Reduction of water turbidity with bio-flocculent: Use of Aloe Vera Gel

Abstract

Presence of turbidity in water reduces its quality and makes it unsuitable for different uses. Turbidity is a result of the presence of negatively-charged, fine particles in the water; causing it being polluted. It is removed by adding a coagulant/ flocculent to the polluted water to neutralize the negative charges on the suspended particles. This step is known as coagulation and is followed by a flocculation step when the uncharged particles form larger flocs capable of settling. Chemical coagulants proved to have many dangerous effects on human health and negative effects on the environment. Thus, the use of biomaterials has become an interesting alternative. The present study is set out to use Aloe Vera Gel (AVG) as an example of a natural coagulant for treating of turbid water. Experiments are conducted on a suspension of clay in water. The variables studied are: coagulant dose, clay concentration, mixing time, hydration of clay and particle size of clay. The highest percentage reduction in turbidity (97.73%) was achieved by clay suspensions of low concentration (20g/l), gel dose (2g/l) after 125 minutes. The recorded value for residual turbidity was 18.1 NTU. Also, clay suspension with 15 g/L concentration gives the lowest value of residual turbidity 21.9 NTU after 125 minutes using 2.4 g/L of gel concentration with percent reduction 97.08%. Hydration of clay particles resulted in a higher percentage reduction in turbidity (60.9% for the hydrated sample and 30.8% for the un-hydrated sample, after 5 minutes of settling). The combination of 10 minutes rapid mixing and 15 minutes of slow mixing gave the best results compared to other combinations tested. Thus, the results of the current research showed that AVG can serve as a promising bio-coagulant with high efficiency in removing turbidity from polluted water.