River pollution. Foam in Tejo (Tagus) River from high organic matter content on the water and toxic chemical pollution. Note that the water is also black from "black liquor" from the kraft process: extracting cellulose fibers from pulpwood.Pulp and paper mills are considered one of the most polluting industries worldwide. Paper making process demands large amount of fresh water and produces enormous quantities of wastewater contaminated by a number of organic and inorganic chemicals. Disposal of such wastewater in aquatic bodies can have severe adverse impacts on the living organisms. Here killed all animals and aquatic plants that lived in this part of the river. Abrantes, Portugal.