A preliminary evaluation of turbidity removal by natural coagulants indigenous to Venezuela

The ability of two plant materials, Cactus latifaria and the seeds of Proso pis juliflora, to act as natural coagulants was tested using a synthetic wa ter formulated to resemble the drinking water supplied to the city of Marac aibo. Turbidity was added as kaolin. The coagulation ability of the two mat erials was assessed by the use of standard jar test measurements. Both mate rials produced comparable turbidity removals and were able to produce a fin al water whose turbidity was close to the required standard of 5NTU with bo th high (100-200 NTU) and low (30-40 NTU) initial turbidities. This was com parable with the performance achieved by previous workers using Moringa ole ifera extracts. The optimum coagulant dose was found to be lower than that for aluminium sulphate. Treatment of the raw vegetable solids with solvents produced coagulants which, in some cases, were different from the raw mate rials and suggested that non-polar material might be involved with the coag ulation process. (C) 1999 Elsevier Science Ltd. All rights reserved.