Asmus said when the pipe failed a black liquor was released to the wastewater treatment plant. Black liquor is a high-strength organic pollutant derived from the breakdown of pulpwood. The black liquor overwhelmed the facilitys wastewater treatment system causing effluent (outflow) violations, Asmus said. The wastewater system remained functional however, it was not capable of treating the black liquor entirely. Black liquor is a byproduct of a process at the mill, not a chemical purchased and stored on site for a specific purpose, Asmus said.