On the History of Water Coagulation

Transfer of Ancient Hindu Practices to the Valleys of the Yangtze River and the Nile

Abstract

Water coagulation is one of the standard methods used by modern water works for the treatment of drinking and waste water. Most laymen and engineers in the Western world believe that this technology was invented by Europeans sometime in the 19th or early 20th century. However, in tropical developing countries, the clarification of turbid waters from rivers, lakes and water holes is an old household method, although only a few traditional materials act as primary coagulants. Seeds of Moringa oleifera containing basic poplypeptides are currently the most promising plant material for utilisation in water supplies. These seeds were detected by Sudan Arab village women at the beginning of the 20th century as substitutes for less efficient beans and groundnuts (Jahn 1981 and 1986). The oldest records of a precursor of these seeds are from ancient India (1st century A.D.). European eyewitnesses reported related water clarification methods in Egypt at the end of the 16th century and China at the end of the 17th century (Baker 1948: 300,302). Striking similarities between the Indian and Egyptian methods of applying a flocculating plant material have already been pointed out (Jahn 1988a: 172), but historical data from Chinese archives have not been considered to date. According to some notes, the author recently obtained from Beijing and Taipei, attempts at water clarification have been reported in China since the 2nd century A.D. The present paper aims at investigating how the Chinese were involved in the transfer of knowledge and contributed to new developments. The work is based on studies of literature, correspondence with historians, and laboratory and field research on traditional water coagulation in the Sudan and other tropical countries in Africa, Asia and Latin America. The historical data are critically analysed from various points of view. Special attention has been paid to the role of religions, their codes of law and local concepts of water treatment. The transliteration of Sanscrit, Arabic and Mandarin is done in various ways. In the present paper it corresponds to the method used by the authors quoted or the informants in their books, articles or personal communications, but special phonetic signs have been omitted to avoid difficulties in printing. As far as Chinese words are concerned, the different systems of transliteration can be compared in a guide by Legeza (1968-69).