The main components of polluted water discharged from paper mills are lignosulfonate, kraft lignin, hemicellulose and fiber-fine. These substances form rather stable colloide and suspension in water due to the negative charges on the surface of substances. Although it is difficult to clarify the polluted water by sedimenting Pollutants with coagulant, the aluminum sulfate (Alum) has conventionally often been served for this purpose. The clarification properties of alum are not sufficient. However, the addition of cationic polymers such as polyethylenimine, protein and chitosan exhibited excellent clarification of polluted water, particularly used with alum. Thus, the combination of cationic polymers with alum could remove more than 99% of the pollutants such as lignosulfonate, kraft lignin and fiber fines through coagulation and sedimentation. Also, it was sujested that these coagulated and sedimented pollutants could be used for animal feed and fertilizer.
The study of antifouling polymers was conducted to destroy and prevent sea weeds from growing over a long period of time. Antifouling polymers were thus synthesized by adducting active toxicants of 2, 4 dichloro-phenoxy acetic acid, tributyltin oxide, and pentachlorophenol, to waste polymers, such as ligno-sulfonate, kraft lignin, bark fiber and crab shell and also chitin and alginic acid. The obtained polymers exhibited better antifouling properties for sea weeds than the original mono toxicants. It was also noted that the condition of very slow tidal movement in which the released toxicants were accumulated, took more time to attain hundred per-cent mortality than that of tidal movement which reduced the accumulation of toxicants. This means that chronic intoxication of sea weeds is induced by exposure to a certain concentration of toxicants over a long period of time. Thus, polymeric toxicants like antifouling polymers which sustained release could be superior to mono toxicants possessing high initial leaching rates which were responsible to environmental pollution.
During electrodeposition in the deposit bath, four electrochemical processes are involved : electrophoresis, electrolysis, electroosmosis and electrodeposition. Electrodeposition has been the center of interest in four processes. It is generally admitted that three reactions are involved in the electrodeposition of resin : (1) Coagulation of the resin in an acid form resulting from the pH decrease in the vicinity of the anode. (2) Coagulation by formation of metallic complexes with the ions resulting from the anodic dissolution. (3) Coagulation of the polymer due to a Kolbe-type degradation. Authors have studied with electrodeposition and reverse electrodeposition on iron and platinum anode using water-soluble alkyd resin to explain mechanism of the abovementioned reaction. As a result, it was admitted that there was a constant ratio between deposit weight and quantities (weight) bonded on the cathode without dropping in reverse electrodeposition. As for film resistance, the authors studied with relationship between film resistance and current densities using the resins of acid values 75 and 123. In consequence, it was obtained that the maximum value of film resistance exists on a certain current density. It was concluded that the film resistance was considered as an index of throwing power.