edit: the column is gone, but the minuscule text remains
after running my entire 573 pp. pdf through it, the processed output pdf is now 169 MB, 1460 pp. This is not what I want for my book archive. Rather a perfectly OCR'd pdf, book layout, 1 column, correct font sizes, that is faithfully transmitted in KOReader reflow. K2pdfopt is good if you want to quickly read a text on your reader and then delete it. But thanks for the tip