A case study: bulk organic matters and nitrogen removal from reclaimed water by enhanced direct injection-well groundwater recharge system.

A new kind of artificial groundwater recharge approach named enhanced direct injection-well recharge (EnDir), consisting of short-term artifical vadose treatment and long-term aquifer treatment, is put forward and demonstrated in Beijing. The results reveal that granular activated carbon (GAC) could remove bulk organic matters with the DOC value decrease from 6.0 mg/L to 4.6 mg/L. The short-term vadose treatment of EnDir exhibited additional organic carbon removal and effective nitrification. DOC and AOX values were reduced to 4.1 mg/L and 56.8 microg/L respectively. Ammonia-N of 3.81 mg/L was converted into equivalent nitrate-N. The long-term aquifer treatment offers favorable denitrification and lower nitrate-N content in the aquifer. The bulk parameters of DOC, SUVA, AOX and ammonia-N detected in the monitoring wells are as the same level as that of local groundwater. Brief financial analysis demonstrated the promising economic aspects of EnDir system in Beijing.