Smog blankets many Chinese cities and the environmental degradation resulting from the country's economic growth is angering its increasingly well-educated and affluent population.
The demonstrations, which have run for more than two weeks, turned violent on Saturday, with hundreds of police descending on to the streets of Yuhang, close to the eastern tourist city of Hangzhou. At least 10 protesters and 29 policemen were injured, more than 30 cars were overturned, two police cars set on fire and four smashed up.
The government says it will shelve plans to build the plant if it does not have popular support.
Eleven suspects involved in the violence had already turned themselves in and 53 had been detained, police said, adding that they were urging others to surrender.
Similar protests have also succeeded in getting projects shut down elsewhere in China.
Hangzhou is best known in China as the site of a famous lake but has seen its lustre dimmed in recent years by recurrent smog.