The Study of Water Lettuce (Pistia stratiotes L.) Application in Reducing COD Levels of Tofu Wastewater Using Batch System Phytoremediation

Abstract

Tofu industry wastewater contains high complex organic materials such as BOD, COD, and an acidic pH. High concentration of tofu wastewater can cause damage to aquatic ecosystems, so it requires treatment before finally being discharged. Phytoremediation is one of wastewater treatment methods that can be applied. The objective of this research was to determine the effect of Water Lettuce application and its COD removal efficiency. The research method used was the experimental method with laboratory-scale batch reactor, using Water Lettuce with amount 200 and 400 grams which had already acclimatized for 7 days, sample 5L of tofu wastewater within and without pH controlled, and was done with 3 replications. The results showed there is an effect of Water Lettuce in reducing COD content of tofu wastewater with removal efficiency of 24%, 57%, 82% for experiment 1 (200 gr, pH acid), 2 (400 gr, pH acid), and 3 (200 gr, pH neutral), respectively. The condition of Water Lettuce in every experiment was differ because pH and weight affected it, but at the end of experiment, the Water Lettuce died because it had a saturation point of growth, it showed the roots and the body was separated and became black, the leaves color became yellow to brown.