Aquatic plants like water hyacinth and water lettuce can help clean up polluted rural rivers by removing nutrients like nitrogen and phosphorus. Water hyacinth is best at removing TN and NH4+-N, while water lettuce is great at removing total phosphorus. These plants work by absorbing nutrients and some also help break down nitrogen with the help of microbes in their roots. By using a combination of these plants and giving them enough time in the water, we can improve the water quality in polluted rivers.