Note 1 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

Financing Receivable, Allowance for Credit Loss [Table Text Block]

	2020			2019
Allowance for doubtful accounts at the beginning of the period	$	612,434		$	971,772
Bad debt expense		320,270			25,044
Receivables written off during the periods		(484,265	)		(362,244	)
Effect of currency translation		49,605			(22,138	)
Allowance for doubtful accounts at the end of the period	$	498,044		$	612,434

Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]

	For the Year Ended December 31
	2020		2019
United States and Canada	$	656,032	$	1,600,298
Australia		524,255		425,560
Asia		3,372,286		5,991,440
Europe		17,973,628		24,620,186
	$	22,526,201	$	32,637,484

Reconciliation of Revenue from Segments to Consolidated [Table Text Block]

	For the Year Ended December 31
	2020		2019
Liquid filters and systems	$	14,147,842	$	25,464,614
Ceramic diesel particulate		5,131,891		5,652,686
Plastics		2,647,366		895,203
Development projects		599,102		625,981
	$	22,526,201	$	32,637,484

Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block]

	2020			2019
Cost incurred	$	3,997,161		$	3,960,199
Unbilled project deliveries		1,015,977			1,971,106
VAT		446,608			862,368
Other receivables		75,010			58,397
Prepayments		(3,112,118	)		(1,732,231	)
Deferred Revenue		(866,680	)		(876,286	)
	$	1,555,958		$	4,243,553
Distributed as follows:
Contract assets	$	2,708,136		$	5,664,929
Contract liabilities		(1,152,178	)		(1,421,376	)
	$	1,555,958		$	4,243,553