganese from the water. The other plants also did a good job, but Eichhornia crassipes was the best. The plants didn't show any signs of being harmed by the metals, so they can be used on a large scale to clean up water with low levels of pollutants.