Stabilization ponds are good at cleaning up wastewater from places like slaughterhouses. A study in Iran looked at how well these ponds worked for treating slaughterhouse wastewater. They found that the water coming out of the treatment plant didn't meet the standards for being safe to use for things like irrigation or putting back into rivers. The levels of stuff like dirt, organic matter, and harmful bacteria were too high. The researchers showed that the water wasn't clean enough for everyday use.