The Mix

Mixing drinking water storage tanks is well recognized as an important tool for improving water quality and protecting tank assets. There are many mixing technologies for operators to choose from, with varying degrees of performance, but to solve serious water quality problems, powerful mixing is key.

Powerful active mixing eliminates thermal stratification and ensures uniform conditions throughout the tank. This has been shown to lower overall disinfectant residual demand, reduce the risk of nitrification and enable safe, reliable boosting of residual disinfectant. Additionally, powerful mixing can protect and preserve tank assets by preventing the ice formation (which can scrape tank coatings or puncture tanks), and lowering summertime headspace temperatures (which reduces corrosion rates).

Chloramines are an attractive option for secondary disinfection - they're chemically stable, persistent and produce much lower levels of disinfection by-products (DBPs). However, because chloramination involves mutiple chemical reactions between ammonia and chlorine, managing the chemistry of chloraminated water distribution systems is tricky. Chlorine is consumed as water travels through the distribution system and reacts with organic matter, and free ammonia can be left behind. For this reason, nitrification becomes a principal water quality management issue for chloraminated water systems. We have received many inquiries from operators about how to manage and avoid nitrification in water storage tanks, below we answered three common questions.