Removal of Hardness Using Ground Water Treatment Plant Sludge

One of the undesirable characteristics of some water sources is hardness, that can
cause many problems including scaling and excessive soap consumption. Therefore
several treatment processes have been introduced to remove or reduce the hardness
from hard waters. One of the new innovations in this regard is using Ground Water
Treatment Plant Sludge by precipitation. Hardness can be removed from hard waters
by precipitation of calcium and magnesium. In the cement factory at Tasek, Ipoh,
hard water is mostly found in the water recycling treatment where is the source of
water is from pond, surrounded by limestone hills. A treatment process which is
using Ground Water Treatment Plant Sludge (GWTPS) was conducted in replicate to
observe the changes in parameters such as total hardness, calcium hardness,
magnesium hardness and pH with varying dosages of GWTPS. A GWTPS dosage
range of 500 - 5000 mg!L was chosen for the experiments. Results indicated that the
removal of calcium can be achieved to 96% with the dosage of 5000 mg/L by
precepitation at pH 9. For instance, GWTPS is not feasible to remove magnesium
hardness. Since only calcium is successfuly removed, the total hardness is still in the
high range. By comparing to the result of jar test, the soda-ash dosage of 5 ml
(5000 mg!L concentration) is the optimum dosage to precipitates CaC03 and
Mg(OH)2 at pH 13 and 12 respectively. The removal of calcium and magnesium by
chemical precipitation in jar test is about 69% and 90% respectively