Mississippi Lime’s Standard Quicklime and Standard Hydrated Lime products are used in both municipal and industrial wastewater treatment applications.  Liquid Calcium Hydroxide (LCH) can be used as a substitute in many “liquid caustic” applications.  Dust free, LCH can be the solution to many alkali handling problems.  The micro-particulated version, Liquid Calcium Hydroxide MP is produced by our micro-particulation process to decrease particle size and increase reactivity and surface area.

Many wastewater streams, whether industrial or municipal, require pH adjustment and/or the removal of metallic contaminants before they can be discharged safely into the environment.  Lime, either as quicklime or hydrated lime, provides a cost efficient and safe solution, particularly when compared to other alkaline alternatives such as caustic soda:

• Lime is not susceptible to dangerous pH excursions in the event of a control problem
• Lime is relatively safe in handling and storage
• The use of lime precipitates metals as a manageable sludge, providing easier dewatering and hence lower sludge volumes
• Lime treatment provides flocculation to work in conjunction with additional polymer treatments resulting in the removal of suspended solids

In municipal wastewater treatment plants, lime precipitation is employed in processes in which phosphorus is precipitated as complex calcium phosphates along with other solids. When alum and ferric chloride are employed for coagulation, lime is used to counteract the low pH induced by these acid salts and to provide the necessary alkalinity for efficient nitrogen removal.
Lime has numerous industrial wastewaters applications.  It is used for the neutralization of acidic wastes, such as sulfuric acid-based wastes, and for the neutralization and precipitation of heavy metals in various processes.  Industrial wastes can be clarified with lime and, if needed, additional coagulants to aid in dewatering of the liquid waste. 

 
Quicklime and hydrated lime are also used in both coal mine and coal washing plant applications.  Highly acidic drainage from active or abandoned mines and from coal washing plants is frequently neutralized with lime.

For more information on the neutralization of acidic waste waters with lime, see “www.lime.org/ACIDNEUTfinal.pdf.”