A review of R&D works carried out at the Industrial Chemistry Research Institute, Warsaw, and commecialized during last 5 years in Plock petroleum refinery and Bydgoszcz chemical factory. Use of nanofiltration and reverse osmosis resulted in recovery of over 90% of ethylene glycon contained in wastewater from the ethylene oxide and glycol plant (Plock) as well as more than 20-fold reduction of the volume of the wastewater stream discharged from the plant. The hydrogenation of alpha-methylstyrene fraction from the cumene phenol and acetone plant with its preliminary extraction in membrane contractors and distn. resulted in recovering 90% acetone contained in the wastewater stream and avoiding formation of precipitates of Na sulfate during the regeneration of the PhOH sorbent bed. Mass crystallization of dinitrotoluenes from the dinitrotoluene plant (Bydgoszcz) resulted in improving their quality control and production of their market-accepted brands.