3036
Overall , free - chlorine treatments ( 0 . 3 or 1 . 0 mg / L ) showed significantly lower heterotrophic plate numbers than those without free chlorine .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 None