Comparative studies between aluminium sulphate, moringa seed and green plantain peel as coagulants

Abstract

Aluminium sulphate (alum) is the most commonly and widely used coagulant in water treatment plants however, literatures have revealed that it has certain setbacks that needs to be addressed including imparting acidity and hardness to water. Hence, the coagulation capacities of the seeds of moringa (Moringa oleifera) and peels of unripe or green plantain (Musa paradisiaca) which are abundantly available and currently considered as waste in most developing countries, were investigated in comparison with alum. This was achieved by using standard methods to treat raw water at different dosages of coagulants (100-600mg/l) prepared from moringa seed and plantain peel, and comparing the performances of these coagulants with that of aluminium sulphate (alum) used in treating same raw water at same dosages. Parameters checked are turbidity, pH and hardness. Results showed that alum performed best in terms of turbidity removal followed by moringa seed solution and then plantain peel solution. This is because alum reduced the water turbidity by 99.94% at an optimum dosage of 100mg/l while moringa seed and plantain peel solutions reduced the turbidity by 80.27% at 300mg/l and 63.99% at 500mg/l respectively. Nevertheless, it was noted that at optimum dosage of alum, the water pH was reduced from 6.7 to 6.2 as against the WHO permissible limits (6.5 – 8.5), and the harness level was increased by 22.43%. On the contrary, at the optimum dosages of moringa seed and plantain peel solutions, the pH were raised to 7.3 and 7.5 respectively, which is within the permissible limits and also, the hardness levels were reduced by 13.41% and 8.52% respectively. It was concluded that moringa seed solution could replace alum successfully but plantain peel solution needs modifications in order to improve the turbidity removal capacity before replacing alum although, it could be used in the absence of other conventional coagulants.