Water Nuggets Practice Exam

If the alkalinity of raw water is too low, floc formation will be poor if the amount that is naturally found in the water source is less than what level?

1. 80 mg/L

2. 100 mg/L

3. 150 mg/L

4. 200 mg/L

The correct answer is: 80 mg/L

In the context of water treatment, alkalinity plays a crucial role in the floc formation process during coagulation and sedimentation. Alkalinity is important because it helps to maintain a stable pH level during these processes, which is essential for the effective functioning of coagulants. When discussing the levels of alkalinity in raw water, a threshold exists below which floc formation becomes inefficient. If the naturally occurring alkalinity in the water source is below 80 mg/L, there may not be enough buffering capacity to support the coagulation process. This inadequacy can lead to poor floc formation because the coagulants rely on a certain level of alkalinity to effectively bind the particulates and facilitate proper sedimentation. At this low level, the water may not have sufficient carbonate and bicarbonate ions which are essential in the neutralization of charges on particles, leading to incomplete or weak floc formation. Therefore, 80 mg/L is often cited as the minimum level to ensure effective treatment and floc formation in water sources.