Reduction of turbidity from water using Lathyrus sativus and Pisum sativum seed powder as natural coagulants and coagulant aids

摘要

Surface water pollution in and around the Dhaka city, especially the waters of the peripheral rivers has been threatening the supply of potable water to the city dwellers. The pollution problem was found stringent during dry season. During dry season there was increasing trends of turbidity from 2006 to 2010 in Buriganga River. Dry season average turbidity level of Buriganga River was found 119 NTU. Traditional coagulants and coagulant aid, like alum and polyacryl amide were not sufficient to treat highly polluted water. A conventional jar test apparatus was employed for the tests. Seed powder of Lathyrus sativus and Pisum sativum were used as natural coagulants and alum as synthetic coagulant in this study. Seed powder of Lathyrus sativus and Pisum sativum were also used separately with suspension of alum as coagulant aid for reduction of turbidity and to lower the dose of alum and polyacryl amide (PAA) was used as chemical coagulant aid in this study to reduce turbidity. The tests were carried out, using artificial turbid water to represent wide range of turbid water. Seed powder of L. sativus and P. sativum could effectively replace synthetic coagulant aid polyacryl amide. Using these natural coagulant aids, suitable, alternative and environment friendly options for water treatment would be achieved.