Title: Applications of a Concentrated, Highly Stable Lime Slurry for Wastewater Treatment
Learner Objectives:
The main objectives of this presentation are to educate the audience on the known benefits of lime in wastewater treatment applications, discuss the operational challenges that have hindered the success of lime in the market, and introduce a concentrated, highly stable lime slurry formulation that alleviates many of these challenges through the discussion of lab data and full-scale applications.
Content/Topic Outline:
Presenter:
Chandler Mancuso will be the exclusive presenter for this presentation. The bio is provided in the ‘Presenter Bio’ section.
Presentation Description:
For decades lime has been used in a myriad of water and wastewater treatment applications and is still considered an effective approach to many wastewater challenges. Because of its dual function as a coagulant and a base, it can be an effective tool for simultaneously precipitating heavy metals and providing the charge neutralization necessary for quality phase separation and effluent clarity. Lime is also efficient at removing phosphorus at pH levels above 9.5, further increasing its utility when both heavy metals and phosphorus are present in the wastewater, such as metal finishing waste streams. Precipitating fluoride with the addition of lime is still a core technique in wastewaters where fluoride contamination is high (>20 mg/L). Lastly, lime is often utilized for improving sludge quality by providing floc nucleation in low-solids wastewaters and enhancing sludge dewatering performance through the effects of coagulation and floc bridging.
While lime is known to be highly functional in wastewater treatment from a mechanistic perspective, the use of lime can also come with many practical challenges. When supplied as a powder, lime is more difficult to dose as the particles have a high clumping tendency, and the dust can be a respiration hazard due to its caustic nature. Furthermore, carbonates present in most make-down or carrier water sources inevitably lead to limestone scaling in pipes and tanks, adding to lime’s reputation of being particularly maintenance-heavy. To accommodate these issues, lime can be alternatively supplied as a pre-manufactured slurry. However, lime slurries tend to be unstable, requiring frequent if not constant mixing to maintain homogeneity. Plugged pumps and feed lines as well as solids accumulation in storage tanks are common problems associated with unstable lime slurries. Finally, some lime products are described as having a large particle size and low reactivity, causing slow reaction rates which may not be suitable for some systems. For these reasons, lime can be perceived as more trouble than it is worth if alternative treatment solutions are available that provide more reliability from an operational viewpoint.
To address the concerns with lime products in the market today, Omya developed a formulation and manufacturing method that produces a concentrated, highly reactive, and stable lime slurry that brings operational reliability back into wastewater treatment applications. Lab studies have characterized the reactivity and stability profiles of the formulation, and full-scale applications have validated its performance in a practical setting.
Presenter Bio:
Chandler’s educational background includes a Bachelor’s degree in Environmental Science and a Master’s Degree in Chemistry, both from Oakland University in Rochester, MI. He has also earned his Certified Water Technologist and LEED Green Associate designations, and in 2020 Chandler was selected for Water and Waste Digest’s 2020 Young Professionals Award. He is published in the industry journal ‘Water Environment Research’ and has delivered technical presentations at numerous industry conferences. Chandler also serves on AWT’s Wastewater Subcommittee. He now works for Omya and has over 5 years of research and application experience in wastewater treatment, specializing in chemical treatment applications.