To treat high ammonia nitrogen wastewater efficiently and low costly

achieving and stabilizing autotrophic nitrogen removal in biology aerated filter (BAF) were studied. The obtained results showed that autotrophic nitrogen removal was achieved through the combination of batch and continuous operation in the BAF with volcanics as filter

using the second pond reflux sludge as seeding sludge. During batch operation

the activity of seeding sludge was recovered. During the continuous operation

high free ammonia (FA) concentration inhibited the growth of nitrite oxidation bacteria (NOB). Through recycling the effluent of anaerobic ammonia oxidation (Anammox) biofilter

very slight of Anammox bacteria was inoculated in BAF. After 80 days operation

autotrophic nitrogen removal was achieved. From the 140th day

the removal rate of total nitrogen (TN) approach to 76.62%

and it can be stable all the time. Since aerobic and anoxic environment occurred in different depth of biofilm

ammonia oxidation bacteria (AOB) and Anammox bacteria can coexist in biofilm. Meanwhile

the filtration of volcanics can prevent Anammox bacteria from flowing out of BAF

making the enrichment of Anammox in the system of autotrophic nitrogen removal. In the meantime

AOB and Anammox as autotrophic bacteria grows slow

preventing the biofilter backwash frequently and simplifying the operation of biofilter. Air and water ratio is one of the key operation parameters in BAF of partial nitrification and Anammox. It was shown that the optimal air and water ratio in this study was 12:1. Accordingly

the removal loading radio of ammonia was 0.91 kg N·m-3·d-1. The removal efficiency of ammonia and TN were 96.86% and 85.47%

respectively.