Abstract
Practical application has been delayed regarding domestic wastewater treatment systems used in detached houses that are capable of removing nitrogen and phosphorus simultaneously. The authors have directed their attention to a process that combines carrier fluidized biofilm filtration and iron electrolysis. They studied a treatment system for removing nitrogen and phosphorus simultaneously in terms of its functions, and conducted the performance and verification tests.
The results confirmed that the treated water constantly showed a BOD and T-N of 10 mg·l-1 or less, an SS of 5 mg·l-1 of less, and a T-P of 0.7 mg·l-1 or less on average, although the tests were conducted during a low-temperature period. The phosphorus removal system using iron electrolysis functioned properly during the test period, dissolving an almost theoretical amount of iron, thus contributing to the steady removal of phosphorus. The amount of sludge accumulated after completion of the study reached 13.0-21.6 g·n-1·d-1, which corresponds to a 3.8-8.5 g·n-1·d-1 increase compared with other systems lacking a phosphorus removal system. It was confirmed that as much as a year's amount of generated sludge can be held in storage even with such an increase.
The present treatment system for removing nitrogen and phosphorus simultaneously was confirmed to be capable of maintaining its design performance. In the future, further investigations on subjects such as condition optimization will be necessary.
