The study used advanced technology to analyze bacteria in wastewater treatment plants in China and the United States. They found that the bacterial communities in these plants were surprisingly similar, with certain core species present in all samples. These core species belonged to specific bacterial phyla, with Proteobacteria being the most common. The differences in bacterial diversity among samples were mainly due to a few specific organisms that were only found in certain samples. Overall, the study showed that despite geographical differences, the microbial communities in these wastewater treatment plants were remarkably consistent.