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Related party transactions - Additional information (Details)
1 Months Ended 12 Months Ended
Jul. 31, 2021
USD ($)
Jul. 31, 2021
CNY (¥)
Aug. 31, 2020
USD ($)
Aug. 31, 2020
CNY (¥)
Jul. 31, 2020
USD ($)
Jul. 31, 2020
CNY (¥)
Oct. 31, 2019
Oct. 31, 2009
USD ($)
Oct. 31, 2009
CNY (¥)
Sep. 30, 2021
USD ($)
Sep. 30, 2020
USD ($)
Sep. 30, 2019
USD ($)
Related Party Transaction [Line Items]                        
Revenue from Related Parties                   $ 1,952 $ 7,200 $ 16,323
Forasen Group                        
Related Party Transaction [Line Items]                        
Monthly rent     $ 1,313 ¥ 9,200       $ 3,293 ¥ 22,400      
Renewed term of lease             10 years          
Terms of lease     1 year 1 year       10 years 10 years      
Zhejiang Tantech Bamboo Technology Co., Ltd.                        
Related Party Transaction [Line Items]                        
Terms of lease 10 years 10 years     10 years 10 years            
Annual rent $ 71,292 ¥ 459,360     $ 67,526 ¥ 459,360            
Hangzhou Forasen Technology Co., Ltd [Member]                        
Related Party Transaction [Line Items]                        
Annual rent     $ 41,639 ¥ 283,258                
Terms of sublease agreement     2 years 2 years