Heat retention covers from Industrial & Environmental Concepts can be essential for wastewater treatment plants where wintertime temperatures affect nitrification. Covers are available from R-4 to R-17 and have proven effective, reliable, and low maintenance. Insulated covers can be used in both aerobic and anaerobic processes. An additional benefit of the covers is algae control and management of offensive odors. 952-829-0731; www.ieccovers.com