Screening Variables in Reducing the Brown Color from the Filtrate of Heavy Metal’s Elimination

Abstract

Heavy metals contamination is a major concern in the world, and also is in Indonesia. Many
attempts have been done to reduce or even eliminate it from the environment, among other ways the
use of agriculture waste, such as rice straw. Why use rice straw? Because it is available abundantly.
Many studies showed that rice straw could adsorb heavy metals from polluted water, and it is cheap.
The drawback of rice straw is the color of the filtrate is brown, so that it cannot be used for everyday
or household purposes. An attempt using enzyme has been tried to reduce the brown color and it did
reduce the brown color. Enzyme L-α-arabino-furanosidase is used in this study. However, as there are
many variables used in the experiments, before optimization can be conducted, a screening needs to be
carried out first. Type of enzyme (optimum temperature of 50oC and 70oC), incubation time and amount
of enzyme, number time of washing, water for washing, place of the rice plantation (high land and low
land), and size of straw, are the variables that need to be screened. The variables that gives the highest
response in this study were enzyme-50, amount of enzyme : straw = 2 : 1 (10 ml of enzyme for each 5
g of straw), 1 hour incubation time, amount of washing : 5 x 5 ml, place of plant: low land, and size of
straw: ground. As for the type of washing liquid, both either demineralised water or Pb solution were the
same. However, the variables are still need to be reduced, and the experiment/study will be continued
to optimize the reduced variables.