Treatment of liquid waste from a textile industry with water hyacinth

Abstract

Waste water treatment using aquatic plants is gradually gaining importance. The aquatic treatment system consists of one or more slmllow ponds in which one or more species of aquatic macrophytes are grown. Waterhyacinth is one of the most promising aquatic plant which has been successfully used all over the world in industrial waste water treatment. In this study an experimental investigation has been carried out to find the effectiveness of water hyacinth in control of pollution by textile liquid waste. Tlds study focuses on the c1mracteristics of liquid waste of existing textile industries in Bangladesh. In our country very small" efforts are made for tlze treatment of industrial waste. Most of the existing industries dispose off liquid waste having pollution indication parameters exceeding the respective environmental quality standard. This study shows that the effluents from these industries can be effectively treated by water hyacinth ponds as an alternate low cost treatment method before discharge of raw liquid waste into a surface waterbody. In this study different experiments have been conducted to determine the removal rate" of pollutants with giving importance to colour, turbidity, suspended solids from textile liquid waste at different concentrations of waste water and at different pH. Ignoring the effect of different types of water hyacinth in the treatment of waste water, in this study plants having long and extensive root system are used. Representative samples of Beximco Textile Industry were collected and polluting parameters were analysed in the Environmental Engineering laboratory of BUET. Water hyacinth was used to treat this liquid waste at different concentrations in some plastic buckets. Samples from these buckets were collected at regular interval and pollutant contents were determined. This process was repeated- to determine the removal of pollutants by water hyacinth at different pH of raw effluent. This study reveals tlmt water hyacinth could be positively used in the treatment of waste water. It has found that removal rate of pollutants by water hyacinth are excellent if the waste water is diluted fifty percent. Test results also show that removal rate of pollutants at pH 4.8 are much better thlm at pH 6.8 of the waste water. Treatment of textile liquid waste by coagulation and sedimentation process gives a better understanding of the effectiveness of alum for removal of pollutant. An attempt was made to remove pollutants from textile liquid waste by sludge blanket and coal filter method.