Note 12 - Business Segment, Geographic and Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2012

Schedule of Segment Reporting Information, by Segment [Table Text Block]

For the year ended December 31, 2012	Air Pollution Control Segment			FUEL CHEM Segment			Other			Total
Revenues from external customers	$	62,441		$	35,203		$	-		$	97,644
Cost of sales		(40,146	)		(16,753	)		-			(56,899	)
Gross margin		22,295			18,450			-			40,745
Selling, general and administrative		-			-			(32,682	)		(32,682	)
Research and development		-			-			(2,863	)		(2,863	)
Operating income (loss)	$	22,295		$	18,450		$	(35,545	)	$	5,200

For the year ended December 31, 2011	Air Pollution Control Segment			FUEL CHEM Segment			Other			Total
Revenues from external customers	$	50,930		$	42,738		$	-		$	93,668
Cost of sales		(28,467	)		(21,390	)		-			(49,857	)
Gross margin		22,463			21,348			-			43,811
Selling, general and administrative		-			-			(33,446	)		(33,446	)
Gain from revaluation of ACT liability		-			-			758			758
Research and development		-			-			(1,474	)		(1,474	)
Operating income (loss)	$	22,463		$	21,348		$	(34,162	)	$	9,649

For the year ended December 31, 2010	Air Pollution Control Segment			FUEL CHEM Segment			Other			Total
Revenues from external customers	$	40,917		$	40,878		$	-		$	81,795
Cost of sales		(27,024	)		(19,797	)		-			(46,821	)
Gross margin		13,893			21,081			-			34,974
Selling, general and administrative		-			-			(30,857	)		(30,857	)
Gain from revaluation of ACT liability		-			-			768			768
Research and development		-			-			(948	)		(948	)
Operating income (loss)	$	13,893		$	21,081		$	(31,037	)	$	3,937

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

For the years ended December 31,	2012		2011		2010
Revenues:
United States	$	70,425	$	76,077	$	69,002
Foreign		27,219		17,591		12,793
	$	97,644	$	93,668	$	81,795

As of December 31,		2012		2011
Assets:
United States	$	86,466	$	99,601
Foreign		19,431		13,389
	$	105,897	$	112,990

Schedule of Quarterly Financial Information [Table Text Block]

For the quarters ended	March 31		June 30		September 30		December 31
2012
Revenues	$	25,212	$	20,911	$	24,907	$	26,614
Cost of sales		13,220		11,880		14,671		17,128
Net income (loss)		1,543		68		1,194		(29	)
Net income (loss) per common share:
Basic	$	0.07	$	0.00	$	0.05	$	0.00
Diluted	$	0.06	$	0.00	$	0.05	$	0.00
2011
Revenues	$	22,622	$	19,021	$	24,023	$	28,002
Cost of sales		11,466		10,553		13,050		14,788
Net income (loss)		1,339		430		2,655		1,724
Net income (loss) per common share:
Basic	$	0.06	$	0.02	$	0.11	$	0.07
Diluted	$	0.05	$	0.02	$	0.11	$	0.07