The improvements at the Los Angeles-Glendale plant are expected to be completed in April 2006, said Lisa Mowery, a senior sanitary engineer with the Los Angeles Public Works Department.
"Right now they are about 79% finished with construction, which is right where they should be," Mowery said.
The modifications at the Burbank plant were made in two phases over a nearly two-year period. The city needed to finish the work by December 2006.
The plant now has microbes that eat up the ammonia and change it into nitrates and nitrites in a process called nitrification. The nitrates and nitrites are then converted by microbes into nitrogen gas that gets released into the air, project manager Rodney Anderson said.
The plant treats about 9 million gallons of wastewater a day. Prior to the improvements, the plant released between 15 and 20 parts per million of ammonia into the Burbank Western Wash that leads to the Los Angeles River.
With the modifications in place, the plant now discharges 0.5 parts per million of ammonia, Anderson said.
A high ammonia level in the river is harmful to fish, Anderson said.
"Too much ammonia can also cause algae growth, which is unpleasant because it's harmful to fish because it uses up all the oxygen," he said.
Another change in the plant was switching to liquid bleach from chlorine gas for the disinfection process, the final stage wastewater undergoes in the plant.
"It's a much safer alternative primarily because with chlorine gas you have plans, drills and safety process to prevent it from being released into the air," Teaford said.
Although the water control board was concerned about Burbank's wastewater discharge to the Los Angeles River, much of the water coming out of the plant is reclaimed for other uses.