Typically, an increase in size is seen as a good thing for a company. However, growth can create new problems that demand thoughtful solutions, as one Michigan-based firm recently discovered.
The Sparta-based fruit juice company had increased its wastewater flow from 7,000 to 11,000 gpd without upgrading its wastewater treatment plant. Its system consisted of an equalization tank, three conventional aeration tanks in series and four rotating biological contactors (RBC) in parallel. The plant was able to reduce the average daily biochemical oxygen demand (BOD) loading of 9,000 mg/L to acceptable levels; however, the low oxygen levels in the hydraulically overloaded aeration tanks resulted in high levels of hydrogen sulfide, which caused an unpleasant odor.
To address the problem, plant personnel chose to add the Mazzei AirJection system to the equalization tank and all three aeration tanks, rather than upgrade the existing blower/ diffuser systems, which would have proven prohibitively expensive.
After the Mazzei system was installed, dissolved oxygen levels increased in the aeration basins; this immediately eliminated the odor issue. The level of BOD in the aeration basin effluent became so low that three of the four existing RBC trains were no longer required. The system was quickly installed with little downtime to the plant.
This system was installed in 2006, and it has provided excellent results and trouble-free operation ever since. In 2009, the plant altered its procedures, mandating that all wastewater be trucked off site and used for hog-feed production. However, the equalization basin is still used with the Mazzei aeration system, which allows for odor-free collection of the wastewater until it is taken off site.
