NOVELTY - Method for extracting low molecular weight phenolic antioxidant compound from olive production wastewater, involves interspersing at least one hydrophobic membrane between the olive production wastewater and an organic solvent, and at least one hydrophobic membrane from the olive production wastewater and an organic solvent, and diffusing the low molecular weight phenolic antioxidant compounds across at least one hydrophobic membrane from the olive production wastewater to the organic solvent while retaining other undesired components in the wastewater.    USE - The method is useful for extracting low molecular weight phenolic antioxidant compound from olive production wastewaters, crude extract composition enriched in hydroxytyrosol, and hydroxytyrosol solution (all claimed). The phenolic antioxidant compound, crude extract composition enriched in hydroxytyrosol, and hydroxytyrosol solution are useful in food, cosmetics and/or nutraceuticals.    ADVANTAGE - The method is environmentally-friendly, and requires less energy. The assembly is portable.    DETAILED DESCRIPTION - Method for extracting low molecular weight phenolic antioxidant compound from olive production wastewater, involves interspersing at least one hydrophobic membrane between the olive production wastewater and an organic solvent, and at least one hydrophobic membrane from the olive production wastewater and an organic solvent, diffusing the low molecular weight phenolic antioxidant compounds across at least one hydrophobic membrane from the olive production wastewater to the organic solvent while retaining other undesired components in the wastewater, and obtaining a solvent fraction enriched for low molecular weight phenolic antioxidant compounds. INDEPENDENT CLAIMS are included for the following:    (1) portable low molecular weight phenolic compound extraction assembly, including a portion defining a first cavity in which olive production wastewater as receivable, a portion defining a second cavity in which an organic solvent is receivable, second cavity separated from the first cavity by a hydrophobic membrane, and pressure unit for urging the olive production wastewater against the hydrophobic membrane;    (2) crude extract composition enriched in hydroxytyrosol; and    (3) hydroxytyrosol solution produced by the method.