Removal of nitrogen and phosphorus in batch reactors with fibrous packing

The sequencing-batch-reactor process, which has become popular in recent years, is effective for the removal of chemical oxygen demand (COD) from wastewater, but requires external carbon for the effective removal of nitrogen. A dual-reactor system operated in sequencing-batch mode was demonstrated in this study to be effective for the removal of not only COD but also nitrogen and phosphorus, without the addition of external carbon. Both reactors were packed with a fibrous medium with a high surface area and porosity. Using a personal computer with a programmable logic controller, the feed-and-draw sequence and aeration patterns were operated automatically. It was able to remove, on average, 89•9% of COD, 97•1% of NH3-N, 97•3% of total-N and 75•2% of total-P from domestic wastewater at 24°C. The sludge yield was estimated as 0•22 g-VSS/g-COD removed.