How are heavy metals, e.g - Leaving Cert Chemistry - Question f - 2004

Heavy metals such as mercury can be effectively removed from industrial waste through a process known as precipitation or tertiary treatment. This method involves the addition of suitable chemicals to the wastewater that cause the heavy metals to form solid particles, which can then be separated from the liquid.

In this treatment, coagulants or flocculants are often utilized. These agents help to aggregate the dispersed metal ions into larger clumps or 'flocs.' Once the particles are formed, they can be easily removed through sedimentation or filtration.

Additionally, it's important to select appropriate precipitating agents that can effectively bind with the specific heavy metals present in the waste. Common precipitating agents include sulfides, hydroxides, or phosphates, specifically tailored for the targeted metal ions.