Investigating the efficacy of Aloevera as an alternative Coagulant and Disinfectant in water treatment.

Abstract

In conventional drinking water treatment, the coagulation processes are applied to destabilize the surface charges of colloids and enhance agglomeration (flocculation). Proper coagulation is essential for good filtration performance and disinfection by-product control. Disinfection processes are also carried out at water treatment plants in order to improve the microbiological quality of drinking water. Some chemicals are used in these processes and these are aluminium and iron salts for coagulation and chlorine for disinfection. However these chemicals are associated with a few setbacks, they are both expensive and not locally available. The raw water source was River Rwizi in Mbarara, it was analysed for turbidity, pH, color, electric conductivity, and microbiological quality which are fundamentals for drinking water treatment. The pH of the raw water sample was 6.68, turbidity; 96.5 NTU, apparent colour; 963 PtCo, true colour; 884.7 PtCo, electrical conductivity; 78 μS/cm. These values generally did not meet both the National portable and WHO standards for drinking water quality. Jar tests were carried to determine the performance of the aloe extract as a primary coagulant, and flocculant and coagulant aid. The performance of alum was also determined for comparison. To investigate the suitability of aloe vera as a disinfectant, raw water samples were treated with aloe vera extract. Parallel tests were done were done with High test sodium hypochlorite. The aloe vera extract proved to be a poor primary coagulant. Aloe had a 51% removal of turbidity at 70mg/l, whereas alum had a removal percentage of 85% at the same dosage. Aloe performed poorer with regards to true colour removal where it had a 35% removal of true colour at 70mg/l whereas alum had a 100% removal of true colour at this same dosage. Aloe Vera presented lower disinfection activity than chlorine.